96 J Clin Pathol 1998;51:96–103 Aetiology, pathogenesis, and of cervical neoplasia J Clin Pathol: first published as 10.1136/jcp.51.2.96 on 1 February 1998. Downloaded from

M J Arends, C H Buckley, M Wells

Abstract cervical neoplasia, emphasising the role of Early epidemiological studies of cervical HPVs. neoplasia suggested a causal relation with (J Clin Pathol 1998;51:96–103) sexual activity and human papilloma- viruses (HPVs) have emerged as prime Keywords: human papillomavirus; cervical neoplasia suspects as venerally transmitted carcino- gens. HPVs fall into two broad camps: low risk types, associated with cervical condy- This review is based on three presentations by lomas and CIN 1; and high risk types the authors to the first National Cervical (mostly 16 and 18), found in 50–80% of Screening Conference organised by Marie CIN 2 and CIN 3 lesions, and 90% of Curie Care and held in Oxford, UK in . This association with cancer is September 1996. It also includes several more very strong, with odds ratios of > 15 (often recent developments. It is important to empha- much higher) in case-control studies that sise that the cervical screening programme aims to detect women who have an epithelial are methodologically sound. An infre- abnormality that might, if untreated, lead to quently detected third group of inter- the development of cervical carcinoma. The mediate risk type HPVs is associated with screening programme is not designed to detect all grades of CIN and occasionally with small or early invasive carcinomas, but no cancers. HPVs have also been detected in screening system will detect all women at risk a wide range of asymptomatic controls, and it is inevitable that in a small proportion of indicating that other events are required smears, evidence of invasive cancer will be for development of neoplasia such as viral found. Cervical smears may also identify non- persistence and/or altered expression of neoplastic epithelial changes, such as koilocy- viral genes, often following integration of tosis and multinucleation, which are believed the viral genome. This leaves the two to be associated with by human pap- major viral oncogenes, E6 and E7, directly illomavirus (HPV), which is strongly suspected coupled to viral enhancers and promoters, to play an aetiological role in cervical neopla- allowing their continued expression after sia. Analysis of the eVectiveness of the cervical http://jcp.bmj.com/ integration. High risk HPV E7 proteins screening programme and its further develop- bind and inactivate the Rb protein, ment should be based on a clear understanding whereas E6 proteins bind p53 and direct of the aetiology, pathogenesis, and pathology of its rapid degradation. A range of putative cervical neoplasia. Department of cofactors has been implicated in progres- Pathology, University sion: HLA type, immunosuppression, sex of Edinburgh, Medical steroid hormones, and smoking; most of School, Teviot Place, Aetiology of cervical neoplasia Edinburgh EH8 9AG, these cofactors appear to influence pro- Early epidemiological studies of cervical neo- on October 5, 2021 by guest. Protected copyright. UK gression to CIN 3. The natural history plasia suggested a direct causal relation with M J Arends includes progression to CIN 3 in 10% of sexual activity, measured as multiple sexual CIN 1 and 20% of CIN 2 cases, whereas at partners and early onset of sexual activity.12A Department of least 12% of CIN 3 cases progress to inva- further risk factor was exposure to the “high Reproductive sive carcinoma. Cervical glandular intra- Pathology, University risk man”, characterised by a history of of Manchester, St epithelial neoplasia (CGIN) often co- promiscuous sexual activity and/or sexual Mary’s Hospital exists with squamous CIN, and the exposure to a partner who develops genital Women & Children, premalignant potential of high grade neoplasia. Over the past 20 years the search for Whitworth Park, CGIN is not in doubt, but the natural his- venereally transmitted carcinogens has in- Manchester M13 0JH, tory of low grade CGIN remains uncer- cluded components of semen and various UK tain. A high proportion of CGIN lesions C H Buckley viruses, including Epstein-Barr virus, cytome- and adenocarcinomas are HPV positive, galovirus, and herpes simplex II virus (HSV), Department of and HPV18 has been implicated more in but without success. The lack of persistent Pathology, University glandular than in squamous lesions. A HSV viral DNA, RNA or protein in most neo- of SheYeld Medical strong clinical case for the application of plastic lesions, and the equivocal findings in School, Beech Hill HPV typing of cells recovered from cervi- prospective studies of HSV in cervical cancers Y Road, She eld S10 cal scrapes can be made; however, a rigor- do not support a key aetiological role for HSV 2RX, UK 3 M Wells ous cost-benefit analysis of introducing in cervical cancer. However, HPVs have HPV typing into the cervical screening emerged as prime suspects, being at the scene Correspondence to: programme is required. Prophylactic and of the crime carrying the tools to start the job: Dr Arends. therapeutic HPV vaccines are under de- high risk HPVs are consistently found in over Accepted for publication velopment. This article reviews the aetiol- 90% of cervical cancers and they possess 9 December 1997 ogy, pathogenesis, and pathology of transforming viral oncogenes (E6 and E7). Aetiology, pathogenesis, and pathology of cervical neoplasia 97

Papillomaviruses other events are required for development of Papillomaviruses are members of the Papova- neoplasia, such as viral persistence and/or viridae family with an icosahedral structure altered expression of viral genes. It is clear that J Clin Pathol: first published as 10.1136/jcp.51.2.96 on 1 February 1998. Downloaded from composed of 72 capsomers and containing only a small minority of persistent HPV infec- closed, circular, double stranded DNA of tions progress to cancer. approximately 8 kb in length. They are classi- HPV types have diVerent eVects on the fied by the host species infected and by the CIN–cancer sequence. An approximate meas- degree of DNA sequence homology within ure of the risk of transition from precursor to specific viral genes. New HPV types must share cancer can be calculated using the ratio of HPV less than 90% identity within the L1 gene type prevalence in squamous cancers to that in compared to existing types. Seventy seven dysplastic squamous intraepithelial lesions types of HPV have been cloned and identified (cancer:CIN prevalence ratio). Several studies to date with more in the pipeline.4 have shown that HPV18 is associated with a higher cancer:CIN ratio than HPV16,71316 MORPHOLOGICAL EVIDENCE OF HPV INFECTION IN suggesting that HPV18 confers a more aggres- THE LOWER GENITAL TRACT sive neoplastic phenotype than HPV16. The most common manifestation of HPV infection is condyloma acuminata, and in the EPIDEMIOLOGICAL STRENGTH OF ASSOCIATION OF vast majority of cases this is caused by infection CERVICAL NEOPLASIA WITH HPV by a non-oncogenic form of HPV, most Data from large, methodologically sound, commonly HPV types 6b and 11. Condylo- case-control studies using sensitive and specific mata acuminata are exophytic, papillary lesions polymerase chain reaction (PCR) based assays composed of long or short fronds of connective strongly suggest that HPV tissue covered by an acanthotic squamous epi- most CIN lesions.8 Munoz and Bosch2 have thelium; the lesions may be multiple. In the recently reviewed the available epidemiological cervix and vagina, the epithelium covering the data on the association of HPV and cervical condyloma is usually parakeratotic but may be cancer and found that the data fulfil the Brad- focally orthokeratotic. Characteristic cellular ford Hill criteria of ; this conclusion changes, which are limited to the superficial was endorsed by an international multidiscipli- layers of the epithelium, include individual cell nary group.17 The association between cervical keratinisation, multinucleation, and koilocy- cancer and certain HPV types is: (1) very totic atypia. are characterised by the strong, with odds ratios of > 15 (often much presence of perinuclear cytoplasmic vacuola- higher) in case-control studies that are meth- tion and nuclear enlargement, hyperchromasia, odologically sound; (2) consistent in high risk and irregularity. Similar cytological changes and low risk countries for cervical cancer; (3) can be seen in a flat, non-papillary epithelium, specific for high risk HPV types (HPV16 and in such cases the lesion may be apparent accounts for the most, followed by HPV18); only on colposcopic examination when it may (4) supported by studies that show HPV infec- be aceto-white, Schiller positive, and have an tion precedes development of CIN 2/3; and (5) http://jcp.bmj.com/ abnormal vascular pattern. Such lesions can be biologically plausible with laboratory evidence distinguished from cervical intraepithelial neo- of the oncogenic potential of high risk type plasia (CIN) by the absence of nuclear atypia in HPV genes (E6 and E7 viral oncogenes). the basal layers of the epithelium. Many epidemiological studies have consist- ently shown that over 90% of cervical cancers HUMAN PAPILLOMAVIRUS TYPES AND CERVICAL can be attributed to specific HPV types. The NEOPLASIA small proportion of cancers apparently nega- Early studies quickly demonstrated that HPVs tive for HPV may be either false negatives, on October 5, 2021 by guest. Protected copyright. detected within the cervix fell into two broad reflecting failure to detect new HPV types or camps: low risk types, such as HPV6b and 11 very low levels of known HPV genomes, or true associated with low grade lesions, including HPV negative cancers and thus comprise a cervical condylomas and CIN 1; and high risk separate group. There is some evidence that types, mostly HPV16 and 18 found in 50–80% HPV negative cancers are found more often in of CIN 2 and CIN 3 lesions, and up to 90% of older women and are associated with a poorer invasive cervical cancers.2 5–9 Furthermore, prognosis. Furthermore, early studies sug- semiquantitative detection methods have gested a possible diVerent molecular pathway shown that high levels of HPV16 DNA have a of carcinogenesis with p53 mutation found high predictive value for CIN 2/3.10 Subse- only in HPV negative tumours (see later).18 quently, an infrequently detected third group of intermediate risk types, such as HPV31, 33, HPV GENOME INTEGRATION AND VIRAL and 35, was found to be associated with all ONCOGENE EXPRESSION grades of CIN and occasionally with cancers. Important diVerences in the physical status of More detailed investigations have detected HPV DNA have been demonstrated in cervical about 30 HPV types in cervical samples, most . Low risk HPV types 6b and 11 are of which occur either very infrequently or maintained as extrachromosomal, circular rarely, including low risk types 40, 42, 43, and DNA episomes in low grade cervical lesions, 44 in low grade lesions, and intermediate types whereas the genomes of high risk HPV types 16 45, 51, 52, 56, 58, and 59 in all grades of CIN and 18 are found integrated into the cellular and cancers.11–14 However, HPVs have also DNA in most human cervical carcinomas and been detected in a wide range (3–30%) of carcinoma derived cell lines.19 20 Although the asymptomatic controls,81415 indicating that site of viral DNA integration into the host 98 Arends, Buckley, Wells

genome of carcinomas varies from case to case, HPV negative tumours have not been con- the pattern in each cancer is monoclonal firmed by recent studies.38 Temporary func- suggesting that this occurs before expansion of tional abrogation of p53 and Rb by HPV E6 J Clin Pathol: first published as 10.1136/jcp.51.2.96 on 1 February 1998. Downloaded from the malignant clone of cells. There is a consist- and E7 proteins is important for viral DNA ent pattern of disruption of the circular viral replication in senescent or terminally diVeren- DNA upon integration. The recombination tiated (non-cycling) squamous epithelial cells. event frequently occurs within the viral genes Following viral DNA integration during carci- E1 or E2, sometimes causing focal nogenic progression, E6 and E7 are persist- deletions.19 21 This leaves E6 and E7 directly ently expressed causing profound loss of func- coupled to the viral enhancer and promoter tion of p53 and Rb proteins. sequences in the HPV upstream regulatory These HPV mediated eVects on p53 and Rb region, allowing their continued expression tend to drive cellular movement around the cell after integration. Furthermore, disruption of cycle as both p53 and Rb are negative growth

E1 or E2 during integration inactivates or regulators that control transit from G0/G1 to S decouples other early and late viral genes from phase. p53 also acts as a “guardian of the the viral promoter and enhancer sequences. In genome” and is involved in responding to DNA particular, this includes E2, which encodes a damage by inducing either growth arrest or cell transcription factor that is the main viral tran- death by apoptosis. Thus, HPV mediated loss scription regulator. Full length E2 protein of p53 function decreases the cancer cell’s sus- binds to the E2 recognition sites within the ceptibility to apoptosis, and promotes cellular HPV regulatory region adjacent to the viral survival after DNA damage or development of promoter, and represses viral gene expression.21 genomic instability, allowing accumulation of Loss of E2 function following integration leads genetic changes that may drive further progres- to de-repression of the viral promoter, with sion to .18 39 40 HPVs have a third enhanced expression of E6 and E7 oncopro- oncogene, E5, which appears to alter signalling teins. Thus, HPV DNA integration appears to from growth factor receptors for epidermal be a critical event in the progression of cervical growth factor and platelet derived growth fac- neoplasia, as HPV oncogenes E6 and E7 are tor. As E5 is often lost or not expressed after conserved intact and show evidence of persist- viral integration its role in the later stages of ent and increased expression in carcinomas.21–23 cervical carcinogenesis is uncertain, although it Integration of HPV16 and 18 DNA also occurs may contribute to development of low grade following experimental introduction into CIN lesions.41 human keratinocytes, and this results in the development of a cluster of growth modulation CLINICAL APPLICATION OF HPV RESEARCH changes including a reduced growth factor There is as yet no clinical situation in which requirement (growth in low serum), develop- knowledge of the presence of HPV infection or ment of aneuploidy, and immortalisation (res- indeed the HPV type, determines clinical man- cue from senescence).24 25 These immortalised agement. There is now abundant evidence that keratinocytes may be the equivalent of CIN 2 women harbouring HPV16 in their cervices are http://jcp.bmj.com/ or CIN 3 in vivo, as raft cultures formed by at greater risk of neoplastic progression, and in them show morphological features similar to the presence of negative or mildly abnormal high grade intraepithelial neoplasia.26 All of cytology, are more likely also to have a severe these changes have been shown to be depend- histological lesion, such as CIN 3.10 42 43 A ent on expression of high risk HPV oncogenes strong clinical case for the application of HPV E6 and E7.26 27 Introduction of HPV E6 and E7 typing of cells recovered from cervical scrapes genes linked to various promoters into trans- can be made.44 There are two possible genic mice, has produced a variety of tumours, approaches: first, HPV typing could augment on October 5, 2021 by guest. Protected copyright. the site of which depends on the promoter or indeed supplant the initial cervical cytologi- used, confirming the transforming properties cal screen; second, HPV typing could be used of these viral oncogenes.27 for cases with borderline or mildly dyskaryotic E6 and E7 have proved transforming activi- cervical smears to identify a subgroup at high ties in vitro, as E6 and E7 can cooperate with risk of progression.45 However, a rigorous cost- activated ras to transform primary rodent cells benefit analysis of introducing routine HPV and human keratinocytes to malignancy.28–30 typing into the cervical screening programme Their main mechanism of action is reduction has yet to be carried out in the UK; some trials of intracellular availability of the host’s cell are in progress in the Netherlands. Prophylac- cycle inhibitor (oncosuppressor) proteins p53 tic and therapeutic HPV vaccines are under and retinoblastoma (Rb) by the E6 and E7 development, with some therapeutic vaccines oncoproteins from high risk HPV types 16 and targeted to induce an immune response against 18, but not from low risk HPV types 6b or 11. tumour cells that express HPV E7 protein.46 E7 proteins bind and inactivate the Rb protein.31–33 E6 proteins bind p53 and direct its Pathogenesis and pathology of cervical rapid degradation.34 35 An alternative mode of neoplasia inactivation of p53 is by mutation, and this has COFACTORS AND CERVICAL NEOPLASIA been shown to be a rare phenomenon in high Epidemiological studies have thrown up a grade CIN and in HPV positive invasive cervi- range of putative cofactors involved in progres- cal carcinomas,36 37 in keeping with loss of p53 sion: HLA type, immunosuppression, sex ster- function by HPV E6 directed rapid degrada- oid hormones (based on associations of tion of p53 protein. However, the early sugges- cervical cancers with high parity and long term tions that p53 mutations are observed only in use of the oral contraceptive pill), and Aetiology, pathogenesis, and pathology of cervical neoplasia 99

smoking.47–49 Furthermore, most of these cofac- It is from the epithelium that covers the tors appear to influence progression to CIN 3 ectopy that most CINs and invasive carcino- (from latent HPV infection or low grade CIN), mas develop. Under physiological conditions, J Clin Pathol: first published as 10.1136/jcp.51.2.96 on 1 February 1998. Downloaded from rather than CIN 3 to cancer.2 The eVects of the columnar epithelium of the ectopy under- smoking have been well studied and there is a goes to a stratified squamous consistent epidemiological association (odds epithelium, and it is during this metaplastic ratio of about 2) between cigarette smoking process that the epithelium seems to be and cervical cancer. The carcinogenic constitu- particularly vulnerable to oncogenic viruses, ents of tobacco smoke are strong candidates for and perhaps to other factors resulting in the co-carcinogenic factors with HPVs in cervical development of an intraepithelial carcinogenesis. Cigarette smokers with mildly rather than a normal epithelium. The intraepi- abnormal cytology are more likely to have thelial neoplasm may be of squamous or larger and more severe histological lesions.50 columnar cell type. The constituents of tobacco smoke (such as CIN is recognised by disturbances of cellular nitrosamines) can be demonstrated in cervical maturation and stratification, and by the pres- mucus, and increased smoking related DNA ence of cytological atypia. It is customarily adducts have been shown in normal epithelium graded according to the degree of cytoplasmic next to cervical intraepithelial and invasive maturation56 but, by definition, nuclear atypia neoplasia, indicating a direct eVect on cervical must be present at all levels of the epithelium. epithelium at the DNA level.51 52 DiVerential It aVects the surface epithelium and extends cervical expression of cytochrome P450 en- down into the underlying crypts. In younger zymes, which activate carcinogenic nitro- women, CIN lies on the ectocervix where the samines, and glutathione S transferase, which ectopy has formed, but in older women the tis- denatures them, may play a role in determining sues that form an ectopy are withdrawn into individual susceptibility to tobacco related the endocervical canal, therefore, CIN in older carcinogens.53 women tends to lie within the endocervical canal where it may be more diYcult to sample. ALTERATIONS IN CELLULAR ADHESION CIN initially forms a single area and thus, if the MOLECULES resection margins of tissue removed for its Integrins are transmembrane glycoproteins treatment are free from , it is likely that important in interactions between epithelial the whole of the lesion has been removed.56–59 cells and basement membranes. Integrin ex- pression is confined to the basal layer of normal Histopathological diagnosis of cervical squamous epithelium. However, the patterns of intraepithelial neoplasia integrin expression in neoplastic cervical epi- In Europe, CIN is usually divided into three thelium diVer from this, with dysplastic cells grades, although other schemes are used.56 The expressing integrins throughout the full thick- lesions range from a well diVerentiated in- ness of the epithelium in CIN 3.54 traepithelial neoplasm (CIN 1) to a poorly dif- Epithelial cadherin (E cadherin) is a cell–cell ferentiated intraepithelial neoplasm (CIN 3). http://jcp.bmj.com/ adhesion molecule that connects epithelial cells CIN 2 occupies an intermediate position. The via homotypic, calcium dependent interac- diVerentiation of CIN is rarely uniform tions. In normal cervix, E cadherin is expressed throughout the aVected area, the most poorly on the cell membrane of basal and parabasal diVerentiated component tending to lie adja- cells. Cytoplasmic reactivity is present in occa- cent to the columnar epithelium of the sional basal cells only. In CIN, there is endocervical canal. For a diagnosis of CIN, increased cytoplasmic reactivity, which is nuclear abnormalities such as enlargement, strongly correlated with the grade of the CIN pleomorphism, and hyperchromasia must be on October 5, 2021 by guest. Protected copyright. lesion. In squamous carcinomas, reduced present at all levels in the epithelium, including membranous and increased cytoplasmic reac- the basal layer. Hyperchromasia is not a tivity is seen with worsening diVerentiation.55 prerequisite, and in some forms of CIN the nuclei do not stain darkly. The degree of CERVICAL INTRAEPITHELIAL NEOPLASIA nuclear atypia tends to be greater in CIN 3 The normal cervix is covered on its outer sur- than in CIN 1. Normal mitoses vary in number face by a non-keratinising, stratified squamous and do not aVect the diagnosis, while atypical epithelium, which is continuous below with the mitoses may be present in all grades of CIN. In squamous epithelium lining the vagina, and CIN 1, cytoplasmic maturation occurs in the above abuts onto the mucus secreting colum- superficial two thirds of the epithelium. In CIN nar epithelium lining the endocervical canal 2 it starts in the middle third of the epithelium, and its associated crypts. The junction between and in CIN 3, cytoplasmic maturation, which is the two epithelia normally coincides with the minimal or even absent, occurs only in the external os but this is not a constant relation. most superficial third of the epithelium. At puberty, in pregnancy (particularly the first Changes usually attributed to the presence of one), and in some steroid contraceptive users, HPV infection, such as koilocytosis and changes in the size and shape of the cervix epithelial multinucleation, are often present result in the squamocolumnar junction being and are most conspicuous in CIN 1 and 2, and carried out on to the anatomical ectocervix. minimal or absent in CIN 3. This may be a This exposes the tissues previously found in the reflection of viral integration in the high grade lower endocervical canal to the vagina. This is lesions. a physiological process and the exposed tissue Most histopathologists in the UK have not forms the “cervical ectopy”. accepted the two tier Bethesda system for 100 Arends, Buckley, Wells

cervical intraepithelial abnormalities,60 but clude frequent mitosis and apoptosis, pericryp- have chosen to retain the present grading tal concentric fibroplasia, pericryptal inflam- system,61 together with a recently introduced matory infiltrates, pronounced cellular J Clin Pathol: first published as 10.1136/jcp.51.2.96 on 1 February 1998. Downloaded from category of epithelial abnormality to encom- pleomorphism, certain nuclear changes (dis- pass lesions in which a diagnosis of CIN cannot tinct nucleoli and chromatin clearing), and the be made with certainty: basal abnormality of emergence of streams of darkly staining spindle uncertain significance.56 This category may be cells orientated at right angles to the basement particularly useful in combating the problem of membrane. In a prospective study, 83% of overdiagnosis of CIN 1, still thought to occur cases illustrating the major microinvasive to a considerable extent, because pathologists carcinoma associated features revealed evi- fail to appreciate that, even in a CIN 1 lesion, dence of microinvasive carcinoma or frank the nuclei are abnormal throughout the full invasion either on serial sections of the original thickness of the epithelium and not just in the biopsy or on subsequent biopsy. None of the 64 lower third above which there is cytoplasmic cases of CIN 3 that lacked these features maturation. However, it is possible to distin- showed evidence of invasion on serial sections guish between CIN 1 and HPV infection alone or on follow up over 18 months. When these by virtue of the presence of koilocytosis features are present in a biopsy specimen, serial without nuclear atypia. sections should be performed to exclude the presence of microinvasion, and closer clinical Natural history of cervical intraepithelial follow up of these patients is appropriate. neoplasia 62 Review of the world literature on the natural INVASIVE CARCINOMA OF THE CERVIX history of CIN indicates that the approximate Most invasive carcinomas of the cervix develop likelihood of regression of CIN 1 is 60%, per- from an intraepithelial neoplasm that has sistence 30%, progression to CIN 3 10%, and formed in the tissues of the cervical ectopy.56 57 progression to invasion 1%. The correspond- They tend to lie, therefore, on the ectocervix in ing approximations for CIN 2 are 40%, 40%, younger women and in the endocervical canal 20%, and 5%, respectively. The likelihood of in older woman (see above). The tumours may CIN 3 regressing is 33% and progressing to have an exophytic or endophytic pattern of invasion greater that 12%. Thus, even the growth, those on the ectocervix being more higher degrees of atypia may regress in a commonly exophytic and those in the endocer- significant proportion of cases, and although vical canal more commonly endophytic. This the probability of an atypical epithelium has clinical importance in that exophytic becoming invasive increases with the severity of tumours on the ectocervix are less likely to have the atypia, this does not occur in every case. extended into the adjacent tissues and organs As 50–60% of the lesions diagnosed as CIN than endophytic tumours of similar size, and 1 will regress spontaneously, if clinicians inter- are less likely to have metastasised.58 59 vene at such an early phase of the process it Cervical carcinomas spread locally into the may result in the unnecessary treatment of cervical stroma, the paracervical and parame- http://jcp.bmj.com/ women who are at little or no risk of developing trial tissues, the body of the uterus, the vagina, carcinoma. A balance has to be struck, and, late in the course of the disease, to the however, between unnecessary treatment and a bladder and rectum.56–59 Lymphatic permeation failure to eradicate a lesion that has the poten- in the cervical stroma may occur even when the tial to progress to invasive carcinoma. In tumour is of low volume, therefore, metastases general, persistence of CIN 1 is regarded as an may be found in the pelvic lymph nodes even indication for eradication. It is also recognised when the tumour is small. It is not possible, that higher grade lesions of CIN 2 and 3 are therefore, to equate “small” with “early” carci- on October 5, 2021 by guest. Protected copyright. more likely to progress to invasive carcinoma noma. and are usually treated without undue delay. MICROINVASIVE SQUAMOUS CARCINOMA OF THE Invasive potential of CIN 3 CERVIX No one doubts the malignant potential of high It is customary to stage invasive carcinomas of grade CIN since the debacle at the National the cervix according to the criteria laid down Women’s Hospital in Auckland, New Zealand by FIGO.59 65 66 The FIGO guidelines do not in the 1970s, in which many women with per- use the term microinvasive carcinoma, but sistent abnormal cytology following biopsy of stage 1A, which encompasses lesions that can “carcinoma in situ” (as it was called at that be diagnosed only on microscopy, and are usu- time) were treated conservatively. Twenty nine ally regarded as being synonymous with micro- of 131 women (22%) developed invasive cervi- invasive carcinoma. When invasive disease is cal cancer (compared to 1.5% of a control identified unexpectedly in women who have group), and eight died.63 been regularly screened, the carcinomas often The main histological features identified in come into this category. Such a finding should CIN 3 associated with microinvasive carci- not be regarded as a failure of the screening noma or predictive of subsequent microin- process because such neoplasms carry only a vasion are extensive involvement of surface low risk of metastatic disease and can, epithelium and deep endocervical crypts by therefore, usually be treated relatively con- expansile CIN 3, luminal , and in- servatively. traepithelial squamous maturation.64 Other FIGO has recently modified its classification features more commonly present in CIN 3 of microinvasive carcinoma by subdividing associated with microinvasive carcinoma in- stage 1A. Stage 1 (carcinoma strictly confined Aetiology, pathogenesis, and pathology of cervical neoplasia 101

to the cervix) is divided into stage 1A (invasive stroma at the point of invasion, and the cancer only identified histologically) and stage presence of a variable stromal round cell infil- 1B (gross lesions even those with only superfi- trate. In the epithelium, at the point of J Clin Pathol: first published as 10.1136/jcp.51.2.96 on 1 February 1998. Downloaded from cial invasion). Stage 1A is further divided into invasion, there is often a subtle change in the stage 1A1 (invasion of stroma up to 3 mm in pattern of tumour cell diVerentiation with depth and no wider than 7 mm) and stage 1A2 increased eosinophilia of the cytoplasm and a (invasion of stroma of 3–5 mm in depth and no change in the degree of nuclear atypia. It is wider than 7 mm). There have only been three important for clinical management that the cases of nodal metastases in 1543 patients in depth of invasion is measured accurately for the literature whose microinvasive carcinomas microinvasive carcinomas, taken from the base invaded the stroma to 1 mm or less (termed of the epithelium (either surface or glandular) early stromal invasion). Therefore it appears from which it originates. that early stromal invasion behaves in the same manner as high grade CIN and may be treated WHAT IS AN EARLY CARCINOMA OF THE CERVIX? by conisation alone provided the cone has been There is some agreement that stage 1A carcino- adequately sectioned, the margins are free from mas can be described as “early” although this tumour, and the curettings do not contain may be a simplistic view of lesions that may be abnormal epithelium. For microinvasive carci- of limited invasive capacity rather than early. nomas invading between 1 and 3 mm, nodal Tumours that are too large to be encompassed involvement was found in only five of 809 by the definition of stage 1A but are still (0.6%) patients who had pelvic lymph node confined to the cervix are included in stage 1B. dissection, and the vast majority of these cases For tumours of stage 1B and higher, radical can also be safely treated by conisation alone. treatment is required and it would, in our opin- For tumours penetrating 3–5 mm (FIGO stage ion, be inappropriate to include such lesions in 1A2), there appears to be a higher risk of a description of early cervical tumours, al- recurrence and nodal metastasis; nodal in- though it could be argued that the term early volvement has been reported in 14 of 214 carcinoma could include all invasive lesions for patients (6.5%).67 which surgery is the first line of treatment. The introduction of the revised staging It has been customary to regard stages 1A, system has recently been criticised.68 The term 1B, and 2A carcinomas as early lesions; early stromal invasion (up to 1 mm invasion) is however, as metastatic disease may already be missing in the new version of the staging present in women with stages 1A2, 1B, and 2A system and has been replaced by “microinva- disease it is clearly inappropriate to call these sion changes” with a depth of invasion up to tumours early. Moreover, the pathologist is 3 mm. This group will inevitably include a rarely in a position to identify, with any large number of cases of early stromal invasion certainty, the woman at risk of having meta- (< 1 mm). Burghardt et al reviewed cases in the static carcinoma from the appearance of the literature with invasion of 1–3 mm (cases with initial cervical biopsy in which the invasion is early stromal invasion (< 1 mm) were ex- recognised. It is more important to consider http://jcp.bmj.com/ cluded) and found that 1.4% of patients died of not just the size of the lesion at the time of disease.68 That is six times more than the death diagnosis, which is the result of a balance rate of patients with early stromal invasion between tumour cell gain and loss,69 but also to (< 1 mm) and not significantly diVerent from consider the biological aggressiveness of the the proportion of patients (1.7%) dying of can- invasive lesion and, to this end, studies of cer whose neoplasms extend to a depth of oncogene activation and overexpression, and between 3 and 5 mm at diagnosis. These disturbances of tumour suppressor genes have authors feel, therefore, that it is inappropriate been done.70 It is apparent from these studies on October 5, 2021 by guest. Protected copyright. to dilute the stage 1A1 group with a large that small volume tumours may behave in quite number of cases in an extremely low risk diVerent ways and many are, in apparent con- category (those showing early stromal invasion tradiction to their small size, actually advanced of < 1 mm), which makes treatment results carcinomas. A more detailed description of the highly favourable. They consider that only pathology of advanced, established carcinoma early stromal invasion (< 1 mm) merits recog- of the cervix can be found elsewhere.57–59 71 nition as a separate category. There is no convincing evidence in the CERVICAL GLANDULAR INTRAEPITHELIAL literature that capillary-like space involvement NEOPLASIA is associated with lymph node metastases or an The term cervical glandular intraepithelial increased incidence of recurrence. Therefore, neoplasia (CGIN) is now used to encompass permeation of endothelial lined spaces is adenocarcinoma in situ and glandular atypia in ignored for the purposes of staging. the endocervix. CGIN is much less common The term microinvasive carcinoma can be than CIN but, as with CIN, most CGIN applied to squamous carcinomas, adenosqua- lesions occur in the region of the cervical mous carcinomas, and adenocarcinomas (see ectopy. In contrast to CIN, in about 10% of below). It cannot, however, be used for small CGIN cases, separate foci may be found higher cell (neuroendocrine) tumours to which the in the endocervical canal.72 Both the surface term microinvasive carcinoma should not be epithelium and the underlying crypts may be applied even when the tumour is small enough aVected by the process, and the junction to be stage 1A. Stromal invasion from both a between the atypical columnar epithelium and squamous and columnar cell intraepithelial the normal columnar epithelium is invariably neoplasm is recognised by loosening of the abrupt. In typical CGIN lesions there are 102 Arends, Buckley, Wells

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