in vivo 19: 787-792 (2005)

Administration of Estramustine in Response to Changes in the Prostate-specific Antigen and Karnofsky Index in the Treatment of Prostate Cancer

OLIVÉR PINTÉR1, JOSEPH MOLNÁR2, CSABA TÓTH3, ZOLTÁN SZABÓ4, JOSEPH LIPTÁK5, PÁL FÉL6, GYÖRGY PAPP7, ENDRE HOLLMAN8, LAJOS HAZAY9, BÉLA STREIT10, LÁSZLÓ KISBENEDEK11, MIKLÓS FEHÉR12, ISTVÁN KOCSIS13 and LÁSZLÓ PAJOR1

1Department of Urology and 2Department of Microbiology, Medical Faculty, University of Szeged; 3Department of Urology, Medical Faculty, University of Debrecen; Departments of Urology 4Kecskemét, 5Nagykanizsa, 6Dombóvár, 7Budapest, 8Kiskunhalas, 9Dunaújváros, 10Szekszárd, 11Budapest, 12Miskolc and 13Eger, Hungary

Abstract. Androgen ablation is palliative and does not cure cancer was formerly diagnosed at around the age of 70. advanced prostate cancer. The hormone-sensitive cells die and However, following the introduction of the early diagnostic the hormone-resistant cells overgrow, resulting in disease protocol based on prostate-specific antigen (PSA), the progression. The drug of choice for secondary treatment is average age at the time of diagnosis has decreased to estramustine (Estracyt). The success of the therapy is followed around 60 years. The time that elapses prior to recognition by changes of the prostate-specific antigen level and Karnofsky is influenced by a number of factors, such as the sensitivity scale. In the present study, the results of estramustine treatment of the screening test, the rate of development of the tumour of 79 patients with advanced prostate cancer in 12 hospitals and the age of the patient. were evaluated. The mean prostate-specific antigen level It has been known since the 1940s that a proportion of improved for 6 months, but rose from the ninth month on. The prostate cancer tumour cells are sensitive to androgen improvement in the subjective condition of the patients withdrawal (3), which is the basis of the therapy. Some 60 paralleled the change in the prostate-specific antigen level. The years later, this procedure remains palliative: hormone- short time of improvement was a consequence of the very high resistant cells can be detected even at the beginning of prostate-specific antigen level and the poor general condition. treatment and, independently of androgen withdrawal, these Estramustine administration is recommended when the persist or even multiply. In consequence, they may come prostate-specific antigen level becomes more than doubled into a relative excess after the primary treatment of total following primary treatment. At a starting prostate-specific androgen blockade (TAB). The literature data indicate that antigen level of >100 ng/ml, the treatment leads to total previously androgen-sensitive cells adapt to androgen androgen blockade. If the prostate-specific antigen level has ablation treatment (4-6). Accordingly, hormone-refractory not decreased after treatment for 3 months, the secondary prostate carcinoma develops, the process displaying the strategy is to apply chemotherapy. signs of progression despite the primary and secondary hormone treatment. The disease is incurable and, although Prostate cancer is one of the most frequent diseases of considerable progress has been made in diagnosis and males over the age of 50. In Hungary, it is in the third place treatment, the local process and/or metastases during of cancer mortality (1), while in the western world it is progression usually lead to the death of the patient. It falls currently the second leading cause of death (2). Prostate to the urologist to seek possibilities for the treatment of the resulting complications (7). It is not clearly understood why the lymph node metastases totally regress in response to treatment (or recur Correspondence to: Dr Olivér Pintér, Department of Urology, Medical only rarely), whereas the bone metastases generally only Faculty, University of Szeged, Szeged Kálvária sgt. 57. H-6722 partially disappear and the tumour cells may reappear at the Hungary. Tel: (+) 36-62-490-590, e-mail: [email protected] same site (8). This indicates that cells at different szeged.hu localizations react to chemotherapy in different ways. This Key Words: Advanced prostate cancer, Estracyt/estramustine, may be explained by the fact that a two-directional paracine prostate-specific antigen. indicating system operates between the epithelial cells and

0258-851X/2005 $2.00+.40 787 in vivo 19: 787-792 (2005) the stroma cells of the bone. In the course of invasion of the etc.), how (i.v. or orally) and at what dose (the prescribed tumour, the transition between the local and metastatic dose is 4-6 capsules daily, though a higher dose than this states means a change in the stromal microenvironment for was applied in many published studies) the patient receives the tumour cells and, thus, the paracrine hormonal the drug. ii). It is important whether the estramustine is environment may be an important determinant of the initially given in monotherapy, or in combination with other development of the tumour (9). cytostatics. The chemotherapy of prostate cancer has lagged far Accordingly, we studied the following features: i). The behind (by close to 20 years) the similar treatment of other effectiveness of treatment as concerns the changes in the solid tumours. The publications that appeared in the 1980s PSA level and the Karnofsky index. ii). The side-effects of clearly stated that chemotherapy is not effective for the the treatment and the need for pain-killers. iii). Is treatment of prostate cancer, although they were published estramustine of value in the primary treatment? prior to the development of PSA examinations. In the majority of studies, individual drugs were investigated and Materials and Methods the results were evaluated on the basis of the changes measured in the tumour. Such changes could be observed in A total of 79 patients with advanced, hormone-refractory, only 10-30% of the patients; hence, the disappointing metastatic prostate cancer were enrolled in the study from 12 findings probably related only to a subgroup with a poor Hungarian urological centres in 2000 and 2001. Their average age prognosis rather than to a lack of effectiveness of the was 72 years (range: 61-79 years). treatment (10). The introduction of PSA examinations Inclusion criteria. The inclusion criteria were: a deterioration in the facilitated the early recognition of these tumours and their condition of a patient with histologically confirmed prostate cancer curative treatment. Following definitive treatment, tumour who had earlier been treated hormonally or castrated surgically, or recurrence is seen in one-third of the cases. Unfortunately, who had participated in radiotherapy; a PSA level >5 ng/ml; even today, around 70% of the cases of prostate tumours in normal or only mildly elevated liver function data; a cardially Hungary are in an advanced stage when they are compensated condition; no known gastrointestinal disease; no recognized. Curative treatment is hopeless. The accepted hypersensitivity to the medication; no other confirmed primary modes of treatment lead to temporary success in 80% of the tumour; no previous chemotherapy. cases; then, after the development of a hormone-resistant state, attention must be turned to a new mode of treatment, Exclusion criteria. The exclusion criteria were: a simultaneous different tumour; failure of the patient to agree to participate; a chemotherapy. The 14th International Congress on Anti- severe accompanying disease; hypersensitivity to the medication; Cancer Treatment, held in Paris on 1-4 February, 2003, anaemia, unless it could be controlled; progression; the occurrence declared that the treatment of prostate cancer is not of side-effects; failure of the patient to collaborate. hopeless. The results reveal that a therapeutic effect can be The condition was assessed via a detailed anamnesis, physical discerned if the data on a sufficiently large group of patients examination, a chest X-ray, abdominal and small pelvic CT, are evaluated (10). McLaren et al. (11) found that only the ultrasound examination, bone isotope examination, a full blood PSA level and the time required for this to double picture, PSA level determination and, in some cases, free PSA determination. The laboratory examinations were carried out by (determined during the follow-up) correlated significantly different methods in the various centres; accordingly, to facilitate a with the clinical progression and other end-points. A uniform evaluation of the laboratory results, each centre also number of publications have reported that the PSA level reported their normal ranges. The patients were asked to attend indicates the progression and the outcome after the control examinations at 3-month intervals. They received medical potentially curative treatment of prostate cancer (12, 13). care if any intermediate event occurred. As for the collection of However, attention should also be paid to the finding, by scientific data, the study was performed with the approval of the Stephenson et al. (14), that the clinical condition may ethical committee at each of the centres. The medication applied was Estracyt injection (300 mg) and Estracyt capsules (140 mg), deteriorate even without a PSA level increase. both supplied by Pharmacia Upjohn AB, Stockholm, Sweden. The The choice of 12 centres was made in the hope that drug is currently marketed by Pfizer. The injection was retrospective studies could be performed on a considerable administered intravenously at a daily dose of 300 mg for 10 days; number of patients. In these advanced cases, this was followed by the administration of 4-6 x 140 mg capsules Estracyt/estramustine (which attacks at two points) is the daily for a minimum of 3 months. Treatment was suspended if drug of choice internationally (15). Besides an oestrogen progression was observed, if digestive or cardiovascular effect, it also acts as an antimycotic. In advanced, hormone- complications developed, or if the liver function data deteriorated. The effectiveness of treatment was assessed via the changes in refractory prostate tumour cases, the extent of the objective the PSA level and the Karnofsky index. A close watch was kept for response to treatment may be expected to be between 19% side-effects of the drug, and the change in condition of the patients and 69%. There are several reasons for this relatively wide was determined via the WHO pain scale. Our aim was to establish range: i). The result is influenced by when (at the PSA level, whether this drug can be used as primary treatment in certain cases.

788 Pintér et al: Indication of Estramustine Treatment via PSA and Karnofsky Index

Table I. Number of patients, number of intervening deaths and mean PSA level at 3-month examinations.

Examination time No. of patients Mean PSA SE Min Max No. of deaths level ng/ml l. Start 79 131.6 56.1 1.3 4000 0 2. After 3 months 68 47.5 12.9 0 475 4 3. After 6 months 56 38.8 13.2 0 500 4 4. After 9 months 40 48.3 11.9 0 283 4 5. After 12 months 28 56.9 22.4 0.06 398.5 7 6. After 15 months 17 31.9 12.6 0.04 147 Not known

Results high, disappeared on reduction of the dose, and the treatment could be continued. In the cases in which the The patients, chosen in accordance with the above criteria, condition improved considerably, the white blood cell count exhibited a very high initial mean PSA level. The mortality rose. The explanation of this is not known, and further statistics at the end of the first 3 months clearly reflected investigations are required to clarify it. the fact that the patients had been enrolled into the study At the beginning of the study, 63 out of 79 patients had in a very advanced condition. multiple bone metastases. Of the numerous associated During the first 3 months, 11 patients were lost to follow- diseases, it is necessary to mention general atherosclerosis, up because of death or other reasons; the data on these hypertension, ischaemic heart disease, pulmonary patients were not included in the data revealing a decrease in emphysema and diabetes mellitus, among many others. the mean PSA level. This decrease amounted to nearly one- According to the WHO recommendation, pain due to third of the starting mean PSA level, pointing to the efficacy tumours must be moderated in a stepwise manner. For this, of the treatment. It should be borne in mind, however, that 4 different groups of drugs should be applied: A. Non- the patients who died had the highest PSA levels. opioids (non-steroidal anti-inflammatory drugs); B. Weak Six months after the beginning of treatment, 56 patients opioids (codeine); C. Strong opioids (narcotic pain-killers); remained in the study. By this time, the mean PSA level had D. Adjuvant medication. Groups A, B and C each comprise decreased further. Again, the data on those patients who one step in the pain-killing process, while the drugs in group were lost to follow-up were omitted. D may be administered when needed in any of the steps. At 9 months, the data on 40 patients were evaluated. At The stepwise pain-killing model is illustrated in Figure 1. this time-point, the mean PSA level had risen; 12 patients Because of their bone metastases, our patients received had died, and the data on 27 others were unknown. The bisphosphonate preparations to promote bone regeneration. elevation in the PSA level pointed to a deterioration in the condition. Discussion After the elapse of 12 months, an improvement was no longer to be expected and the mean PSA had further The treatment of hormone-resistant prostate cancer continues worsened. Seven patients had died within the previous 3 to be a topic of debate; there is still no standard therapeutic months, bringing the total to 19 in 1 year. The data on 28 protocol (16). Estramustine was initially recommended for the patients were evaluated. treatment of breast cancer, but it later acquired an important By 15 months, only 17 patients remained in the study. role in the treatment of prostate cancer (17). In consequence These patients had responded very well to the treatment. of its oestrogen content, the preparation decreases the serum The fall in the PSA level was indicative of the better testosterone level and (through its mustard nitrogen content, prognosis (Table I). acting as an alkylating agent) it inhibits the multiplication of Subjective improvement in the state of the patients the tumour cells (18). occurred in parallel with the change in the PSA level, The mean PSA data indicated an improvement in the though the Karnofsky index did not improve to the extent condition in our study. For 6 months, the drug caused a expected from the treatment. The improving data observed substantial PSA level decrease, which correlated with the for the 17 patients during the 15-month control could be improvement in the subjective state of the patients. From the explained by the comparatively better prognosis (Table II). ninth month, the mean PSA level rose, and the Karnofsky No side-effect emerged that necessitated cessation of the index pointed to a deterioration in the subjective complaints treatment. Gastrointestinal complaints (nausea, vomiting of the patients. These latter were difficult to assess since the and diarrhoea), that were experienced when the dose was patients received pain-killers and bisphosphonates as

789 in vivo 19: 787-792 (2005)

Table II. Mean Karnofsky index at 3-month examinations. effects of these at the level of the prostate may be blocked by the administration of androgen receptor blockers. TAB is the Examination No. of Mean SE Min Max combination of surgical or chemical castration with androgen time patients receptor blockers, as proposed by Labrie et al. in 1983 (21). 1. Start 78 59.3 5.1 0 100 The duration of the progression-free period of the disease is 2. After 3 months 62 75.2 2.8 0 100 prolonged, but there is no change in the survival. It is a known 3. After 6 months 47 69.4 4.1 0 100 fact that hormone-resistant cells are already present at the 4. After 9 months 36 69.2 4.9 0 100 commencement of treatment and, through selection, they 5. After 12 months 25 55.2 7.4 0 100 6. After 15 months 16 60.0 8.2 0 90 become predominant in the course of the treatment. As a consequence of the deterioration in the condition, the treatment must be modified after 22-24 months. After the primary treatment of advanced prostate cancer, supplementary treatment. A study in the United Kingdom estramustine is the drug of choice, being the only one that can indicated that bisphosphonates shorten the time to be recommended for monotherapy (22). However, the symptomatic progression in the bone system (19); in another estramustine effect is substantially better when it is given in investigation, in which this drug was administered in combination and it is, therefore, often administered together conjunction with chemotherapy, improvements were found in with vinblastine (23). An essentially better result may be the extents of moderate or severe bone pain (20). attained if the treatment strategy is based on monitoring of The very slight improvement in condition observed in the the PSA level. A number of publications have appeared on remaining 17 patients at 15 months could be explained by the changes over time of the PSA level, the results indicating their good response; the mean PSA level too decreased. that the PSA level reflects the progression outcome after Treatment did not have to be interrupted because of severe curative treatment (12, 13). All considerations relating to the side-effects. Any gastrointestinal symptoms that appeared changes over time of the PSA level are based on the could be eliminated by reducing the dose. assumption that the PSA level depends on the tumour mass. The patients had numerous associated diseases, which had Various authors have attempted to find a correlation between to be taken into consideration during the treatment. the PSA level measured in the serum and the volume of the Differentiation of fluid retention caused by cardial prostate tumour (24, 25). Recent data, however, do not decompensation and that due to the oestrogen content of the support the original result (26), though certain facts do drug was difficult in a number of cases. We treated such fluid indicate that the rise with time of the PSA level, and retention by administration of a diuretic, but assessment and particularly its doubling-time, are valuable prognostic factors. elimination of the cause was the task of the care-providing At the same time, it should be borne in mind that a clinical physician. deterioration can also occur without a PSA level elevation, in Drug-induced deterioration of the liver functions led to a cases of prostate cancer regularly treated hormonally, but deterioration of the patients’ condition and necessitated proving refractory to this treatment (27). modification of the therapy. Our investigations suggested that, if a PSA level that is Every patient needed a pain-killer. When the state was normalized or close to normal during the primary treatment relatively acceptable, this was taken only as required. As the increases two-fold, it is recommended to switch over to process progressed, the need for pain-killers became constant, chemotherapy and not to wait for an extreme increase in the and their administration followed the stepwise pain-killer scale. PSA level. The essence of the currently accepted primary treatment of Taxane-based chemotherapy, especially with docetaxel, is advanced prostate cancer is androgen withdrawal. It is effective in the treatment of solid tumours. Ongoing studies considered that 95% of the testosterone circulating in the indicate that, when it is applied in monotherapy or in blood is produced by the testicular Leydig cells. The residual combination with estramustine, good results can also be 5% is adrenal androgen. Orchidectomy, a mode of surgical achieved in advanced prostate cancer (28). Data are not yet castration currently applied, involves a rapid and simple available on survival, but the progression-free period is operation. It has the disadvantages of the associated lengthened. psychological stress and the resulting irreversible impotence. The current treatment strategy in cases of advanced prostate Chemical castration consists of the administration of cancer, even when the PSA level is extremely high, is primarily luteinizing hormone-releasing hormone analogues. These two TAB treatment. Following a 3-month period of TAB treatment, modes are alternative possibilities, but the chemical procedure it is worthwhile to consider modification of the treatment at a can be interrupted; there is also an opportunity for PSA level >100 ng/ml if the PSA level decrease does not attain intermittent treatment, during which potency is restored. It is 50%. The recommended primary care is estramustine known that adrenal androgens continue to be produced. The monotherapy or combined chemotherapeutic treatment.

790 Pintér et al: Indication of Estramustine Treatment via PSA and Karnofsky Index

Figure 1. The stepwise pain killing model.

The results of research at a cellular level may expose the the dynamism of the tumour tissue, the development of a basis of new treatment possibilities. Disturbance of the hormone-resistant state. It is in this situation, and not in the equilibrium between molecules that promote or inhibit event of an extremely high PSA level, that we recommend apoptosis is accompanied by multiplication of the tumour modification of the treatment to chemotherapy. Research cells. The most frequently described abnormalities in cases of must be carried out to establish the optimum treatment forms, advanced prostate cancer are a p53 gene mutation (29) and and targeted treatment modes with new compositions must be an enhanced expression of the BCL2 gene (30). Pro-apoptotic elaborated in the knowledge of the resistance properties and molecules are blocked by activated AKT and, thus, are able the process of cell death. Estramustine treatment is currently to increase the survival of the cells (31, 32). not accepted as primary treatment. If the 3-month control examination after TAB treatment begun at a PSA level Conclusion >100 ng/ml does not reveal a PSA level decrease of >50%, modification of the therapy is recommended, to estramustine, To summarize, it may be stated that, in the treatment of as combined chemotherapy in the event of necessity. advanced prostate cancer previously regarded as therapy- resistant, the results of research at a cellular level, which draw References attention to the dynamic changes in the state of the tumour, must be taken into consideration. The change in the PSA level 1 Ottó Sz: Cancer epidemiology in Hungary and the Béla Johan faithfully reflects the course of the disease and is a laboratory National Program for the Decade of Health. Pathol Oncol Res parameter that is suitable for monitoring of the cellular 9: 126-130, 2003. changes occurring in the background. The results of our own 2 Greenlee RT, Hill-Harmon MB, Murray T and Thun M: Cancer statistics. CA Cancer J Clin 51: 15-36, 2001. investigation, together with the literature data, lead us to point 3 Huggins C and Hodges CV: Studies on prostatic cancer, effect out that the doubling of a PSA level that is normal or nearly of castration, of estrogen and of androgen injection on serum normal after the primary treatment should be regarded as an phosphatases in metastatic carcinoma of the prostate. Cancer alarm signal. It may be indicative of an unfavourable event in Res 1: 293-297, 1941.

791 in vivo 19: 787-792 (2005)

4 Bruchovsky N, Rennie PS, Coldman AJ, Goldenberg SL, To M 20 Ernst DS, Tannock IF, Winquist EW, Venner PM, Reyno L, and Lawson D: Effects of androgen withdrawal on the stem cell Moore MJ, Chi K, Ding K, Elliot C and Parulekar W: composition of the Shionogi carcinoma. Cancer Res 50: 2275- Randomized, double-blind, controlled trial of mitoxantrone/ 2282, 1990. prednisone and clodronate versus mitoxantrone/ prednisone and 5 Craft N, Chhor C, Tran C, Belldegrun A, DeKernion J, Witte placebo in patients with hormone-refractory prostate cancer ON, Said J and Reiter RE: Evidence for clonal outgrowth of and pain. J Clin Oncol 21: 3335-3342, 2003. androgen-independent prostate cancer cells from androgen- 21 Labrie F, Dupont A, Belanger A, Lefebvre FA, Cusan L, dependent tumors through a two-step process. Cancer Res 59: Monfette G, Laberge JG, Emond JP, Raynaud JP and Husson 5030-5036, 1999. JM: New hormonal treatment in cancer of the prostate: 6 Isaacs JT and Coffey DS: Adaptation versus selection as the combined administration of an LHRH agonist and an mechanism responsible for the relapse of prostatic cancer to antiandrogen. J Steroid Biochem 19: 999-1007, 1983. androgen ablation therapy as studied in the Dunning R-3327- 22 Yagoda A and Petrylak D: Cytotoxic chemotherapy for advanced H adenocarcinoma system. Cancer Res 41: 5070-5074, 1981. hormone-resistant prostate cancer. Cancer Supplement 71: 1098- 7 Clarke NW: The management of hormone-relapsed prostate 1109, l993. cancer. BJU Int 92(8): 860-868, 2003. 23 Seidman AD, Scher HI, Petrylak D, Dershaw DD and Curley 8 Goldenberg SL, Bruchovsky N, Rennie, PS and Coppin CM: T: Estramustine and Vinblastine: use of prostate specific The combination of cyproterone acetate and low dose antigen as clinical trial end point for hormone refractory diethylstilbestrol in the treatment of advanced prostatic prostatic cancer. J Urol 147: 931-934, 1992. carcinoma. J Urol 140(6): 1460-1465, 1988. 24 Stamey TA, Kabalin JN, Ferrari M and Yang N: Prostate 9 Keller ET, Zhang J, Cooper CR, Smith PC, McCauley LK, specific antigen in the diagnosis and treatment of Pienta KJ and Taichman RS: Prostate carcinoma skeletal adenocarcinoma of the prostate. IV. Antiandrogen treated metastases: cross-talk between tumor and bone. Cancer Metast patients. J Urol 141: 1088-1090, 1989. Rev 20: 333-349, 2001. 25 Schmid HP, McNeal JE and Stamey TA: Observations on the 10 A second chance for prostate-cancer chemotherapy? The doubling time of prostate cancer. The use of serial prostate- Lancet Oncol 4(3): 131, 2003. specific antigen in patients with untreated disease as a measure 11 McLaren DB, McKenzie M, Duncan G and Pickles T: Watchful of increasing cancer volume. Cancer 71: 2031-2040, 1993. waiting or watchful progression? Prostate specific antigen 26 Stamey TA, Johnstone IM, McNeal JE, Lu AZ and Yemoto CM: doubling times and clinical behavior in patients with early Preoperative serum prostate specific antigen levels between 2 and untreated prostate carcinoma. Cancer 82: 342-348, 1998. 22 ng/ml correlate poorly with post-radical prostatectomy cancer 12 Hanks GE, Hanlon AL, Lee WR, Slivjak A and Schultheiss TE: morphology: prostate specific antigen cure rates appear constant Pretreatment prostate-specific antigen doubling times clinical between 2 and 9 ng/ml. J Urol 167: 103-111, 2002. utility of this predictor of prostate cancer behavior. Int J Radiat 27 Schoder FH, de Vries SH and Baugma CH: Watchful waiting Oncol Biol Phys 34: 549-553, 1996. in prostate cancer: review and policy proposals. BJU Int 92: 13 Goluboff ET, Heitjan DF, DeVries GM, Ktz AE, Benson MC 851-859, 2003. and Olsson CA: Pretreatment prostate specific antigen doubling 28 Taplin ME, Bubley GJ, Rajeshkumar B, Shuster T, Ko YJ and times: use in patients before radical prostatectomy. J Urol l58: Morganstem DE: Docetaxel, estramustine, and short-term 1876-1878, 1997. anrogen withdrawal for patients with biochemical failure after 14 Stephenson AJ, Aprikian AG, Souhami L, Behlouli H, definitive local therapy for prostate cancer. Sem Oncol 28: 32- Jacobson AI, Begin LR and Tanguays: Utility of PSA doubling 39, 2001. time in follow-up of untreated patients with localized prostate 29 Eastham JA, Stapleton AM, Gousse AE, Timme TL, Yang G, cancer. Urology 59: 652-656, 2002. Slawin KM, Wheeler TM, Scardino PT and Thompson TC: 15 Benson RC and Hartley-Asp B: Mechanisms of action and Association of p53 mutations with metastatic prostate cancer. clinical uses of estramustine. Cancer Invest 8: 375-380, 1990. Clin Cancer Res 1: 1111-1118, 1995. 16 Veronesi A, Lo Re G, Foladore S, Merlo A, Giuliotto N, 30 McDonnell TJ, Troncoso P, Brisbay SM, Logothetis C, Chung Talamini R and Monfardini S: Multidrug chemotherapy in LW, Hsieh JT, Tu SM and Campbell ML: Expression of the the treatment of non-elderly patients with hormone- protooncogene bcl-2 in the prostate and its association with refractory prostatic carcinoma. A phase II study. North- emergence of androgen-independent prostate cancer. Cancer Eastern Italian Oncology Group (GOCCNE). Eur Urol 29: Res 52: 6940-6944, 1992. 434-438, 1996. 31 Cantley LC and Neel BG: New insights into tumor suppression: 17 Kreis W: Current chemotherapy and future directions in PTEN suppresses tumor formation by restraining the research for the treatment of advanced hormone-refractory phosphoinositide 3-kinase/AKT pathway. Proc Natl Acad Sci prostate cancer. Cancer Invest 13: 296-3121, 1995. USA 96: 4240-4245, 1999. 18 Hudes G: Estramustine-based chemotherapy. Semin Urol 32 Testa JR and Bellacosa A: AKT plays a central role in Oncol 15: 13-19, 1997. tumorgenesis. Proc Natl Acad Sci USA 98: 10983-10985, 2001. 19 Dearnaley DP, Sydes MR, Mason MD, Stott M, Powel CS, Robinson AC, Thompson PM, Moffat LE, Naylor SL and Parmar MK, Mrc Pr05 Collaborators: A double-blind, placebo- controlled, randomized trial of oral sodium clodronate for metastatic prostate cancer. J Natl Cancer Inst 95: 1300-1311, Received February 1, 2005 2003. Accepted April 21, 2005

792