Primary Lung Cancers in Birds and Mammals of the Philadelphia Zoo'

(CANCER RESEARCH 26, Part 1: 514-518,March 1966]

ROBERTL SNYDERAND HERBERTLRATCLIFFE

Penrose Research Laboratory, Zoological Society of Philadelphia and the Department of Pathology, University ofPennsylvania, Philadelphia, Pennsylvania

Summary possible contributing factors, and describe and illustrate the microscopic appearance of the tumors. Postmortem examinations at the Philadelphia Zoological Garden have been continuous since 1901 and by December 31, 1964, included records on over 19,000 animals. Approximately Materials and Methods 300 malignant neoplasms were recognized in the mammals and All tumors in this series of animals, whatever their origins, birds of this series, and of these 23, or about 7 %, were primary were recognized initially by the changes they caused in shape, epithelial tumors of the lungs. Lung cancers were not discovered color, and texture of the organs and sites in which they devel in reptiles and amphibians. oped. Diagnosis and classification have been guided by accepted Pulmonary cancers were found in 7 families of mammals and criteria (5). 4 families of birds as follows : in mammals 4 squamous cell car Statistics were prepared for each family of mammals and birds cinomas and 5 adenocarcinomas, and in birds 13 adenocarcinomas represented by at least 1 lung cancer. Two potential sources of and 1 undifferentiated carcinoma. error are recognized : diagnosis and selection. Errors in diagnosis Aside from its occurrence in the family Anatidae, primary would increase frequency of occurrence either by including lung cancer would be considered a rare tumor in the collection lesions that were not cancerS or that were not primary in the of the Philadelphia Zoo. Ten pulmonary adenocarcinomas lungs. Errors in selection would decrease frequency of occurrence occurred among ducks and geese between 1943 and 1961. Average by failure to recognize a lesion macroscopically and save tissue longevity of anatids on exhibition had not changed significantly for microscopic examination. We will attempt to determine the during the period from 1901 to 1964; thus increased frequency probable degree of these errors in presenting these records. of lung cancers could not be attributed to advanced age of the Age is expressed in months and represents exhibition periods ducks and geese on exhibition. Rather, attention was focused in the zoo. A majority of birds and mammals are placed in this on the possibility of increasing amounts of carcinogens in the collection as juveniles or as young adults; thus exhibition periods atmosphere because ducks and geese were kept outdoors the in most instances approximate actual life-spans. year around. Observations Introduction FAMILIES INVOLVED. Pulmonary cancers were found in 7 Postmortem examinations at the Philadelphia Zoological families of mammals and 4 families of birds as follows: Canidae Garden have been continuous since 1901 and by December 31, â€”foxes, wolves, and other doglike animals; Felidaeâ€”lions, 1964, included records on over 19,000 animals. Approximately tigers, leopards, and other cats; Mustelidaeâ€”mink, skunks, 30% of this series have been mammals, 60% birds, and 10% otters, etc. ; Viverridaeâ€”civets, genets, etc. ; Didelphiidae reptiles and amphibians. These animals have represented up American marsupials, common opossum; Paramelidaeâ€”Aus wards of 50 orders and 200 families with correspondingly greater tralian marsupials; Capromyidaeâ€”aquatic rodents; AnO.&Lae numbers of genera and species. ducks, geese, and swans; Phasianidaeâ€”pheasants and quail; Approximately 300 malignant neoplasms had been recognized Cathartidaeâ€”group of vultures; and Ploceidaeâ€”smal! passerine in the mammals and birds of this series by December 31, 1964, birds. and of these 23, or about 7 C/@were primary epithelial tumors CLASSIFICATION. Table 1 lists each animal, its exhibition of the lungs. Current concern with lung cancer in man suggests period, sex, and the type of lung cancer found. These tumors are that a description of lung cancer in mammals and birds that all considered malignant and derived from epithelium. The have shared the urban environment may warrant interest at termsâ€”adenocarcinoma, squamous cell carcinoma, and un this time. Accordingly, we will consider the frequency of lung differentiated carcinomaâ€”refer to the predominant microscopic cancer in these animals in relation to age, sex, species, and other Structure. Adenocarcinomas were relatively well-differentiated tumors that formed glandular structures. The cells resembled

1 Supported in part by Grant HE-04759 from the USPHS. We the epithelium of the bronchi, bronchioles, or the bronchial are indebted to Dr. H. L. Stewart, National Cancer Institute, for glands. Squamous cell carcinomas were tumors in which the reviewing this material. predominant cells resembled squamous epithelium and were

514 CANCER RESEARCH VOL. 26

distinguished from simple squamous metaplasia by local infiltra TABLE 1â€”Continued tion with or without metastasis. Undifferentiated carcinomas BIRDS were tumors that formed solid masses of cells with few if any Anatidaea acinar structures. These cells were anaplastic and did not sug Red-billed tree duck (Dendrocygna autumnalis) 9 (96) 1943 . . gest the appearance of bronchial epithelium. Adenocarcinoma, spread to abdominal air sacs and adrenals The tumors listed in Table 1 include examples from the review and metastasis to liver of 1933 (3), when all specimens to that date were reexamined Shoveler duck (Spatula clypeata) 9 (72) 1953 . . . Adenocar and doubtful ones, chiefly squamous metaplasia, omitted. We cinoma, spread to pericardium, esophagus, and air sacs, and had available for this review microscopic slides from 5 of the 7 metastasistoliver examples of lung cancer listed in the 1933 report. These 7 exam Shoveler duck (Spatula clypeata) aâ€•(31) 1954 . . . Adenocar cinoma, primary in left lung. Metastasis to syrinx, air sacs. ples of lung cancer are 3 squamous cell carcinomas, 2 adeno pectoral muscles, and right lung carcinomas, and 2 pleural endotheliomas. The last 2 named were Cinnamon teal (Anas cyanoptera) 9 (72) 1955 . . . Adeno from a Cape hunting dog and a clouded leopard. They were carcinoma, metastasis to heart, aorta, liver, and muscles termed pleural endotheliomas when 1st examined in 1912 and Redhead duck (Nyroca americana) 9 (130) 1957 . . . Adeno. 1929, but we prefer to regard them as carcinomas of the lung carcinoma, spread to thoracic air sacs and not primary in the pleura. Sections of the tumor of the Cape Redhead duck (Nyroca americana) 9 (52) 1957 . . . Adeno. hunting dog show adenocarcinoma which suggests the possi carcinoma biity of a hidden primary growth in the lung. The leopard had Upland goose (Chloephaga leucoptera) aâ€•(9) 1957 . . . Adeno. advanced pulmonary tuberculosis which might have obscured or carcinoma, spread to thoracic and abdominal air sacs destroyed a deeply located primary tumor. The term pleural Shoveler duck (Spatula clypeata) aâ€•(129) 1957 . . . Adenocar cinoma, spread to right thoracic air sac endothelioma reflects a period in history when rigid classifica Chiloe widgeon (Mareca sibilatrix) dâ€•(12days) 1961 . . . Adeno tions were attempted. This does not imply that mesothelioma is carcinoma, spread to thoracic and abdominal air sacs, and an improper term, but that these tumors in all probability did metastasis to an adrenal not develop from the pleura. Redhead duck (Nyroca americana) 9 (121) 1961 . . . Adeno. The earlier examples of squamous cell carcinomas might have carcinoma, spread to thoracic air sacs represented squamous metaplasia. However on review the cases Phasianidaea listed here were considered to be malignant because tumor cells Silver pheasant (Gennaeus nycthemerus) o@ (107) 1927 . . infiltrated locally. Also the tumor in the Malayan civet, although Adenocarcinoma predominantly of the squamous type, contained elements of Red-jungle fowl (Gallus gallus) 9 (160) 1947 . . . Adenocar adenocarcinoma. A major bronchus was greatly dilated and the cinoma Cathartidaea Africaii eared vulture (Torgos tracheliotus) 9 (276) 1951 . . TABLE 1 Adenocarcinoma COMMON NAME, SCIENTIFIC NAME, SEX, EXHIBITION PERIOD IN Ploceidae MoN@rais(IN PARENTHESES), YEAR OF DEATH, ANDTYPE AND Java sparrow (Padda oryzivora) 9 (5) 1942 . . . Undifferentiated BEHAVIOR OF TUMORS OF AFFECTED ANIMALS carcinoma, spread to air sacs

MAMMALS a Caged outdoors for the major part of the exhibition period. Canidaea Cape Hunting dog (Lycaon pictus) 9 (4) 1929 . . . Pleural peribronchial spaces packed with squamous cells. The adeno endothelioma carcinomatous structures might have represented greatly hyper Red wolf (Canis niger) 9 (177) 1962 . . . Adenocarcinoma, trophied and distorted bronchial glands. These tumors did not metastasis to a kidney Felidae metastasize. Clouded leopard (Felis nebnlosa) ciâ€•(127) 1912 . . . Pleural The 2 adenocarcinomas seem to have been truly malignant as endothelioma they involved large portions of both lungs. Mustelidaeâ€• Since 1934, 2 adenocarcinomas and 1 squamous cell carcinoma Striped skunk (Mephitis mephitis) @? (71) 1955 . . . Adeno were recorded in mammals. The adenocarcinoma in the red carcinoma wolf metastasized to a kidney. Structural elements of this tumor North American otter (Lutra canadensis) d' (185) 1962 . . are illustrated in Fig. 1. The adenocarcinoma in the striped Squamous cell carcinoma, spread to mediastinum and heart skunk is illustrated in Figs. 2 and 3. These 2 tumors were not Viverridae alike. In Fig. 1 the structures are acini although not well differ Malayan civet (Viverra tangalunga) d' (2) 1906 . . . Squamous entiated and cells are columnar. The acinar structures in the cell carcinoma skunk might be termed alveologenic since they bear a resem Didelphiidae Common opossum (Didelphis marsupialis) 9 (7) 1930 . . blance to alveoli of the lungs and the cells are cuboidal (Fig. 3). Squamous cell carcinoma The squamous cell carcinoma in the otter spread to the mcdi Peramelidae astinum and covered a portion of the visceral pericardium (Figs. Rabbit-eared bandicoot (Thylacomys lagotis) aâ€•(68) 1918 . . 4-6). Squamous cell carcinoma Ten pulmonary cancers occurred among the anatids between Capromyidaeâ€• 1943 and 1961. Characteristically these cancers involved large ... â€” Coypu (Myocastor coypu d (41 1924 Adenocarcinoma portions of both lungs and spread over the surfaces of the air

MARCH 1966 515

TABLE 2 TABLE 3 PRIMARY LUNG CANCERS IN MAMMALS AND BIRDS PROPORTION OF ANATIDS THAT DIED DURING EACH QUARTER OF A POTENTIAL MAXIMUM EXHIBITION PERIOD OF 320 MoNnis

FAMILY1901â€”19341935â€”1964No. QUARTERSI ex exhibited with cx exhibited with hibited% 12 mo or lung hibited% 12 mo or lung NUMBERSLi@z cancerMammals longerNo. cancerNo. longerNo. IV1901â€”1934 II III

0.30 0.07 0.02 Canidae 1935â€”1964330 8690.61 0.66 0.28 0.04 0.02 Felidae 190 53 1 112 70 0 Mustelidae 128 48 0 71 83 2 This table excludes birds that died before 12 months on ex Viverridae 60 73 1 25 92 0 hibition. I)idelphiidae 248 4 1 25 40 0 Peramelidae 6 17 1 0 Capromyidae 15 87 1 2 0 0 Aside from its occurrence in the Anatidae primary lung cancer Totals 848 40 6 360 71 3 would be considered a rare tumor in the collection of the Phila Birds delphia Zoo. Frequency among the 7 families of mammals listed Anatidae 560 59 0 1127 77 10 in Table 2 was 0.7075% during the period from 1901 to 1934 Phasianidae 480 58 1 411 76 1 and 0.8333% during the period from 1935 to 1964. Only 1 lung 45 67 0 21 91 1 Cathartidae cancer was recorded in birds before 1943. The frequency of lung Ploceidae 931 55 0 259 73 1 cancer among the 4 families of birds listed was 0.7150% for the Totals201 201656 571 1125 181869 761 13 period from 1935 to 1964. The increasing liability to cancer with advanced age is well documented so consideration of age of the anatids is of prime sacs. I'@Ietastases involved the liver 3 times, muscles twice, and importance. Table 2 illustrates a significant improvement in the syrinx, the heart, the aorta, and the adrenals once. The 12-month survival of ducks, geese, and swans after 1934 from cancer cells tended to extend along the surfaces of the air sacs 57 to 77 %. The mean exhibition period for anatids that survived in continuous sheets, but in a few instances isolated nodules in the initial 12-month period was 84 months for the 1st period the air sacs suggested that cancer cells were transported to these and 74 for the 2nd. Patterns of life-spans in the 2 periods are sites in the blood stream or in the fluid exudate sometimes found compared in Table 3 (x2 = 5.79, P = 0.10). Comparison of life in the air sacs. Most of these tumors consisted of acini contain spans in the 2 periods indicates that occurrence of lung cancers ing mucinous secretions (Fig. 7). Typical structures consisted of in these birds was not associated with increased age at death. well-differentiated columnar cells like those illustrated in Fig. 8. The significance of the increased frequency of lung cancer in Pulmonary cancers of the anatids were all termed adenocarci birds and in the family Anatidae particularly was tested in a nomas. 2 x 2 contingency table according to the method of Fisher and Three adenocarcinomas and 1 undifferentiated carcinoma Yates (1). The increase in cancer from 1 case to 13 is significant were found in the families Phasianidae, Cathartidae, and Plocei at the 1% level; however, most of the cancers occurred among dae. Essentially the adenocarcinomas resembled those found anatids and when this family is excluded the increased frequency among the anatids ; however, air sacs were not invaded and is not significant. Anatids treated alone show a statistically metastases were not found. The histologic appearance of the significant increase in lung cancer (P < 0.05). tumor from the African eared vulture is illustrated in Fig. 9. The tumor in the Java sparrow of the family Ploceidae consisted Discussion of solid sheets of cells which did not form acini. Nuclei were round, hyperchromatic, and the cytoplasm was clear. Cancers have not been uncommon in the collection of the FREQUENCY OF LUNG CANCERS. Table 2 summarizes data per Philadelphia Zoo (2â€”4).In general the incidence of cancer in taining to frequency of occurrence of lung cancers in mammals mammals has been highest in the families Canidae, Felidae, and birds between 1901 and 1964. The table is divided into 2 Mustelidae, Ursidae, and Viverridae and lowest in the families periods, 1901â€”1934and 1935â€”1964.New and improved stand Procyonidae, Bovidae, Cervidae, Cercopithecidae, and Cebidae. ardized diets instituted in 1933 and 1934 brought about a sig Also, the incidence has been much lower in all families of birds nificant increase in survival time for most families of mammals as compared with mammals. These differences cannot be ac and birds. A detailed statistical treatment of life-spans in the counted for by differences in longevity alone (4). Thus, the zoo as related to frequency of cancer was published earlier (4). unexpectedly large number of cancers that occurred among In that paper average exhibition periods were listed for 9 families anatids between 1943 and 1961 is worth consideration. of mammals and 5 families of birds, but the data included only Lombard and Witte (2) have already suggested air pollution animals that had lived in the collection for at least 12 months as a possible causative factor for cancers among the waterfowl to emphasize the high mortality common to newborn animals in the zoo. The ducks, geese, and swans were kept outdoors and recent arrivals. Data in Table 2 were derived from all ani the year around on a large lake and a series of connecting pools mals, regardless of age, and show a significant improvement in or ponds. The pheasants were kept outdoors in wire enclosures. survival of young animals after 1934. Other birds were caged indoors continuously or were moved

516 CANCER RESEARCH VOL. 26

outdoors for the summer months. If airborne carcinogens were mals caged outdoors more attention should be focused on the involved, one must assume that concentrations were lower role of airborne carcinogens. Particles settling out of the air may indoors. In this respect mammals that have developed lung be concentrated in the water or on the soil, in which case a roof cancers as a rule have spent the major part of their life in the might provide some protection for the animals inside. Apparent zoo in outdoor enclosures. For example, the otter spent 15 species susceptibility in the shoveler and redhead ducks might years in an outdoor pool and the dogs had outdoor runs and be a matter of behavior that places these birds in close contact small sheltered dens. The bandicoot and the civet would be the with the carcinogen. exceptions to the general rule. The civet, of course, was only These conclusions, of course, are only valid if the primary in the collection for 2 months, so might have had lung cancer data are reasonably correct. We cannot say as eye witnesses on arrival. Two of the ducks fall into this category too, 12 days how complete or how carefully each necropsy was done from and 9 months on exhibition, which only proves that lung cancers 1901 to 1964. It has been the practice of this laboratory to pub in these birds are not limited to this zoo population. lish an annual report in which patterns of disease are discussed The role of species susceptibility to lung cancers should also in some detail. We judged from reading the protocols and the be discussed briefly. Primates have been free of lung cancers annual reports that errors of selection of cases due to unreliable even though longevity has increased. The average exhibition postmortem work must be scattered at random over the entire period of adapted (12-month survival) members of the family 64-year period. The preponderance of lung cancers in anatids Cercopithecidae for the period 1935â€”1962was 96 months. How from 1943 to 1961 is the only significant departure from the ever, one might argue that these were still comparatively young norm and cannot be accounted for by reason of longer life-spans. animals at death. These animals are caged indoors except during It seems highly unlikely that lung cancers were not recognized the summer months. The families Cervidae and Bovidae have in anatids prior to 1943, because necropsy procedures have al been well represented in the collection and are caged outdoors ways been the same. Lung tissue was not examined microscopi the year around. Exhibition periods have been reasonably long, cally in every instance, but detection of tumor nodules must yet lung cancers have not been encountered. Mean exhibition depend initially on careful gross examination of the lungs. Thus periods of 77 bears, which were also caged outdoors, were 100 in the last analysis the degree of error of cancer frequency sta months during the period before 1935 and 206 months after tistics depends on the completeness of the gross examination. 1935. In this respect there is no reason to believe that the statistics From a statistical viewpoint one can argue (from Table 2) presented in this report are grossly in error. that only 1 or 2 cases have occurred in any 1 family over a period covering 64 years ; the exception, of course, is the family References Anatidae. The occurrence of a single lung cancer in the next few years in a family hitherto free of this disease would not be 1. Fisher, R. A., and Yates, F. Statistical Tables for Biological, unexpected. Thus, there is no reason to conclude that certain Agricultural, and Medical Research, Ed. 4. Edinburgh and families of mammals might be resistant to lung cancer. London: Oliver and Boyd, 1953. Within the family Anatidae is an apparent predilection for 2. Lombard, L. S., and Witte, E. J. Frequency and Types of Tu lung cancer among 2 species, the shoveler duck and the redhead mors iii Mammals and Birds of the Philadelphia Zoological Garden. Cancer Res., 9: 127â€”41,1959. duck, for the 2 species combined accounted for 6 of the 10 cases 3. Ratcliffe, H. L. Incidence and Nature of Tumors in Captive of lung cancer. Such an occurrence suggests a familial relation Wild Mammals and Birds. Am. J. Cancer, 17(1): 116â€”35,1933. ship, identical sites of capture, or a peculiar feeding habit for 4. Snyder, R. L., and Ratcliffe, H. L. Factors in the Frequency these species. and Types of Cancer in Mammals and Birds at the Philadelphia We conclude from this review that lung cancers are compara Zoo. Ann. N. Y. Acad. Sci., 108: 793â€”804,1963. tively rare tumors of captive birds and mammals, but in view 5. Willis, R. A. Pathology of Tumors, Ed. 3. Washington : Butter of the occurrence of pulmonary cancers among birds and mam worths, 1960.

FIG. 1. Adenocarcinoma, red wolf 9 on exhibition 177 months. X 100. @ FIG. 2. Adenocarcinoma, striped skunk on exhibition 71 months. X 100. FIG. 3. Higher magnification of tumor illustrated in Fig. 2. The cells are cuboidal and acini resemble aveoli. X 560. FIG. 4. Portions of the lungs and mediastinum from North American otter aâ€•on exhibition 185 months. Tumor was squamous cell carcinoma. FIG. 5. Microscopic appearance of tumor illustrated in Fig. 4. Nests of tumor cells are found within the wall of a major bronchus, between a cartilaginous ring and the lumen. X 100. FIG. 6. Higher magnification of squamous cell carcinoma in the otter's lungs. Tumor cells scattered in connective tissue stroma. x 560. FIG. 7. Adenocarcinoma, Chiloe widgeon ci@ on exhibition 12 days. Cells are arranged in acini with abundant mucinous secre tions. X 100. FIG. 8. Adenocarcinoma, redhead duck 9 on exhibition 121 months. Structures consist of relatively well-differentiated tall columnar cells with basal nuclei. X 560. FIG. 9. Adenocarcinoma, African eared vulture 9 on exhibition 276 months. Tumor consists of large glandular structures with abundant stroma. Black spots are deposits of coal pigment. X 100.

MARCH 1966 517

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518 CANCER RESEARCH VOL. 26

Robert L. Snyder and Herbert L. Ratcliffe

Cancer Res 1966;26:514-518.

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