A Retrospective Study in 1,070 Feline Tumor Cases of Japan.

Abstract

This retrospective study was based on spontaneous feline tumor cases that were either cytologically or histologically diagnosed at Azabu University Veterinary Teaching Hospital in Japan from April 1985 to March 2008. Tumor-bearing cats were analyzed for age, sex, breed, type of tumors, site-specific tumor incidence, and frequency of malignant diseases. The classification for anatomic site was based on TNM Classification/WHO in domestic animals. The data were compared between the tumor-bearing cat population and the baseline hospital population of cats including all the cat patients seen during the same period. T test was used to analyze age distribution. Chi square（X 2 ）was used to analyze sex, breed, and the frequency of malignant tumors, and Yates calibration and Fisher's exact test were used as needed. Breed distribution, the frequency of malignant tumors and site-specific tumor incidence were multiple comparisons, and Bonferroni correction was applied in the statistical adjustment. P values less than 0.05 were considered significant for all of the statistical analyses. Relative risks（odds ratio）by breed, sex and the most frequent tumor site were estimated. Results The population studied A total of 1,078 feline tumors obtained from 1,070 cats were studied. The baseline hospital population during the same period included 6,748 cats. Comparison between tumor-bearing cat population and baseline hospital cat population Mean age of the baseline hospital cat population was 5.6±4.9 years old, with 53.3％（3,599）of the cats under 5 years of age. The mean age of tumor-bearing cats（9.9±3.8 years old）was significantly higher（p<0.001）than that of the baseline hospital population mentioned above. In the baseline hospital population, however, at 8 years or older, 35.6% （777 cases）were tumor-bearing cats. Age distribution of the baseline hospital population and tumor-bearing cats is summarized in Figure 1. The male to female ratio of cats in the baseline hospital population was 1：0.93（p=0.025） , and was 1：1.42（p<0.001） in tumor-bearing cats. This sex distribution was significantly different between the two groups（p<0.001）. The chances for female cats to develop any tumors were greater than in male with an odds ratio of 1.54. The cat breeds in the baseline hospital population included mixed breed（71.8%） , American Shorthair（5.6%） , Chin-Fig. 1． Age distribution of the baseline hospital population and tumor-bearing cats.