Factors in the Causation and Incidence of Ovarian Cancer

This paper presents an overview of the present knowledge about etiologic factors in the development of ovarian cancer. It is divided into 3 main headings: 1) epidemiologic observations about human ovarian cancer; 2) studies on spontaneous animal ovarian tumors that gave rise to an interesting field in comparative oncology; and 3) studies on experimental ovarian tumors. Factors which have been related to the causation and incidence of human ovarian cancer are: 1) racial and geographical incidence; 2) socioeconomic factors; 3) genetic factors; 4) age; 5) menstrual characteristics; 6) marital status and parity; 7) relationship to intersex states; 8) laterality; 9) endometriosis; 10) previous hysterectomy; 11) previous oophorectomy; 12) relationship to other neoplasms; 13) thyroid disease; 14) mumps; 15) x-irradiation; 16) asbestosis; and 18) incessant ovulation. A review of literature on ovarian tumors in animals showed that animals have a much lesser incidence than humans and thus was attributed to the infrequency of tumors arising from the ovarian surface epithelium which in humans comprise the great majority of ovarian tumors. On the other hand the prevalence of ovarian cancer among egg-laying domestic fowls is attributed to the frequency of adenocarcinoma. Such data may be helpful in determining the etiology of certain types of ovarian cancer. Experimental ovarian tumors have been induced in animals by x-irradiation; ovarian grafting; ligature of blood vessels; partial castration; and progestrational steroids. The implications of these experiments in human problems are briefly discussed as are the need for more studies in the field of epidemiology of human ovarian cancer.