Cancer Mortality Among Nuns: Role of Marital Status in Etiology of Neoplastic Disease in Women

To clarify the role of marital status in human carcinogenesis, a study was conducted of the cancer mortality experience of 31,658 white Catholic nuns belonging to 41 religious orders in the United States from 1900–54. Cause-specific comparisons were made with the national white female population. The total cancer mortality rate among nuns was somewhat lower than that of controls up to the older ages, when it became appreciably higher. The pattern for cancer of reproductive sites was consistent with the relation of cancers of the breast, corpus uteri and ovary (higher frequencies among nuns) to infertility, and cancer of the cervix (a much lower frequency among nuns) to coital factors. Furthermore, cancer of the large intestine showed an excess frequency among nuns, especially at postmenopausal ages. In combination with other observations, this finding implicates an effect of marital status and infertility on this site of cancer and suggests that in some women cancers of the large intestine and certain reproductive sites may share pathogenic mechanisms of a hormonal nature.