Nuns and Contraceptives

Every now and then an article catches the eye because it has humanity woven into the story it tells. The comment piece by Britt and Short entitled The Plight of Nuns: Hazards of Nulliparity contains both pathos and science.¹ According to the article, 300 years ago it was noted that Italian nuns had a high incidence of breast cancer, which was evocatively described as an “accursed pest.” The observation had no scientific explanation but the point it makes is reflected upon by the authors, who discuss how nuns today are affected by their choice of lifestyle.

Catholic nuns have a mortality advantage of about 25% over the general population, presumably assisted by their abstemious traits and reduced chances of motor vehicle accidents and the other vagaries of urban life. Against this must be weighed their exercise patterns and habits (!) of less sunlight exposure and sparse diets. But it is their reproductive organ pathophysiology that intrigues. The risk of breast cancer is known to be reduced by child bearing and breast feeding, especially by early reproduction and greater numbers of children, but the precise mechanisms of this decrease in risk have not been elucidated. Because nuns are celibate, breast cancer risk reduction by having children is not an option; neither is manipulation of the “estrogen window,” which is dictated by early menarche or late menopause and is unrelated to lifestyle. The other possible variable is the use of hormonal contraception, but this appears to be risk neutral, at least with regard to oral contraceptives.

Nuns have an increased risk of breast cancer that rises with age compared with the general population; beyond the age of 80 years their risk is three times the average. At present this predisposition is not amenable to hormonal or adjuvant therapy and the reasonable precautions seem attention to exercise, breast awareness, and possibly mammography. But what of other reproductive cancers?

Cervical cancer is best understood in terms of its etiology and nuns’ celibacy renders their risk of malignancy extremely low. However, ovarian and uterine cancers have both been shown to be affected by oral contraceptive use with relative risk reductions of 50% to 60% compared with never-users and the benefits persist over at least two decades.^2,3

The beneficial effects of combined estrogen and progestogen pills may be mediated in the case of ovarian malignancy by reducing the monthly trauma of ovulation and endometrial protection by decreased menstruation in frequency and volume. If the amenorrhea of pregnancy and lactation has beneficial effects on these cancers then induced absence of menstruation through the use of birth control pills or progesterone-releasing intrauterine systems may carry similar benefits.

If pill-induced amenorrhea seems positive, why stick with 21-day cycles with placebos to follow (when ovulation could occur)? Is the “red badge of femininity” going to yield to proven protection? Will nuns take the pill continuously to protect themselves from reproductive cancers? These are scientific questions that do not take emotional, social, and religious factors into account but make for provocative thinking.