It is beyond ludicrous to attempt to say that by virtue of their contemplative lifestyle, nuns are more prone to cancer than others. The sheer rankness of the contention compares favorably, with anthropomorphic global warming. This article smells of agenda. And feces.

An increased cancer risk, especially breast cancer, among nuns is not "by virtue" of a "contemplative lifestyle." It's just a matter of biology.

It's been known for some time that women who go through more fertile cycles throughout their lifetime are at greater risk of developing breast cancer. The factors (aside from surgery or drugs) that determine the total number of fertile cycles are these: age of menarche, pregnancy, and age of menopause.

There is also the matter of breast feeding. Women who breast feed for longer periods of time over a greater range of time from an earlier time in their lives have a correspondingly lower risk of developing breast cancer than those who do not.

From this, two things are evident:

A. the group of women with the lowest risk of developing breast cancer would be those who had a later onset of menarche, early and multiple pregnancies followed by lengthy breast feeding, and an earlier, rather than later, menopause.

B. the group of women with the highest risk of breast cancer (aside from those who carry the BRCA mutations) would be those with an earlier onset of menarche, no pregnancies or breast feeding, and a later menopause.

Which group of women do most nuns belong to? A or B?

Unfortunately, your unexamined prejudices are causing you to look for motives for this study rather than at the biological and epidemiological basis for the study itself. Furthermore, unlike "anthropomorphic" (you really mean "anthropogenic") global warming, no one stands to make trillions of dollars carbon-trading with no added benefit to society off a relatively smaller number of women (those who have never had a child or been pregnant) having an increased risk of breast cancer.

All women should be thankful to nuns whose lifestyle more clearly isolates certain variables and has made it possible for researchers to get better epidemiological insight into factors determining the risks of breast cancer.

Noticing the difference in the rates of disease through epidemiology led to investigation of the biological basis for pregnancy and lactation reducing the risk of breast cancer. See the abstract of a review article posted below (emphasis added).

J Mammary Gland Biol Neoplasia. 2011 Sep;16(3):221-33.

Pregnancy-induced changes in breast cancer risk.

Russo IH, Russo J.

Molecular Endocrinology Section, Breast Cancer Research Laboratory, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA. Irma.Russo@fccc.edu

Abstract

Breast cancer is the malignant disease most frequently diagnosed in women of all races and nationalities. Since the 1970s the worldwide incidence of this disease has increased 30-40% in postmenopausal women, in whom, paradoxically, the risk of developing breast cancer is significantly reduced by an early first full term pregnancy (FTP) as compared to nulliparous and late parous women. Although the cause of breast cancer is not known, the mechanisms mediating the protection conferred by an early FTP have been identified to reside in the breast itself, and to be modulated by endogenous and environmental exposures that might negatively affect this organ during specific windows in its development that extend from prenatal life until the first pregnancy. Soon after conception the embryo initiates the production of human chorionic gonadotropin (hCG), the glycoprotein hormone that is diagnostic of pregnancy. HCG in conjunction with ovarian steroid hormones primes the hypothalamic neuroendocrine system for maintaining the pregnancy. Higher levels of hCG during the first trimester of pregnancy have been associated with a reduction in maternal breast cancer incidence after age 50. In preclinical studies it has been demonstrated that both FTP and hCG treatment of virgin rats prevent the development of chemically-induced mammary tumors, a phenomenon mediated by the differentiation of the mammary gland epithelial cells prior to carcinogen exposure. Complete differentiation proceeds through complex morphological, physiological and molecular changes that occur during pregnancy and lactation, that ultimately result in increased DNA repair capabilities of the mammary epithelium, activation of genes controlling differentiation and programmed cell death and imprinting in the breast epithelium a specific and permanent genomic signature of pregnancy. This signature is indicative of a reduced breast cancer and serves as a molecular biomarker of differentiation for evaluating the potential use of chemopreventive agents.