|Written by NHS Choices|
|Thursday, 08 December 2011 06:00|
"Nuns should take the pill to cut cancer threat," the Daily Mail has reported.
The news is based on an article in a medical journal which argues that Catholic nuns are likely to be at greater risk of breast, ovarian and womb cancers because they do not bear children. The authors say that nuns "pay a terrible price for their chastity" and they should be offered the oral contraceptive pill to suppress their ovulation in order to cut their cancer risk.
As might be expected about a story that mentions nuns and the pill in the same sentence, the editorial was widely covered by newspapers. However, despite this coverage, it's important to note that the article was an opinion piece rather than a study, and therefore should not be taken as gospel. That said, it does raise the issue that the risk of certain cancers that may be greater among women who do not have children.
The pill has potential side effects, including headaches, weight changes and breast tenderness. It also carries a small increase in the risk of blood clots, cervical cancer and stroke. In addition, research into whether it increases the risk of breast cancer has had mixed results. Therefore there needs to be further research into whether the possible benefits of the pill in reducing the risks of some cancers outweigh its potential risks.
Where did the story come from?
The editorial was written by researchers from Monash University and the University of Melbourne, Australia. It was published in the peer-reviewed medical journal The Lancet.
As might be expected of a story linking nuns to the pill, the editorial and its accompanying press release got plenty of coverage, for the most part uncritical.
What did the editorial say?
The authors said that the world's estimated 94,790 nuns have a greatly increased risk of breast, ovarian and uterine (womb) cancers compared with women in the general population, because nuns generally do not bear children. Its argument is based on various pieces of research that show that nuns and other women without children have an increased chance of dying from breast, ovarian and uterine cancers compared to women who have reproduced. This is thought to be because women without children have a higher number of ovulatory menstrual cycles than women with children, due to not going through pregnancy and lactation. Similarly, the authors quoted research to show that women who have earlier puberty or late menopause have a higher risk of breast, ovarian and uterine cancers.
The authors said: "It is not known how to improve the health of breasts that do not need to lactate, ovaries that do not need to ovulate and a uterus that does not need to menstruate."
They cited large studies as showing that the oral contraceptive pill:
They pointed out that while most types of the pill produce a monthly period, newer types can result in fewer menstrual periods and some can prevent all periods. Whether continuous suppression of monthly cycles will increase the protection from uterine and ovarian cancer is as yet unknown, they added.
They also noted that although the Catholic Church condemns all forms of contraception except abstinence, taking the pill for health reasons would be allowed under church laws. The Church, they concluded, should make the oral contraceptive pill freely available to all nuns to reduce the risks of ovarian and uterine cancers and "give the nuns' plight the recognition it deserves".
This opinion piece, which linked together different pieces of research, raises a serious issue: the increased risk of reproductive cancers among nuns and other women who do not bear children. It argued that nuns should be offered the pill because it has been shown to reduce the risk of two of these cancers and has also been shown to reduce mortality rates overall.
However, the research cited by the authors as showing that the pill reduces mortality rates was an epidemiological study that cannot show any causal effect between the pill and reduced mortality. It is quite possible that women taking the pill lived longer because of other factors.
Furthermore, the pill has side effects including headaches, weight changes and breast tenderness. It also carries a small increase in the risk of blood clots, cervical cancer and stroke. In addition, the combined contraceptive pill contains oestrogen, which can stimulate breast cancer cells to grow. While the authors quoted one large study that showed there is no increase in breast cancer risk from taking the pill, other studies have shown a slight increase in risk. Therefore, it is not yet possible to say for certain that these women would be better off on the pill.
Whether the possible benefits of the pill in reducing the risks of some cancers outweigh its potential risks needs further exploration.