This the second part of Philippa Taylor’s analysis of a medical controversy which women should know about. You can read Part 1, published yesterday on TCW, here.
THE link between abortion and breast cancer is showing up more clearly in the world’s most populous countries, where the disease used to be rare. Evidence suggests that the growing epidemic in China is an entirely predictable result of their ‘one-child-policy’ and associated forced abortions.
A few months ago research on 800 women, published in the Journal of Epidemiology by Xuelian Yuan, found that women in China with a history of medical abortion more than triple their odds of breast cancer – not too dissimilar to Huang’s findings which I discussed yesterday – and particularly concerning considering that 77 per cent of UK women now have a medical abortion.
Xuelian summarises his findings: ‘The relationship between induced abortion and birth control methods and breast cancer was complex, though being exposed to induced abortion and two or more birth control methods in one’s lifetime appeared to be risk factors for breast cancer in Chinese women.’
He reports that the incidence of breast cancer rose significantly between 2007 and 2013 while the mean age at the time of diagnosis in Chinese women dropped by ten years. His conclusion is clear: ‘Not coincidentally, women of this age were generally at reproductive age during the period when the Chinese birth-control policy (one child per family) was fully implemented.’
He explains why there is a link:
‘It is well known that women’s estrogen and progesterone levels increase during a pregnancy, which promotes the growth of the mammary glands. When a pregnancy is terminated by surgical abortion, estrogen and progesterone levels suddenly drop, which consequently terminates the growth of breast cells, leading to acinar atrophy. Incompletely differentiated breast epithelial cells are more susceptible to stimulation by carcinogenic substances, and therefore become cancerous relatively easily.’
While for medical abortions, ‘the antiprogestin contained in the drug may interfere with the internal hormone environment, making it conducive to the development of hormone-related tumors.’
Added to this: ‘Surgical and medical abortion can increase the risk of breast cancer by delaying the timing of a full-term pregnancy, which is considered to be a protective factor of breast cancer.’
As an aside, it is simple to estimate the ultimate effects of such an exposure as abortion on a population of about 1.4billion women in India and China alone: if 30 per cent had an abortion and even just three per cent of these had breast cancer because of it, that is 12.6million women who would get breast cancer because of an abortion.
The importance of reproductive history
Promotion of abortion has not been limited to China. In South Asia alone, between 2007-2017, at least 20 studies report data on this issue. As this report shows, there was a significant and moderately strong dose-dependent association between abortion and breast cancer. The authors conclude: ‘The moderately strong association identified between abortion and breast cancer explains in part the spread of the breast cancer epidemic to South Asia as it has become Westernised.’
Women in India and neighbouring countries are ideal for studies of the link, especially those in rural areas. They generally marry, have children early, have several children, breastfeed their babies and do not use the pill, smoke or have high alcohol consumption. In other words, most of the other major risk factors for breast cancer are absent. In South Asia, both breast cancer and induced abortion have been relatively rare until recent years.
Many ‘Western’ women, as I noted in my earlier blog, engage in other behaviours besides abortion that can cause breast cancer. They have fewer children and have them later (or not at all). They use oral contraceptives when young and go on HRT when older, and they have lower rates of breastfeeding. These ‘confounding factors’ make it difficult to separate out the effect of induced abortions on a woman’s lifetime breast cancer risk. These factors are largely absent in India, so the abortion-breast cancer link comes out more clearly.
Though the independent effect of induced abortion is not always statistically large, it is important to consider the overall influence that abortion has in shaping a woman’s reproductive history.
The single effect of induced abortion on breast cancer risk is trumped by the overall effect of a long-term avoidance of pregnancy. In this (more ‘Western’) lifestyle pattern, the effects of late age at first full-term pregnancy, or nulliparity (never having given birth), oral contraceptive use, and induced abortion (possibly while nulliparous or long before first birth, if any) could all be evident and will work together to increase a woman’s breast cancer risk.
It is worth noting that as well as the difficulty in separating out confounding factors, another problem with the research is that studies (particularly those showing no association) often use poor research design – failing to ensure adequate follow-up time, using inaccurate abortion registers and inappropriate study populations, and not dealing with the known problem of under-reporting of abortion.
What do we need to do now?
An updated meta-analysis is needed, and a genuinely transparent independent review of the evidence: Brind, Beral and Huang published very different conclusions and since their publication, many additional studies have been published across the world.
Informed consent: Women need the opportunity for informed consent when choosing a procedure that will elevate breast cancer risk, a leading cause of cancer death in women. It is clearly crucial that the 200,000 women who have induced abortions in Britain each year are fully informed about the possibility of any link and that all official guidance on the matter is properly evidence-based. The incidence of breast cancer in the UK is on a large scale and while the aetiology is not resolved, this is an issue where the precautionary principle should apply.
More screening: Women who do choose induced abortion should be made aware of their increased risk, so that they can be screened at an appropriate time and through early detection find more curable cancers. If the abortion occurs at a young age when breast tissue is very dense, more appropriate screening with the use of ultrasound and MRI in addition to mammograms could be offered earlier than the age at which screening is standard, which is normally age 40. Ten years after an induced abortion would be an appropriate time to start this early screening.
Changing social norms: This is a tricky one, for obvious reasons. However, a social norm that encouraged carefully planned first pregnancies at the beginning of advanced education and career development would help reduce breast cancer rates.
Exposing ideologies: As I mentioned yesterday, I have a particular ideology on abortion which I do not hide. But so does the Royal College of Gynaecologists. How much is medical research on abortion truly free from the influence of ideological agendas? When will British medical journals publish papers that report a link of breast cancer to induced abortions?
Ultimately, women have a right to know that there is a continuing debate on the link, and that the matter is not settled.
