carcinogen2

The 2013 study “Incidence of Breast Cancer With Distant Involvement Among Women in the United States, 1976 to 2009″ published in the Journal of the American Medical Association found that metastatic breast cancer in women under 40 has been increasing at a rate 2% a year, every year, from 1976 to 2009.1 Given that there has been no corresponding increase in older women, it’s worth asking what younger women have been doing differently since the 1970’s to increase their risk of breast cancer. Which brings us to hormonal contraception.

Hormonal contraception, used increasingly by young, American women since its introduction in the 1960’s, is described by The International Agency for Research on Cancer as a “Group 1 carcinogen,” which means the agent is “definitely carcinogenic to humans.” Hormonal contraception associated with an increased risk of breast cancer.

Why?

Hormonal contraception causes a significantly higher rate of breast cell division, and in general, cells that divide more rapidly are more likely to become cancerous.2

By how much?

That’s the hard part. Different studies have found different results.

A 2012 study of Chinese women found a 2.5 increased risk of breast cancer in women who ever used oral contraceptives.3 According to the 2009 study “Risk Factors for Triple-Negative Breast Cancer in Women Under the Age of 45 Years,” published in the journal Cancer Epidemiology, Biomarkers, and Prevention, found that “oral contraceptive use ≥1 year was associated with a 2.5-fold increased risk for triple-negative breast cancer.”4 Triple-negative breast cancer is a particularly aggressive subtype of breast cancer which makes up between 10% and 19% of breast cancer cases. The 2003 study “Breast cancer and specific types of oral contraceptives: A large Norwegian cohort study” found “the adjusted risk of breast cancer increased with 25% for ever use of OCs and the risk increased with increasing duration of use.”5 Obviously there is a serious need for scholarly consensus. The great news is that this increased risk decreases immediately after ending the use of hormonal contraception, and is gone approximately 10 years after discontinuation.6

The vast number of factors involved with breast cancer, and the many studies — some better than others — have lead to a need for more, detailed, extensive, and impeccable research. The bottom line is this: We know that hormonal contraceptives increase a woman’s risk of breast cancer. For women concerned with the carcinogenic nature of hormonal contraception, it might be worth considering what natural methods of family planning have to offer. These methods are effective and hormone-free, with absolutely zero side-effects, enabling women to treat any reproductive health problems they might have without the use of potentially dangerous substances.

But doesn’t the Pill reduce ovarian cancer risk?

A recent study published in the European Journal of Cancer Prevention found that “the overall estimated protection[...]is approximately 30% for ever OC users,” and up to 50% for those who use oral contraceptives for more than ten years.7
This is a significant reduction of risk, especially considering that this protection continues long after the use of oral contraceptives.8 But by the time a woman reduces her risk of ovarian cancer by 50%, those same Pills increase her risk of breast and cervical cancer. Women should be informed that there are other ways to reduce ovarian cancer risk — ways that don’t simultaneously increase the risk of other diseases. According to the review Epidemiological and Genetic Factors Associated With Ovarian Cancer, giving birth to just one child results in a 40% decreased risk of ovarian cancer, with a further 14% risk reduction for every birth afterwards, and a further decreased risk if a woman chooses to breastfeed.9 What takes approximately 10 years for the Pill to achieve can be achieved naturally in 9 months.


What about the 2002 study “Oral Contraceptives and the Risk of Breast Cancer”?

This study, ((Marchbanks et al, “Oral Contraceptives and the Risk of Breast Cancer” The New England Journal of Medicine, 2002, Volume 346, Pages 2025-2032)) titled as a definitive answer, is often used to claim that oral contraceptives are really no big deal when it comes to breast cancer, and that women shouldn’t worry. They claim that “among women from 35 to 64 years of age, current or former oral-contraceptive use was not associated with a significantly increased risk of breast cancer.”
The problem is obvious. The vast majority of Pill users are younger than 35:(( Mosher WD, Jones J. Use of contraception in the United States: 1982–2008. National Center for Health Statistics. Vital Health Stat 23(29). 2010.))
Given that we know breast cancer risk is highest during oral contraceptive use and decreases after ending use, this study is unhelpful.


  1. Johnson, Chien, Bleyer, “Incidence of Breast Cancer With Distant Involvement Among Women in the United States, 1976 to 2009,” Journal of the American Medical Association, 2013, Volume 309, Number 8, Pages 800-805 

  2. Anderson et al, “Oral contraceptive use influences resting breast proliferation,” Human Pathology, Volume 20, Issue 12, December 1989, Pages 1139–1144 

  3. Yanhua et al, “Reproductive Variables and Risk of Breast Malignant and Benign Tumours in Yunnan Province, China” Asian Pacific Journal of Cancer Prevention, Volume 13, 2012, Pages 2179-2184 

  4. Dolle et al, “Risk Factors for Triple-Negative Breast Cancer in Women Under the Age of 45 Years, Cancer Epidemiology, Biomarkers & Prevention, 2009, Volume 18; 1157-1166 

  5. Dumeaux, Alsaker, Lund, “Breast cancer and specific types of oral contraceptives: A large Norwegian cohort study” International Journal of Cancer, 2003, Volume 105, Issue 6, Pages 844–850 

  6. Collaborative Group on Hormonal Factors in Breast Cancer, “Breast cancer and hormonal contraceptives: collaborative reanalysis of individual data on 53 297 women with breast cancer and 100 239 women without breast cancer from 54 epidemiological studies” Lancet, 1996, Volume 347, Issue 9017, Pages 1713-27 

  7. La Vecchia, Oral contraceptives and ovarian cancer: an update, 1998-2004 European Journal of Cancer Prevention, 2006, Volume 15, Issue 2, Pages 117-124 

  8. Bosetti et al, “Long-term effects of oral contraceptives on ovarian cancer risk” International Journal of Cancer, 2002, Volume 102, Issue 3, pages 262–265 

  9. McLemore et al, “Epidemiological and Genetic Factors Associated With Ovarian Cancer” Cancer Nursing, 2009, Volume 32, Number 4, Pages 281-288