The Pill And Breast Cancer:
Your questions answered.

John Wilks, B.Pharm MPS MACPP
Pharmacist in Baulkham Hills, Australia
Reproduced with permission

Question one:

I have heard different opinions about whether the pill causes breast cancer. What are the facts on this important issue?


Is true that the issue of the pill's link to breast cancer is one of considerable academic and media discussion. In research prior to publication of "A Consumer's Guide to the Pill",1  I reviewed 20 studies over the last decade which all point to an increased incidence of breast cancer for pill users.2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  Consistently reported findings include:

Question two:

But couldn't the development of breast cancer be something that you are born with, like developing diabetes?


This may be true for some women. If you have a parent or relative who had breast cancer, your chances of developing it are certainly increased. But consider this: results cannot beset aside as merely the result of a genetic pre-disposition. Researchers have shown that the risk of breast cancer was 110% higher for pill taking women than for their non-using biological sisters. (Ursin, 1992)

Question three:

This looks very convincing. But how does the pill cause this increase in breast cancer ?


Researchers have offered a number of possible reasons to explain how the artificial hormones in the pill cause such a dramatic increase in the number of breast cancer cases seen since the pill was made available in the late 60's.

  1. Early age pill users presented with tumours which had spread more extensively into the lymphatic area of the armpit than that seen in nonusers.23  Once tumours begin to spread to other parts of the body, a woman has a reduced chance of survival.
  2. Pill hormones may have a direct influence over how cells within normal breast tissue divide and grow which may "increase the potential for carcinogenesis [the process of cancers starting].".24 
  3. "Another possible mechanism [of cancer generation] may involve permanent changes of hormonal systems or growth factors after early OC use.".25  A woman's hormonal system is delicate and finely tuned. Interfering with it by the use of artificial hormones may cause cells to grow irregularly.
  4. Tumours induced by the pill in young women, 'grow' at a rate faster than that of tumour growth induced by the pill in older women.26  [It is as though the more rapid, age-appropriate rate of normal breast tissue growth in young women is grabbed and adopted as the 'normal', but never reducing rate of cell growth by the tumour.] This is an interesting hypothesis which I have translated into this Fig 1, in collaboration with a consultant physician/medical oncologist.
  5. Some of the artificial hormones in the pill, those called the progestins, attach themselves to cells more strongly than the same natural hormones made by your body. That is, artificial pill hormones influence the way cells grow and behave to a greater extent than do the natural hormones made by your body. This is why women using the pill have bigger and more deadly tumours than women of the same age who do not use the pill.

Question four:

O.K., I see now that the medical studies regularly report an increase in breast cancer. I think I also understand how the pill causes these cancers. But what proof is there that Australian women suffer from pill-induced breast cancer?


To answer this important question, look at the increase in the incidence of breast cancer in New South Wales as set out in Graph 1.

Graph 1: Age-specific incidence of breast cancer per 100,000 women (NSW, Australia). 1972-82-93

Can you see that for women in the 20-24 age bracket, the incidence of breast cancer has increased 600% in 21 years, from 0.5 cases per 100,000 women in 1972 to 3 cases per 100,000 women in 1993. For the 25-29 age bracket there has also been a jump in the incidence, from 3.3 cases per 100,000 women in 1972 to 7.9 cases per 100,00 women in 1993; an increase which is in excess of a 100% .

The pill was introduced in the late 60's. Today more and more women are using it. Therefore it is not surprising to see an increase in the number of women with breast cancer.

Some caution must be exercised in reading too much into these figures because the number of cases of diagnosed breast cancer for each age-bracket and year was small.

Question five:

But surely the reason that more women are diagnosed with breast cancer because more women have mammograms to test for this form of cancer?


It is true that the increasd incidence is partly as a result of better public awareness of the need for regular breast cancer screening. This though is not the full explanation. The Cancer in NSW Incidence and Mortality 1994 report said there was a "real" increase in the incidence of breast cancer, not an increase due to early detection programs (mammography) alone.27  Research cited above would support the view that the prescribing of the pill to young women, particularly those under 20, is a contributing factor.

The Sydney Breast Cancer Institute has also reported that "the incidence of the disease is increasing...".28  The Media Tracking Service (1995) reported that there had been an "an annual rise of 3% p.a. since the mid 1980's" in breast cancer.29 

Question six:

So if the pill is so dangerous, what happens in countries were the pill isn't used?


The chances of a woman developing breast cancer over her lifetime is one in eight in the U.S.A., and one in 16 in Australia. Remember, the pill has been available in these countries for almost 30 years. But in Japan, the chances of breast cancer in a woman's lifetime are one in 5030  Some have sought to explain these international variations in breast cancer rates by attributing it to the high-fat diet in America.31 

Question seven:

The leaflet I get inside my pill packet says that the pill is safe. Is this correct?


No, this information is completely false. From a consumer's perspective, these leaflets act as a source of disinformation on certain key aspects of female health. For example, many major brands tell the consumer: "Although some components of oral contraceptives have been associated with the development of cancer when given continuously to certain animals, there is no evidence that they have such an effect in humans.".32  33  As I have shown, this statement is medically incorrect.

In a booklet entitled 'Modern Oral Contraceptives - Your Questions Answered' and dated Jan '95 we were presented with the following:

question: "Are there any side-effects"

answer:"The pill is one of the most thoroughly tested and widely prescribed prescription medicines... However, some women should not use the pill (for example those who suffer from certain forms of cancer)." 34 

As you can see, these leaflets do not tell women the full truth.


When used as a method of birth control, the pill represents a chemical abuse of a healthy woman's body.

It is the only time in medicine when potent drugs are given to a healthy person who then becomes sicker than they were before they started using the drug. Since the hormones in the pill are very potent, are usually taken for some years, and mostly are taken by healthy women, it is not surprising that women gt sick and frequently die.

For women wishing to avoid pregnancy, the only safe options are the various methods of natural family planning, which the World Health Organisation has rated as more reliable than the pill.

Other leaflets in this series deal with the pill's role in cervical cancer and blood clots, as well as an explanation of how the pill acts as an abortifacient.


1.  ; Wilks J. A Consumer's Guide to the Pill and other Drugs. 2nd Ed. ALL Books [Back]

2.  ; Stadel BV. Oral contraceptives ad premenopausal breast cancer in nulliparous women. Contraception.1988;38(3):287-309. [Back]

3.  ; Olsson H et al. Early oral contraceptive use and breast cancer in Southern Sweden. Proc Annu Meet Soc Clin Oncol.1989;8:A367. [Back]

4.  ; Romieu I et al. Oral contraceptives and beast cancer. Review and meta-analysis. Cancer. 1990;66 (11):2253-63. [Back]

5.  ; Ranstam J, Olsson H et al. Survival in breast cancer and age at start of oral contraceptive usage. Anticancer Research.1991;11:p.2043. [Back]

6.  ; Olsson H, Ranstam J, et al. Proliferation and DN ploidy in malignant tumours in relation to early oral contraception use and early abortions. Cancer.1991;67:(5)1285-90. [Back]

7.  ; Olsson H, Borg A, Ferno M et al. Early oral contraceptive use and premenopausal breast cancer - a review of studies performed in Southern Sweden. Cancer Detection and Prevention.1991;15(4):265-271. [Back]

8.  ; Tryggvadottir L, Tulinius H, et al. Oral contraceptive use at a young age and the risk of breast cancer: an Icelandic, population-based cohort study of the effect of birth year. Br J Cancer 1997;75:1,139-43. [Back]

9.  ; Meirk O, Farley T, Lund E, Adami H-O et al. Breast cancer and oral contraceptives: patterns of risk among parous and nulliparous women-further analysis of the Swedish-Norwegian Material. Contraception. 1989;39(5):471-5. [Back]

10.  ; Chivers C et l. Oral contraceptive use and breast cancer risk in young women. Lancet.1989;May.973-982. [Back]

11.  ; Olsson H. Oral contraceptives and breast cancer: A review. Acta Oncologica. 1989;28:849-63. [Back]

12.  ; Olsson et al. Early oral contraceptive use and breast cancer among premnopausal women: Final report from a study in Southern Sweden. J National Can Instit.1989;81(12):1000-4. [Back]

13.  ; Johnson JH. Weighting the evidence on the pill and breast cancer. Family Plan Perceptives 1989: 21 (2):89-92. [Back]

14.  ; Olsson et al. Proliferation and DNA poidy in malignant tumours in relation to early oral contraceptive use and early abortion. Cancer 1991;67(5) 1285-90. [Back]

15.  ; Ranstam JP. Oral contraceptives and breast cancer. Diss Abstr Int (C) 1992;53(4)705. [Back]

16.  ; Wingo PA et al, Age-specific differences in the relationship between oral contraceptive use and breast cancer. Cancer. 1993;71(4 suppl):1506-7. [Back]

17.  ;Rookus MA et al, Oral contraceptives and risk of breast cancer in women aged 20-54 years. Lancet.1994;334:884-851. [Back]

18.  ; Palmer JR, Rosenberg L et al. Oral contraceptive use and breast cancer risk among African-American women. Cancer Causes & Control.1995;6(4):321-31. [Back]

19.  ; Rosenberg L, Palmer JR, et al. Case-control study of oral contraceptive use and risk of breast cancer. Amer J Epidemiol. 1996;143:25-37. [Back]

20.  ; Olsson , Jernstrom H, et al. Proliferation of breast epithelium in relationship to menstrual cycle phase, hormonal use, and reproductive factors. Breast Cancer Research and Treatment.1996;143:25-37. [Back]

21.  ; Newcomb PA, Longnecker MP et al. Recent oral contraceptive us and risk of breast cancer. Cancer Causes Control.1996; Sep, 7:5,525-32. [Back]

22.  ; Brinton LA, Gammon MD, et al. Modification of oral contraceptive relationships in breast cancer by selected factors among younger women. Contraception.19797;55:4:197-203. [Back]

23.  ; Olsson , Borg A, Ferno M, et al. Her-2/neu and INT2 proto-oncogene amplification in malignant breast tumours in relation to reproductive factors and exposure to exogenous hormones.J Natl Cancer Inst.1991; 83:1483-87. [Back]

24.  ; Olsson H, Borg A, Ferno M et al. Early oral contraceptive use and premenopausal breast cancer - a review of studies performed in Southern Sweden. Cancer Detection and Prevention.1991;15(4):265-271. [Back]

25.  ; Ibid. [Back]

26.  ; Olsson H. et al ., Cancer. 1991;67(5): 1285-90. [Back]

27.  ; Sweet, op.cit. 1997. [Back]

28.  ; Hills Shire Times 13.6.95 (Baulkham Hills, NSW Aust). [Back]

29.  ; Media Tracking Service. 1995;186:Monday 18th Dec. [Back]

30.  ; Armstrong D. Breast Cancer - Women's Health Enemy No.1 Ita. May 1994. Sydney Aust. , p.27. [Back]

31.  ; Ibid. [Back]

32.  ; How to use your 28 day pack . Nordette, Nordiol , Triphail, Biphasil. Wyeth Pharmaceuticals, Gregory Place, Parramatta, NSW 2150 Aust. Product Information. [Back]

33.  ; Patient information leaflet- Microgynon 30 ED, Levlen ED, Logynon ED. Schering AG. Product Information. [Back]

34.  ; Modern Oral Contraceptives. Your questions answered. Schering Pty. Ltd 27-31 Doody St. Alexandria NSW. Patient Booklet. [Back]