Cervical cancer and use of hormonal contraceptives: a systematic review
The Lancet 2003 Vol 361 pp.1159- 67: A Brief Summary.

John Wilks
Consultant Pharmacist.
April 8th 2003
Reproduced with Permission

A Brief Summary.


Soon after the introduction of the birth control pill in the late 1960s, evidence emerged suggesting a link between the use of the birth control pill, and an increased incidence of cervical cancer in users.

Since 1988 fifteen papers have been published supporting the claim that users of the birth control pill were at an increased risk of developing cervical cancer. These studies have been documented in my text A Consumer's Guide to the Pill and other Drugs (3rd Ed, National Bookstore, Manilla, 2000).

A major issue that emerged in the medical literature during those years was the role of a viral infection called human papilloma virus (HPV). Many studies reported that pill users who presented with cervical cancer had been or were infected with human papilloma virus (HPV), a sexually transmitted disease.

It was known that this virus contained genetic material that had a proven carcinogenic capacity. Hence the question arose - was the pill the cause of the cervical cancer; was it the virus; or was it a synergistic interaction between the two suspected carcinogens?

The data published in this weeks Lancet supports the view that use of the pill, particularly for 10 years or more, is exclusively linked to an increased risk of cervical cancer (compared to non-users). The presence of HPV is not necessary for the genesis of cervical cancer. Unfortunately if a woman is infected with HPV and also taking the pill, her risk of developing cervical cancer is higher, at least after 10 years pill use, when compared to the increased risk seen in a woman free of the virus but having used the pill for the same length of time. (150% increased risk v. 120% increased risk - see below).(1)

The finding.

  1. 28 studies were analysed, which included a total of 12,531 women.
  2. The study was a joint literature review conducted by the International Agency for Research on Cancer (Lyon, France), the Cancer Research UK Epidemiology Unit (oxford, UK), the Institute of Cancer Research (Sutton, Surrey) and the London School of Hygiene and Tropical Medicine (London).
  3. The risk of cervical cancer increased with duration of pill use compared to non-users. For pill users not infected with HPV:
    1. The risk of cervical cancer increased by 10% for pill use of less than 5 years.
    2. The risk increased by 60% for pill use of between 5-9 years.
    3. The risk increased by 120% for all women using the pill for more than 10 years.
  4. For pill users who were infected with the human papilloma virus (HPV), the increased risk of cervical cancer was also linked to the duration of use of the pill.
    1. The risk decreased by 10% for pill use of less than 5 years
    2. The risk increased by 30% for pill use of 5-9 years
    3. The risk increased by 150% for all women using the pill for more than 10 years.

In my view the opening sentence of the "Discussion" section of this paper by Smith, Plummer and Franceschi aptly summarised the irrefutable nature of these findings.

"The results of this systematic review of published data show that the relative risk of cervical cancer increases with increasing duration of oral contraceptive use, in virtually every way that data were examined."

It is to be hoped that this definitive study will finally silence those who have sought to discredit my writings on this topic in the three editions of my book, dating back to the first in 1996.

In my opinion, many women have been denied the opportunity to become familiar with the truth about the carcinogenic nature of the birth control pill because of the actions of my detractors.

[1. Ory HW et al A Preliminary analysis of oral contraceptive use and risk of developing premalignant lesions of the uterine cervix. In: Garratini S, Berendes HW, eds Pharmacology of steroid contraceptive drugs. New York, Raven Press 1977 211-24. in Brinton LA. Oral contraceptives and cervical neoplasia. Contraception 1991; 43:(6). p. 584. Table 2.]