Why the silence about studies that show a link between oral contraceptives and cancer?
What’s the difference between taking hormones for menopause and taking hormones as a contraceptive? If you’re the Canadian Cancer Society, you’ll warn of the cancer risks of one, but not the other. For more than a year, the society has cautioned women that hormone replacement therapy – a treatment of estrogen and progestin, used to curb symptoms of menopause – increases their risk of breast cancer. But while growing numbers of experts suspect that birth control pills – which also contain estrogen and progestin – pose similar cancer risks, the CCS is silent on that product’s dangers, leading some to question whether the CCS is allowing politics to influence the way it treats matters of public health.
In 2004, when the CCS added HRT, in use for decades, to its list of possible causes of breast cancer, it seemed not only reasonable, but urgent, to do so. That year, a U.S. study into HRT was forced to a premature halt when researchers found the cancer risks of HRT for the female subjects outweighed the benefits of continuing the trial.
But the society has been taking a go-slow approach when it comes to gauging the potential risks of a close cousin of HRT, the pill, which has been used at some point by 84 per cent of Canadian women. Several doctors say there’s little difference between the two – except that the pill is riskier. “HRT is different from the pill in that HRT is actually much safer,” says Dr. Stanislaw Iwanicki, who has practised obstetrics and gynecology in Calgary for 20 years. The dose of estrogen, a carcinogen, is about three to five times higher in the pill than in HRT, he notes. And women often take the pill over longer periods of time and at a younger age.
Heather Logan, director of cancer control policy at the Canadian Cancer Society, says she’s not aware of any conclusive study proving the pill causes cancer, so the group makes no comment. “What I can comment on is that we are aware that there is a need to really look at the literature and we will be doing that in the coming months,” she says. Of the $21 million the CCS spent on breast cancer research between 2001 and 2006, none was allotted to probing the cancer risks of oral contraceptives.
Still, other studies raise worrying questions. Dr. Chris Kahlenborn, a Pennsylvania internist and author of Breast Cancer: Its Link to Abortion and the Birth Control Pill, says there are more than 18 studies – from such groups as the National Cancer Institute and the World Health Organization – that suggest the pill increases cancer risk.
As recently as July, the WHO’s International Agency for Research on Cancer released study results showing that both HRT and hormone-based oral contraceptives were “carcinogenic.” But, Kahlenborn says, in an era when the pill is seen as a liberator for women and sexuality in general, the subject is threatening. When Kahlenborn was asked to testify before the Food and Drug Administration in 2000, many people at the hearing refused to listen to him. “One woman walked out before I even started my talk,” Kahlenborn says. “And the rest of them just put their heads down.”
U.S. journalist Barbara Seaman has covered hormones since the 1960s, authoring books including 2003’s The Greatest Experiment Ever Performed on Women, which cited evidence that the birth control pill poses manifold health risks. Seaman noted that Dr. Edward Charles Dodds, who invented synthetic estrogen in 1938, cautioned that it should be used only when necessary (say, for young girls born without ovaries and thus lacking estrogen). “It stimulates cells to grow faster, which is not always a good idea,” he warned. “If you take too much for too long, you may get cancer.”
Nearly 70 years later, Kahlenborn worries that the refusal of cancer groups – and not just in Canada – to warn women about the pill’s risks is endangering lives. “For the last 40 years, doctors said hormone replacement is safe,” he says. “In the last five years or so, they said, ‘Uh-oh, we made a big boo-boo.’ And I think they are going to do that with the pill in the next 10 years.” If that happens, women will want to know what took them so long.
This article first appeared in the Jan. 30 edition of The Western Standard. It is reprinted with permission.