Wednesday, June 18, 2008

The dangers of exclusionary science, or: Can you trust your doctor?

If you're female, perhaps you can't. People tend to think of their own doctors and medicine as a whole as objective, scientific and above all, ethical. Perhaps this is a coping tactic in the face of the unappealing truth that medicine is far from free of sociocultural bias. As an element of our society, the medical profession is subject to influence by modern social values. This influence becomes a problem, however, when it urges doctors to disregard science in favor of whim, driven by exclusionary doctrines that treat sections of the population as inferior.

Case in point: the "special" category of women's health (which, of course, applies to about half the people in the world) is but a few decades old. Nearly all of the research that informs current medical practice was done solely on white males. How did we get to this point? Here's a short history lesson:

Language "urging" (but not requiring) the inclusion of women in federally-funded health research was first published in the National Institutes of Health's (NIH) Guide to Grants and Contracts in 1987. In 1994, NIH finally enacted a Congressional mandate to include women and minorities in research. Prior to 1994, it was considered a good idea, but not mandatory, and the flimsiest of excuses (such as cost) would suffice for excluding half of the population to which the findings would be applied.

"Interference" by women's hormonal vicissitudes and the risk of pregnancy were cited as reasons for excluding women from research before 1994, although this was obviously many years after the development of oral contraceptives. Researchers apparently felt safe concluding that the factors that justified exclusion of women did not preclude generalizing the results of research done on white males to women of all races.

The media's love affair with breast cancer, when heart disease is the top killer of women, is emblematic of the sociocultural influence on women's health. Although public polls show that women think breast cancer is the top killer, breast cancer is not even the most common cancer killer of women. What is? Lung cancer. According to SEER, from 2001-2005, the "median age at diagnosis for cancer of the breast was 61 years of age." From a very large study of lung cancer published in Annals of Oncology (2002), "women developed the disease at an earlier age than men (60.02 versus 62.18 years; P <0.001)." In other words, both lung and breast cancer are usually found around age 60, so the "popularity" of breast cancer cannot be attributed to younger age at diagnosis.

There are alternative explanations for our culture's breast cancer fascination. Among them is the idea that lung cancer, and some other cancers, are self-induced whereas breast cancer is blameless. A second is that our culture loves breasts so much that damaged or missing breasts are seen as horrible, even if the woman survives. No one mourns a lost lung this way.

Most of the women answering those public polls do not know that heart disease is actually the greatest threat to their health. Heart disease is the greatest killer of both women and men, yet the image of the older man clutching his chest is what comes to mind when Americans think "heart attack." The so-called classic heart attack symptoms do not happen in women, who are more likely to experience jaw pain, back pain, fatigue, and nausea. Something's very, very wrong with this picture: although women die of heart attacks more than anything else, why do they still think the signs of a heart attack in a man are what they ought to be looking for? It's a different syndrome in women, but few women know that because of the emphasis placed on male symptoms of heart attack. Indeed, the science behind heart attack symptoms in women is relatively new - no one thought to do research on women and heart disease until after the 1994 NIH mandate.

This brings us to the terrifying tale of hormone treatment. Hormone replacement therapy was perpetuated by physicians who simply assumed that restoring a woman's youthful hormone balance would yield cardiovascular benefits. The temporal relationship between hormonal changes at menopause and increased incidence of heart disease later in life was never shown to be causal. Hormones were prescribed to millions of women for decades with barely a shred of evidence that hormone treatment decreased cardiovascular risk, or at least did not elevate it. In 1990, the FDA declined to add heart disease prevention to the list of indications for hormone therapy because of the lack of evidence. When the proper studies were finally done, it became clear that estrogen/progestin combinations actually increased women's risk of heart attack and stroke.

An early form of hormone treatment was diethylstilbestrol, or DES. The Food and Drug Administration approved DES for use in pregnant women to prevent miscarriage in 1947. The drug had not undergone safety testing, and as a consequence, many women who took DES suffered consequences that included breast cancer in the mothers and a higher rate of cancers and birth defects in their children. Nonetheless, the FDA did not remove DES from the market until 1971.

Estrogen has been used since the 1930s to treat hot flashes and other physical changes that women experience at menopause. But starting in the 1960s, the list of reasons for women to take hormones began to grow. In 1966, the book Feminine Forever became a best seller with its claim that "menopause is completely preventable." The book's author, Dr. Robert A. Wilson, asserted that postmenopausal women who didn't accept hormone replacement were no longer truly female. Wilson traveled the country, lecturing on this topic and promising that with the help of estrogen therapy, "Every woman alive today has the option to remain feminine forever." He was later revealed to be a paid spokesman for a firm that sold estrogen replacement. Nice guy.

Dr. Wilson's tactic, reframing the natural as pathological in order to sell a treatment, is well-known in medicine. Consider the promotion of the medical diagnosis "micromastia" by plastic surgeons. Micromastia means small breasts. It does not mean inadequate mammary tissue to lactate and breastfeed a child, which would be a physiologic problem. It refers to a cosmetic problem that plastic surgeons can "cure."

So are you still confident that medicine's not sexist? I consider hormone treatment and the breast cancer fascination sufficient evidence of bias in medicine, but if you need more, just look up the derivation of the word "hysteria."