Tuesday, August 29, 2006

Nuns, hookers and blind alleys

An interesting article in today's New York Times provides some insights into the on-going success of modern medical science, and the dangers of the obsession with health and lifestyle.

Two new vaccines have recently been approved in the United States to protect women against human papillomavirus (HPV) which in recent years has been confirmed as the cause of the vast majority of cases of cervical cancer. However, the search for the cause of cervical cancer has taken many twists along the way. As early as 1842, apparently, a doctor in Florence noted that prostitutes and married women died of cervical cancer, but nuns very rarely did. The logical answer was that the disease was in some way sexually-transmitted, but unfortunately the doctor was sidetracked by the observation that nuns died of breast cancer instead and concluded it was a problem with nuns' corsets being too tight.

In the 1970s, the disease was linked to genital herpes. Obviously, people who are prone to one sexually-transmitted disease are frequently exposed to others, but this only goes to reinforce the old lesson that correlation does not equal causation. The link between herpes and cancer was pure coincidence. The observation that women who have more sex are more likely to get cervical cancer is correct - but it is not the sex itself that is causing the cancer, any more than gay sex per se causes AIDS. Sex merely makes transmission more likely for particular infections. While a typical response to such observations has been to moralise about the lifestyles of the victims of these diseases, a better approach is to provide a vaccine that frees people from the danger of contracting a deadly disease and allows them to have sex without fear.

There are parallels between the story of cervical cancer and ulcers. After years of being told to avoid spicy food, alcohol, stress and myriad other lifestyle risks, it was discovered that most peptic and duodenal ulcers were caused by an infection, helicobacter pylori, which can be simply treated with antibiotics.

Which begs the question: when health authorities and researchers focus so much on gleaning correlations between behaviour and illness, are we proceeding up yet more blind alleys? Will people remain ill, even die, because avenues for investigation are frequently ignored in favour of lectures about how we should eat, drink, smoke and shag?

How a Vaccine Search Ended in Triumph, New York Times, 29 August 2006

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