Yesterday’s New York Times had an excellent story on the discovery of the human papilloma virus as the cause of cervical cancer, and ultimately, the development of a vaccine against it. It’s also a good lesson in how, while solid evidence triumphs over anecdotes, even folk stories can be useful in ultimately pointing to a cause if they’re rigorously investigated.
If you’re curious about what all this has to do with the messed-up looking rabbit in the picture, click on through…
I’ve written previously about the new cervical cancer vaccine, and its potential to lessen dramatically the incidence of cervical cancer in the U.S. and, especially, in developing countries, where pap smears are less common and therefore, cervical cancer is often not detected until it’s too late. Even in the U.S., the disease still kills 3,700 women each year, and affects 10,000. The vaccine is a huge step forward for women’s health, but its production is the result of a tangled lineage of just-missed insights, odd experiments, and finally, of course, big payoff.
Although cervical cancer is being beaten in rich countries thanks to Pap smears, it is still a great killer of the world’s poor. Fulminating tumors that can hemorrhage the womb or burst the intestine make death every bit as agonizing as it was for our great-grandmothers. Even in wealthy countries, aggressive forms appear in rare cases, forcing women barely in their 20’s to get hysterectomies.
Species as different as birds and whales have their own papillomas. There are more than 100 human strains. Many are harmless. Some cause warts on hands, noses or genitals, and some cause cancer. As a result, blame has been laid on origins like toads, witchcraft and God’s anger at promiscuous women.
Against that background of superstition, the two newest vaccines use technologies that sound almost like science fiction.
But each step forward to those techniques was a triumph of hard science over the pseudoscientific myths that for centuries surrounded the disease.
The writer, Donald McNeil Jr., notes many strange stories (and lots of bumps) along the road from the first observations about papilloma viruses to today’s vaccines. For example, a doctor recognized at least 150 years ago that cervical cancer appeared in women who engaged in sexual activity, but not in nuns (a crucial component of study of the disease in the past century). However, rather than investigate further just what it is about sex that may lead to the disease, he blamed it on tight corsets. Similarly, McNeil notes other observations that were close, but didn’t quite hit the mark, such as the idea that the herpes virus caused cervical cancer, or that it was due to exposure to male smegma.
On a parallel path was research such as that done by Richard Shope in the early 1900s. Shope was a noted virologist (he’d recently isolated and begun to characterize the first influenza viruses), and heard from a friend a story of rabbits with “horns.”
Dr. Shope asked his friend to send some of the horns. He then ground them up, filtered them through porcelain that let only tiny virus-size particles through, and injected the filtrate into other rabbits, which grew horns in turn.
Dr. Shope’s work showed the cause was a virus, but it was not until the 1980’s that DNA amplification allowed a German researcher, Dr. Harald zur Hausen, to pin down papilloma as the cause.
Another conventional wisdom stated that cervical cancer was rare among Jewish women, and this was the subject of a 1901 Lancet article musing about the reason.
More pseudoscientific myths arose trying to explain that. (The Lancet writer, whose thesis was that salt caused cancer, believed that Jews were protected by avoiding bacon.) But it took the founding of Israel, drawing Jewish women from all over the world, to debunk them.
Rather than being an effect of culture, it was found that a particular mutation in the tumor suppressor gene p53 was uncommon in this group of women; therefore, many were genetically more protected against this form of cancer.
A fascinating little romp through history, stories like these show the value of listening to “wive’s tales,” but also the utility that comes from a rigorious scientific investigation of them rather than an acceptance of their validity wholesale.
Image from http://graphics8.nytimes.com/images/2006/08/29/science/hpv.3.190.jpg