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News from the War on Cancer
Although much research has been ongoing over the past several decades in the area of cancer prevention, true major breakthroughs are uncommon. One possible candidate-a vaccine for cervical cancer--was recently reported in the New England Journal of Medicine by Koutsky and associates (NEJM 2002;347:1645-51).
In the early 1980s, it was recognized that cervical cancer had its origins in human papillomavirus (HPV) infection; later research indicated that several specific strains were the major pathogens in this regard, notably HPV 16 and 18. These viruses are sexually transmitted and probably reflect the observed risk factors for this disease. It has been estimated that one particular HPV strain, type 16, is responsible for approximately 50% of cervical cancers.
One advantage of recognizing infectious causes of cancer is the possibility of developing vaccines, as has been done for hepatitis B and hepatocellular carcinoma, which has experienced a 75% decline in incidence in East Asia that continues to fall. In this recent NEJM article, Koutsky and colleagues report on a randomized trial of a new HPV-16 vaccine, in which 2,392 women, ages 16-23 years, were randomized to receive the vaccine or placebo. Even with only 17 months of follow-up, there was a 3.8/100 women-years incidence of HPV-16 infection in the placebo group, with no new infections in the vaccine group (100% efficacy). Furthermore, all nine cases of cervical neoplasia that occurred were in the placebo group, with none in the vaccine group.
Cervical cancer is one of the most common causes of cancer-related mortality among females in the world, especially in Latin America and Africa. Pap smears have dramatically reduced its impact in the US and the Western world. With this new technology, perhaps we will soon see cervical cancer go the way of other formerly dreaded but vaccine-receptive diseases, such as polio. |
