Anal Cancer Rates Up, Particularly in Men
Changing Sexual Trends, More Infections, Increase the Risk
July 13, 2004 -- Anal cancer is on the rise among Americans. Men -- especially black men -- are at highest risk, a new study shows. Changing trends in sexual behavior and infections are among the causes, researchers say.
The report, appearing in the journal Cancer, is based on data from tumor registries in five states and four metropolitan areas: Connecticut, Hawaii, Iowa, New Mexico, and Utah; and Atlanta, Detroit, San Francisco, and Seattle, from 1973 to 2000.
Researcher Lisa G. Johnson, PhD, an epidemiologist with Fred Hutchinson Cancer Research Center in Seattle, reports:
- The incidence of precancerous (in situ) anal cancer increased fourfoldin men, from 7% in 1973 to 25% in 2000. Women's cases ranged from 8% to 10% during the same time period.
- Women's five-year survival improved substantially, from 59% in the 1970s to 73% in 2000. Men's survival rate stayed about the same during the three decades -- about 60%.Yet black men had a decrease in the five-year survival rates from anal cancer. During this same time period the five-year survival rates went from 45% down to only 27%.
- Black men had the sharpest increase in anal cancer -- more than double the rate of earlier years -- one case per 100,000 in the 1970s, compared with nearly three cases per 100,000 in 2000.
- Black men had increasingly bad survival odds during the 30-year period; 62% lived five years after diagnosis, compared with 79% of white men.
- Black women had the highest race-specific and gender-specific rates of anal cancer in the 1970s, with one case per 100,000. However, by 2000 black women had the lowest incidence, with two cases per 100,000. Black women had slightly worse survival odds, with 57% living five years compared with 65% of white women.
Increased screening of high-risk people may partially explain the pattern, explains Johnson.
However, evolving sexual trends are also taking a toll. More sex partners, human papillomavirus (HPV) infection, HIV infection, and anal intercourse have all contributed to this pattern, she writes. More black men seem to be having anal sex with other men than in early decades, she says.
Also, because black men and women have less access to health care, their survival rates may be affected. Advances in chemotherapy and radiation for treating anal cancer may be improving the survival odds for white people, Johnson writes. Also, because blacks have more cases of HIV infection, they may have a different response to treatment for anal cancer -- which would also affect their odds of surviving the cancer.
It's important that high-risk groups such as these are given regular screenings for anal cancer, to improve survival odds, says Johnson.
SOURCE: Johnson, L. Cancer, July 15, 2004; vol 101: pp 281-288.