SAN FRANCISCO (AP) – Some Bay Area doctors are promoting Pap tests for gay men to reduce rising rates of anal cancer.

U.S. cases of anal cancer have risen 37 percent in the last 10 years, compared to a 1 percent increase in overall cancer cases. Part of the increase is believed to be because of better reporting.

Anal Pap smears would help doctors detect precancerous lesions before they turn malignant, said Dr. Joel Palefsky, director of the Anal Neoplasia Clinic at the University of California, San Francisco.

“We haven’t proven it yet, but we believe that we are likely to be preventing anal cancer,” said Palefsky, who is preparing a report on anal cancer prevention.

Other doctors say there is disagreement over whether the tests are necessary or effective. The test should be left to the doctor’s and patient’s discretion, said Dr. Michael Horberg, director of HIV-AIDS for Kaiser Permanente and an HIV specialist at Kaiser Santa Clara Medical Center.

The American Cancer Society said there were about 4,660 cases of anal cancer in the United States last year, resulting in 660 deaths. Anal cancer accounts for less than 1 percent of cancer cases and is readily treatable if detected.

Overall, more women than men get anal cancer. But the disease is disproportionately high among gay men and people who are HIV-positive or have other immune-suppressive conditions.

Studies have found rates of anal cancer as high as 35 cases for every 100,000 gay men, similar to rates for cervical cancer before women began routinely getting Pap tests 60 years ago. Cervical cancer rates have dropped 70 percent since then. Both cancers are caused by the same sexually transmitted virus.

“Anal cancer is a silent issue that’s been building for at least 10 years,” said Jason Riggs, a spokesperson for the Stop AIDS Project. “And it’s sad because it’s incredibly preventable.”