amfAR, The Foundation for AIDS Research

Improving Understanding of Anal Cancer Risk Among MSM in Thailand

March 2009—Among men who have sex with men (MSM), anal cancer has been diagnosed more frequently among those engaging in receptive anal intercourse and those infected with HIV. In a study conducted in the U.S., anal cancer was reported at an incidence of 35 in 100,000 MSM, with the risk of anal cancer among HIVpositive MSM double that of HIV-negative MSM.1 But in Asia, anal cancer has remained largely understudied.

In Asia, anal cancer has remained largely understudied.
Doctors can screen for anal cancer with a Pap smear, which checks for the presence of cancerous cells under a microscope, and then confirm abnormal results with a biopsy. The Thai Red Cross Anonymous Clinic (TRCAC) in Bangkok found that of the 174 anal Pap smear tests its staff performed on MSM between January 2007 and April 2008, 73 percent were normal, 13 percent were troubling but not clearly cancerous, and 14 percent had some evidence of cancer known as squamous intraepithelial lesions (SIL).2  HIV-positive MSM had a significantly higher rate of SIL (18 percent) than HIV-negative MSM (5 percent).

To increase regional capacity to diagnose and treat anal cancer among MSM, amfAR's MSM Initiative provided funding to TRCAC in April 2008 to establish an MSM sexual health clinic in Bangkok. The clinic provides screening and treatment for sexually transmitted infections, anal Pap smear testing, treatment of abnormal anal Pap smears, and risk reduction counseling services.

From April to September 2008, 1,719 MSM clients visited the clinic. Of these, 253 received anal Pap smears and 27 percent had abnormal results. These clients are now receiving follow-up care through the TRCAC MSM sexual health clinic. More resources are needed to study anal cancer risk among MSM in Asia and provide diagnostic screening and treatment.

1Frisch M, Biggar RJ, Goedert JJ. Human papillomavirus-associated cancers in patients with human immunodeficiency virus infection and acquired immunodeficiency syndrome. J Natl Cancer Inst. 20 Sept. 2000;92(18):1500-1510.
2 Li A, Phanuphak N, Sathianthammawit W, Avihingsanon A, Chaithongwongwatthana S, Teeratakulpisarn N, et al. HPV-associated anal disease in HIV-positive and HIV-negative men who have sex with men in Thailand. In: XVII International AIDS Conference. Mexico City, Mexico; 3-8 August 2008. Abstract no. THPE0222.