The number of HIV patients with Kaposi sarcoma, a once-rare cancer that became a marker for AIDS in the early days of the epidemic, has declined sharply due to the use of antiretroviral drugs, according to a European study released on Monday.

The annual incidence of the cancer fell 39 percent between 1994 and 2003, according to a study of nearly 10,000 people with HIV by the Royal Free and University College in London and a handful of other European hospitals and health centers.

Kaposi sarcoma first appears as a brownish-colored skin lesion, although it can also develop in the lungs, liver and other internal organs. Until AIDS surfaced in 1981, the cancer was seen primarily in elderly Mediterranean men.

It became one of the most common ailments plaguing AIDS patients in the 1980s.

But the introduction a decade later of highly active antiretroviral therapy (HAART) - a treatment based on a combination of drugs - gave doctors a powerful new weapon against the opportunistic diseases that killed many AIDS victims.

Anecdotal data and small studies had indicated Kaposi Sarcoma cases were declining as the new drugs suppressed levels of HIV in patients’ blood and allowed their immune systems to recover.

The large European study was, however, the first conclusive indication of a link between the therapy and declining cases of Kaposi sarcoma. The findings were published in the May 10 online edition of the American Cancer Society’s journal Cancer.

In their study, the Europeans noted that those with a higher current CD4 count - a measure of immune system health - or who had been on HAART therapy for a longer period of time had a decreased incidence of the cancer.

“This indicates that the current CD4 count remains one of the most important prognostic factors for Kaposi sarcoma, and patients who start HAART should experience a reduction in the risk of Kaposi sarcoma if the CD4 count starts to rise,” the researchers said.

The good news was partly overshadowed by a significantly increased incidence of the disease among gay men and in patients from Central and Western Europe. Kaposi sarcoma makes up 6 percent of all AIDS-defining illnesses each year.

AIDS has killed more than 21 million people around the world, including about 500,000 Americans since 1981. About 40,000 Americans become infected with HIV every year.

SOURCE: Cancer, June 15, 2004.