Anti-herpesvirus treatment and risk of Kaposi's sarcoma in HIV infection. Royal Free/Chelsea and Westminster Hospitals Collaborative Group.

OBJECTIVE: With the recent identification of a new herpesvirus in patients with Kaposi's sarcoma (human herpesvirus-8 or Kaposi's sarcoma-associated herpesvirus), there have been several reports on the use of anti-herpesvirus therapy (foscarnet, ganciclovir and aciclovir) and risk of developing Kaposi's sarcoma. We therefore investigated the association between use of anti-herpesvirus drugs and Kaposi's sarcoma in a large unselected group of patients with AIDS. PATIENTS AND METHODS: We studied a group of HIV-positive patients at the Chelsea and Westminster Hospital, for whom details on all AIDS-defining diagnoses made during follow-up, treatment and regular CD4 counts were available. Cox proportional hazards models with time-dependant covariates were used to assess the association between treatment with aciclovir, foscarnet and ganciclovir and risk of Kaposi's sarcoma.
RESULTS: A total of 3688 patients have been followed up for a median period of 4.2 years, during which time 598 patients (16.2%) developed Kaposi's sarcoma. After adjustments for sex, exposure category, age, treatment with antiretrovirals or Pneumocystis carinii pneumonia prophylaxis, the development of AIDS-defining conditions (including separate adjustment for the development of cytomegalovirus and herpes simplex virus) and CD4 count, there was a decreased risk of developing Kaposi's sarcoma with foscarnet [relative hazard (RH), 0.38; 95% confidence interval (CI), 0.15-0.95; P = 0.038] and with ganciclovir (RH, 0.39; 95% CI, 0.19-0.84; P = 0.015), but not with aciclovir (RH, 1.10; 95% CI, 0.88-1.38; P = 0.40).
CONCLUSIONS: These results suggest that both foscarnet and ganciclovir may have some activity in preventing the occurrence of Kaposi's sarcoma, but that aciclovir has no benefit. Further studies of the effect of these drugs on the risk of Kaposi's sarcoma is warranted.