Herpes simplex virus infection in cancer patients: prevention and treatment.

Herpes simplex virus (HSV) infection is common in patients receiving cytotoxic therapy for cancer. Almost all infections result from reactivation of latent virus during treatment-induced immunosuppression. Typical, self-limited orolabial or genital ulceration does not always require laboratory diagnosis or treatment, but HSV may present in an atypical fashion in cancer patients and cause more severe and prolonged mucocutaneous infection or visceral disease. The presence of antibodies to HSV identifies patients at risk for recurrent HSV infection. The treatment of choice is acyclovir, which may also be used to prevent infection in high-risk patients. Acyclovir resistance has been reported in patients with profound and prolonged immune deficiency, but remains rare in patients treated for cancer.