Patients enrolled in the Swiss HIV cohort study initially gave their consent for participating in this type of study. Almost all patients at the HIV centres consented to take part in genetic research in order to identify specific factors that might result in differences in the course of the disease. Obviously, all analyses will be performed on tumor specimen, and these will not be traceable to the patients' identities. Thus, all genetic testing will be totally anonymous. By contrast, further approval by the local Ethics Committee in Geneva will be sought, should the analysis be performed on tumor specimen from HIV-negative patients.