Objective: To study the incidence of AIDS-defining and non-AIDS-defining malignancies in injecting drug users with and without HIV infection in a methadone maintenance treatment program (MMTP).
Design: Prospective study within a hospital-affiliated MMTP with on-site primary medical services. The MMTP has been the site of a voluntary longitudinal cohort study of HIV infection since 1985.
Methods: Active surveillance for all new cancer cases occurring among patients in the MMTP between July 1985 and August 1991. Cancer cases were identified by review of clinic and hospital records, hospital-based tumor registries, and New York City vital records. Cancer incidence was determined for the overall MMTP population and for HIV-seropositive and HIV-seronegative cohort study subgroups.
Results: During the study period the MMTP population comprised 2174 patients followed for 5491 person-years; 844 patients (380 HIV-seropositive, 464 HIV-seronegative) also participated in the cohort study. Fifteen non-AIDS-defining malignancies occurred among all MMTP patients (2.73 cases per 1000 person-years); the most frequent sites were lung, larynx, and cervix (n = 6, 2 and 2, respectively). Eighty per cent of patients with these cancer diagnoses and known HIV serologic status were seropositive. Within the cohort study group, six out of 380 HIV-seropositives developed non-AIDS-defining cancers versus one out of 464 HIV-seronegatives (P = 0.05, Fisher's exact test). Lung cancer cases in HIV-seropositive patients tended to occur at an earlier age and was more aggressive than in patients with HIV-seronegative or unknown status. During the same period, two cases of AIDS-defining lymphoma and one case of Kaposi's sarcoma were diagnosed in the MMTP population (0.5 cases per 1000 person-years).
Conclusion: Solid neoplasms, while infrequent, were associated with HIV infection and were more common than AIDS-defining cancers in this population of drug injectors. Further study is needed to explore the relationship between HIV, behavioral factors, and cancer risk in injecting drug users.