Colon adenocarcinoma in HIV infected patients

Background

Non AIDS-defining cancers (NADC) have emerged as a growing problem in the HIV-positive population, especially given that HIV-infected patients are living longer with antiretroviral therapy (ART). HIV-Tat protein appears to have oncogenic properties in colorectal cancer cells in vitro. To date, there has been no large series studying HIV-associated colon adenocarcinoma. Therefore, the aim of this study was to examine the clinicopathologic features of this NADC in a series of HIV-positive patients.

Methods

Cases of HIV-associated colon adenocarcinoma (excluding anorectal location and non-epithelial cancers) were accrued from the personal archives of the authors and from case reports with available information published in the literature. Available data regarding demographics (age, gender), HIV acquisition, ART use, immunosuppression (AIDS and/or CD4 count), cancer location, pathology (tumor grade, TNM stage), and outcome were extracted and analyzed.

Results

A total of 15 patients were identified, including five personal cases and 10 published reports. Patients were an average age of 42 years (range 25–67) and predominantly male (M:F 12:3), of which six were known intravenous drug users and four homosexual. Most (59%) carcinomas involved the right colon, and less frequently the sigmoid (25%), transverse (8%) or entire (8%) colon. Tumor differentiation ranged from grade 1 (17%), to grade 2 (50%) and grade 3 (33%) carcinomas. Most (62%) were stage 4 cancers, and less often stage 3 (23%) or 2 (15%) malignancies. Metastases when present were mainly to the liver, but included the lung, ascites and subcutaneous tissue. Many (62%) individuals died shortly (within 1–26 months) after their cancer diagnosis. Immunosuppression (AIDS diagnosis and/or CD4 <200 cells/mm³) noted in eight (53%) individuals did not appear to correlate with tumor grade, stage, nor an adverse outcome. Neither did ART use, which was reported in eight (53%) of these patients.

Conclusion

Adenocarcinoma of the colon should be added to the growing list of NADC. These data show that HIV-infected patients manifesting with colon cancer tend to be younger than their HIV-negative counterparts, with a male predominance. HIV-associated immunosuppression and prior exposure to antiretroviral therapy do not appear to have a major impact on tumor biology or patient outcome. Frequent involvement of the right colon suggests that colorectal cancer screening of the entire colon should be offered to HIV-infected individuals.