CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

717 Excess Risk of Rectal Squamous Cell Carcinoma in HIV-Infected Persons Anna E. Coghill ; Meredith S. Shiels; Eric A. Engels National Cancer Institute, Rockville, MD, US

Background: The majority of rectal cancers diagnosed in the US are adenocarcinomas. Rectal squamous cell carcinoma (RSCC) is rare, representing only 1-2% of rectal tumors in the general population. However, we observed in preliminary analyses that ~30% of rectal tumors in HIV-infected persons were RSCC. We therefore explored whether HIV-infected persons have a significantly higher risk of RSCC. Methods: We utilized the HIV/AIDS Cancer Match, a linkage of US HIV and cancer registries (1991-2010), to ascertain cases of rectal (squamous and non-squamous) and anal cancer. We calculated standardized incidence ratios (SIRs) comparing the number of observed cases in HIV-infected persons to the number expected based on general population rates. To examine whether RSCC in HIV-infected persons represents systematically misclassified anal cancer rather than a distinct entity, investigators reviewed case notes for a subset of rectal and anal tumors. Results: Among 1,194 HIV-infected persons, 89 cases of RSCC were diagnosed. HIV-infected persons had an elevated risk of RSCC (SIR=28.9; 95% CI 23.2-35.6), similar to that reported for anal cancer (SIR=32.3; 95% CI 30.0-34.6). The largest RSCC excess occurred in MSM (SIR=61.2; 95% CI 47.8-77.0). In contrast, non-squamous rectal cancer risk was not elevated among HIV-infected persons (SIR=0.88; 95% CI 0.74-1.04). Approximately 33% of RSCC cases were determined to be misclassified anal cancer cases after review, but misclassification was non-differential (HIV-infected: 34.5%; HIV-uninfected: 33.3%).

Poster Abstracts

Conclusions: HIV is associated with a substantial excess risk of RSCC. The pattern of excess risk is similar to that observed for anal cancer, an HPV-associated tumor. Although a portion of cases may be misclassified anal cancer, the amount of misclassification was too small to explain the excess. RSCC in HIV-infected persons could represent a previously unrecognized and etiologically distinct subset of rectal tumors, with the particularly high risk in MSM pointing to involvement of a sexually transmitted infectious agent such as HPV.

WEDNESDAY, FEBRUARY 25, 2015 Session P-O2 Poster Session 2:30 pm– 4:00 pm AIDS-Related Cancers: Lymphoma and KS 718 Incidence and Outcomes of HIV-Associated Lymphomas in Botswana

Poster Hall

Michael G. Milligan 1 ; Elizabeth Bigger 3 ; Musimar Zola 7 ; Mukendi Kayembe 6 ; Heluf Medhin 5 ; Gita Suneja 4 ; Shahin Lockman 2 ; Jeremy Abramson 3 ; Bruce Chabner 3 ; Scott Dryden-Peterson 2 1 Harvard Medical School, Brookline, MA, US; 2 Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, US; 3 Massachusetts General Hospital, Harvard Medical School, Boston, MA, US; 4 University of Utah, Salt Lake City, UT, US; 5 Botswana Ministry of Health, Gaborone, Botswana; 6 Botswana National Health Laboratory, Gaborone, Botswana; 7 Princess Marina Hospital, Gaborone, Botswana Background: In the US and Europe, lymphoma incidence fell with introduction of ART. However, incidence of non-Hodgkin’s (NHL) and Hodgkin’s lymphoma (HL) has risen despite excellent ART access in Botswana. We sought to better understand the paradoxical rise in incidence and assess the treatment and outcomes of patients with NHL and HL in Botswana.

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CROI 2015