Characteristics of persons with AIDS are described in . Eighty percent were male, and the median age at AIDS onset was 38 years. Overall, 38.8% of the cohort were non-Hispanic whites, but this proportion declined over time, and the proportion of non-Hispanic blacks and Hispanics increased. The most common HIV risk group was men who have sex with men (MSM, 43.4%). At AIDS onset, the median CD4 count was 108 cells/mm3. Half of the subjects lived in U.S. areas with ultraviolet radiation index less than 4.0, while 38.4% lived in areas with an ultraviolet radiation index of at least 5.5.
Characteristics of subjects (N=497,142) in the U.S. HIV/AIDS Cancer Match Study, according to calendar year of AIDS diagnosis
For the overall cancer risk period, people with AIDS had a 30% increased risk of melanoma (SIR=1.3, 95%CI 1.1-1.4, n=292 cases) (). Risk was greatly increased for Merkel cell carcinoma (SIR=11, 95%CI 6.3-17, n=17 cases) and, to a lesser extent, for appendageal carcinomas (SIR=4.2, 95%CI 2.5-6.7, n=17 cases). Risk was especially elevated for sebaceous carcinoma (SIR=8.1, 95%CI 3.2-17, n=7 cases), which was the most common subtype of appendageal carcinoma.
Risk of skin cancers among subjects in the HIV/AIDS Cancer Match Study
As shown in , the risk for melanoma appeared similarly elevated for tumors of the face/head, trunk, and upper extremities. In contrast, risk was not increased for melanoma of the lower extremities. Risk of Merkel cell carcinoma was significantly increased for all skin sites evaluated. For all appendageal carcinomas (including sebaceous carcinoma), risk was significantly elevated for the face/head, and 3 to 9-fold increased risks (although not significant) were observed at other sites as well. Although risk of sebaceous carcinoma was elevated for the face/head, no sebaceous carcinomas of the eyelid were reported.
Risks for melanoma, Merkel cell carcinoma, and appendageal cancers relative to the time of AIDS onset are depicted in . Risk for melanoma increased non-significantly over time (p=0.10, ). The trend for Merkel cell carcinoma was not significant (p=0.66, ). In contrast, risk of all appendageal carcinomas combined increased significantly over time relative to AIDS onset (p=0.03, ). Cases of sebaceous carcinoma were too few to be analyzed separately.
Figure 1 Risk of skin cancers among persons with AIDS, as a function of time relative to AIDS onset. Results are shown for melanoma (panel A), Merkel cell carcinoma (panel B), and all appendageal skin carcinomas (panel C). The standardized incidence ratios are (more ...)
compares the risk of these skin cancers across subgroups of the cohort. During the overall cancer risk period, melanoma risk was higher in males than females, while the other tumors were observed only in males. Risk for each cancer type increased with age and was higher in non-Hispanic whites than in other race/ethnic groups. Melanoma risk was highest among the MSM group, the only HIV risk group with significantly higher risk than the general population (SIR 1.6, 95%CI 1.4-1.8). A similar pattern was seen for appendageal carcinomas (), with significantly elevated risk observed in MSM (SIR 6.8, 95%CI 3.6-12) and MSM who were also injection drug users (SIR 11, 95%CI 1.3-38). Melanoma risk was consistently elevated across all calendar years of AIDS diagnosis, whereas risk for appendageal carcinomas declined across calendar year of AIDS diagnosis (p-trend=0.03). For melanoma, CD4 counts at AIDS onset were unrelated to incidence in the early post-AIDS period (p-trend=0.32, based on n=185 melanoma cases with data on CD4 counts).
Risk of skin cancers among subjects in the HIV/AIDS Cancer Match Study, according to demographic characteristics
As shown in , the risk for each cancer appeared to rise with increasing exposure to ultraviolet radiation, as measured by the registry area’s ultraviolet index, with significant trends seen for melanoma and appendageal carcinomas. depicts this relationship in more detail for melanoma, restricted to non-Hispanic white adults (among whom the majority of cases occurred). Risk increased with increasing ultraviolet radiation index for melanomas of the face, head, and upper limb (i.e., body sites with the greatest sun exposure, p-trend=0.003, ), as well as for melanomas of the trunk, lower limb, and other/unspecified sites (p-trend=0.06, ). When we considered all melanoma sites together, risk among non-Hispanic whites was independently associated with HIV risk group (MSM vs. others: odds ratio 1.7, 95%CI 1.2-2.4) and increasing ultraviolet radiation exposure (p-trend=0.005).
Figure 2 Melanoma risk among persons with AIDS, according to ultraviolet radiation exposure. Results are shown for melanomas of the face, head, and upper limb (Panel A) and melanomas of the trunk, lower limb, and other/unspecified sites (Panel B). Results are (more ...)
Four persons were diagnosed with two melanomas each. Among the melanoma cases, the following additional cancers were seen: 45 with KS, 15 with NHL, and two with Hodgkin lymphoma. Four individuals with Merkel cell carcinoma had additional cancers, including one case each of KS, Hodgkin lymphoma, anal cancer, and carcinoma of unknown type. Among persons with sebaceous carcinoma, one subject also had NHL (subtype unspecified), and one had KS. Finally, among individuals with other appendageal carcinomas, five had additional malignancies: two with KS, one with both KS and NHL (diffuse large B cell subtype), and one each with acute myeloid leukemia and carcinoma of unknown type.