Association between educational level and risk of cancer in HIV-infected individuals and the background population: Population-based cohort study 1995-2011

BACKGROUND:  Risk of cancer is increased in HIV-infection. To our knowledge, no previous study has examined the association between socioeconomic position and risk and prognosis of cancer among HIV-infected individuals.

METHODS:  Population-based cohort-study including HIV-infected individuals diagnosed in Denmark 1995-2011 (without intravenous drug abuse or hepatitis C infection) (n=3,205), and a comparison cohort from the background population individually-matched by age, gender and country of birth (n=22,435). Educational level (low or high) and cancer events were identified in Danish national registers. Cumulative incidences, Incidence rate ratio (IRR) and survival using Kaplan-Meier methods were estimated.

RESULTS:  Low educational level was associated with increased risk of cancer among HIV-infected individuals compared to the comparison cohort: all cancers (Adjusted-IRRs: 1.4(95% CI;1.1-1.7) vs. 1.1(95% CI;0.9-1.2)), tobacco- & alcohol-related cancers (2.1(95% CI;1.3-3.4) vs. 1.3(95% CI;1.1-1.6)), and other cancers (1.7(95% CI;1.1-2.8) vs. 0.9(95% CI;0.7-1.0)). No association with educational level was found for Infection-related or Ill-defined cancers. 1-year-survival was not associated with educational level, but 5-year-survival following Infection-related and Ill-defined cancers was lower among HIV-infected individuals with low educational level.

CONCLUSION:  Education is associated with risk and prognosis of some cancers in HIV-infection, and this association diverges from what is observed in the background population.