Background: Studies suggest lower risk of breast cancer in women with versus without HIV. These estimates may be biased by lower life expectancy and younger age distribution of women with HIV. Our analysis evaluated this bias and characterized secular trends in breast cancer among women with HIV initiating ART. We hypothesized breast cancer risk would increase over time as mortality decreased.
Setting: Women with HIV prescribed ART in the North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD) from 1997-2016.
Methods: We estimated breast cancer hazard (cause-specific hazard ratios [csHR]) and cumulative incidence accounting for competing risks (subdistribution hazard ratios [sdHR]) to assess changes in breast cancer risk over time. This was assessed overall (1997-2016) and within/across calendar periods. Analyses were adjusted for race/ethnicity and inverse probability weighted for cohort. Cumulative incidence was graphically assessed by calendar period and race/ethnicity.
Results: We observed 11,587 women during 1997-2016, contributing 63 incident breast cancer diagnoses and 1,353 deaths (73,445 person-years [median follow-up=4.5 years]). Breast cancer cumulative incidence was 3.2% for 1997-2016. We observed no secular trends in breast cancer hazard or cumulative incidence. There were annual declines in the hazard and cumulative incidence of death (csHR and sdHR: 0.89, 95% CI 0.87, 0.91) which remained within and across calendar periods.
Conclusion: These findings contradict the hypothesis of increasing breast cancer risk with declining mortality over time among women with HIV, suggesting limited impact of changing mortality on breast cancer risk. Additional inquiry is merited as survival improves among women with HIV.