Temporal trends in treatment-related incidence of diseases of the circulatory system among Hodgkin lymphoma patients

While Hodgkin lymphoma (HL) survival has improved, treatment-related complications remain a concern. As a measure of treatment-related diseases of the circulatory system (DCS) we report excess incidence of DCS and absolute risks among HL patients diagnosed in the modern treatment era. From the Swedish Cancer Register, we identified all HL patients diagnosed 1985 through 2013, at ages 18-80 years. Excess incidence rate ratios (EIRRs) with 95% confidence intervals (CIs) comparing excess DCS incidence between calendar periods were estimated overall, and at 5 and 10 years after diagnosis using flexible parametric models. Model-based predictions were used to obtain probabilities of being diagnosed with DCS, in the presence of competing risks. During follow-up, 726 (16%) of the 4,479 HL patients experienced DCS. Overall, the excess DCS incidence was lower during all calendar periods compared to the first (2009-2013 vs. 1985-1988: EIRR = 0.63, 95% CI: 0.42-0.95). The 5- and 10-year excess incidence of DCS decreased between 1985 and 1994 for 25-year-olds (5-year-EIRR₁₉₉₄ = 0.32, 95% CI: 0.12-0.92) and 60-year-olds (5-year-EIRR₁₉₉₄ = 0.45, 95% CI: 0.24-0.88), but remained stable thereafter. No improvements were observed among 75-year-olds. The probability of excess DCS remained the same throughout the study period. In 2009, the percentage of patients aged 25, 60 and 75 experiencing excess DCS within 5 years was 3.4, 15.0 and 17.0% (males) and 2.3, 10.8 and 12.6% (females). Treatment-related incidence of DCS has declined since the mid-1980s, but more recent improvements are absent and an excess risk remains. Continued efforts towards less toxic treatments are warranted, alongside primary prevention strategies.