Treatment-Related Circulatory Diseases and Mortality in Hodgkin Lymphoma Patients Using Multi-State Modelling and Relative Survival

Introduction Diseases of the circulatory system (DCS) are some of the most common late effects of Hodgkin lymphoma (HL), primarily due to mediastinal radiotherapy and/or anthracycline-containing chemotherapy (e.g., ABVD and BEACOPP). As DCS is very common in the general population, modelling DCS attributable to HL therapy versus that expected in the general population is relevant to understand the magnitude of DCS reduction that could be achieved with less cardiotoxic therapies. This real-world data study used multi-state modelling and relative survival to estimate treatment-related DCS risk in HL survivors.

Material and methods All HL patients registered in the Swedish Lymphoma Register 2000-2018, aged 18-80 years at diagnosis, and treated with anthracycline-containing therapy were included. DCS events were identified in the Swedish National Inpatient Register (ICD-10 codes I00-I99) and defined as the first admission for DCS after HL diagnosis. Sex-, year-, and age-specific DCS incidence rates in the general population were retrieved from public records. Patients were followed from treatment initiation through a series of states: alive and DCS-free, alive and with (excess or expected) DCS, dead without DCS, and dead after DCS. Follow-up ended on date of death, emigration, or December 31^st, 2019, whichever came first. All state transitions were modelled separately using flexible parametric survival models, yielding hazard ratios (HR) with 95% confidence intervals (CI). A relative survival model incorporating the expected DCS rates was fitted to allow for estimation of excess DCS, which was then interpreted as treatment-related. Transition probabilities (i.e., the likelihood of being in a state) were predicted for specific patient groups, by sex and low/high (≤200/>200 mg/m²) cumulative anthracycline dose.

Results In a total of 1,929 HL patients, the mean age at diagnosis was 42 years, 54% were males, and 49% were treated with high dose anthracycline (Table 1). The distribution of treatments was 66% ABVD, 20% CHOP-like, and 14% BEACOPP. During a median follow-up of 7.6 years (IQR: 4.5-11.0), 145 (7.5%) died without DCS, 377 patients (20%) were diagnosed with DCS, and 87 (5%) died after DCS.

Figure 1a shows the sex-specific transition probabilities for a patient with advanced stage disease, diagnosed in 2000, at age 50, and treated with a cumulative anthracycline dose of >200mg/m² in a ABVD regimen. The probability of being in the treatment-related (excess) DCS state at 10 years after first line treatment was 0.35 (95% CI: 0.09-0.75) for males and 0.41 (95% CI: 0.10-0.81) for females in this patient group. Figure 1b shows the probabilities for limited stage male patients diagnosed in 2000 at age 50, treated with ABVD, by low/high anthracycline dose. Here, the probability of being in the treatment-related (excess) DCS state at 10 years was 0.44 (95% CI: 0.16-0.76) and 0.53 (95% CI: 0.25-0.80) for low and high dose anthracycline patients, respectively.

There were no significant differences in treatment-related (excess) DCS incidence rates or post DCS all-cause mortality rates (Table 1). Females had a significantly lower non-DCS mortality rate than males (adj. HR=0.69, 95% CI: 0.49-0.97), as did patients treated with high compared to low anthracycline dose (adj. HR=0.28, 95% CI: 0.18-0.44).

Conclusion After 10 years, females had higher risks of treatment-related (excess) DCS compared to males, although not statistically significant and likely due to superior survival. The same was seen for high compared to low cumulative doses of anthracycline.

Female sex and high dose anthracycline reduced the non-DCS mortality rate, but not the excess DCS incidence rate.

Baech:Gilead Sciences Nordic: Research Funding. Jakobsen:Roche: Honoraria. El-Galaly:Roche: Ended employment in the past 24 months; Abbvie: Other: Teaching in 2021. Molin:Roche: Honoraria; BMS: Honoraria; MSD: Honoraria; Takeda: Honoraria. Glimelius:Janseen Cilag: Research Funding; Takeda: Research Funding. Crowther:StataCorp: Consultancy. Ekstroem Smedby:Janseen Cilag: Research Funding. Eloranta:Janseen Cilag: Research Funding. Weibull:Janseen Cilag: Research Funding; Red Door Analytics: Membership on an entity's Board of Directors or advisory committees; War On Cancer: Current Employment.