Second Primary Malignancy Risk Among HIV-Uninfected and HIV-Infected Survivors of Hodgkin Lymphoma: A 30-Year Follow-up Population-Based Study

Introduction Second primary malignancy (SPM) is one of the most devastating late complications following Hodgkin lymphoma (HL) treatment. Historically, the most common SPMs in patients treated for HL are solid tumors, which are largely related to radiation exposure during initial therapy. For the last three decades, efforts to address the risk of SPM after HL therapy have focused on reducing exposure to radiation, as well as refining the approach for patients where radiation is indicated. To date, few population-based studies in the United States have quantified the burden of SPMs and evaluated the potential effect of changes in therapeutic management over time. Additionally, to our knowledge, no study has compared SPM risk between human immunodeficiency virus (HIV)-infected and HIV-uninfected HL survivors.

Methods We used data from the California Cancer Registry on 21,043 patients diagnosed with primary HL between 1988 and 2015 with follow-up through 2017. We calculated standardized incidence ratios (SIRs) with corresponding 95% confidence intervals (CIs) and absolute excess risks (AERs) to compare SPM incidence in our HL cohort with the expected number of first primary cancer incidence in the general California population, based on patient’s age at diagnosis (5-year categories), sex, calendar year (3-year intervals), cancer site, and race/ethnicity. SIRs are presented by HIV status, SPM latency, treatment era, and cancer type. P-values for trends were used to examine whether SPM risk changed over time.

Findings Among 20,303 HIV-uninfected patients (median follow-up of 14.1 years), overall SPM risk was increased 1.95-fold compared with the general population (SIR=1.95, 95% CI 1.86–2.04). In 740 HIV-infected patients (median follow-up of 11.7 years), overall risk was increased 2.68-fold compared with the general population (SIR=2.68, 95% CI 2.0–3.40), translating to an 37% higher incidence of SPM in HIV-infected vs. HIV-uninfected patients. The AER (per 10,000 person-years) of SPM was 43.1 in HIV-uninfected and 76.5 in HIV-infected patients, resulting in a 33.4 excess SPM per 10,000 person-years in HL survivors with HIV. Malignancies that contributed the most to overall AER were non-Hodgkin lymphoma (NHL), female breast and lung cancers in HIV-uninfected patients; and Kaposi sarcoma, NHL, anorectal and head & neck (HNC) cancers in HIV-infected patients. Notably, among HIV-uninfected patients, the highest overall risk of SPM occurred ≥20 years after diagnosis (SIR= 2.27, 95% CI 1.99–2.58) (Figure). In contrast, the highest overall risk in HIV-infected patients was observed <2 years after diagnosis (SIR=4.42, 95% CI 2.53–7.19). Radiation used decreased from 46.9% in 1988–1996 to 29.5% in 2007–2015. Among HIV-uninfected patients, there was a trend towards decreased risk over time of overall and selected solid SPMs (lung, female breast, and gastrointestinal cancers) (Table). In an analysis restricted to HIV-uninfected patients who received radiation irrespective of chemotherapy, findings also suggested a declined risk of overall and selected solid SPMs over time: any solid (SIR=2.15 in 1988–1996 and SIR=1.30 in 2007–2015, p<0.0001), lung (SIR=3.69 in 1988–1996 and SIR=1.81 in 2007–2015, p=0.0031), and female breast (SIR=2.95 in 1988–1996 and SIR=0.63 in 2007–2015, p<0.0001).

Conclusion Compared with the general population, the risk of developing a SPM following HL treatment was significantly higher among both HIV-uninfected and HIV-infected patients, with the absolute excess risk greater for those with HIV infection. There were different temporal patterns and types of SPM between HIV-uninfected and HIV-infected patients. These findings prompt the question on whether earlier and/or more intensive cancer screening should be pursued for HIV-infected survivors. The trend towards decreased risk for selected solid SPMs among HIV-uninfected patients, especially lung and female breast cancers, suggest that strategies to reduce radiation in HL survivors may be working. Despite promising trends in this group, the observation that SPM risk was highest ≥20 years after initial therapy further highlights the need for long-term surveillance and survivorship care in this at-risk population.