P1225: SECONDARY PRIMARY MALIGNANCIES (SPM) AFTER HIGH-DOSE CHEMOTHERAPY (HDT) WITH AUTOLOGOUS STEM CELL TRANSPLANT (ASCT) FOR LYMPHOMA: A DANISH NATIONWIDE COHORT STUDY

Abstract

Background: High-dose chemotherapy (HDT) with autologous stem cell transplant (ASCT) have resulted in more long-term lymphoma survivors. However, HDT-ASCT is potentially associated with an increased risk of secondary primary malignancies (SPM) leading to loss of lifetime for these patients. Aims: To investigate the risk and types of SPM in lymphoma patients treated with HDT-ASCT compared to the risk of malignancies in a matched background population and to explore risk factors for SPM in HDT-ASCT treated lymphoma patients. Methods: In a nationwide matched cohort study, The Danish Lymphoma Register was used to identify all adult patients treated with HDT-ASCT in Denmark between 2001-2017 for diffuse large B-cell lymphoma, Hodgkin lymphoma, peripheral T-cell lymphoma, or mantle cell lymphoma, excluding patients with other prior cancers. Patients were matched in a ratio of 1:5 to cancer-free comparators from the Danish background population. Malignancies were identified in the Danish National Patient Register using ICD-10 codes and compared between the two groups using the Aalen-Johansen estimator, Cox regression, and incidence rate ratios (IRRs). Results: A total of 856 HDT-ASCT treated lymphoma patients and 4,280 matched comparators were followed for a median of 8 years. The cumulative risk of SPM with death as competing risk was higher for patients compared to comparators with risks at 5, 10, and 15 years of 8.9% [95% confidence interval 6.9;11.0], 16.3% [13.3;19.3], and 20.1% [16.1;24.2] for patients compared to 4.8% [4.1;5.5], 10.5% [9.3;11.7], and 16.6% [14.6;18.5] for comparators (Fig. 1a). The crude hazard ratio (HR) of SPM among patients vs comparators was 2.26 [1.83;2.79]. After adjusting for sex, educational level (low/high), chronic obstructive pulmonary disease (COPD), and alcohol-related diseases (neurological, mental, cardiovascular, or chronic use), the HR was 2.50 [2.02;3.10]. Compared to comparators, patients had increased rates of non-melanoma skin cancer (IRR 3.47 [2.18;5.38]) and myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) (IRR 35.32 [15.73; 94.26]) (Table 1). Rates of other malignancies (oral, gastrointestinal, respiratory, breast, female- or male genital, urinary, soft tissue, and melanoma) were similar between the two groups. The 15-year cumulative risk of MDS/AML was 4.6% [2.8;6.3] for patients (Fig. 1c) and the median overall survival following secondary MDS/AML was only 7 months. In comparison, median overall survival was 40 months in a sex- and age matched background population with newly diagnosed MDS/AML (Fig. 1d). Risk factors for SPM in lymphoma patients were older age (HR 1.06 [1.04;1.08] per year) and COPD (HR 3.15 [1.16;8.57]). Prior therapy (number of lines, intensive chemotherapy, radiotherapy), time since diagnosis, Ann Arbor stage, performance status, alcohol-related disease, and education were not associated with SPM. Table 1. - Rates of SPM per 1,000 person-years in lymphoma patients and matched comparators Comparators Patients SPM type Rate Rate IRR IRR 95% CI Overall 11.35 24.77 2.18 1.76; 2.18 Hematological 0.45 7.74 17.05 9.5; 32.16 MDS/AML 0.18 6.41 35.32 15.73; 94.26 MDS 0.12 3.98 32.89 12.27; 113.84 AML 0.06 2.43 40.19 10.79; 259.78 Non-melanoma skin cancer 1.79 6.19 3.47 2.18; 5.38 Image:Summary/Conclusion: Lymphoma patients treated with HDT-ASCT have an increased risk of SPM compared to a matched background population, especially for non-melanoma skin cancer and MDS/AML. Risk factors for SPM in patients were older age and COPD. These findings are important in the light of new potential treatment alternatives, such as CAR-T.