Second primary acute lymphoblastic leukemia in adults: a SEER analysis of incidence and outcomes

We conducted a surveillance epidemiology and end results (SEER)-based analysis to describe the incidence and characteristics of second primary acute lymphoblastic leukemia (sALL) among adults (≥18 years) with a history of primary malignancies (1M). Standardized incidence ratios (SIRs) of sALL cases were calculated by site and 1M stage. We also evaluated the differences in 5-year sALL survival by age, site, and extent of 1M, latency of sALL after 1M, and evidence of underlying racial/ethnic disparity. We identified 10,956 patients with de-novo/primary acute lymphoblastic leukemia (1ALL) and 772 with sALL. Women (49.1% vs. 42.9%), white patients (72.0% vs. 59.5%), older patients (58.8% vs. 25.2%; age ≥65 years), and patients diagnosed between 2003 and 2012 (66.8% vs. 53.9%) had a higher proportion of sALL compared with 1ALL. There was a significantly inferior median 5-year survival for sALL patients compared to 1ALL (6 vs. 15 months; HR 1.20, 95% CI 1.10-1.31, P < 0.001). The median latency period was 60.0 months; the most common 1M among sALL patients were breast (17.9%) and prostate (17.4%). Patients with any 1M were at increased risk of developing sALL (SIR 1.76, 95% CI 1.58-1.95, P < 0.001). Hematological-1M sites had significantly higher SIRs (hematological-SIR 7.35; solid-SIR 1.33; P < 0.001). We observed a significant increase in sALL incidence after a 1M and a significantly worse 5-year survival with different demographic characteristics from 1ALL. There is a need to define appropriate screening methods for patients surviving their primary cancer.