Authors
Chunkit Fung
James P. Wilmot Cancer Center, University of Rochester School of Medicine and Dentistry, Rochester, NY
Chunkit Fung , Sophie D. Fossa , Michael T Milano , Mandi Yu , Melissa Worman , Lois B. Travis
Organizations
James P. Wilmot Cancer Center, University of Rochester School of Medicine and Dentistry, Rochester, NY, Oslo University Hospital, The Norwegian Radium Hospital, Oslo, Norway, Department of Radiation Oncology, University of Rochester School of Medicine and Dentistry, Rochester, NY, National Cancer Institute, National Institutes of Health, Rockville, MD, James P. Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY
Research Funding
No funding sources reported
Background: Increased risks of SMN after radiotherapy (RT) for testicular cancer (TC) are well established. Few population-based studies, however, have focused on SMN risk among a contemporary group of TCS managed initially with non-RT approaches, including CHEM. Methods: Standardized incidence ratios (SIR) of SMN stratified by site and time since TC diagnosis were calculated for 18,627 TCS reported to the SEER program (1980-2008) who initially had CHEM (n=8,058) or SURG (n=10,569) alone without RT, with each cohort accruing 65,398 and 92,681 person-years (PY) of follow-up respectively. Results: After CHEM, significantly increased risks of solid cancers (n=154; SIR 1.3; 95% CI 1.1-1.5; absolute excess risk (AER) 5.4 per 10,000 PY) and leukemias (n=18, SIR 3.9; 95% CI 2.3-6.1; AER 2.0) were observed. Solid cancer risk remained elevated for > 20 yrs, whereas excess leukemias were concentrated within 10 years after diagnosis. SIRs for solid cancers during the <1, 1-4, 5-9, 10-14, 15-19, and 20+ yr periods were 2.0 (95% CI 1.03-3.5), 1.4 (95% CI 0.97-2.0), 0.8 (95% CI 0.5-1.2), 1.3 (95% CI 0.9-1.8), 1.6 (95% CI 1.05-2.2), and 1.5 (95% CI 0.95-2.2) respectively (P-trend 0.5) whereas SIRs for leukemia were 3.2, 9.9 (P<0.05), 2.6, and 2.3 respectively, with no cases reported in the latter 2 intervals. Median latencies to the development of solid cancers and leukemia were 12.5 yr (0.1-28) and 2.5 yr (0.1-14) respectively. Increased site-specific risks were apparent for cancers of liver (SIR 1.9; 95% CI 0.6-4.4); pancreas (SIR 2.1; 95% CI 0.8-4.6); soft tissue (SIR 4.9; 95% CI 2.1-9.7); bladder (SIR 1.9; 95% CI 1.02-3.3); kidney (SIR 2.6; 95% CI 1.4-4.3); brain/CNS (SIR 1.8; 95% CI 0.7-3.7), and thyroid (SIR 3.9; 95% CI 2.1-6.6). Secondary leukemias included 16 non-lymphocytic and 2 lymphocytic leukemias. In contrast, among TCS managed initially with SURG alone, no excess solid cancers were observed (n=198; SIR 1.0; 95% CI 0.8-1.1), albeit an increased risk of leukemia (n=15; SIR 1.9; 95% CI 1.1-3.2, AER 0.8) was seen. Conclusions: Future analytic studies should further evaluate the site-specific risks of SMN after modern CHEM for TC and the baseline risk among patients managed with non-cytotoxic approaches.