Estimating the risk of cancer associated with imaging related radiation during surveillance for stage I testicular cancer using computerized tomography.

Abstract

Computerized tomography has a critical role in the surveillance of stage I nonseminomatous germ cell tumors of the testis. Some protocols call for up to 16 computerized tomography scans over 5 years, thereby exposing young patients to a significant amount of radiation. We estimated the lifetime risk of cancer incidence and cancer death from imaging related radiation received during surveillance of stage I nonseminomatous germ cell tumor. Using a model with a 64-slice computerized tomography scanner obtaining images of the abdomen and pelvis with or without chest in a standardized, phantom male patient, organ specific radiation doses were estimated using Monte Carlo simulation techniques. Lifetime attributable risks of cancer were estimated using the approach outlined in the Biological Effects of Ionizing Radiation VII Phase 2 report. With a 5-year surveillance protocol as suggested by the National Comprehensive Cancer Network, lifetime cancer risk ranged from 1 in 52 (1.9%) for an 18-year-old to 1 in 63 for a 40-year-old patient (1.2%). If chest computerized tomography is also performed the risk increases to 1 in 39 (2.6%) and 1 in 85 (1.6%), respectively. Lung and colon cancer accounted for most of the risk. The relative risk of a secondary malignancy with surveillance compared to a single scan after retroperitoneal lymph node dissection is approximately 15.2. Computerized tomography used in testicular cancer surveillance protocols imparts large radiation doses and is associated with a significant risk of cancer. This risk should be factored into counseling patients with stage I nonseminomatous germ cell tumor.