Individualized assessment of the probability for developing in-field solid tumors from radiation therapy for testicular cancer

Abstract

Introduction Testicular cancer is a highly treatable malignancy which is usually presented in young adults. Purpose The purpose of this study was to combine individualized dosimetric data with an advanced non-linear risk model for the patient-specific assessment of the probability for solid cancer induction after three-dimensional conformal radiotherapy for testicular cancer. Materials and methods Ten patients with early stage seminomatous testicular cancer were subjected to a planning computed tomography scan. Treatment plans were generated with an 18 MV photon beam delivering 20 Gy in 10 fractions to para-aortic lymph node region. Differential dose-volume histograms were defined with a bin width of 0.01 Gy for radiosensitive organs exposed to primary radiation. For each study participant, the organ equivalent dose (OED) of colon, stomach and liver and the associated lifetime risk for carcinogenesis were estimated with a mechanistic model. This model accounts for the effects of cell repopulation and target dose fractionation. Results The range of the calculated OEDs of the colon, stomach and liver was found to be 251.3–500.4 cGy, 37.3–79.8 cGy and 43.0–70.3 cGy, respectively. The patient-specific lifetime probability for the appearance of colon malignancies varied from 0.74% to 1.94% by the patient’s age at the time of irradiation and the organ radiation exposure. The corresponding lifetime risk ranges for stomach and liver cancer induction were equal to 0.42–0.81% and 0.14–0.22%, respectively. Conclusion The knowledge of the patient-specific probability for developing solid tumors prior to radiotherapy for testicular cancer may facilitate treatment decisions and improve risk management. Disclosure There is not any relationship that may bias our presentation.