A small decrease in testosterone level has been documented after prostate irradiation, possibly owing to the incidental dose to the testes.
Testicular doses from prostate external beam radiation plans with either intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) were calculated to investigate any difference. Testicles were contoured for 16 patients being treated for localized prostate cancer. For each patient, 2 plans were created: 1 with IMRT and 1 with VMAT. No specific attempt was made to reduce testicular dose. Minimum, maximum, and mean doses to the testicles were recorded for each plan. Of the 16 patients, 4 received a total dose of 7800cGy to the prostate alone, 7 received 8000cGy to the prostate alone, and 5 received 8000cGy to the prostate and pelvic lymph nodes. The mean (range) of testicular dose with an IMRT plan was 54.7cGy (21.1 to 91.9) and 59.0cGy (25.1 to 93.4) with a VMAT plan. In 12 cases, the mean VMAT dose was higher than the mean IMRT dose, with a mean difference of 4.3cGy (p = 0.019). There was a small but statistically significant increase in mean testicular dose delivered by VMAT compared with IMRT. Despite this, it unlikely that there is a clinically meaningful difference in testicular doses from either modality.
Martin JM, Handorf EA, Price RA, Cherian G, Buyyounouski MK, Chen DY, Kutikov A, Johnson ME, Ma CM, Horwitz EM. Are you the author?
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA; Department of Biostatistics, Fox Chase Cancer Center, Philadelphia, PA; Department of Radiation Oncology, Stanford University, Stanford, CA; Department of Urologic Oncology, Fox Chase Cancer Center, Philadelphia, PA.
Reference: Med Dosim. 2015 Jan 13. pii: S0958-3947(14)00126-5.