RESUMEN
AIMS: The aim of this study was to evaluate and compare the effect of radiotherapy on testicles with different treatment positions and plans for rectal cancer patients. SETTINGS AND DESIGN: Mono-institutional prospective study. PATIENTS AND METHODS: Three different plans; supine 4-fields (s4f), prone 4-fields (p4f), and prone 3-fields (p3f) of 15 male patients with rectal carcinoma receiving 45 Gy pelvic radiotherapy were evaluated. Testicular doses in each plan were calculated. Since the localizations of the primary tumor may affect testicular dose, boost doses were not taken into account. STATISTICAL ANALYSIS USED: Kruskal Wallis test, Pearson and Spearman correlation analysis. RESULTS: Median cumulative testicular doses of s4f, p4f, and p3f plans were 19.8, 69.3, and 100.8 cGy, respectively (P = 0.013). Median V0.5 (Volume receiving more than 0.5 Gy) and V1 (Volume receiving more than 1 Gy) for testicles were also significantly lower in s4f plans (3%, 60.7%, and 78.1% for V0.5 and 0.3%, 35.8%, and 52.3% for V1 in s4f, p4f, and p3f, respectively) (P = 0.001). The median distances between lower edge of fields and testicles in s4f, p4f, and p3f plans were 65 mm, 29 mm, and 29 mm, respectively (P < 0.01). Median bladder doses were significantly lower in p3f plans (P = 0.002). CONCLUSIONS: S4f external beam radiotherapy for rectal carcinoma allows better testicular dose than p3f and p4f. The probably reason was the increase of distance between lower edge of the field and testicles.
