Optimisation of Radiation Therapy in Bladder Preservation Therapy for Patients With Clinical Stage T2N0M0 Bladder Cancer.

ABSTRACT

AIMS: A novel bladder preservation therapy, the OMC (Osaka Medical College) regimen, which combines radiation therapy with balloon-occluded arterial infusion of anticancer agents, is a treatment option for patients with muscle-invasive bladder cancer (MIBC). We retrospectively analysed the effects of changes in radiation dose and irradiation field on treatment efficacy and adverse events.The purpose of this study is to use the results of this study to help determine a course of radiation therapy for bladder preservation therapy of cT2N0M0 MIBC. MATERIALS AND METHODS: We examined 352 patients with clinical stage T2N0M0 (cT2N0M0) MIBC classified into the following groups based on the irradiation method: group A, the whole pelvis (50 Gy/25 fractions) + local bladder (10 Gy/5 fractions); group B, the small pelvis (50 Gy/25 fractions) + local bladder (10 Gy/5 fractions); group C, the whole pelvis (40 Gy/20 fractions) + local bladder (10 Gy/5 fractions). RESULTS: The complete response rate, 3-year overall survival and progression-free survival rates in group A were 92.9%, 94.9% and 82.1%, respectively; in group B were 87.2%, 86.7% and 76.7%, respectively; and in group C were 95.2%, 92.6% and 71.1%, respectively. No significant differences between the groups were noted. The incidence of ≥grade 3 urinary tract and gastrointestinal toxicities were not significantly different among the groups (group A 7.8%, 1.7%; B, 11.1%, 0%; C, 7.1%, 1.8%, respectively). The 3-year progression-free rates of the common iliac lymph node (CILN) region in patients who received whole-pelvis and small-pelvis irradiation were 99.0 and 89.0% (P < 0.01), respectively, with the latter group having significantly high lymph node recurrence in the CILN region. CONCLUSIONS: Our findings showed that the optimal radiation therapy for patients with cT2N0M0 MIBC undergoing the OMC regimen is whole-pelvis irradiation including the CILN region, with a total dose of 50 Gy/25 fractions.