Adjuvant Radiation Therapy Common in MIBC
Survey finds that 46% of radiation oncologists have administered ART to patients with muscle-invasive bladder cancer on at least one occasion.
Although controversial, radiation oncologists practicing in the United States commonly treat muscle-invasive bladder cancer (MIBC) patients with adjuvant radiation therapy (ART) after radical cystectomy, researchers revealed at the 2017 Genitourinary Cancers Symposium in Orlando.
“Adjuvant radiotherapy is more frequently utilized than would be expected in muscle-invasive bladder cancer patients, despite limited data of efficacy in the North American population,” lead investigator Abhishek Solanki, MD, MS, of Loyola University Chicago, told Renal & Urology News. “And the optimal indications for use are not clear.”
Previous trials have suggested significant toxicity with ART after radical cystectomy for MIBC.
Of 277 radiation oncologists surveyed, nearly half (46%) have administered ART to patients diagnosed with cT2-3N0M0 transitional cell MIBC on at least one occasion. Users reported the following indications following cystectomy: gross residual disease (93%), positive margins (92%), pathologic nodal involvement (64%), pT3 or T4 disease (46%), lymphovascular invasion (16%), and high-grade disease (13%).
On multivariate analysis, specific factors predicted ART use. Radiation oncologists who routinely conducted pre-cystectomy consultation with patients were nearly twice as likely to administer ART. In addition, ART use almost tripled when intensity-modulated radiotherapy (IMRT) was considered and performed. Just 23% of those surveyed reported that they “almost never consider IMRT.”
Although the results did not hold after adjustment, analyses hinted that radiation oncologists were nearly twice as likely to treat non-metastatic bladder cancer patients who were fit for cystectomy compared with those who were unfit. Moreover, established radiation oncologists practicing for more than 10 years were more likely to use ART on average than those just starting a practice. Overall, 4 in 5 survey respondents served in specialty clinics versus multidisciplinary clinics.
Dr Solanki noted that NRG GU001, a randomized trial designed to compare observation vs ART in radical cystectomy patients, recently closed due to poor accrual. A contemporary trial of an Egyptian population had found improved locoregional control of MIBC with ART. He added that National Comprehensive Cancer Network guidelines released in 2017 suggest that ART be considered for select patients at high risk of local recurrence.
See more coverage from the Genitourinary Cancers Symposium.
- Solanki AA, Martin B, Korpics M, et al. Adjuvant radiotherapy use after radical cystectomy in muscle-invasive bladder cancer: A survey of U.S. radiation oncologists. Data presented in poster format at the 2017 Genitourinary Cancers Symposium in Orlando, Florida, February 16-18, 2017. Poster Session B (Board #H6). Abstract: 369.