IMRT Linked With Low Rates of Pelvic Recurrence in Bladder Cancer

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Delivering intensity-modulated radiotherapy (IMRT) to the bladder and pelvic nodes in patients with node-positive bladder cancer (NPBC) or high-risk node-negative bladder cancer (NNBC) is feasible with patients experiencing low toxicity and demonstrating low pelvic nodal rates of recurrence, researchers reported at the 2017 Global Congress on Bladder Cancer.

Pelvic node relapse after IMRT within 3 months was reported in just 2 (5%) patients.

The 1-, 2- and 5-year pelvic relapse-free survival rates after IMRT were 55%, 37% and 26%, respectively. At a median follow-up of 5.2 years, 5 (13%) patients had no relapse and were alive.

Median overall survival (OS) was 1.9 years (95% CI, 1.1-3.8); the 1-, 2- and 5-year OS rates were 68%, 50%, and 34% respectively.

Patients with NPBC generally have poorer outcomes compared to patients with NNBC, where 5-year recurrence-free rates of 35% versus 78%, respectively, have been reported according to Melissa Tan BSc, FRCR, Radiotherapy & Imaging, Institute of Cancer Research of the Royal Marsden Hospital in Sutton, United Kingdom.

“A subset of NPBC patients demonstrated long-term disease control and 5-year cancer-specific survival of 63.5% with combined neoadjuvant chemotherapy and surgery but little has been reported on the use of radiotherapy of pelvic nodes in bladder cancer,” she explained during a poster discussion session.

Tan and colleagues conducted the IMPART study to evaluate the feasibility of delivering IMRT to the bladder and pelvic nodes for the treatment of 38 patients with NPBC or high-risk NNBC, such as diseased classified cT3b/T4 or small cell histopathology.

IMRT was delivered in doses of 52 Gy, 64 Gy, 52 Gy, and 60 Gy in 32 fractions to the whole bladder, tumor bed, pelvic nodes, and any involved nodes, respectively. Both neoadjuvant chemotherapy and/or concurrent chemotherapy were permitted.

The patients’ median age was 71 years (range, 47-88), and 82% of patients were male. Prior treatments included a previous cystectomy in 8% of patients. Of the 58% of patients with NPBC involving one, 2, and 3 nodes, 24% had N1, 24% had N2, and 11% had N3 disease.

Neoadjuvant chemotherapy was administered to 82% of patients and 47% also received concurrent chemotherapy.

During follow-up, disease recurrence was reported for 27 (71%) patients. Twelve (32%) patients had distant metastasis, 7 (18%) had local muscle-invasive bladder disease, 6 (16%) had local non-muscle invasive disease, and 2 (5%) had pelvic nodal relapse.

Of the patients experiencing a first relapse of locoregional disease after treatment, 47% had ≥T2 disease, 27% had carcinoma in situ, 13% of patients had pelvic lymph node disease, and an additional 13% of patients had pTa/pT1 disease.

Grade 3 acute toxicity rates were 20% for gastrointestinal adverse events and 6% for genitourinary adverse events. The 1-year grade 3 late toxicity rate was 5%.

Two patients (5%) died during radiotherapy from causes unrelated to treatment and 4 (11%) died without showing relapse.

“Relapse patterns suggest that strategies targeting local bladder recurrence, such as radiation dose escalation or concomitant therapies, and reducing distant metastasis with immunotherapy are required to improve patient outcomes, in patients with node-positive or high-risk node-negative bladder cancer,” commented Tan.

No study funding was reported.

Tan M, Harris V, Warren-Oseni K, et al. Clinical outcomes from the intensity-modulated pelvic node and bladder radiotherapy (IMPART) trial - A phase 2 single-centre study. Presented at: 2017 Global Congress on Bladder Cancer; October 5-6, 2017; Edinburgh, United Kingdom. Abstract 43.