ESTRO 2024 - Abstract Book

S2500

Clinical - Urology

ESTRO 2024

Anuradha Krishnan 1 , Sheetal Kashid 1 , Namrata Pansande 1 , Priyamvada Maitre 1 , Pallavi Singh 1 , Amit Joshi 2 , Reena Phuralipatram 3 , Gagan Prakash 4 , Mahendra Pal 4 , Amandeep Arora 4 , Vedang Murthy 1 1 Tata Memorial hospital, Radiation oncology, Mumbai, India. 2 Tata Memorial hospital, Medical oncology, Mumbai, India. 3 Tata Memorial hospital, Medical Physics, Mumbai, India. 4 Tata Memorial hospital, Surgical oncology, Mumbai, India

Purpose/Objective:

Hypofractionated chemoradiotherapy (HFRT) as a curative treatment for muscle-invasive bladder cancer has shown survival outcomes similar to conventionally fractionated radiotherapy (CFRT), but the available real world evidence is limited. Having moved at our institution from CFRT to HFRT in clinical practice after the publication of the IPD meta analysis, we report early clinical experience with the shorter radiotherapy schedule for bladder preservation.

Material/Methods:

Consecutive patients from a prospectively maintained institutional database with histological diagnosis of muscle invasive urothelial bladder cancer, with clinicoradiological stage T1-T4, N0-N3 M0 treated with curative radiotherapy to the bladder were included for analysis. From 2009 to 2020 radiotherapy dose of 60-64Gy in 30-32 fractions (conventional fractionation, CFRT) was used while 55Gy in 20 fractions (hypofractionation, HFRT) was prescribed from 2021 to the entire bladder. Patients received a simultaneous integrated dose of 55Gy/32# (CFRT) or 44Gy/20# (HFRT) to the pelvic lymph nodes if indicated. All patients were planned with adaptive plan-of-the-day IMRT and treated with daily image guidance. Patients were reviewed weekly during radiotherapy, and 3 to 6 monthly thereafter. Acute (within 3 months of radiotherapy) and late urinary and gastrointestinal toxicity were assessed using the RTOG and CTCAE criteria. Local recurrence (non-invasive or invasive) free survival (LRFS), invasive local recurrence-free survival (ILRFS), disease-free survival (invasive bladder recurrence, nodal or metastatic disease) (DFS), bladder cancer specific survival (BCSS), and overall survival (OS) were analysed and compared for CFRT and HFRT. A total of 222 patients were eligible for analysis, of which 50 were treated with HFRT and 172 with CFRT (Table 1). Majority of the patients had T2 (56%) or T3 (27.5%) cancer, without involved pelvic nodes (85%). Chemoradiation included neoadjuvant chemotherapy in 31% patients, and concurrent chemotherapy for 79.3% patients, most commonly with gemcitabine (49%) or cisplatin (42%). Pelvic nodes were included in radiotherapy fields for 82% patients (HFRT 76%, CFRT 84%). Most patients (93.2%) completed the planned course of chemoradiation in both the groups (HFRT 98%, CFRT 91.9%). Acute urinary toxicity was grade 3 in 3.7% and grade 2 in 16.1% patients, similar between HFRT and CFRT (p=0.26). Acute gastrointestinal toxicity was grade 3 in 0.9% and grade 2 in 15.1% patients, also similar between HFRT and CFRT (p=0.17). Median follow up was 32 months for the entire cohort (HFRT 21 months, CFRT 46 months). No statistically significant difference was observed between HFRT and CFRT for 2-year LRFS (76.0% v 83.4%, p=0.23) as well as ILRFS (88.5% v 90.2%, p=0.97). The 2-yr DFS (75.0% v 83.3%, p=0.30), BCSS (84.8% v 87.2%, p=0.88), and OS (79.4% v 80.2%, p=0.93) were similar between the two groups as well. Late grade 2+ urinary (22.2% v 23.8%, p=0.83) and gastrointestinal (4.4% v 0.7%, p=0.08) toxicity did not differ significantly for HFRT versus CFRT. Results: