ESTRO 2020 Abstract Book

S640 ESTRO 2020

PO-1216 Can sarcopenia predict outcomes in bladder cancer patients treated with chemoradiotherapy? M. Corden 1 , S. Chin 2 , A. Cree 2 , P. Hoskin 1 , A. McWilliam 1 , A.D. Satiti 1 , Y.P. Song 2 , A. Green 1 , A. Choudhury 1 1 The University of Manchester, Radiotherapy Related Research, Manchester, United Kingdom ; 2 The Christie NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom Purpose or Objective Bladder cancer is the tenth commonest malignancy in the UK, with approximately 10,200 new diagnoses and 5,400 deaths annually. Sarcopenia shows promise as a prognostic factor for bladder cancer and has been shown to predict overall survival (OS) in patients treated with radical cystectomy. The present study aims to assess sarcopenia as a predictor of OS and progression-free survival (PFS) in patients with urothelial carcinoma (UC) of the bladder treated with organ-sparing concurrent gemcitabine and 244 patients with non-metastatic UC, treated from 2010- 2017 with 52.5Gy in 20 fractions of curative intent radiotherapy with weekly gemcitabine, were identified for analysis. Pre-treatment computed tomography (CT) scans were obtained for 185 patients. The L3 vertebra was identified manually and machine learning software was used to assist skeletal muscle segmentation. Cross- sectional area of skeletal muscle was obtained and normalised to patients’ height. This provided skeletal muscle index (SMI). Sarcopenia was defined using sex- specific international consensus SMI definitions of <39 cm²/m² in women and <55 cm²/m² in men. Associations between pre-treatment sarcopenia and OS and PFS were analysed using univariate and multivariate Cox proportional hazards models and Kaplan-Meier (KM) Of 244 patients, 114 (46.7%) were sarcopenic, 71 (29.1%) were non-sarcopenic and 59 (24.2%) had unknown SMI as CT scans were not available. Sarcopenic patients tended to be male (85.1% vs 61.1% in non-sarcopenic patients). No significant differences were observed with respect to age, T stage, smoker status, presence of carcinoma in situ, albumin, haemoglobin, adult comorbidity evaluation-27, World Health Organisation Performance Status (WHO PS), hydronephrosis, neutrophil count, lymphocyte count, tumour stage and provision of neoadjuvant chemotherapy. Median OS and PFS were 40 (interquartile range [IQR] 23.8 – 62) and 32 (IQR 14 - 54.3) months respectively (see figure 1). Univariate analysis showed no association between sarcopenia and OS or PFS. On multivariate analysis, WHO PS, hydronephrosis and neutrophil count were associated with worse OS and PFS. radiotherapy (GemX). Material and Methods curves. Results

Historically, the entire empty bladder is included in a single clinical target volume (CTV). An empty bladder aims to reduce dose to organs at risk and improve reproducibility. Advances in imaging and radiotherapy techniques allow visualisation of the bladder wall and delivery of higher radiation dose to the tumour bed. Such techniques require bladder-filling to separate bladder walls for tumour bed boost. We evaluate the impact of bladder size in radiotherapy planning (RTP) scans on outcomes. Material and Methods This retrospective study included all patients treated with radical chemoradiotherapy for urothelial carcinoma of the bladder in a tertiary cancer centre from 2010 to 2014. An empty bladder imaging and treatment protocol was used. The whole bladder and extravesicle extension of tumour was treated to a uniform dose of 52.5Gy in 20 fractions with weekly chemotherapy. Bladder volume was measured on RTP scan. Overall survival (OS) was defined as time from start of treatment to death and patients still alive were censored at time last known alive. Progression free survival (PFS) was defined as time to local or metastatic recurrence. Cox proportional hazard ratio was used to investigate the association of bladder volume with outcomes. Results 132 patients were included in this study. One patient had high grade T1 disease and all others had muscle-invasive cancers. None had distant metastases. 5 patients did not complete radiotherapy but all had at least 16 of planned 20 fractions. 79 patients had neoadjuvant chemotherapy. With a median follow up of 74.1 months, the median OS of patients was 73.2 months (58.7-108.4). Median PFS was 64.3 months (35.5-108.4). Mean bladder volume was 109.50cm 3 (39.2- 433.3). Due to the large range of bladder volumes, a log scale was used. Larger log(bladder volume) on RTP scan was associated with poorer OS (HR 1.78 p=0.03) and PFS (HR 1.71 p=0.03). This is not clinically significant after multivariate analysis. (Table 1).

Conclusion Advances in radiotherapy technique allow more precise treatment plans. As clinical trials adopt bladder-filling protocols, it is vital that the impact of bladder volume on clinical outcomes is considered. Our relatively small study shows that bladder volume is not related to survival in a multivariate analysis. Factors like hydronephrosis and CIS impact survival, and should be considered in formulation of management plans. Bladder volume in this study reflects poor bladder emptying which may differ from planned bladder filling. Further evaluation in a prospective patient cohort with planned bladder filling will improve our understanding of the impact of bladder size on outcomes in the modern era.

Conclusion Sarcopenia is not associated with worse OS or PFS in bladder cancer patients treated with concurrent chemoradiotherapy.