Retrospective evaluation of the impact of dose escalation using pre-operative simultaneous integrated boost volumetric modulated arc therapy on the outcome of locally advanced rectal cáncer patients

Abstract

Abstract Purpose evaluating the outcome of preoperative simultaneous integrated boost volumetric modulated arc therapy (SIB-VMAT) concomitant with Capecitabine in patients diagnosed with locally advanced rectal cancer (LARC) at King Faisal Specialist Hospital and Research Centre (KFSH&RC), Riyadh, Saudi Arabia during the period January 2013 - December 2019. Results Total of134 patients were enrolled. The median age at diagnosis was 59 years. All patients received pre-operative concurrent chemo-radiation therapy (CCRT) usingSIB-VMAT with oral capecitabine. Neoadjuvant chemotherapy was administered prior to CCRT in 32 patients (23.9%). The dose of radiation was 55 Gy in 94 patients (70.1%), while 40 patients (29.9%) received 50 Gy. All patients completed the CCRT treatment without breaks. No records of acute and late grade III and IV toxicities. Curative surgery was performed in all patients with a median interval of 11 (6-52) weeks between the end of CCRT and the date of surgery. No reported 30-days postoperative mortality and no grade III and IV Clavien-Dindo complications. PCR was reported in 26 patients (19.4%), while pathologically negative nodes (pN0) were achieved in 103 patients (76.9%). Adjuvant chemotherapy was utilized in 57 patients (42.5%). The 5-year local recurrence-free survival (LRFS), disease-free survival (DFS), and overall survival (OS) were 93.2%, 67.1%, and 87.3%, respectively. Only Tumor regression grade (TRG) was significantly correlated with LRFS, (p-value 0.043). On multivariate analysis, only (TRG) and achievement of pN0 were significantly correlated with DFS,(p value<0.001). Conclusion Dose escalation utilizing (SIB-VMAT) in the preoperative treatment of LARC is well tolerated and provides effective local control.