Abstract
BACKGROUND: To identify tumor size could be taken as a decision-making factor in the management of preoperative radiotherapy (RT) for patients with locally advanced rectal cancer (LARC). METHODS: In this study, patients diagnosed with rectal adenocarcinoma and staged at II/III from the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2014 were included. Kaplan-Meier curve was conducted to investigate the overall survival (OS) between subgroups with different tumor sizes and the relationship between the tumor size and the efficacy of preoperative RT. RESULTS: There were 1402 patients eligible for this study, of whom 1105 (78.8%) received preoperative radiotherapy (RT + S group) and 297 (21.2%) underwent surgery alone (S group). The median OS was comparable between groups of RT + S and S before and after propensity score matching (both P > 0.05), but tumor size was a robust independent risk factor of OS (P < 0.05). 5 cm was then identified to the optimal cut-off value of tumor size using the minimum P value. Further analysis showed that preoperative RT could only benefit those with tumor size > 5 cm (P < 0.05); while on the contrary, it would hamper the OS of those with tumor size ≤ 5 cm and no OS risk factors (P > 0.05). CONCLUSION: Data from this retrospective analysis of patients with LARC seems to indicate that tumor size might play a role in the decision-making process for (tumors > 5 cm) or against (tumors ≤ 5 cm) preoperative radiotherapy.