Factors affecting tumor regression after neoadjuvant chemoradiotherapy of locally advanced rectal cancer

초록

Neoadjuvant chemoradiotherapy(NACR) is now commonly used to increase success rate of radical dissection of locally advanced rectal cancer and reduce local recurrence, allowing effective excision of the tumor and preservation of anal sphincter function by reducing tumor size and metastasis of lymph nodes. Post-operative TRR (tumor regression response) after NACR in rectal cancer is evaluated with tumor down-staging and pathological complete response. Tumor down-staging is assessed by comparing tumor and lymph node grade clinically assessed before and after treatment. Pathological complete response is assessed by grading the remaining tumor in the specimen. Although the correlation between TRR, local recurrence, and survival rate is controversial, Maas et al. reported that complete response was observed in 24% of NACR group with increased survival rate. The aim of this study is to identify factors affecting tumor regression after NACR of locally advanced rectal cancer along with clinical and pathological factors, thus aid in treatment planning. From January 2011 to December 2016, retrospective analysis was performed on 93 patients with locally advanced rectal cancer who were received neoadjuvant chemoradiotherapy followed by radical surgery. The total dose of radiation was 54Gy, 2Gy was irradiated once a day for 5 days per week. Of 93 patients, 72 patients received concurrent infusional 5-fluorouracil and leucovorin, while 21 patients received oral capecitabine during radiotherapy. Tumor regression grade(TRG) system was applied by simplifying Dworak TRG. Of the 93 patients, 54 (58.1%) cases were excellent tumor regression response(TRR)(Dworak TRG 3-4). Univariate analysis demonstrated that age, over 65 years old, was significant predictive factor for excellent TRR (P=0.003). The results from the multivariate analysis 1 also indicated that age (Odd ratio, 0.21; P=0.002) was significant predictive factor. This study analyzed factors affecting tumor regression after NACR