Pathologic response prediction and neoadjuvant rectal score evaluation in patients with rectal cancer

Aim: In this study, we aimed to evaluate the factors of neoadjuvant chemoradiotherapy (nCRT) affecting the pathologic response in locally advanced rectal cancer. Material and Method: A total of 80 rectal cancer patients undergoing nCRT were included in the study to investigate clinical and pathological factors associated with tumor regression grade. Neoadjuvant rectal scoring (NAR) was calculated to predict overall survival. Results: Thirteen patients (16%) were detected to have pathologic complete response (pCR) and 24 patients (30%) as pathologic poor response (pPR). Tumor size in pCR group was smaller than the in other groups (p-0.003). Distal tumor localization and clinical complete response (cCR) were associated with pCR (p=0.007, p<0.005 respectively). Higher rates of pPR were observed in patients with residual tumours (cPR) (p=0.007). The factors correlated to low NAR were distal tumor localization, pathologically negative lymph nodes, cCR, and pCR (p=0.003, p=0.017, p<0.005, p<0.005 respectively). Statistically significant correlations were identified between high NAR and PET-CT stage III disease (p=0.03), pathologic lymph node metastasis (p<0.005) and cPR (p=0.007). Discussion: Clinical and pathologic factors are correlated with tumour regression grade and 5-year overall survival expectancy. Studies with larger sample sizes are needed to better elucidate these groups of patients and develop more effective treatments.