Reduction in the size of enlarged pelvic lymph nodes after chemoradiation therapy is associated with fewer lymph node metastases in locally advanced rectal carcinoma

Purpose We hypothesized that a reduction in the size of the lymph nodes after neoadjuvant therapy for locally advanced rectal carcinoma would be associated with decreased lymph node metastases and/or a better prognosis. Methods Between March 2006 and April 2012, 71 patients with primary rectal cancer received neoadjuvant chemoradiation therapy (CRT). For all lymph nodes 5 mm or larger in size, the major and minor axes were measured on CT scan images, and the product was calculated. The lymph node size was determined before and after CRT. The patients were divided into three groups based on the lymph node size before and after treatment. Group A exhibited a reduction in size of 60 % or more, Group B a reduction of less than 60 % and Group C had no lymph node enlargement before treatment. Results The incidence of lymph node metastases on pathological examination was 15 % in Group A and 50 % in Group B ( p = 0.006). The five-year disease-free survival in Group A was 84 % compared with 78 % in Group B (log rank p = 0.34). The five-year overall survival in Group A was 92 % compared with 74 % in Group B (log rank p = 0.088). Conclusions A reduction in the size of enlarged lymph nodes after neoadjuvant therapy may be a useful prognostic factor for recurrence and survival.