Lymph node retrieval after resection of rectal cancer following preoperative chemoradiotherapy

According to the current guidelines of proper TNM staging, 12 lymph nodes per specimen are crucial. This study assessed the role of preoperative radiochemotherapy on the number of lymph nodes detected in the tumor-bearing specimen.

Retrospective data of 138 patients who underwent surgery for stage II and III rectal cancer without preoperative radiochemotherapy during the period of 2004-2006 (control group) were compared with prospective data of 38 patients who received preoperative radiochemotherapy during the period of 2007-2008 (study group). The number of patients with metastatic lymph nodes, number of lymph nodes per specimen, number of metastatic lymph nodes per specimen, and the size of the tumor between the groups were compared.

Positive lymph nodes were detected in 88 (64%) patients in the control group as compared with 9 (21%) patients in the study group (P<0.05). The mean number of lymph nodes per specimen in the control group was 13.5, while in the study group, the mean number of lymph nodes per specimen was 6.29 (P<0.05). There was a significant difference in the mean number of metastatic lymph nodes per specimen between the groups (5.12 in the control group versus 2.11 in the study group; P<0.05). The mean size of the tumor was 4.37 cm in the control group and 2.45 cm in the study group (P<0.01).

Preoperative radiochemotherapy for advanced rectal cancer significantly decreased the number of lymph nodes detected in the tumor-bearing specimen. This also resulted in a significant decrease in the number of metastatic lymph nodes detected in the specimen, and fewer patients with stage III (N+) cancer were diagnosed. Preoperative radiochemotherapy could induce a significant downsizing and downstaging of advanced rectal cancer, but great care in operative and pathologic examination techniques must be taken to ensure appropriate staging.