[Clinicopathological factors affecting the lymph node yield from laparoscopically resected specimens of rectal...

Objective: To identify the clinicopathological factors affecting the number of lymph nodes yielded from specimens obtained by laparoscopic-assissted resection of rectal cancer, and discuss further the possible causes of insufficient lymph nodes retrieval (<12). Methods: The clinicopathological data of 422 consecutive rectal cancer cases, who underwent radical laparoscopic rectal resection (R0) at our department during January to October 2015, were analyzed retrospectively. The correlation between the clinicopathological factors and the number of lymph nodes yielded from the surgical specimens was assessed statistically. Results: Age of the patient, length of specimen, tumor size and operating surgeon were significantly associated with the lymph node yield (all P<0.05). The total number of lymph nodes yielded in 351 patients without neoadjuvant therapy ranged 8-49, with an average of 22.5, and the lymph node metastasis rate was 0-100% with an average of 7.6%.The total number of lymph nodes yielded from the 71 patients receiving neoadjuvant therapy ranged 9-70, with an average of 18.3, and the lymph node metastasis rate was 0-73.0%, with an average of 7.6%. Neoadjuvant therapy decreased the total lymph node yield obviously (P<0.001), but didn't decrease the lymph node metastasis rate (P=0.636). Of all the patients investigated, 19 cases had less than 12 dissected lymph nodes, and 403 cases had at least 12 lymph nodes removed. Gender, tumor size and neoadjvant therapy were independent risk factors for yield of twelve or more lymph nodes (all P<0.05). Conclusions: Age of the patient, length of specimen, tumor size, operating surgeons and neoadjuvant therapy are significantly correlated with the total number of lymph nodes yielded from laparoscopically resected specimens of rectal cancer. Neoadjvant therapy may obviously decrease the number of yielded lymph nodes, while not decreases the lymph node metastasis rate. Male gender, small size of the tumor, and neoadjvant therapy are possible risk factors for harvesting less than 12 lymph nodes.