Lymph Node Retrieval in Rectal Cancer is Dependent on Many Factors—the Role of the Tumor, the Patient, the Surgeon, the Radiotherapist, and the Pathologist

Abstract

Lymph node status is the strongest prognostic factor for survival in colorectal cancer. There are several guidelines concerning the minimum numbers of lymph nodes that need to be examined to make reliable staging possible, but there is no consensus in the available literature. In this study, we determine in patients with rectal cancer factors that relate to the number of lymph nodes found and the presence of lymph node metastasis. In addition, the number of examined lymph nodes was correlated with prognosis. A total of 1227 patients were selected from a multicenter prospective randomized trial investigating the value of neoadjuvant radiotherapy. The median number of examined lymph nodes in all patients was 7.0. The number of retrieved lymph nodes in patients with node metastasis was significantly higher than in node negative patients. After neoadjuvant radiotherapy fewer lymph nodes were retrieved (6.9 vs. 8.5; P<0.0001). Variations in lymph node yield between pathology laboratories and individual pathologists were striking. The following patient and tumor characteristics are associated with a significant lower lymph node retrieval: age over 60 years, overweight, small size, and low invasion depth of the tumor, poor differentiation grade, and absence of a lymphoid reaction. Node negative patients in whom seven or less lymph nodes were examined had a lower recurrence free interval than patients in whom at least 8 lymph nodes were examined (17.0% vs. 10.7%, P=0.016). We conclude that in pathology laboratories a median of at least 8 lymph nodes need to be examined in rectal cancer specimens, but that higher numbers are desirable and achievable in most cases, even after preoperative radiotherapy.

The clinical significance of lymph node size in colon cancer

“…34 Most of the lymph nodes detected were found in the groups between 41 and r5 mm. Interestingly, the size distribution differs only slightly between node-positive and -negative cases.…”

Methylene blue-assisted lymph node dissection technique is not associated with an increased detection of lymph node metastases in colorectal cancer

“…[5][6][7] The harvest is especially negatively influenced by neoadjuvant radiochemotherapy in rectal cancer patients. 8,9 On the other hand, the threshold of 12 lymph nodes itself is debated controversially. 10 The recommendations in the literature range from 9 to 430 lymph nodes that should be harvested per case.…”

Metastatic lymph node ratio in stage III rectal cancer; prognostic significance in addition to the 7th edition of the TNM classification

“…Especially in rectal cancer adequate retrieval of lymph nodes may be troublesome as it is dependent on many factors such as age over 60, obesity, female sex, small tumour size and localisation, poor differentiation grade, the absence of a lymphoid reaction and neo-adjuvant therapy (27)(28)(29). The aim of this study is to assess the prognostic capacity of the metastatic lymph node ratio in stage III rectal cancer in addition to the 7 th edition of the TNM classification and to identify high risk patients.…”