Lymph node counts and survival rates after resection for colon and rectal cancer.

It may be important that a sufficient number of lymph nodes are removed and examined at the time of resection for colon and rectal cancers. More extensive nodal resection has been associated with lower rates of cancer recurrence; allows for more accurate cancer staging and thus, more appropriate use of adjuvant chemotherapy for node-positive patients; and has been associated with improved survival following resection for colon and rectal cancers. Many factors affect the number of lymph nodes examined, including extent of surgical resection, patient age, tumor location, and pathology techniques. A 12-node minimum has been endorsed as a consensus standard for hospital-based performance with colectomy for colon cancer. However, using the number of lymph nodes examined on a hospital level may not significantly influence staging, use of adjuvant chemotherapy, or patient survival. For rectal cancer, the increasing emphasis on adequate circumferential radial margins and use of preoperative radiotherapy for intermediateand high-risk tumors may complicate assessment of the relationship between number of lymph nodes examined and patient outcomes; data suggest that the number of lymph nodes (total and number positive) in a rectal specimen is significantly lower following administration of preoperative radiotherapy. While there remains little controversy about the prognostic importance of higher lymph node counts for individual patients, it is not clear that node counts are useful indicators of hospital quality.