Lymph node ratio is the ratio of positive lymph nodes to examined lymph nodes. The authors explained that this ratio is an important prognostic factor in pancreatic, breast, colorectal, and other cancers, but there is a little evidence about the relationship between lymph node ratio and survival in patients with node-positive rectal carcinoma.

Dr. Young Seok Kim from University of Ulsan, Seoul, Korea and team used data from two prospective studies conducted at their institution to investigate whether lymph node ratio has prognostic value for survival in patients with stage III rectal cancer.

The authors found that overall survival significantly decreased as the lymph node ratio increased from 0.1 or less (89%) to 0.2 or less (67%), 0.4 or less (64%), to greater than 0.4 (50%).

The same significant trend was followed by five-year disease-free survival (local and distant), declining from 75% for those with a lymph node ratio of 0.1 or less, to 33% for those with a lymph node ratio above 0.4.

The investigators explained that there was no change in the prognostic value of the lymph node ratio for survival and disease-free survival after adjustment for other variables with prognostic significance.

Lymph node ratio is an important prognostic factor in patients with stage III rectal cancer who underwent total mesorectal excision followed by chemoradiation and should be considered a stratification factor in future randomized controlled trials, the researchers conclude.

More intensive or further chemotherapy is indicated for patients with higher lymph node ratios, they add, because most treatment failures were distant metastases.