A study of lymph node ratio as a prognostic marker in colon cancer

The aim of this study was to evaluate and describe the lymph node ratio (LNR) as a prognostic parameter for patients with colon cancer. As lymphatic involvement is the key, focus was set at stage III disease. Interest was directed at the possibility of identifying high-risk groups and the clinical implementation and consequence.

The study was retrospective using a database of clinical data of all cancer patients treated at our unit. It has been continuous in registration, inclusion and update since 1999 including survival and clinical features. All patients (n=265) diagnosed with stage III colon cancer during 1999-2003 were included for the study. LNR was calculated and quartile groups were created. LNR and associated parameters were analysed towards 3-year disease-free survival (DFS). Basic patient data as well as surgery, pathology and postoperative treatment were taken into consideration.

Significant differences in disease-free survival were found for TNM N-status, tumour differentiation grade and LNR quartile group. There was a difference in 3-year DFS from 80% in LNR group 1 compared with less than 30% in group 4. These results were of prognostic interest both independently and in interaction with each other. High-risk groups could be identified and in the worst prognosis LNR group we also found a tendency towards more side effects with adjuvant chemotherapy.

The lymph node ratio, the quota between the number of lymph node metastasis and assessed lymph nodes, is a highly significant (p<0.001) prognostic factor in stage III colon cancer. It can be an aid in identifying risk groups that could benefit from a more intense postoperative surveillance and possibly bring changes in adjuvant treatment strategy. More studies of clinical data, genetic and biochemical markers are needed in this patient group to understand the possible difference in tumour behaviour and tailor the treatment.