A study of lymph node ratio in stage IV colorectal cancer

BACKGROUND: The finding of metastasis in colorectal cancer, stage IV disease, has a major impact on prognosis and treatment strategy. Known important factors include the extent of the metastasis and the patients' performance status. The lymph node factors are of known importance in earlier cancer stages but less described in metastatic disease. The aim of the study was to evaluate lymph node status and ratio as prognostic markers in stage IV colorectal cancer. METHODS: The study was retrospective and assessing all patients operated, with bowel resection, for an initial stage IV colorectal cancer during 1999-2003 (n = 136). Basic demographic data as well as given treatment was assessed. The Lymph node ratio (LNR), the quota between the number of lymph node metastasis and assessed lymph nodes, was calculated. LNR groups were created by ratio thirds, 3 equally sized groups. The analysis was made by LNR group and by eligibility for chemotherapy with cancer specific survival as outcome parameter. RESULTS: The median survival (CSS) for the entire group was 431 days with great variability. For the patients eligible for chemotherapy it ranged from 791 days in LNR-group 1 to 433 days for the patients in group 3. For patients ineligible for chemotherapy the corresponding figures were 209 and 91 days. The eligibility for chemotherapy was a major prognostic factor which also takes co-morbidity, age and performance status into consideration. The LNR (p < 0.01) and the tumour differentiation grade were also significant (p < 0.05) factors regarding survival. The LNR group 3 was also associated with a higher frequency of multiple metastasis locations (p < 0.05) and of more side effects with chemotherapy and thus of reductions in dosage or pre-emptive treatment ending (p < 0.05). CONCLUSION: Stage IV colorectal cancer is a heterogeneous group regarding the survival prognosis. The lymph node ratio was found to be a significant marker for the survival prognosis (p < 0.0049). High and low risk groups could be identified with a survival difference of up to one year. It could be of importance when planning a treatment strategy or evaluating clinical data materials. A pathology report should include a node assessment even at presence of synchronous metastasis.