The prognostic importance of lymph node ratio in colorectal cancers in which curative resection was implemented

ABSTRACT The Prognostic Importance of Lymph Node Ratio in Colorectal Cancers in Which Curative Resection Was Implemented Purpose: This study was carried out to define the prognostic importance of lymph node ratio (LNR) in colorectal cancers in which curative resection was implemented. Materials and Methods: The characteristic and pathological features of 205 patients who had been operated because of colorectal cancer at the General Surgery Department of Çukurova University were recorded after being investigated retrospectively. The patients were classified into 4 groups (1/4, 1/2, 3/4 and 1) according to the rate of metastatic lymph nodes to the removed total lymph nodes. LNR1 represents the patients whose lymph node ratio is between 0 and 1/4, LNR2 represents the patients whose lymph node ratio is between 1/4 and 1/2, LNR 3 represents the patients whose lymph node ratio is between 1/2 and 3/4, LNR 4 represents the patients whose lymph node ratio is between 3/4 and 1. Moreover in this study, two groups were formed as the difference of the rate of lymph node below 1/2 and above 1/2 were aimed to evaluate and two other groups were formed to evaluate the effect of the number of removed total lymph node on survival. These groups are named as LNRA and LNRB. LNRA represents the patients whose lymph node ratio is between 0 and 1/2, LNRB represents the patients whose lymph node ratio is between 1/2 and 1. The relevancy of the data obtained from the study to the normal distribution was tested; independent groups t-test and one way variance analysis were used in the analysis of continuous variables that showed normal distribution and Mann Whitney U test or Kruscall Wallis test were used in the analysis of continuous variables that did not show normal distribution. In the analysis of categorical variables, chi-square test was used. Kaplan-Meier and Cox regression analysis were used for life analysis and Long rank test was used in the group comparisons. The results in which p value was <0.05 were accepted as statistically significant. The statistical analysis of the data was made by SPSS 17.0 Evaluation Version (Statistical Package for Social Sciences Chicago, USA) package program. Findings: When the rates of survival in the groups which were formed according to the LNR were evaluated, it was found out that the rate of 5-year survival in LNR1 was 57% while it was 52% in LNR2, 31% in LNR3 and 28% in LNR4. The difference between the groups was found as statistically significant when they were compared in terms of survival time and rates (p=0.026). The rate of mortality in LNRA and LNRB groups were found as 48.8% and 74.4%, respectively whereas 5-year survival rates were 57% and 29%, respectively. The results of the statistical study between LNRA and LNRB groups revealed that the values were more significant compared to the other grouping and as the lymph node rate, which was the strongest prognostic factor of all prognostic factors taken into this study, increased while survival rate decreases. It was also observed that both mortality increased significantly (p=0.004) and survival decreased a lot more significantly than the other prognostic factors (p=0.002) as LNR increased. It was determined that LNR was the most important prognostic factor in terms of mortality, 5-year survival and GSK. Result: LNR can be one of the important parameters on the decision of the medical doctors about the adjuvant therapy for the correct surgical staging and on the better prediction of prognosis in the patients with insufficient lymph node removal. Key Words: Colorectal cancer, lymph node rate, staging, prognosis