Log odds of positive nodes as a prognostic factor for rectal cancer: a retrospective study

SUMMARY OBJECTIVE: Rectal cancer is an important cause of mortality and morbidity globally. The aim of this study was to investigate whether the log odds of positive nodes system is a better indicator than tumor node metastasis and lymph node ratio systems to determine rectum cancer prognosis, which is an important cause of mortality and morbidity globally. METHODS: This was a single-center retrospective cross-sectional study. Data were obtained from the medical records of patients with rectum adenocarcinoma followed at Gazi University Hospital. The clinicopathological data of 128 patients with rectum adenocarcinoma who underwent low anterior resection or abdominoperineal resection between January 2010 and December 2018 was retrospectively reviewed. Patients with rectum adenocarcinoma as the first and only primary diagnosis, which was confirmed by histopathological examination, than those who had undergone complete curative resection via low anterior resection or abdominoperineal resection were included. Those with familial adenomatous polyposis or Lynch syndrome, those under 18 years of age, with a synchronous tumor, peritoneal spread, or metastatic disease at the time of diagnosis, and those with <12 lymph nodes dissected from the resection material were excluded from the study. RESULTS: In multivariate analysis, age, perineural invasion, tumor node metastasis stage, lymph node ratio stage, and log odds of positive nodes stage were found to be independent prognostic factors (p<0.05). LODDS2 patients’ mortality rates were 9.495 times higher than LODDS0 patients [hazard ratio=9.495, (95%CI 4.155–21.694), p<0.001] while LNR2 stage patients’ mortality rates were 7.016 times higher than LNR0 stage patients [hazard ratio=7.016, (95%CI 3.123–15.765), p<0.001] and N2 stage patients had a 5.135 times higher risk of mortality than those who were in N0 stage [hazard ratio=5.135 (95%CI 2.451–10.756), p<0.001]. CONCLUSION: Log odds of positive nodes is a more valuable prognostic factor for rectal cancer patients than tumor node metastasis and lymph node ratio systems to determine rectum cancer prognosis.