Clinical baseline and prognostic difference of platelet lymphocyte ratio (PLR) in right-sided and let-sided colon cancers

Background: Right-sided colon cancer (RCC) and left-sided colon cancer (LCC) differ with respect to their biology and genomic patterns, but inflammatory index variation did not fully investigate. This study aimed to examine the difference of inflammatory indexes and its value between RCC and LCC.

Methods: The differences of common clinicopathologic factors, inflammatory indexes including PLR (Platelet lymphocyte ratio) between LCC and RCC were analyzed in the training cohort with logistic regression model, subsequently, confirmed in validation cohort. Kaplan-Meier analysis was applied for the analysis of the survival difference distinguished by the PLR and the Nonparametric Test was adopted to demonstrate the difference of PLR variation with the standard TNM classification between RCC and LCC.

Results: A total of 1846 CRC patients entered the study, 744 (40.3%) patients were RCC, 1102 (59.7%) were LCC. The patients' number in both cohorts was 923. It was found that LCC patients in the training cohort significantly to be with higher CEA, adenocarcinoma, early UICC/AJCC stage, p-MMR (mismatch-repair proficient), and lower PLR, and the later four features were confirm in validation cohort. Higher PLR, the unique inflammatory index, was significantly associated with poorer OS in LCC cohort (P = 0.002) and was elevated with the TNM stage in the LCC patients (P < 0.001), however, the two relationships did not sustain in RCC patients.

Conclusion: Expect the classical characteristics, PLR, an inexpensive and easily assessable inflammatory index was found first time to be significant differ between LCC and RCC. Further, elevated PLR associated with poor OS (overall survival) in the LCC and more common in advanced TNM stage.