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Rectal cancer constitutes over one-third of all colorectal cancers (CRCs) and is one of the leading causes of cancer-related deaths in developed countries. In order to identify high-risk patients and better adjust therapies, new markers are needed. Systemic inflammatory response (SIR) markers such as LMR, NLR, and PLR have proven to be highly prognostic in many malignancies, including CRC; however, their roles in locally advanced rectal cancer (LARC) are conflicting and lack proper validation. Sixty well-selected patients with LARC treated at the Maria Sklodowska-Curie National Research Institute of Oncology in Warsaw, Poland, between August 2017 and December 2020 were prospectively enrolled in this study. The reproducibility of the pre-treatment levels of the SIR markers, their correlations with clinicopathological characteristics, and their prognostic value were evaluated. There was a significant positive correlation between LMR and cancer-related inflammatory infiltrate (r = 0.38, p = 0.044) and PD-L1 expression in tumor cells, lymphocytes, and macrophages (combined positive score (CPS)) (r = 0.45, p = 0.016). The PLR level was correlated with nodal involvement (p = 0.033). The SIR markers proved to be only moderately reproducible and had no significant prognostic value. In conclusion, the LMR was associated with local cancer-related inflammation and PD-L1 expression in tumor microenvironments. The validity of SIR indices as biomarkers in LARC requires further investigation. [ABSTRACT FROM AUTHOR]

Simple Summary: Colorectal cancer (CRC) is one of the most common cancers worldwide. Novel markers have been investigated in order to better predict the course of disease and adjust the treatment. Markers associated with cancer-related inflammation (CRI), both in the bloodstream and the tumor tissue, have been in the spotlight for years. In this study, we investigate whether blood-based markers: lymphocyte-to-monocyte ratio, neutrophil-to-lymphocyte ratio or platelet-to-lymphocyte ratio, correlate with tissue-based markers, such as tumor-infiltrating lymphocytes. We retrospectively analyzed 87 patients with locally advanced left-sided CRC treated with radical surgery. Fifty patients were found suitable for the study. We compared the results of their blood tests from the time of the surgical intervention and the density of lymphocytes in the resected tumors. We found no correlation between local and peripheral markers of CRI. Further prospective studies are needed to confirm the results. Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide. Novel markers are required in order to select high-risk patients and better adjust the treatment. Both peripheral and local markers of cancer-related inflammation (CRI) such as lymphocyte-to-monocyte ratio (LMR), neutrophil-to-lymphocyte ratio (NLR) or platelet-to-lymphocyte ratio (PLR) and tumor-infiltrating lymphocytes (TILs) have been thoroughly investigated in recent years and deemed to be highly prognostic. We hypothesized that there is an association between local and peripheral CRI indices and that blood-based biomarkers may serve as a surrogate of TILs. We retrospectively analyzed 87 patients with locally advanced left-sided CRC treated with radical-intent surgery in the Maria Skłodowska-Curie National Research Institute of Oncology in Warsaw, Poland, between January 2014 and December 2015. Fifty patients were found eligible for the study. The patients were divided in terms of pre-treatment values of systemic inflammatory response (SIR) markers into LMR/NLR/PLR-high and low groups. We evaluated the resected specimens by immunohistochemistry in order to assess the densities of CD3+ and CD8+ lymphocytes in the center of the tumor and in the invasive margin. We found that the level of CD3+ lymphocytes in the center of the tumor was statistically significantly higher in patients with low pre-treatment NLR (p = 0.044); however, no correlation between any of the SIR markers and CD3+ or CD8+ TILs was observed. Five-year overall survival (OS) was longer in patients with high LMR (p < 0.001), low NLR (p = 0.001) and low PLR (p = 0.095). No correlation between the density of TILs and OS was demonstrated. In conclusion, based on our study, peripheral blood-based markers and CD3+ and CD8+ TILs are not interrelated. [ABSTRACT FROM AUTHOR]