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Received Jan 21, 2018; Revised Apr 21, 2018; Accepted Apr 26, 2018
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Pancreatic cancer is one of the most fatal cancers. It is ranked the fourth leading cause of cancer deaths in the United States for both sexes [1]. In China, the incidence of pancreatic cancer was noted to be 90,100 with a mortality rate of about 79,400 per year in 2015 [2]. Pancreatic cancer cases are usually diagnosed only in an advanced stage. Also, it is associated with limited available effective treatment options. For these reasons, the 5-year survival rate of pancreatic cancer is below 5%. For patients suffering from advanced pancreatic cancer, the Karnofsky performance status (KPS) usually gets worsened, so effective treatment and precise selection of patients are of great importance. Currently, feasible prognosis prediction methods are still lacking for this ailment. Although pathological classification could be used as a good predictor, it is not easy to harvest the tumor tissue for biopsy in most of the patients.
However, certain recent blood test results provide us with clues for cancer prognosis prediction. These results include white blood cell counts, neutrophil counts, lymphocyte counts, granulocyte counts, neutrophil-to-lymphocyte ratios (NLRs), and platelet to lymphocyte ratios (PLRs). These parameters reflect the inflammatory status of the patient, which may play decisive roles at different stages as the tumor progresses. The stages include initiation, promotion, invasion, and metastasis [3, 4]. Both innate (including macrophages, neutrophils, mast cells, myeloid-derived suppressor cells, dendritic cells, and natural killer cells) and adaptive (T and B lymphocytes) immune cells exist in the tumor’s microenvironment. These immune cells participate in inflammatory responses within the microenvironment of the tumor. The consequences of inflammation in cancer are still under debate. On the one hand, inflammation may promote tumor progression [5]. On the other hand, it enhances tumor antigen cross-presentation and subsequently induces antitumor immune responses [6].
Neutrophil is the most common and vital element of inflammation that plays a significant role influencing the microenvironment of the tumor [7]. NLR is a general inflammatory indicator that can be estimated by dividing the neutrophil count...