PD-L1 testing in advanced gastric cancer-what physicians who treat this disease must know-a literature review.

Background and Objective: Immune checkpoint inhibition has shed light on a new era in cancer therapy, and randomized clinical trials have demonstrated that a meaningful portion of the overall population of metastatic gastric cancer (GC) patients may derive clinical benefit from immunotherapy, which raises the relevance in identifying predictive biomarkers. Programmed cell death-ligand 1 (PD-L1) expression has demonstrated a significant association between level of expression and the magnitude of benefit derived from immune checkpoint inhibition in GC. Nevertheless, this biomarker shows several pitfalls that must be considered in the therapeutic decision to incorporate immune checkpoint inhibition as the standard of care of GC, such as spatial and temporal heterogeneity, interobserver variability, immunohistochemistry (IHC) assay, and influence by chemotherapy or radiation therapy. Methods: In the present comprehensive review, we revised the main studies regarding PD-L1 evaluation in GC. Key Content and Findings: Here we describe the molecular characteristics of the tumor microenvironment in GC, the obstacles in the interpretation of PD-L1 expression and present the data of the clinical trials that have evaluated the efficacy and safety of immune checkpoint inhibition and the association with the biomarker expression, both in first-line and later lines of therapy. Conclusions: From the emerging predictive biomarkers for immune checkpoint inhibition, PD-L1 has demonstrated a meaningful association between level of expression in tumor microenvironment and the magnitude of benefit derived from immune checkpoint inhibition in GC.

Vitamin D and colorectal cancer - A practical review of the literature.

Colorectal cancer (CRC) is the third leading cause of cancer-related mortality in the United States and the second cause worldwide. Its incidence rates have been decreasing in the overall population in the US in the past few decades, but with increasing rates in the population younger than 50 years old. Environmental factors are supposed to be involved in the development of the disease, with strong evidence favoring an influence of the diet and lifestyle. A diet high in red meat and calories, and low in fiber, fruits and vegetables increases the risk of CRC, as well as physical inactivity. The influence of low calcium intake and low levels of vitamin D on the risk of the disease and on the clinical outcomes of CRC patients has also been investigated. Hypovitaminosis D has been highly prevalent worldwide and associated with several chronic diseases, including malignancies. Vitamin D is a steroid hormone with the main function of regulating bone metabolism, but with many other physiological functions, such as anti-inflammatory, immunomodulatory, and antiangiogenic effects, potentially acting as a carcinogenesis inhibitor. In this review, we aim to describe the relation of vitamin D with malignant diseases, mainly CRC, as well as to highlight the results of the studies which addressed the potential role of vitamin D in the development and progression of the disease. In addition, we will present the results of the pivotal randomized clinical trials that evaluated the impact of vitamin D supplementation on the clinical outcomes of patients with CRC.