Prognostic biomarker in advanced gastric cancer
Gastric cancer is considered one of the most lethal tumors. Even with the decline in its incidence, the mortality rate of this disease has remained high-gastric cancer ranks third in terms of cancer-related death worldwide. Patient survival is highly dependent on the tumor stage at the time of diagnosis. Yet, gastric cancer is often either asymptomatic or causing only nonspecific symptoms in its early stages. By the time the symptoms occur, the cancer has usually reached an advanced stage. The current management for advanced gastric cancer (AGC) is a multidisciplinary approach; nevertheless, the prognosis of AGC is poor. The primary tumor (T), regional nodes (N), and metastasis (M) (TNM) classification, which was validated as the best predictor of patient survival, has limited power to fully reflect the prognosis. In the last decade, several biomarkers are identified to ameliorate the accuracy of patient prognosis and subsequent treatment decision-making. Undoubtedly, the discovery of novel molecular biomarkers and their establishment in clinical practice make sense in the era of “personalized” oncologic practice. The purpose of this review is to discuss the prognostic significance of the currently well-known biomarkers as well as to highlight some of the new candidate prognostic molecular markers. These prognostic markers include conventional tissue-based genetic and epigenetic alterations, noncoding RNAs, and proteins. We will also discuss the non-invasive biomarker with the ability to monitor real-time tumor dynamics, such as circulating tumor cells (CTCs) and cell-free nucleic acids (cfNAs): DNA, microRNA and long ncRNAs (lncRNAs).