Concise update on colorectal cancer epidemiology

Colorectal cancer is a type of gastrointestinal malignancy originating from either the colon or the rectum. Although both forms can be simply defined as colon or rectal cancers, depending on their origin, they are often merged because of the many biologically and clinically common features (1). Adenocarcinoma is the most frequent colorectal malignancy (up to 95% of cases), followed by carcinoid tumors, gastrointestinal stromal tumors (GISTs), lymphomas and sarcomas (2). Well differentiated adenocarcinoma presents with over 95% of tumor gland formation, whereas gland formation is only 50–95% or <50% in moderately and poorly differentiated adenocarcinomas, respectively. Moderately differentiated adenocarcinoma is the most frequent diagnosis (~70%) in clinical practice, whilst poorly or well differentiated adenocarcinomas account for 20% and 10% of cases, respectively (2). The left rather than the right colon is more frequently affected (i.e., ~5:1)