Colon cancer

Colon and rectal cancer (CRC) affect approximately 1 million individuals worldwide annually. In Western countries, disease-specific mortality has been declining by 1.6%–2% per year on account of screening programs. However, the incidence of colorectal cancer in individuals under 50 years of age has been increasing by 2.1% per year. Males and females are affected equally. Most colorectal cancer is sporadic and is derived from adenomas. Chronic inflammatory bowel disease (ulcerative colitis, Crohn’s disease) increases the risk for developing CRC. Adenomatous polyps form in the colon when normal mechanisms regulating epithelial renewal are disrupted. This is known as the adenoma-carcinoma sequence. Mutations of several oncogenes and tumor-suppressor genes are involved in this sequence. In right-sided colon cancer, suspicious symptoms include anemia, weakness, malaise, and abdominal pain. In left-sided CRC, suspicious symptoms include changes in bowel habits, constipation, blood per rectum, abdominal pain, tenesmus, and obstruction. Surgery is the mainstay of colon cancer treatment. Adjuvant chemotherapy is recommended in patients with lymph node metastases. Complete mesocolic excision refers to anatomic resection of the mesentery with an intact visceral peritoneum, tumor-free bowel proximal and distal to tumor, and central venous ligation, thus retrieving lymph nodes and tissue overlying the superior mesenteric vein and artery (D3 lymph nodes).