colorectal Carcinoma

Colorectal cancer is a malignancy arising from the colonic or rectal epithelium, typically developing through a well-characterized adenoma-to-carcinoma sequence driven by accumulated genetic mutations including APC, KRAS, and p53, though alternative pathways involving microsatellite instability and serrated polyps also exist. It represents one of the most common cancers worldwide with significant morbidity and mortality, yet is highly preventable through screening colonoscopy and early polypectomy, making understanding of risk factors, hereditary syndromes like FAP and Lynch syndrome, and screening guidelines essential for primary care and surgical practice. Medical students must recognize that clinical presentation differs by tumor location, with right-sided lesions causing occult bleeding and anemia while left-sided tumors present with obstructive symptoms, and that management decisions hinge on accurate TNM staging, molecular testing for markers like MSI status and KRAS mutations, and the distinct treatment considerations for rectal cancer involving neoadjuvant therapy and surgical approaches relative to the mesorectal fascia.