adenocarcinomas

Adenocarcinomas are malignant tumors that arise from glandular or secretory epithelium and form malignant glands or gland-like structures. They can occur in many organs and are the most common histologic type of carcinoma in several tissues.

Common sites include the lung, colorectum, pancreas, breast, stomach, and prostate. In the lung, adenocarcinoma is the most common histologic type and often harbors driver mutations such as EGFR, ALK, or KRAS. Colorectal adenocarcinomas arise from adenomatous polyps and frequently involve APC, KRAS, TP53, and mismatch repair genes. Pancreatic ductal adenocarcinoma is the leading pancreatic cancer and has a poor prognosis, with mutations in KRAS, CDKN2A, TP53, and SMAD4. Breast adenocarcinomas include invasive ductal and lobular types; treatment is guided by receptor status. Prostate adenocarcinoma is common in men and is evaluated with PSA testing and risk-based management.

Pathologically, adenocarcinomas show gland formation, mucin production, and may display acinar, papillary, or solid patterns. Immunohistochemistry helps determine tissue origin and may include markers such as CK7, CK20, TTF-1, and Napsin A, along with mucin stains. Molecular profiling identifies actionable alterations in some tumors, enabling targeted therapy.

Diagnosis relies on biopsy with histopathology and imaging. Staging uses tumor size, nodal involvement, and metastasis. Treatment is site- and stage-dependent, typically combining surgery when feasible with chemotherapy, radiotherapy, and, in select cases, targeted or hormonal therapies. Prognosis varies widely by site and stage, with particularly poor outcomes for advanced pancreatic cancer and many metastatic adenocarcinomas.