Carcinoma — Malignant Epithelial Tumours Explained

A carcinoma is a malignant neoplasm derived from epithelial cell lineages, including the skin, mucous membranes, and glandular parenchymal tissues of internal organs. Pathologically, carcinomas are broadly categorised by their cellular morphology into adenocarcinomas (originating in glandular cells) and squamous cell carcinomas (arising from flat, protective surfaces).

Carcinomas develop through sequential genetic and epigenetic alterations that disrupt cellular division, differentiation, and tissue architecture. As these malignant cells proliferate, they acquire the ability to breach the basement membrane, invading surrounding stroma and accessing lymphatic channels and blood vessels to form distant metastases.

Knowing that a diagnosis is a carcinoma gives the care team essential information about how the cancer is likely to grow and spread. Carcinomas frequently spread first to nearby lymph nodes before reaching other organs. This predictable biological pattern guides surgical planning, determines pathological staging, and directs decisions regarding chemotherapy, radiation, or targeted therapies.

Carcinoma is confirmed by core needle or surgical biopsy examined under light microscopy. Pathologists use histochemical and immunohistochemical stains (such as cytokeratins, p40, or HER2) to verify epithelial lineage, determine the carcinoma subtype, assess histological grade, and evaluate margin status.

Carcinomas represent the vast majority of adult cancers. Major examples include adenocarcinoma of the breast, prostate, pancreas, and colon; squamous cell carcinoma of the skin, cervix, head and neck, and oesophagus; transitional cell carcinoma of the bladder; and both adenocarcinoma and squamous cell carcinoma of the lung.

Because carcinomas often progress locally and regionally before spreading distantly, localised disease is routinely treated with surgical resection and adjuvant or neoadjuvant radiotherapy. Systemic therapy is widely utilised and can include conventional cytotoxic chemotherapy, hormone blocking therapies, targeted therapies (such as EGFR or VEGF inhibitors), and immune checkpoint inhibitors.