squamous cell carcinoma

Squamous cell carcinoma is a lung cancer made of flat, scale-like cells (the word squamous comes from the Latin for scale). Normally the lining of the large airways is not made of such cells, but years of irritation — classically from tobacco smoke — can prompt the lining to transform into a tougher, flatter type that can then turn cancerous. It is a story of injury, adaptation, and eventually malignancy.

This subtype tends to arise centrally, in or near the main bronchi at the lung's center, rather than in the periphery. Because of that location, it can grow into an airway and cause symptoms relatively early, such as a persistent cough, coughing up blood, or a pneumonia that keeps coming back behind a blocked airway. It is one of the lung cancers most tightly linked to smoking.

Squamous cell carcinomas less commonly carry the targetable mutations found in adenocarcinoma, so for advanced disease the mainstays have been chemotherapy and immunotherapy rather than the EGFR- or ALK-directed pills used for many adenocarcinomas. Early-stage tumors may still be cured with surgery or radiation.

A useful caveat: a central squamous tumor can sometimes erode into a blood vessel, which is why hemoptysis (coughing blood) deserves prompt evaluation in a smoker.