The changing anatomic position of squamous cell carcinoma of the lung - a new conundrum

Traditionally, squamous cell carcinoma (SCC) of the lung is a central rather than a peripheral form of lung cancer. Rates of SCC in the lung periphery are typically sited in the 15-30% range. Recently, we observed that a significant portion of newly diagnosed SCC was located on a periphery. A comprehensive review of the tumor data at our facility, a busy teaching hospital with a large cohort of cancer patients, was undertaken to assess whether there had been a substantive change in the traditional epidemiologic distributions of the lung cancer, specifically with respect to SCC. Given the differences in cell biology and carcinogenesis of central versus peripheral SCC, a potential epidemiologic shift might suggest a change in tumor biology.

From May 12, 2012 through May 13, 2013, all histopathologically confirmed diagnoses of SCC of the lung were retrospectively reviewed. Each patient's lesion was then classified as peripheral or central based on CT evidence.

A total of 56 patients were diagnosed with SCC. Of these, 55% (n=31) had peripheral and 45% (n=25) had central SCC. Twenty-nine patients did not have any prior history of malignancy. Of this subset of patients, 62% (n=18) had peripheral SCC, and 38% (n=11) had central SCC.

Our findings appear to correlate with our initial observation that, within our institution, there has been a substantive shift in the traditional distribution of SCC with the majority of these cancers now being diagnosed in the lung periphery as opposed to the more central locations.