Lung cancer in non-smokers a separate disease

NEW YORK (Reuters Health) - Japanese investigators say that survival rates are better for patients with non-small cell lung cancer (NSCLC) who never smoked than in NSCLC patients with a history of smoking. Other disease characteristics are different as well between the two populations.

As such, NSCLC in patients who never smoked should be considered a separate disease entity from NSCLC in current and former smokers, say Tokujiro Yano and colleagues at Kyushu University in Fukuoka, Japan, in the journal Cancer.

The researchers reviewed the medical records of 1,405 patients with primary NSCLC, the most common type of lung cancer, who underwent complete removal of the cancer between 1974 and 2004. Disease-related variables and postoperative survival were compared for patients who never smoked and those who reported smoking currently or at some time in their past.

Yano's team found a steady increase in the proportion of never-smokers among all NSCLC patients during the 30-year study period, from 15.9 percent in 1974 to 32.8 percent by 2004. Women represented 85.8 percent of NSCLC never-smokers but only 11.2 percent of NSCLC patients with a history of smoking.

Also, the researchers found, 40.1 percent of the NSCLC never-smokers had pathologic stage IA disease, compared with 25.4 percent of the smokers.

Overall survival and cancer-specific survival rates among the never-smoking NSCLC patients was "significantly superior" to NSCLC patients with a history of smoking.

The Kyushu University team found factors other than smoking to be significantly associated with postoperative survival. The factors included gender, cancer cell type and classification.

Further analysis found that pathologic classification and never-smoking status were independent prognostic factors, Yano and colleagues report.

There is "a need to carefully obtain the smoking history from patients because precise information regarding smoking status is a prerequisite for making an accurate diagnosis of 'never-smoking NSCLC,'" the authors advise.

SOURCE: Cancer, September 1, 2008.