Contribution of smoking habit to the prognosis of stage I KRAS-mutated non-small cell lung cancer.

BACKGROUND: One of the known risk factors for non-small cell lung cancer (NSCLC) is somatic mutation in the Kirsten rat sarcoma (KRAS) gene. The relationship with smoking is well known.

METHODS: We retrospectively studied the data of 92 patients who underwent pulmonary resection January 2003 and June 2012 and were diagnosed as KRAS-mutated pathological stage I adenocarcinoma.

RESULTS: Among them, 33 patients who were non to light smoker (NLS) (smoking index, 0 to 400) were compared with 59 middle to heavy smoker (MHS) (> 400). The 5-year overall survival (OS) was significantly better in NLS (96.9%) than in MHS (80.0%); however, no significant difference was observed compared with wild-type KRAS (92.8%) (p= 0.66). The presence of p53 was significantly associated with smoking history (p< 0.01). The 5-year OS for NLS with p53-negative KRAS codon 12-mutated NSCLC (n= 28) was significantly better (96.3%) than that for MHS with both p53-positive and -negative KRAS mutation (p= 0.03 and p< 0.03, respectively).

CONCLUSIONS: A non to light smoking habit might contribute to an improvement in prognosis that is equivalent to that of wild-type KRAS, and p53 mutation did not affect survival in smokers harboring KRAS codon 12.