We previously showed that Asian ethnicity was an independent favorable prognostic
factor in non-small cell lung cancer (NSCLC). Many Asian NSCLC patients were never-smokers,
and never-smokers had improved survival than ever-smokers. We investigated whether
Asian ethnicity is a favorable prognostic factor independent of smoking status.
Retrospective population-based study of NSCLC cases from the cancer surveillance programs
of three Southern California counties from 1991 to 2005.
A total of 20,140 NSCLC patients with known smoking status were analyzed of which
9.1% were never-smokers and 6.5% were Asians. There was a threefold increase in the
percentage of Asian never-smokers as compared with ever-smokers. Asians had the highest
overall survival (OS) among the 4 major ethnicities (p < 0.0001) and never-smokers
had improved OS over ever-smokers (p = 0.0183) by univariate analyses. By multivariate
analyses, Asian ethnicity was an independent and favorable prognostic factor for OS
(versus non-Asian; hazard ratio [HR] = 0.861, 95% confidence interval [CI]: 0.808-0.918,
p < 0.0001), among smokers (versus non-Asian; HR = 0.867, 95% CI: 0.807-0.931, p <
0.0001), and among never-smokers (versus non-Asian; HR = 0.841, 95% CI: 0.728-0.971,
p = 0.0180). Never-smoker was a favorable prognostic factor if ethnicity was not accounted
for (versus ever-smoker; HR = 0.936, 95% CI: 0.886-0.988, p = 0.0169) but was no longer
an independent favorable prognostic factor (versus ever-smoker; HR = 0.953, 95% CI:
0.902-1.007, p = 0.0861) after accounting for ethnicity.
Asian ethnicity is an independent favorable prognostic factor for OS in NSCLC regardless
of smoking status.