Changes in survival of patients with non–small cell lung cancer in Japan: An interrupted time series study

The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‐TKIs) gefitinib and erlotinib were approved for metastatic or relapsed non–small cell lung cancer (NSCLC) in Japan in 2002 and 2007, respectively. EGFR mutation testing was also approved in 2007. Although clinical trials showed efficacy in NSCLC patients harboring activating EGFR mutations, these effects have rarely been reported in real‐world practice. We evaluated changes in survival in NSCLC patients following introduction of these agents and EGFR mutation testing by extracting patients diagnosed with NSCLC from 1993 through 2011 from six prefectural population‐based cancer registries in Japan. Relative survival (RS) was calculated by sex, histological subtype, and cancer stage. We conducted interrupted time series analysis to assess survival changes following introduction of EGFR‐TKIs and EGFR mutation testing. 120,068 patients with NSCLC were analyzed. One‐ and three‐year RS gradually increased in overall NSCLC for men and women. For adenocarcinoma, among men, slopes of 1‐ and 3‐year RS increased steeply in patients diagnosed from 2007 through 2011; among women, significant level increases were seen in 1‐year RS in patients diagnosed in 2002 (4.55% [95% confidence interval: 1.76‐7.33]) and 2007 (3.40% [1.27‐5.52]). These significant level increases were particularly obvious in women with adenocarcinoma at an advanced stage. Our results suggest that recent improvements in survival in men and women with adenocarcinoma are due at least partly to introduction of EGFR‐TKIs into real‐world practice, and to prescription based on appropriate patient selection following introduction of EGFR mutation testing into real‐world practice in Japan.