Different strategies between Japan and other countries for the diagnosis and treatment of early-stage lung cancer

Lung cancer screening has been determined to be efficacious in Japan, while in Western countries it is considered to be ineffective. As a result, the strategies employed for the diagnosis and treatment of early-stage lung cancer (ESLC) differ, with more ESLC cases detected in Japan. Furthermore, a clinicopathological methodology has been developed by Japanese investigators in which an intentional segmentectomy is strictly indicated for patients with clinical T1NOM0 peripheral non-small cell lung cancer (NSCLC) of 2 cm or less in diameter, and wedge resection is only performed for type A or B adenocarcinoma classified according to Noguchi. The outcome of both procedures is similar to that of a lobectomy. On the other hand, a randomized, controlled trial (RCT) performed in North America showed the superiority of lobectomy compared with limited resection for T1NOM0 NSCLC, in which such strict criteria were not employed. Recently, procedures to reduce the area of mediastinal lymph node dissection (MLND) have been attempted for ESLC in Japan, while Western countries consider MLND important even in ESLC. Thus a large-scale RCT has been conducted to determine the superiority of MLND over lymph node sampling.