Long-term prognosis of patients with resected adenocarcinoma in situ and minimally invasive adenocarcinoma of the lung.

Abstract Introduction The WHO classification of lung tumors defines adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) as cancers with no or limited histological invasive components. The probability of patients with AIS or MIA being recurrence-free for 5 years postoperatively has been shown to be 100%. This study aimed to analyze the prognosis of patients with AIS or MIA after more than 5 postoperative years. Methods We reviewed the pathological findings of 4,768 patients who underwent resection for lung cancer between 1998 and 2010. Of these, 524 patients with curative resection for AIS (207 cases, 39.5%) and MIA (317 cases, 60.5%) were included. Postoperative recurrence, survival, and development of secondary primary lung cancer were analyzed. Results Of the included patients, 342 (65.3%) were females, 333 (63.5%) were non-smokers and 229 (43.7%) underwent sublobar resection. Average pathological total tumor diameter was 15.2±5.5 mm. Median postoperative follow-up period was 100 months (range: 1-237). No recurrence of lung cancer was observed for either AIS or MIA cases. Estimated 10-year postoperative disease-specific survival rates were 100% / 100% (p = 0.72), overall survival rates were 95.3% / 97.8% (p = 0.94) for AIS / MIA cases, respectively. Estimated incidence rates of metachronous secondary primary lung cancer at 10 years after surgery were 5.6% and 7.7% for AIS and MIA, respectively (p = 0.45), and these were not correlated with the EGFR mutation status. Conclusions Although the development of metachronous secondary primary lung cancer should be noted, the risk of recurrence is quite low more than 5 years after resection of AIS and MIA. This finding strengthens the clinical value of distinguishing AIS and MIA from other adenocarcinomas of the lung.