Loco-regional relapse pattern and timing after segmentectomy in patients with c-IA non-small cell lung cancer.

Background: Segmentectomy has been recognized as the standard procedure for small peripheral lung cancer; however, it has been shown that loco-regional relapse is more common with segmentectomy than with lobectomy. This study aims to investigate the long-term outcomes and loco-regional relapse patterns in patients with clinical stage IA (c-IA) non-small cell lung cancer (NSCLC) after segmentectomy and compare them with those after lobectomy.

Methods: We retrospectively compared the long-term outcomes of 115 patients who underwent segmentectomy for c-IA NSCLC with those of 292 patients who underwent lobectomy between January 2008 and December 2015. Segmentectomy was indicated intentionally or chosen in patients who were considered intolerable to lobectomy. New isolated growing lung lesions were defined as relapses if they were not diagnosed with a second primary lung cancer.

Results: The median observation period was 2,150 days. The 10-year overall survival (OS) rates and relapse-free survival (RFS) rates of the two groups were similar: 79.4% and 68.7% for segmentectomy, and 68.2% and 61.2% for lobectomy. Even after propensity score matching, no significant differences were observed in the OS and RFS rates between the groups. The segmentectomy group had a higher loco-regional relapse rate (14% vs. 8%), including the surgical margin, remnant lobe, ipsilateral lung, mediastinal lymph node, and ipsilateral dissemination; however, no relapse was observed in the ipsilateral hilar lymph node. Loco-regional relapse occurred significantly later after segmentectomy than after lobectomy (median: 1,246 vs. 512 days, P=0.03), especially four years after segmentectomy. Loco-regional relapse occurred even when the tumor diameter was <1.0 cm. Most patients with loco-regional relapse had solid-dominant tumors.

Conclusions: Segmentectomy, both intentional and compromised, showed comparable long-term outcomes to lobectomy; however, loco-regional relapse can develop in a later phase than lobectomy, requiring careful follow-up.