Objective To explore the optimal interval length between two-stage surgery, based on the reduction of pulmonary function after the first operation and the safety of follow-up of the lesion.

Methods A total of 121 patients with simultaneous bilateral multiple primary lung cancers were retrospectively enrolled, who underwent two-stage resection in one year from 2008 to 2019 in Zhongshan Hospital, Fudan University. According to the interval length between the two-stage surgery, patients were distributed into short-term (≤6 months) and long-term (6-12 months) groups. Changes in preoperative pulmonary function (forced expiratory volume in the first second) and lesion features (size and solid component) between two-stage operation were compared between 2 groups.

Results The reduction degree of FEV1 in the short-term group was higher than that in the long-term group (0.36±0.25 L vs 0.26±0.24 L, P＝0.047). There was no significant difference in postoperative complications after the first-stage operation (11.1% vs 12.2%) and the two-stage operation (8.3% vs 0) between the two groups. The progress rate of lesion in the long-term group was higher than that in the short-term group. The progression rates of ground glass nodules (21.1% vs 0), sub-solid nodules (47.6% vs 6.5%) and solid nodules (67.0% vs 16.7%) in the long-term group were higher than those in the short-term group (P < 0.05). During the follow-up time, the incidence of progression occurred had elevating trand, with solid components in the lesion increased.

Conclusion The interval length of 6-12 months between two-stage operation is relatively safe for the pulmonary function, and when lesion is solid, the interval should be as short as possible, even underwent one-stage resection under ensuring surgical safety.