Ground-Glass Opacity Component as a Protective Factor for Patients with Invasive Adenocarcinoma ≤3 cm with Micropapillary or Solid Pathological Patterns

Objectives Micropapillary and solid pathological patterns are known to correlate with poor prognosis in invasive adenocarcinoma (IAC). Meanwhile, ground-glass opacity (GGO) components have been identified as a protective factor in IAC. This study investigated the prognostic significance of GGO component in IAC ≤3 cm with micropapillary/solid (MP/S) pathological patterns. Methods We retrospectively enrolled 547 patients who underwent lobectomy at Shanghai Chest Hospital between June 1, 2014, and December 31, 2016, with 74 recurrence events and 54 death events observed during follow-up. Invasive adenocarcinoma was classified into 4 groups according to the presence of MP/S pathological patterns and a consolidation-to-tumour ratio (CTR) of 0.5: MP/S-CTR-, MP/S-CTR+, MP/S+CTR-, and MP/S+CTR+. Kaplan-Meier estimator with log-rank test was used to compare overall survival (OS) and recurrence-free survival (RFS) among these 4 subgroups. Cox regression models were applied to identify factors influencing survival. Results The distribution of the enrolled patients was as follows: MP/S-CTR- type(173 cases, 31.6%, 3 recurrences, 2 deaths); MP/S-CTR+ (178 cases, 32.5%, 10 recurrences, 6 deaths); MP/S+CTR-(42 cases, 7.7%, 10 recurrences, 9 deaths); and MP/S+CTR+(154 cases, 28.2%, 51 recurrences, 37 deaths). The median follow-up time was 66 months (95% CI, 52-78 months). The 5-year RFS rates were 98%, 94%, 76%, and 67%, respectively (P < 0.001). The 5-year OS rates were 99%, 97%, 79%, and 76% for the 4 groups, respectively (P < 0.001). For CTR- nodules, the presence of MP/S pathological patterns did not affect RFS (P = 0.27) or OS (P = 0.50). However, in CTR+ nodules, MP/S pathological patterns was associated with worse RFS (P < 0.001). Conclusions The GGO component may be a protective factor for patients who underwent lobectomy for invasive adenocarcinoma ≤3 cm with micropapillary or solid pathological patterns. This finding may contribute to a more accurate assessment of recurrence risk and provide guidance for determining adjuvant strategies in such patients.