The Critical Role of Minor Histological Patterns in Prognosis Prediction in Early-Stage Lung Adenocarcinomas.

Lung adenocarcinomas often contain multiple histological components. This study discusses the role of minor components in the progression of the disease. A retrospective evaluation was conducted on 108 patients with lung adenocarcinoma who underwent surgery at our center between 2013 and 2018, with tumor sizes less than 3 cm. The patients were categorized into four groups based on the presence of lepidic (L) and micropapillary/solid (MP/S) patterns at a minimum threshold of 5% ("L+, MP/S-", "L+, MP/S+", "L-, MP/S-", "L-, MP/S+"). The groups were compared in terms of standard uptake value, pleural invasion, lymphovascular invasion, perineural invasion, spread through air spaces, N1-N2 station lymph node metastasis, recurrence, and survival. No tumors of perineural invasion, spread through air spaces, or lymph node metastasis was observed in the "L+, MP/S-" group, and lymphovascular invasion was found to be significantly lower compared to other groups (p = 0.040). The standard uptake value levels in groups containing the lepidic pattern were significantly lower than in other groups (p = 0.006). The time to recurrence in the "L+, MP/S-" group was 121.5 ± 10.9 months, with a median survival time of 110.9 ± 10.6 months, which was longer compared to the other groups (86.2 ± 5.9 and 77 ± 13.4 months). In lung adenocarcinomas, prognosis estimation should be based not only on the dominant component but also on the presence of histological components such as lepidic and micropapillary/solid, even if they are minor.