Is there significance in identification of non-predominant micropapillary or solid components in early-stage lung adenocarcinoma?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was 'in early-stage lung adenocarcinomas, does the presence of non-predominant micropapillary (MIP) or solid (SOL) growth component influence long-term survival and surgical strategy?'. Altogether, more than 600 papers were found using the reported search, of which 13 presented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group, study type, relevant outcomes and results of these papers were tabulated. The data collected showed that non-predominant MIP or SOL components in early-stage lung adenocarcinoma can be up to 60.4 and 41.8%, respectively. MIP or SOL components were associated with significantly reduced period of disease-free or overall survival. One study also showed a higher incidence of occult lymph node metastasis in patients with a minor MIP component. Furthermore, the presence of an MIP/SOL component in early-stage adenocarcinomas (ADCs) could influence the oncological outcome following sublobar resection. We conclude that a non-predominant MIP/SOL pattern is a negative prognostic factor and an indicator of early recurrence after limited resection.