Does multiplicity of synchronous multiple lung primaries (SMLPs) affect prognosis.

Abstract

e20530 Background: SMLPs are detected more commonly due to advancements in screening technology. Their workup and classification; however, are still lacking a clear standard. T stage of the largest lesion has been used as the major prognostic marker. This; however, does not take the number of SMLPs and their genomic drivers into consideration. This study aims to identify and review common risk factors associated with SMLPs and determine whether the number of primaries influence the prognosis. Methods: A systematic review of the literature published between 2000 and 2021 was conducted through PubMed and Medline by using the combination of keywords, including: “synchronous multiple primary lung cancer”, “simultaneous multifocal lung cancer”, “synchronous solitary lung metastasis”, “risk factor” and “prognosis”. A total of fifty studies were identified, among them only sixteen retrospective research articles and two review articles were relevant to the study at hand. Results: Sixteen retrospective studies including a total of 1685 eligible patients were reviewed. Thirteen of these studies reported the main histology type to be adenocarcinoma with a ratio ranging from 35% to 96.8%. Eight studies have reported the numbers of synchronous primary lung cancers, including one study found 11 SMLPs. Among these, one study by van Rens found number of SMLPs impact prognosis adversely compared to a single lung cancer. However, three other studies demonstrated multiple SMPLs do not adversely affect survival (Finley et al, 2010; Kocaturk et al, 2011; Li et al, 2020). Four of the sixteen studies analysed the effect of multiple lobes involvement and distance between tumors, with varying conclusions; two studies reported no difference in prognosis while one study revealed worse survival with multiple lobe involvement and one study found favorable outcome. Most studies confirm the usual prognostic factors for SMLPs, including: gender, smoking, type of surgery, comorbidities and adjuvant therapy. The median 5 year OS reported for SMLPs is 66%, with a wide range from 19% to 95.8%.The 3 year OS is 75% in most studies. Conclusions: The data on how the number of SMLPs affects the prognosis is uncertain. The current recommendation to base the decision for adjuvant therapy on the highest T stage is not supported by prospective evidence or consistent among published case series. Considering the recent approval of targeted therapies in early stage lung cancers, a better prognostic scoring system for SMLPs is required.