Prognostic significance of vascular invasion in intermediate-grade subtype of lung adenocarcinoma

<span class="paragraphSection"><div class="boxTitle">Abstract</div><div class="boxTitle">Objectives</div>Although the recent reclassification of histological subtypes of lung adenocarcinoma reflects disease prognosis better, the prognosis of papillary and acinar-predominant adenocarcinoma, which are highly prevalent, is heterogeneity. The present study aimed to identify the prognostic indicators for papillary and acinar-predominant adenocarcinoma.<div class="boxTitle">Methods</div>This retrospective study included 315 consecutive patients with completely resected pathological N0 lung adenocarcinoma tumors ≤3 cm from two institutions. Tumors were classified according to histologically predominant subtypes as low-grade (adenocarcinoma <span style="font-style:italic;">in situ</span>, minimally invasive adenocarcinoma or lepidic predominant), intermediate-grade (papillary or acinar predominant) or high-grade (solid or micropapillary predominant). Prognostic factors in intermediate-grade group were assessed among clinicopathological factors of age, gender, surgical procedure, tumor size, pleural, lymphatic and vascular invasion using Cox proportion hazards analyses.<div class="boxTitle">Results</div>There were 174 patients in the low-grade group, 109 in the intermediate-grade group and 32 in the high-grade group. The 3-year recurrence-free survival rates were 98.1%, 86.3% and 74.8% for these groups, respectively (<span style="font-style:italic;">P</span> < 0.001). In the intermediate-grade group, the presence of vascular invasion was an independent prognostic factor on multivariate Cox regression analysis of recurrence-free survival (hazard ratio, 3.48; 95% confidence interval, 1.26–9.57, <span style="font-style:italic;">P</span> = 0.01). Classification of intermediate-grade group based on vascular invasion revealed a clear division into favorable and unfavorable prognostic subgroups.<div class="boxTitle">Conclusions</div>Consideration of the vascular invasion status in addition to the predominant subtype could provide a more accurate assessment of malignant aggressiveness and prognosis of patients with early-stage lung adenocarcinoma.</span>

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