Frequent EGFR Mutations and Better Prognosis in Positron Emission Tomography-Negative Solid Cancer

PET-negative, solid-type lung cancers are rare subgroup of lung cancers with limited data. Among over 1900 resected lung cancer cases, we identified only 27 PET-negative, solid-type lung cancers. All of them were lung adenocarcinomas, and EGFR mutation was frequent in this cohort. These patients had significantly better prognosis compared with their PET-positive counterparts who were extracted using propensity score matching. Background: The differential diagnosis of a solitary solid-type lung nodule is diverse. 18F-fluorodeoxyglucose positron emission tomography (PET) has a high sensitivity in the diagnosis of solid-type lung cancers; however, PET-negative, solid-type lung cancers are rarely observed. In this study, we analyzed the clinical/genetic features and prognosis of PET negative, solid-type lung cancers. Patients and Methods: Between January 2007 and February 2020, 709 patients with solid-type lung cancers (tumor size >= 2.0 cm) underwent pulmonary resection. Clinical, genetic, and prognostic features were evaluated in 27 patients (3.8%) with tumors showing negative PET results defined as SUVmax < 2.0. Results: All 27 patients had lung adenocarcinoma; 23 had invasive adenocarcinomas and 4 had invasive mucinous adenocarcinomas. The PET-negative group showed high frequencies of females and never-smokers. Recurrence-free survival was significantly better in the PET-negative group compared with PET-positive counterparts extracted using propensity score matching from patients who underwent pulmonary resection during the same period (P = .0052). Furthermore, 83% of PET-negative, solid-type invasive lung adenocarcinoma patients harbored EGFR mutation, which was significantly higher than that of PET-positive, solid-type invasive lung adenocarcinoma patients (38%, n = 225) who received EGFR mutation testing in our cohort (P < .0001). PET-negative, solid-type lung adenocarcinoma patients with EGFR mutations had significantly better recurrence-free survival compared with PET-positive, solid-type lung adenocarcinoma patients with EGFR mutations extracted using propensity score matching (P = .0030). Conclusion: PET-negative, solid-type lung cancers are characterized with a high incidence of EGFR mutation and a better prognosis compared with PET positive, solid-type lung cancer. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

PET-negative, solid-type lung cancers are rare subgroup of lung cancers with better prognosis and frequent EGFR mutation.