Difference between "Lung Age" and Real Age as a Novel Predictor of Postoperative Complications, Long-Term Survival for Patients with Esophageal Cancer after Minimally Invasive Esophagectomy

Background: This study aimed to investigate whether the difference between "lung age " and real age (L-R) could be useful for the prediction of postoperative complications and long-term survival in patients with esophageal cancer followed by minimally invasive esophagectomy (MIE). Methods: This retrospective cohort study included 625 consecutive patients who had undergone MIE. "Lung age " was determined by the calculation method proposed by the Japanese Respiratory Society. According to L-R, patients were classified into three groups: group A: L-R ? 0 (n = 104), group B: 15 > L-R > 0 (n = 199), group C: L-R >= 15 (n = 322). Clinicopathological factors, postoperative complications evaluated by comprehensive complications index (CCI), and overall survival were compared between the groups. A CCI value > 30 indicated a severe postoperative complication. Results: Male, smoking status, smoking index, chronic obstructive pulmonary disease, American Society of Anesthesiologists status, lung age, and forced expiratory volume in 1 s were associated with group classification. CCI values, postoperative hospital stays, and hospital costs were significantly different among groups. Multivariate analysis indicated that L-R, coronary heart disease, and 3-field lymphadenectomy were significant factors for predicting CCI value > 30. Regarding the prediction of CCI value > 30, area under the curve value was 0.61(95%: 0.56-0.67), 0.46 (95% CI, 0.40-0.54), and 0.46 (95% CI, 0.40-0.54) for L-R, Fev1, and Fev1%, respectively. Regarding overall survival, there was a significant difference between group A and group B + C (log-rank test: p = 0.03). Conclusions: Esophageal cancer patients with impaired pulmonary function had a higher risk of severe postoperative complications and poorer prognosis than those with normal pulmonary function. The difference between "lung age " and "real age " seems to be a novel and potential predictor of severe postoperative complications and long-term survival.