Survival impact of locoregional metachronous malignancy in survival of lung cancer patients who received curative treatment

Background: Metachronous malignancy is also found in the lung cancer population and may be identified before or after diagnosis of lung cancer. No prior studies have documented lung cancer patients with metachronous malignancy and its survival impact in this population. The aim of this study was to try to clarify the survival impact of locoregional metachronous malignancy in the lung cancer population with resectable disease from a pathology point of view. Methods: From January 2005 to December 2009, 199 lung cancer patients received curative treatment in Chang Gung Memorial Hospital, of which 34 were identified as having lung cancer and metachronous malignancy and 165 patients as having lung cancer only. Clinico-pathologic factors were collected from the medical records. Differences in clinical presentations between the two groups and survival impact were further analyzed. Results: Of these patients, 165 patients (82.9%) had lung cancer only (lung cancer group), and the remaining 34 patients (17.1%) had lung cancer and metachronous malignancy (metachronous malignancy group). There were no significant differences in clinical characteristics between the two groups. The disease free survival (P=0.3199) and overall survival (P=0.71) between these two groups showed no statistically significant difference. Metachronous malignancy only showed survival impact in lung cancer patients with pathologic stage IIIA (P=0.0389). Conclusions: Metachronous malignancy is also seen in the lung cancer population and may be identified before or after diagnosis of lung cancer. Locoregional metachronous malignancy has no survival impact on lung cancer patients who receive curative treatment. Anatomic resection with regional lymph node (LN) dissection is recommended if different tumor cell type and resectable disease are confirmed.