Metachronous and synchronous primary lung cancers: diagnostic aspects, surgical treatment, and prognosis.

The average lifelong rate of developing a new primary lung cancer approximates 1% and 6% per year after radical therapy for non-small-cell lung cancer and small cell lung cancer, respectively. The frequency of recorded synchronous and metachronous lung cancers has been increasing in the recent years because of the development of early detection techniques and advances in cancer therapy. The distinction between multiple synchronous or metachronous primary lung cancers and intrapulmonary metastases is based on established clinicopathological criteria, however it is often difficult, although of great importance for the management and prognosis of these patients. Newly developed molecular and genomic methods are expected to contribute to a more solid and clear differentiation. Surgical treatment, whenever feasible, is considered the modality of choice for the management of patients with second primary lung cancers, as opposed to those with metastases. The type and extent of surgery are under discussion. The prognosis of patients with second primary lung cancers largely depends on the time of detection and the stage and location of the second cancer, thus surveillance after surgical resection of the initial tumor is mandatory.