Multiple lung cancers prognosis: What about histology?

Background. Among multiple lung cancers (MLC), some may have similar histologic classification. Demonstrating that the second tumor is a metastasis would change the stage and consequently the management. Our purpose was to reconsider this consequence. Methods. We reviewed 234 patients (194 male and 40 female, from 37 to 83 years of age) with synchronous and metachronous non-small cell MLC. Surgery consisted of a potentially curative complete resection with lymphadenectomy. Patients with similar histologic MLC (considered as metastasis) were compared with those with different histologic classification in terms of MLC chronology, type of resection, pT and pN, stage, and overall survival. Results. There were 116 metachronous (ipsilateral, n = 48; contralateral, n = 68) and 118 synchronous MLCs (bilateral, n = 10; same lobe, n = 57; other lobe, n = 51). Pneumonectomy was performed in 77 patients, lobectomy in 103, and lesser resection in 54. Histologic classification was similar in 57.9% of patients and different in 42.1%. The 5-year survival rates tended to be lower in patients with synchronous MLCs (23.4% versus 31.6%; p = 0.07). They were higher when synchronous MLCs were located in the same lobe than if they were located in another lobe (29.9% versus 15.6%; p = 0.022). Whatever the type of MLC, the 5-year survival rates were not correlated with similar or different histologic classification. Conclusions. Our analysis supports that surgery is safe and warranted in MLC patients even if synchronous MLCs present ominously. Changing the staging by establishing the diagnosis of metastasis is probably an important issue warranting further biologic research, but according to our results this diagnosis must not in any case preclude surgery.