title: Impact of a Contralateral Tumor Nodule on Survival in Non-Small-Cell Lung Cancer.
abstract: BACKGROUND
  Contralateral lung tumors in non-small-cell lung cancer (NSCLC) are classified as stage M1a yet may represent hematogenous metastases or synchronous primary tumors. The impact of these tumors on overall survival (OS) is poorly understood. Here, we aim to determine whether NSCLC patients with M1a disease due only to a contralateral tumor nodule exhibit a favorable prognosis relative to other M1a or M1b patients.
  
  
  METHODS
  Retrospective evaluation of the impact of contralateral tumor nodules on OS in NSCLC stratified by primary tumor size and N stage attained from Surveillance, Epidemiology, and End Results database.
  
  
  RESULTS
  Of 173,640 patients, 5161 M1a-contra patients were identified. Median and 3-year OS for these patients exceeded that of patients with M1b (p < 0.0001) or other M1a disease (p < 0.0001). Primary tumor size and N stage were strongly associated with OS in M1a-contra patients. Three-year OS demonstrated a delayed convergence between M1a-contra and other M1a patients with primary tumors greater than or equal to 3 cm or mediastinal lymph node involvement. Proportional hazard modeling indicated that T1-2N0-1M1a-contra patients exhibit OS not significantly different (p = 0.258) from that predicted with comparable T and N stage disease plus a second early-stage primary.
  
  
  CONCLUSIONS
  Contralateral tumors in NSCLC carry a more favorable prognosis than other M1a or M1b disease. Primary tumor size and N stage may help distinguish M1a-contra patients with hematogenous metastasis from those with a synchronous, second primary.
authors: *Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; †St. Luke's Mountain States Tumor Institute, Twin Falls, Idaho; ‡Division of Biostatistics and Bioinformatics, University of Maryland Greenebaum Cancer Center, Baltimore, Maryland; §Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland; and ‖Department of Radiation Oncology, Mercy Regional Cancer Center, Janesville, Wisconsin.
authors: Zachary S
authors: ZS
authors: Morris
authors: Donald M
authors: DM
authors: Cannon
authors: Brett A
authors: BA
authors: Morris
authors: Søren M
authors: SM
authors: Bentzen
authors: Kevin R
authors: KR
authors: Kozak
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality* / Q000473:pathology*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016019:Survival Analysis