Survival comparison of right and left side non-small cell lung cancer in stage I-IIIA patients: A Surveillance Epidemiology and End Results (SEER) analysis.

Background Primary tumors located in the right and left side have distinctive prognoses, but the details have not been fully identified in non-small cell lung cancer (NSCLC). This study investigated the impact of primary tumor side on long-term survival in NSCLC patients. Methods Data of 90 407 patients from the Surveillance, Epidemiology, and End Results (SEER) Program were analyzed. To avoid bias between groups, we used innovative propensity score matching (PSM) analysis. Results There was no significant distinction in overall survival (OS) between right (n = 53 496) and left (n = 36 911) side tumors (hazard ratio [HR] 0.993, 95% confidence interval [CI] 0.9756-1.011; P = 0.432). Left side was associated with superior five-year cancer-specific survival (CSS) compared to right side NSCLC (HR 0.977, 95% CI 0.9574-0.9969; P = 0.024). No significant difference was observed in OS (P = 0.689) or CSS (P = 0.288) after PSM analysis. In the 51 319 patients who underwent surgery, left side (n = 21 245) was associated with poor OS compared to right side (n = 30 074) NSCLC (HR 1.039, 95% CI 1.011-1.067; P = 0.006), while CSS was similar (HR 1.031, 95% CI 0.997-1.065; P = 0.069). In patients who underwent surgery, there was also no significant difference in OS (P = 0.986) or CSS (P = 0.979) after PSM analysis. Conclusion The prognosis between right and left side NSCLC in stage I-IIIA was similar regardless of whether patients underwent surgery. Primary tumor side cannot be considered a prognostic factor when choosing appropriate treatment.