Evaluating The Conditional Survival Benefit Of Minimally Invasive Lobectomy In Early-stage Non-small Cell Lung Cancer
William Graber1, Nathaniel Deboever2, Jiangong Niu3, Michael Eisenberg2, Mara Antonoff2, Wayne Hofstetter2, Reza Mehran2, Jack Roth2, Boris Sepesi2, Stephen Swisher2, Garrett Walsh2, Ara Vaporciyan2, Sharon Giordano3, Ravi Rajaram2, David Rice2.
1The University of Texas Southwestern Medical School, Dallas, TX, USA, 2Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX, USA, 3Department of Health Services Research, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
BACKGROUND: While minimally invasive surgery (MIS) has been shown to be non-inferior to thoracotomy in patients undergoing lobectomy for non-small cell lung cancer (NSCLC), little is known about the conditional survival of this cohort, defined as 5-year survival probability following an initial period of survival. Thus, we sought to evaluate traditional survival and longitudinal conditional survival in a large cohort of patients with NSCLC managed with lobectomy.
METHODS: The National Cancer Database was queried for patients who underwent lobectomy for clinical stage IA1/2 NSCLC (8th AJCC). Patients were included if they were induction-therapy naïve, then stratified by operative approach (MIS or thoracotomy). Traditional survival analysis was performed, as was conditional survival, with outcomes assessed yearly after resection for 5 years. Multivariable models controlled for age, gender, race, insurance, income, education, rural status, distance to hospital, Charlson-Deyo score, lymphovascular invasion, tumor grade, receipt of adjuvant therapy, number of nodes examined, tumor size, facility type, and operative volume.
RESULTS: 23,570 patients met the inclusion criteria between 2004 and 2019, of whom 12,252 (52.0%) received MIS, and 11,318 (48.0%) received thoracotomy. The average age in this cohort was 65 years (standard deviation [SD]: 10), most patients were female (n=14,475, 61.4%) with adenocarcinoma (n=16,183, 68.7%), and tumor size averaged 15mm (SD: 4). Traditional survival confirmed survival benefit with MIS (hazard ratio [HR]: 0.91, 95% confidence interval [CI]: 0.86-0.97). Conditional survival revealed survival superiority with MIS at 1- and 2-years post-resection (HR: 0.93, CI:0.88-1.00 and HR: 0.91, CI: 0.85-0.98, respectively. However, for patients surviving 3-, 4-, or 5-years post-resection, survival between MIS and thoracotomy was similar (p=0.107, 0.315, 0.832, respectively, Figure).
CONCLUSIONS: While it appears that MIS is associated with traditional survival benefit, conditional analysis revealed that this benefit was most significant in the first 2 years post-resection. After surviving 3 years, patients managed with MIS or thoracotomy fared similarly. These findings suggest equivalent long term oncologic survival in patients managed with MIS or thoracotomy. 
LEGEND: Kaplan-Meyer curve representing traditional survival (a) in patients who underwent lobectomy for Stage IA NSCLC, and conditional survival at 1-,3-, and 5- years following resection (b, c, d, respectively)
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