Factors Predicting Poor Survival After Resection of Stage IA Non-small Cell Lung Cancer
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Objectives: To determine whether the survival of stage IA NSCLC patients in the United States is improving, characterize the factors that influence their survival, and identify patients at increased risk of death.
Methods: Using data from the Surveillance, Epidemiology, and End Result (SEER) Program, 7759 patients were identified as having stage IA NSCLC and underwent curative surgery from 1988 to 1995. Overall survival was determined using the Kaplan-Meier method. Using log rank tests, univariable analyses were performed to determine factors that influenced survival. Multivariable analysis was performed using a Cox regression model constructed with the significant factors from the univariable analyses.
Results: Overall 1, 3, and 5-year survival for the entire cohort was 91%, 74%, and 61%, respectively. The survival is not improved compared to patients treated in the 1970's and early 1980's. On univariable analysis, tumor size, gender, age, and extent of resection were significant predictors of survival. Five year survival of patients with tumors 2.0 to 3.0 cm had worse 5 year survival than patients with tumors <2.0 cm: 58% vs. 63% (p<.001). Males faired significantly worse than females, with a 5-year survival of 55% vs. 66% (p<.001). Patients older than the median age of 67 years had worse 5 year survival than those under the median age: 53% vs. 68% (p<.001). Patients undergoing sub-lobar resections showed poorer survival compared to patients undergoing anatomic resections, with a 5-year survival of 47% vs. 65% (p<.001). Since patient co-morbidity data were not available for analysis, extent of resection may not be an independent predictor, but rather a marker of overall poor health. On multivariable analysis using a Cox regression model, all 4 variables remained statistically significant as shown below. A total of 842 patients had all 4 positive prognostic variables (female, small tumor, age<65, lobectomy), and 246 patients had all 4 negative prognostic variables. The 5 year survival of the low risk group was 77% compared to 35% for the high risk group (p<.001).
Conclusions: Despite advances in staging and treatment over the past few decades, the survival of stage IA NSCLC patients is no better than historical data, and is significantly worse than small single institution studies. This study identified 4 factors that impact survival in stage IA NSCLC: tumor size, gender, age, and extent of resection. Patients exhibiting all 4 negative prognostic factors may be a logical group to study the use of adjuvant chemotherapy.
Multivariable analysis - Cox Regression Model| Predictor | Hazard Ratio | 95% Confidence Interval | P-value |
| Male vs female | 1.37 | 1.296, 1.461 | <0.001 |
| Tumor 2 -3 cm vs < 2 cm | 1.19 | 1.119, 1.263 | <0.001 |
| Age = 65yo | 1.70 | 1.594, 1.802 | <0.001 |
| Sub-lobar rxn vs lobe + | 1.59 | 1.485, 1.699 | <0.001 |
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