PV QA 4 - Poster Viewing Q&A 4
Purpose/Objective(s):Stereotactic body radiation therapy (SBRT) is a highly effective non-invasive treatment that can be offered as curative therapy in medically inoperable patients with early stage non-small cell lung cancer (NSCLC). The prognostic relevance of comorbidity status in this patient population who are treated with SBRT is not known. We analyzed outcomes after lung stereotactic body radiotherapy for early stage NSCLC and stratified patients by their comorbidity status. We used the Adult Comorbidity Evaluation-27 (ACE-27) Index as a measure of comorbidity.
Materials/Methods:We retrospectively analyzed medical records for 139 patients with stage I/II(N0) NSCLC who were treated with SBRT (18Gy x 3 or 10-12Gy x5) at our institution between 2009 and 2014. The ACE-27 index was calculated for each patient to compute an overall score between 0 and 3, which correlated with the severity of their baseline comorbidity status. Patients with scores 1 and 2 were grouped together to form one cohort (ACE1&2) and patients with an overall ACE-27 Index score of 3 formed the second cohort (ACE3). The primary endpoint was overall survival (OS) computed using Kaplan-Meier method/Cox regression model. The Fine-Gray method was used to analyze non-cancer death with death due to lung cancer as a competing event.
Results:There were 50(36%) patients in the ACE1&2 group and 89(64%) in the ACE3 cohort. The median age was 74 (range, 46 – 88), with 51.8% women and 37.4% with Eastern Cooperative Oncology Group performance status 2 to 4. Majority of the patients were stage IA (85.6%) with 60% of the treated tumors greater than 2cm in size. 42.4% of these lung tumors were of adenocarcinoma histology and most of the patients were treated with three-dimensional conformal radiotherapy, 3DCRT (74.8%) while the remainder were treated with volumetric arc therapy, VMAT (25.2%). With a median follow-up of 36.5 months among survivors, the median OS was 47 months for the ACE1&2 cohort vs. 28.5 months for patients in the ACE3 group, p=0.014. After adjusting for death from cancer as a competing risk, those with severe co-morbidities are more likely to die of other causes than those with fewer co-morbidities (for patients in the ACE3 cohort; hazard ratio 2.24, 95% CI: 1.11 - 4.52, p=0.02] although median lung cancer-specific survival and median other cause-specific survival was not reached.
Conclusion:In medically inoperable patients with early stage NSCLC treated with SBRT, the ACE-27 comorbidity index is an important prognostic factor. Patients with severe commodities face a substantial decrease in overall survival. The ACE-27 comorbidity index may, therefore, be an appropriate tool to use in stratifying patients and carefully identifying those who will derive the most benefit from SBRT.
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