Lung Cancer

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TU_38_3696 - Outcomes of T1-2N0M0 Small Cell Lung Cancer Treated With Either Conventionally Fractionated Chemoradiotherapy or Stereotactic Body Radiation Therapy (SBRT): A National Cancer Database Study

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Outcomes of T1-2N0M0 Small Cell Lung Cancer Treated With Either Conventionally Fractionated Chemoradiotherapy or Stereotactic Body Radiation Therapy (SBRT): A National Cancer Database Study
N. B. Newman1, and E. C. Osmundson2; 1Department of Radiation Oncology Vanderbilt University Medical Center, Nashville, TN, 2Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN

Purpose/Objective(s): Current NCCN guidelines recommend treating patients with T1-T2 N0 M0 small cell lung cancers (SCLC) who do not undergo surgical resection with concurrent chemoradiation. The use of stereotactic body radiotherapy (SBRT) in SCLC is controversial due to limited data and the perceived systemic nature of this disease, however it is being used with increased frequency. This study was designed to compare survival outcomes for non-surgically managed T1-2N0M0 SCLC patients using the National Cancer Data Base (NCDB) who received either SBRT vs. conventionally fractionated radiotherapy (CFRT) with or without chemotherapy.

Materials/Methods: The National Cancer Database (NCDB) was queried between 2004-2015 for patients with T1-T2N0M0 SCLC. Patients must have been treated with curative intent SBRT (BED10 of 72-180 Gy in ≤10 fractions) or CFRT (delivered daily or twice daily, 45-70 Gy) with or without chemotherapy. Patients who had missing survival times, received surgery, or had conflicting staging data were excluded. Chemotherapy delivery must have been initiated within 21 days prior to RT administration or up to 14 days after completion of RT. Overall survival (OS) was measured from date of treatment. Univariable and multivariable cox proportional hazard models were constructed to measure the effects of treatment modality on survival and were adjusted for relevant clinical parameters.

Results: Of the 1326 patients evaluated in this study, 176 patients received SBRT and 1150 received CFRT, with a median follow-up time of 21.6 months. Ninety percent (90%) of those treated with CFRT received chemotherapy in contrast to only 44% of those treated with SBRT (p=0.02). Univariable cox regression demonstrated that receipt of chemotherapy (HR 0.66, p=<0.001) and female sex (HR 0.77, p=0.001) were associated with improved survival, while older age (HR 1.02, p=0.01) had a detrimental effect on survival. In contrast, T stage, tumor size, and radiotherapy modality (SBRT vs CFRT) had no association with survival (all p ≥ 0.35). In a multivariable cox regression model adjusting for sex, age, receipt of chemotherapy, charlson-deyo score, and T stage, treatment with SBRT trended toward a survival benefit (HR 0.81, 95% CI 0.64-1.03, p=0.067). Multivariable analysis also demonstrated a survival benefit for use of chemotherapy (HR 0.67, p= <0.001) and female sex (HR 0.76, p=<0.001), while older age (HR 1.02 , p= <0.001) negatively impacted survival.

Conclusion: In this population based analysis, patients with T1-2N0M0 SCLC treated with SBRT regimens incorporating chemotherapy had comparable survival outcomes to concurrent chemoradiotherapy using standard fractionation. The addition of chemotherapy significantly improved OS independent of radiotherapy treatment regimen delivered and it is being underutilized in SBRT patients. Treatment paradigms for T1-2N0M0 SCLC using SBRT warrant further exploration and should incorporate chemotherapy as clinically tolerated.

Author Disclosure: N.B. Newman: None. E.C. Osmundson: None.

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TU_38_3696 - Outcomes of T1-2N0M0 Small Cell Lung Cancer Treated With Either Conventionally Fractionated Chemoradiotherapy or Stereotactic Body Radiation Therapy (SBRT): A National Cancer Database Study



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