Histology of non-small cell lung cancer predicts the response to stereotactic body radiotherapy.

ABSTRACT

BACKGROUND AND PURPOSE: To investigate the prognostic impact of different histological subtypes of non-small cell lung cancer (NSCLC) on outcome following stereotactic body radiotherapy (SBRT) for NSCLC patients. MATERIALS AND METHODS: We analyzed 126 consecutive patients with early-stage adenocarcinoma or squamous cell carcinoma treated with SBRT from 2004 to 2016. Adenocarcinoma patients were further sub-classified as high-risk or low-risk tumors. RESULTS: With a median follow-up time of 22months, 2-year overall survival (OS), local (LC), and distant control (DC) were 68%, 90% and 79%, respectively. For LC, histologic subtype was identified as major independent prognostic factor (p=0.033) while LC was 81% for squamous cell carcinoma patients, LC was significantly improved for high-risk and even more non-high-risk adenocarcinoma patients with 96% and 100%, respectively (p=0.026). The negative prognostic impact of the histologic subtype "squamous cell carcinoma" was not evident when patients received SBRT with higher total doses in EQD2 (2Gy equivalent dose) if patients were treated with a total dose in EQD2≥150Gy, no significant difference in LC for histologic subtypes was detected anymore (p=0.355). CONCLUSION: In the current study, histologic subtypes of NSCLC predicted local control probabilities following SBRT. Prospective, multi-center studies are needed to evaluate the prognostic impact of histology and consecutively the need for SBRT dose adaptation.