Role of Stereotactic Body Radiation Therapy in Early Stage Small Cell Lung Cancer in the Era of Lung Cancer Screening: A Systematic Review

With the obvious benefit from low dose computed tomography to reduce the lung cancer-specific mortality, lung cancer screening is on the rise. With the implementation of the screening programs, diagnosis of early stage lung cancer is expected to increase, and small cell lung cancer (SCLC) would account for 10% of screen-detected lung cancer. Apart from Concurrent chemoradiation (CRT), the present guidelines virtually do not support other options for radiation (RT). There is a paucity of data addressing the role of Stereotactic Body Radiation Therapy (SBRT) in SCLC and we conducted the current systematic review on this topic. We systematically searched literature using the electronic databases PubMed and Embase with no language, year or publication status restrictions. After removal of duplicate records, 3469 screened, 3446 excluded with reasons, 23 full-text articles were assessed for eligibility, and 7 studies (8 reports) were included. Unsuitability for surgery or refusal for surgery was the most common reason for the use of SBRT in early stage SCLC in the included studies. Variable patterns of SBRT—chemotherapy (CT) sequencing including concurrent, pre-CT and post-CT and radiation doses were noted. Within the reported studies overall survival (OS) at 1 year, 2 year and 3 year varied from 63% to 87%, 37% to 72%, and 35% to 72%, respectively. Distant metastasis was the most common pattern of failure ranging from 38% to 53%. There was no increase in the reported grade III toxicity. SBRT could be a potential option in stage I SCLC with comparable outcomes with no added toxicity. Acknowledging the limitations and absence of high-quality data, presently cautious interpretation is warranted and further studies are needed to establish the role of SBRT in SCLC.

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