A UK centre’s experience of stereotactic ablative radiotherapy (SABR) for very early-stage small-cell lung cancer (SCLC)

Abstract

Introduction: SCLC is an aggressive malignancy with high-risk of metastatic disease. Limited-stage SCLC is treated with chemoradiotherapy curatively. SABR delivers significantly higher doses of radiation over fewer fractions compared to standard radiotherapy. SABR or conventional radiotherapy (with chemotherapy) is recommended for very early-stage SCLC in the 2020 ASTRO guidelines. Prophylactic cranial irradiation (PCI) is not recommended. Our institution is one of the first UK centres to use SABR in this setting. Methods: SCLC patients treated with SABR were identified electronically. A retrospective case note review was performed. Dose/fractionation follows guidance from the UK-SABR consortium. Results: 6 patients treated between 12/2021 and 11/2022 were identified: 5 males, 1 female. Mean age=75.5 years (64-85), 1 PS1, 4 PS2, 1 PS3. Median frailty score=5, median comorbidities=5. One had T1a, four T1b, and one T2a primaries, all N0M0. 2 patients did not receive chemotherapy (comorbidities, refused). 2 had chemotherapy prior to SABR - 1 and 4 cycles respectively. 2 are planned for chemotherapy post SABR - treatment is ongoing. Doses prescribed were 48Gy/3#, 54Gy/3#, 56Gy/8#, 60Gy/5# and 60Gy/8#. Mean ITV=11.5cm3 (2.3-21.4), average mean lung dose 4.10Gy (1.06-6.55), median LungV20=4.85% (1.2-7.92). No patients received PCI. No severe SABR-related toxicities were reported. 4 patients have completed treatment. 2 had progressive disease outside the radiation field (one did not have chemotherapy). Two have no evidence of progression. No patients developed brain metastases. Conclusion: SABR is a new treatment modality for very early-stage SCLC, which is more convenient for frailer patients. We acknowledge small numbers and limited follow-up. Our data suggests the importance of integrating chemotherapy and SABR in this setting. Reference: [1] Simone CB 2nd, Bogart JA, Cabrera AR, et al. Radiation Therapy for Small Cell Lung Cancer: An ASTRO Clinical Practice Guideline. Pract Radiat Oncol. 2020;10(3):158-173. Disclosure: No significant relationships.