Is consolidative thoracic radiotherapy of extensive-stage small cell lung cancer still beneficial in the era of immunotherapy? A retrospective analysis

Abstract

Purpose Extensive-stage small cell lung cancer (ES-SCLC) carries a dismal prognosis. The benefit of consolidative thoracic radiotherapy (TR) after first-line chemoimmunotherapy with PD-L1 inhibitors in this setting remains unclear. As TR can improve overall survival (OS) after conventional chemotherapy, we retrospectively analyzed OS of an inhouse cohort treated either with TR or with chemoimmunotherapy alone. Methods A total of 41 patients treated with chemoimmunotherapy with PD-L1 inhibitors (atezolizumab or durvalumab) for ES-SCLC at our hospital since 2019 were analyzed. TR was administered in 10 fractions of 3 Gy. Patient characteristics, number of immunotherapy cycles received, brain irradiation, and presence of hepatic and cerebral metastasis at diagnosis were assessed. Primary endpoint was OS after first diagnosis. Results Consolidative TR was associated with a significantly longer OS than systemic therapy alone (1-year OS 78.6% and 2‑year OS 37.1% vs. 1‑year OS 39.7% and 2 years not reached, p = 0.019). With regard to radiotherapy indication, survival at 1 year was 88.9% (log-rank p = 0.016) for patients receiving consolidative TR. For patients receiving TR in case of progression, 1‑year survival was 66.7%. Hepatic and cerebral metastasis at first diagnosis had no significant effect on OS. Conclusion TR was significantly associated with longer OS. The survival benefit of TR was most pronounced for consolidative radiotherapy after initial chemoimmunotherapy compared to TR in case of progression. Although retrospective findings need to be interpreted with caution, in the absence of prospective data, our findings provide a basis for offering consolidative TR in the era of chemoimmunotherapy.

Consolidative thoracic radiation therapy for extensive-stage small cell lung cancer in the era of first-line chemoimmunotherapy: preclinical data and a retrospective study in Southern Italy

“…Only one G3 AE was reported in the TRT group compared to two G3 AEs in the non-TRT group. Moreover, no G4–G5 AEs were observed in the present study, which was similar to other reports ( 13 , 18 ). A good safety profile for TRT in SCLC patients treated with chemoimmunotherapy was also noted.…”

“…With regard to toxicity, low AE rates have been reported in prior published retrospective studies ( 13 , 18 , 21 ). Only Peng et al.…”

“…Currently, the absence of prospective data makes it necessary to analyze the available retrospective evidence. A monocentric case series evaluating 23 ES-SCLC patients treated with TRT during immunotherapy maintenance reported OS and PFS improvement ( 18 ). Accordingly, survival improvement was noted in a more extensive cohort in a study by Peng et al.…”

Twenty-Month Regression Following Concurrent Conventional Whole-Brain Irradiation and Chemoimmunotherapy for ≥3.8 cm Cerebellar Metastasis From Small Cell Lung Cancer

“…To prevent or attenuate the development of new metachronous BMs, improving extracranial disease control is important. Consolidative thoracic radiotherapy for a partial response after CIT remains controversial [ 1 , 2 , 13 , 19 ]; however, some studies reported positive survival outcomes in patients who received this serial treatment [ 19 ]. Consolidative thoracic radiotherapy with a modest dose (e.g., 30 Gy) and image-guided VMA was a potential treatment option for the regressed thoracic lesions during the maintenance phase with atezolizumab in the present case.…”

Radiotherapy for extensive-stage small-cell lung cancer in the immunotherapy era

“…However, the value of cTRT in the immunotherapy era is controversial, as it was not included in the IMPower 133 and CASPIAN trials. But a retrospective study including 41 patients with ES-SCLC, 23 patients received 30Gy/10 fractions cTRT after systemic therapy and 18 patients did not receive cTRT, showed that cTRT significantly improved OS compared with systemic therapy only group (1-year OS 78.6% vs. 39.7%, p=0.019 ( 39 ). Furthermore, several single-center retrospective studies have also demonstrated a survival benefit of cTRT after first-line chemoimmunotherapy ( 40 , 41 ).…”