Neutrophil to lymphocyte ratio (NTLR) predicts local control and overall survival after stereotactic body radiotherapy (SBRT) in metastatic sarcoma

The neutrophil to lymphocyte ratio (NTLR) and absolute lymphocyte count (ALC) recovery are prognostic across many cancers. We investigated whether NLTR predicts SBRT success or survival in a metastatic sarcoma cohort treated with SBRT from 2014 and 2020 (N = 42). Wilcox Signed Rank Test and Friedman Test compare NTLR changes with local failure vs. local control (N = 138 lesions). Cox analyses identified factors associated with overall survival. If local control was successful, NLTR change was not significant (p = 0.30). However, NLTR significantly changed in patients with local failure (p = 0.027). The multivariable Cox model demonstrated higher NLTR before SBRT was associated with worse overall survival (p = 0.002). The optimal NTLR cut point was 5 (Youden index: 0.418). One-year overall survival in SBRT metastatic sarcoma cohort was 47.6% (CI 34.3%-66.1%). Patients with an NTLR above 5 had a one-year overall survival of 37.7% (21.4%-66.3%); patients with an NTLR below 5 had a significantly improved overall survival of 63% (43.3%-91.6%, p = 0.014). Since NTLR at the time of SBRT was significantly associated with local control success and overall survival in metastatic sarcoma treated with SBRT, future efforts to reduce tumor inhibitory microenvironment factors and improve lymphocyte recovery should be investigated.

Neutrophil to Lymphocyte Ratio (NTLR) Predicts Local Control Failure and Overall Survival after Stereotactic Body Radiotherapy (SBRT) In Metastatic Sarcoma

The neutrophil to lymphocyte ratio (NTLR) and absolute lymphocyte count (ALC) recovery are prognostic across many cancers. We investigated whether NLTR predicts SBRT success or survival in a metastatic sarcoma cohort treated with SBRT from 2014 and 2020 (N = 42). Wilcox Signed Rank Test and Friedman Test compare NTLR changes with local failure vs. local control (N = 138 lesions). Cox analyses identified factors associated with overall survival. If local control was successful, NLTR change was not significant (p = 0.30). However, NLTR significantly changed in patients local failure (p = 0.027). The multivariable Cox model demonstrated higher NLTR before SBRT was associated with worse overall survival (p = 0.002). The optimal NTLR cut point was 5 (Youden index: 0.418). One-year overall survival in SBRT metastatic sarcoma cohort was 47.6% (CI 34.3%-66.1%). Patients with an NTLR above 5 had a one-year overall survival of 37.7% (21.4%-66.3%); patients with an NTLR below 5 had a significantly improved overall survival of 63% (43.3%-91.6%, p = 0.014). Since NTLR at the time of SBRT was significantly associated with local control success and overall survival in metastatic sarcoma treated with SBRT, future efforts to reduce tumor inhibitory microenvironment factors and improved lymphocyte recovery should be investigated.

Association between biologically effective dose and local control after stereotactic body radiotherapy for metastatic sarcoma

Introduction

Stereotactic body radiation therapy (SBRT) is increasingly utilized for patients with recurrent and metastatic sarcoma. SBRT affords the potential to overcome the relative radioresistance of sarcomas through delivery of a focused high biological effective dose (BED) as an alternative to invasive surgery. We report local control outcomes after metastatic sarcoma SBRT based on radiation dose and histology.

Methods

From our IRB-approved single-institution registry, all patients treated with SBRT for metastatic sarcoma between 2014 and 2020 were identified. Kaplan-Meier analysis was used to estimate local control and overall survival at 1 and 2 years. A receiver operating characteristic (ROC) curve was generated to determine optimal BED using an α/β ratio of 3. Local control was compared by SBRT dose using the BED cut point and evaluated by histology.

Results

Forty-two patients with a total of 138 lesions met inclusion criteria. Median imaging follow up was 7.73 months (range 0.5-35.0). Patients were heavily pre-treated with systemic therapy. Median SBRT prescription was 116.70 Gy BED (range 66.70-419.30). Desmoplastic small round cell tumor, Ewing sarcoma, rhabdomyosarcoma, and small round blue cell sarcomas were classified as radiosensitive (n = 63), and all other histologies were classified as radioresistant (n = 75). Local control for all lesions was 66.7% (95% CI, 56.6-78.5) at 1 year and 50.2% (95% CI, 38.2-66.1) at 2 years. Stratifying by histology, 1- and 2-year local control rates were 65.3% and 55.0%, respectively, for radiosensitive, and 68.6% and 44.5%, respectively, for radioresistant histologies (p = 0.49). The ROC cut point for BED was 95 Gy. Local control rates at 1- and 2-years were 75% and 61.6%, respectively, for lesions receiving >95 Gy BED, and 46.2% and 0%, respectively, for lesions receiving <95 Gy BED (p = 0.01). On subgroup analysis, local control by BED > 95 Gy was significant for radiosensitive histologies (p = 0.013), and trended toward significance for radioresistant histologies (p = 0.25).

Conclusion

There is a significant local control benefit for sarcoma SBRT when a BED > 95 Gy is used. Further investigation into the dose-response relationship is warranted to maximize the therapeutic index.