Does Time to Retreatment Matter? A Normal Tissue Complication Probability Model to Predict Radionecrosis After Repeat Stereotactic Radiosurgery for Recurrent Brain Metastases Incorporating Time-dependent Discounted Dose.
retrospective_cohort · Level III
Where this comes from
- Record sourced from PubMed, PMID 39900228.
- Also identified by DOI 10.1016/j.ijrobp.2025.01.017.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
To develop and compare normal tissue complication probability (NTCP) models for recurrent brain metastases (BMs) treated with repeat single-fraction stereotactic radiosurgery (SRS), considering time-dependent discounted prior dose. We developed three NTCP models (M0, M1-retreat, and M1-combo models) of BMs treated with GammaKnife-based SRS. The maximum dose is 0.2 cc (D<sub>0.2cc</sub>) of the lesion-specific brain, and the 1-year radionecrosis risk is modeled using a logistic response with doses converted into equivalent dose in 2-Gy fractions (EQD2) based on a linear quadratic linear model. The M0 and M1-retreat models, respectively, predicted radionecrosis risk after SRS to 1029 nonrecurrent lesions (patients, 262) and second SRS to 149 recurrent lesions (patients, 87). The M1-combo model accounted for the second SRS and time-dependent discounted first SRS dose for recurrent lesions estimated using a modified Gompertzian function. All 3 models fitted the data well (χ<sup>2</sup>, 0.039-0.089, and P = 0.999-1.000). The fitted EQD2<sub>50</sub> was ∼ 103 Gy for the M0 model, ∼ 88 Gy for the M1-retreat model, and ∼ 165 Gy for the M1-combo model. The fitted γ<sub>50</sub> exhibited a progressively flatter dose-response curve across the three models, with values of 1.2 per gray for the M0 model, 0.6 per gray for the M1-retreat model, and 0.4 per gray for the M1-combo model. For the brain D<sub>0.2cc</sub> of 29 and 19 Gy, the steepest to shallowest dose-response or largest change in NTCP values, ie, NTCP<sub>29Gy</sub> - NTCP<sub>19Gy</sub>, was observed in the M1-retreat (0.16), M0 (0.14), and M1-combo (0.06) models. The model-fitted parameters predicted that recurrent BMs would have a lower threshold dose tolerance and a more gradual dose response to the second SRS than nonrecurrent BMs. This gradual dose-response becomes even more apparent when considering the time-dependent discounted first SRS as a cumulative second SRS. Tailoring SRS retreatment protocols based on NTCP modeling can potentially enhance therapeutic efficacy.
Medical subject headings
- Brain Neoplasms
- Radiosurgery
- Radiation Injuries
- Neoplasm Recurrence, Local
- Organs at Risk
- Brain