The biological advantage of single-session radiosurgery

Tumor volume and sphericity as predictors of local control after stereotactic radiosurgery for limited number (1-4) brain metastases from nonsmall cell lung cancer

AIM

This study aims to evaluate the usage of brain metastases (BM) tumor volume and sphericity as prognostic factors in local control (LC) after stereotactic radiosurgery (SRS) for limited number (1-4) BM from nonsmall cell lung cancer (NSCLC).

METHODS

We retrospectively reviewed 80 patients, with 141 BM, who were treated with SRS from 2012 to 2017. Local failure was defined as an increase in lesion size after SRS. LC and overall survival (OS) were estimated using Kaplan-Meier method. The Cox proportional hazards model was used for univariate and multivariate analysis.

RESULTS

The median clinical and radiographic follow-up was 11.2 and 9.0 months, respectively. The median BM tumor volume was 0.31 cm³ (0.01-21.64 cm³ ) and the median tumor sphericity was 0.76 (0.39-0.95). The median LC of the entire cohort was 28.8 months. LC rate at last follow-up was achieved in 84.4% of patients (35.5% CR, 35.5% PR, and 13.5% SD). LC was 83.8% at 1 year and 56.3% at 2 years. On multivariate analysis, only sphericity (P < .001) and volume (P = .004) were found to be a strong predictor for LC. The median OS of the entire cohort was 24.1 months. On multivariate analysis, only GPA score was found to be a predictor for OS.

CONCLUSION

BM tumor sphericity and volume were found to be strong predictors for LC. Tumor sphericity and volume should be taken into consideration when treating patients with BM and when designing future prospective studies and developing prognostic indices.

Radiosurgery or hypofractionated stereotactic radiotherapy for brain metastases from radioresistant primaries (melanoma and renal cancer)

Background

Until 50% of patients with renal cancer or melanoma, develop brain metastases during the course of their disease. Stereotactic radiotherapy has become a standard of care for patients with a limited number of brain metastases. Given the radioresistant nature of melanoma and renal cancer, optimization of the fractionation of stereotactic radiotherapy is needed. The purpose of this retrospective study was to elucidate if hypofractionated stereotactic radiotherapy (HFSRT) impacts local control of brain metastases from radioresistant tumors such as melanoma and renal cancer, in comparison with radiosurgery (SRS).

Methods

Between 2012 and 2016, 193 metastases, smaller than 3 cm, from patients suffering from radioresistant primaries (melanoma and renal cancer) were treated with HFSRT or SRS. The primary outcome was local progression free survival (LPFS) at 6, 12 and 18 months. Overall survival (OS) and cerebral progression free survival (CPFS) were secondary outcomes, and were evaluated per patient. Objective response rate and radionecrosis incidence were also reported. The statistical analysis included a supplementary propensity score analysis to deal with bias induced by non-randomized data.

Results

After a median follow-up of 7.4 months, LPFS rates at 6, 12 and 18 months for the whole population were 83, 74 and 70%, respectively. With respect to fractionation, LPFS rates at 6, 12 and 18 months were 89, 79 and 73% for the SRS group and 80, 72 and 68% for the HFSRT group. The fractionation schedule was not statistically associated with LPFS (HR = 1.39, CI95% [0.65–2.96], p = 0.38). Time from planning MRI to first irradiation session longer than 14 days was associated with a poorer local control rate. Over this time, LPFS at 12 months was reduced from 86 to 70% (p = 0.009). Radionecrosis occurred in 7.1% for HFSRT treated metastases to 9.6% to SRS treated metastases, without any difference according to fractionation (p = 0.55). The median OS was 9.6 months. Six, 12 and 18 months CPFS rates were 54, 24 and 17%, respectively.

Conclusion

Fractionation does not decrease LPFS. Even for small radioresistant brain metastases (< 3 cm), HFSRT, with 3 or 6 fractions, leads to an excellent local control rate of 72% at 1 year with a rate of 7.1% of radionecrosis. HFSRT is a safe and efficient alternative treatment to SRS.

Electronic supplementary material

The online version of this article (10.1186/s13014-018-1083-1) contains supplementary material, which is available to authorized users.

Evaluation of Prognostic Factors for Early Mortality After Stereotactic Radiosurgery for Brain Metastases: a Single Institutional Retrospective Review

BACKGROUND

Stereotactic radiosurgery (SRS) is used commonly for patients with brain metastases (BM) to improve intracranial disease control. However, survival of these patients is often dictated by their systemic disease course. The value of SRS becomes less clear in patients with anticipated short survival.

OBJECTIVE

To evaluate prognostic factors, which may predict early death (within 90 d) after SRS.

METHODS

A total of 1427 patients with BM were treated with SRS at our institution (2000-2012). There were 1385 cases included in this study; 1057 patients underwent upfront SRS and 328 underwent salvage SRS. The primary endpoint of the study was all-cause mortality within 90 d after first SRS. Multivariate analyses were performed to develop prognostic indices.

RESULTS

Two hundred sixty-six patients (19%, 95% confidence interval 17%-21%) died within 90 d after SRS. Multivariate analysis of upfront SRS patients showed that Karnofsky Performance Status, primary tumor type, extracranial metastases, age at SRS, boost treatment, total tumor volume, prior surgery, and interval from primary to BM were independent prognostic factors for 90-d mortality. The first 4 factors were also independent predictors in patients treated with salvage SRS. Based on these factors, an index was defined for each group that categorized patients into 3 and 2 prognostic groups, respectively. Ninety-day mortality was 5% to 7% in the most favorable cohort and 36% to 39% in the least favorable.

CONCLUSION

Indices based on readily available patient, clinical, and treatment factors that are highly predictive of early death in patients treated with upfront or salvage SRS can be calculated and used to define well-separated prognostic groups.