F. Thillays

Stereotactic radiotherapy following surgery for brain metastasis: Predictive factors for local control and radionecrosis

PURPOSE To evaluate local control and adverse effects after postoperative hypofractionated stereotactic radiosurgery in patients with brain metastasis. METHODS We reviewed patients who had hypofractionated stereotactic radiosurgery (7.7Gy×3 prescribed to the 70% isodose line, with 2mm planning target volume margin) following resection from March 2008 to January 2014. The primary endpoint was local failure defined as recurrence within the surgical cavity. Secondary endpoints were distant failure rates and the occurrence of radionecrosis. RESULTS Out of 95 patients, 39.2% had metastatic lesions from a non-small cell lung cancer primary tumour. The median Graded Prognostic Assessment score was 3 (48% of patients). One-year local control rates were 84%. Factors associated with improved local control were no cavity enhancement on pre-radiation MRI (P<0.00001), planning target volume less than 12cm3 (P=0.005), Graded Prognostic Assessment score 2 or above (P=0.009). One-year distant cerebral control rates were 56%. Thirty-three percent of patients received whole brain radiation therapy. Histologically proven radionecrosis of brain tissue occurred in 7.2% of cases. The size of the preoperative lesion and the volume of healthy brain tissue receiving 21Gy (V21) were both predictive of the incidence of radionecrosis (P=0.010 and 0.036, respectively). CONCLUSION Adjuvant hypofractionated stereotactic radiosurgery to the postoperative cavity in patients with brain metastases results in excellent local control in selected patients, helps delay the use of whole brain radiation, and is associated with a relatively low risk of radionecrosis.

Radiothérapie stéréotaxique hypofractionnée des métastases osseuses

Hypofractionated stereotactic radiotherapy can deliver high doses of bone metastases while sparing adjacent healthy tissue not only for a decompressive or analgesic purpose, but also to improve the local control of the irradiated region. Various phases I or II studies showed the feasibility of such an approach at the cost of limited toxicity, including during re-irradiation. Hypofractionated stereotactic radiotherapy to oligometastases may also improve the long-term control of metastatic disease.

Radiothérapie cérébrale postopératoire : indication de l’irradiation en conditions stéréotaxiques

The addition of whole-brain radiotherapy is a standard of care for patients with single, resectable intracranial metastasis. Stereotactic irradiation of the postoperative resection cavity seems to offer excellent local control rates and avoid the neurocognitive risks of whole-brain radiation therapy. The risk of remote intracranial recurrence imposes a strict surveillance imaging in order to proceed to a possible irradiation before a symptomatic stage. It must be validated in future randomized trials.

Dynamic conformal arc radiosurgery for arteriovenous malformations: Outcome and influence of clinical and dosimetrical data

PURPOSE To assess efficacy, toxicity, and their predictive factors for dynamic conformal arc arteriovenous malformations (AVM) stereotactic radiosurgery. METHOD Data concerning 90 consecutive patients were retrospectively studied. Clinical, radiological, dosimetrical data and quality indexes were computed. RESULTS AVM median volume was 1.06cc. Median prescribed dose was 22Gy. Total occlusion was obtained for 69% of patients. Post-radiosurgery annual hemorrhage rate was 2.2%. Predictive factor for total occlusion was delivered dose. Undesirable events occurred for 28% of patients. Predictive factors for adverse events were AVM revealing mode with seizure or headache, age≤28, AVM diameter≥3cm Spetzler-Martin score≥4, V12Gy≥2cc, large target volume and low homogeneity index (p<0.05). Brain parenchymal radiological reactions concerned 23% of patients, and their predictive factors were AVM revelation by seizure, deep localization, AVM diameter≥3cm, Spetzler-Martin score≥4, previous radiosurgery, numerous embolization, target volume, V12Gy and low homogeneity index (p<0.05). CONCLUSION Occlusion rate and toxicities are comparable to other series. Specific attention must be paid on pre-treatment clinical data, and target volume should be as small as possible, without reducing the delivered dose.