Application of a multi-institutional nomogram predicting salvage whole brain radiation-free survival to patients treated with postoperative stereotactic radiotherapy for brain metastases

PURPOSE

The ultimate goal of stereotactic radiotherapy (SRT) of brain metastases (BM) is to avoid or postpone whole brain radiotherapy (WBRT). A nomogram based on multi-institutional data was developed by Gorovets, et al. to estimate the 6 and 12-months WBRT-free survival (WFS). The aim of the current retrospective study was to validate the nomogram in a cohort of postoperative BM patients treated with adjuvant SRT.

MATERIAL AND METHODS

We reviewed the data of 68 patients treated between 2008-2017 with postoperative SRT for BM. The primary endpoint was the WFS. The receiver operating characteristic curve and area under the curve (AUC) were calculated for both 6- and 12-months time points.

RESULTS

After a median follow-up of 64 months, the 1-year cumulative incidence of local and distant brain relapse rates were 15% [95% CI=8-26%] and 34% [95% CI=24-48%], respectively. At recurrence, repeated SRT or salvage WBRT were applied in 33% and 57% cases, respectively. The WFS rates at 6 and 12 months were 88% [95% CI=81-97%] and 67% [95% CI=56-81%], respectively. Using the Gorovets nomogram, the 6 months rates were overestimated while they were accurate at 12 months. AUC values were 0.47 and 0.62 for the 6- and 12-months respectively. Overall, Harrell's concordance index was 0.54.

CONCLUSION

This nomogram-predicted well the 12 months WFS but its discriminative power was quite low. This underlines the limits of this kind of predictive tool and leads us to consider the use of big data analysis in the future.

Surgical bed stereotactic radiotherapy of brain metastases: Clinical outcome and predictors of local and distant brain failure

PURPOSE

To retrospectively analyze the outcomes of stereotactic radiotherapy (SRT) targeted at surgical bed of brain metastases (BM) and identify patterns of local/distant brain relapses (LR/DBR).

PATIENTS/METHODS

Seventy patients were treated with SRT between 2008-2017. Marginal dose prescription on the 70% isodose line depended on the maximal diameter of the target volume and range between 15-18Gy for single fraction radiosurgery and 23.1-26Gy in 3-5 fractions for fractionated SRT.

RESULTS

At 12 months, the overall survival (OS) was 69% [CI _95%=59%-81%]. At 6 and 12 months, the cumulative incidence functions (CIF) of local relapse were 4% [1%-13%] and 15% [8%-26%], respectively. According to univariate analysis, factors associated with LR were an initial volume larger than 7cc (hazard ratio: 4.6 [1.0-20.8], P=0.046) and a positive resection margin [hazard ratio: 3.6 [1.1-12.0], P=0.037. DBR occurred in 54.3% of patients with a median time of 8 months. None of the variables tested (histology, location or number of lesions) were found correlated with the DBR. Leptomeningeal disease occurred in 12.9% of cases. Salvage whole brain radiotherapy (WBRT) was required in 45.7% of patients and delayed by a median time of 9.6 months. Symptomatic radionecrosis (RN) occurred in 7.1%.

CONCLUSIONS

Adjuvant SRT was an effective and well-tolerated treatment to control the postoperative risk of recurrence of BM without compromising OS. Positive resection margins and large volumes were predictors factor of local relapse.

P03.02 Risk of leptomeningeal dissemination in patients treated with postoperative stereotactic radiotherapy of brain metastases

Background

There is a body of evidence that the risk of leptomeningeal dissemination (LMD) is increased in the postoperative stereotactic radiotherapy (SRT) of brain metastases (BM) compared to adjuvant whole brain radiotherapy (WBRT). The proposed mechanism is an iatrogenic tumor dissemination into the cerebrospinal fluid at time of surgery. Including a wider volume of meningeal wall and the entire surgical track in the definition of the postoperative SRT clinical target volume (CTV) to decrease LMD is still controversial. The aim of this study was to retrospectively analyze the outcome of adjuvant SRT targeted at resection cavities of BM without previous WBRT.

MATERIAL / METHODS

We reviewed 70 patients treated with postoperative SRT for BM. Stereotactic planning computed tomography and planning MRI were imported into iPlan RT image software for image registration and TV delineation. The CTV consisted of any residual enhancement and all resected cavity including a safety margin of 1 to 2 mm. Only in cases of superficial initial tumor with meningeal contact was the CTV enlarged to the adjacent meningeal wall, but never included edema or the entire surgical track. Patients underwent regular follow-up MRI. The cumulative incidence rates of LMD was retrospectively calculated as well as patterns of failure.

RESULTS

The most common histological type was non small cell lung cancer in 61.4%. There were 38.6% infratentorial locations and 37.2 % superficial lesions. En bloc resection was achieved in 60% and compete resection in 75.7%. After a median imaging follow up time of 16.7 months, 54.3% of patients experienced distant brain failure. LMD occurred in 9 of 70 patients (12.9 %) at a median time of 10.7 months. Survival without LMD was 88% at 1 year (IC 95% 79%-97%) and 82% at 2years (IC 95% 72%-94%). In three quarter of cases, LMD interested superficial lesions. In univariate analysis, survival rates without LMD at 1 year for superficial and deep lesions were 88 % and 94 %, respectively (p=0.49). We report only one recurrence in the surgical track (1.42%).

CONCLUSION

The risk of LMD was comparable to the literature (11–17%). Superficial lesions were slightly more likely to relapse in the meninges, but it was non-significant. The risk of recurrence in the surgical track is negligible. Our results do not support the current guidelines recommending the systematic inclusion of the surgical track and the related meninges in the CTV.

P03.03 Dynamics of brain metastasis cavities between resection and adjuvant stereotactic radiotherapy and impact of the delay on local control

BACKGROUND

Adjuvant stereotactic radiotherapy (SRT) to the surgical cavity of brain metastases (BM) improves the local control. An early post-operative irradiation is desirable to limit the risk of recurrence while delaying it might reduce the risk of radionecrosis by reducing the size of the target volume (TV) thanks to the cavity constriction. The purpose of our study was to examine cavity dynamics after resection to determine if delaying SRT influences cavity size as well as local progression (LP).

MATERIAL AND METHODS

We reviewed 70 BM resection cavities treated with adjuvant SRT. A preoperative, immediate postoperative and at the time of SRT, 3D T1-weigthed MRI, were available for all patients. The volumes were retrospectively calculated with the PACS software Telemis® version 4 and the iPlan RT image software. For all cavities, the TV was obtained by expanding the cavity by a median margin of 2mm to account for microscopic spread. The surgical track and edema areas were not included in the TV. The dynamic evolution of cavities and LP according to the delay of SRT were analyzed.

RESULTS

The median time from surgery to SRT was 27 days (3–99). The median preoperative and SRT cavity volumes were 7.2 cc (ranges: 0.5–29.5) and 8 cc (ranges: 0.8–31), respectively. After margin expansion, the TV was increased to a median of 14.8 cc. The volumetric cavity changes were an increase by 2 cc in 35 %, whereas only 22.5 % decreased by 2 cc and 42.5% cavities were stable (defined as a change ≤2 cc). We noted that 11% of volume change were attributable to the delay (r2 = 0.11). forty-seven patients were treated within a delay of 30 days and experienced early LP in 10.6 % against 20 % beyond 30 days (p= 0.6).

CONCLUSION

In the interval between surgery and SRT, BM cavities dynamics are inconstant and unpredictable in function of time. Furthermore, delaying SRT may compromise local control, though the difference was not statistically significant due to the small size of our population. A preoperative SRT strategy looks more promising by alleviating the problem of time and reducing the volume of irradiated brain.

[Secondary amenorrhea and cerebral ventriculomegaly]

Cerebral ventriculomegaly and hydrocephalus are not frequently associated with endocrine disorders of the gonadotropic axis. The mechanism of this association is not clarified. The most probable cause is however a partial hypothalamic dysfunction. The examination of the few reported cases is in favour of this explanation. We present the case of a young woman with a cerebral ventriculomegaly and suffering from secondary amenorrhea. Shunt was not necessary from the neurological point of view, the problem of secondary amenorrhea and anovulatory infertility was solved by clomiphen citrate therapy.

[Management of medulloblastoma in children: the experience of a single institution in Liege from 1991 to 2005]

We present the experience of the Citadelle Hospital (Liege, B) in the diagnosis, treatment and follow-up of medulloblastoma in children. A retrospective study of 10 cases of medulloblastoma was performed. Five years after diagnosis, the event-free survival was 77%.

[Hydrocephalus in children]

The files of all young patients, aged from one day to 17 years, that were operated for hydrocephalus in the Service of Neurosurgery of the Citadelle Hospital from 1987 to 2003 were reviewed and analysed. Over these 16 years of practice, a shunt was placed in a total of 194 children. This paper is mainly concerned with the etiologies of hydrocephalus and the complications related to the surgical procedure.

Hypothalamic stimulation in chronic cluster headache: a pilot study of efficacy and mode of action

We enrolled six patients suffering from refractory chronic cluster headache in a pilot trial of neurostimulation of the ipsilateral ventroposterior hypothalamus using the stereotactic coordinates published previously. After the varying durations needed to determine optimal stimulation parameters and a mean follow-up of 14.5 months, the clinical outcome is excellent in three patients (two are pain-free; one has fewer than three attacks per month), but unsatisfactory in one patient, who only has had transient remissions. Mean voltage is 3.28 V, diplopia being the major factor limiting its increase. When the stimulator was switched off in one pain-free patient, attacks resumed after 3 months until it was turned on again. In one patient the implantation procedure had to be interrupted because of a panic attack with autonomic disturbances. Another patient died from an intracerebral haemorrhage that developed along the lead tract several hours after surgery; there were no other vascular changes on post-mortem examination. After 1 month, the hypothalamic stimulation induced resistance against the attack-triggering agent nitroglycerin and tended to increase pain thresholds at extracephalic, but not at cephalic, sites. It had no detectable effect on neurohypophyseal hormones or melatonin excretion. We conclude that hypothalamic stimulation has remarkable efficacy in most, but not all, patients with treatment-resistant chronic cluster headache. Its efficacy is not due to a simple analgesic effect or to hormonal changes. Intracerebral haemorrhage cannot be neglected in the risk evaluation of the procedure. Whether it might be more prevalent than in deep-brain stimulation for movement disorders remains to be determined.