Selected-Lesion SRS as a Novel Strategy in Treatment of Patients with Multiple Brain Metastases

PURPOSE/OBJECTIVE(S)

With the increasing use of intracranial SRS (SRS) for treatment of patients with >10-15 brain metastases treatment; debate remains in the literature about how these patients should be treated. While many advocate for treatment of all lesions with either SRS or whole brain radiation therapy (WBRT), several groups are considering selected-lesion SRS (SL-SRS) where only a subset of intracranial lesions are treated. However, the current practice patterns of SL-SRS are not known.

MATERIALS/METHODS

A survey of 19 questions was created using open-ended and multiple-choice style questions on SL-SRS practices and indications. The survey was distributed to providers in the US and internationally who perform SRS frequently. Ten out of 50 institutions provided responses reflecting the practices of 16 providers. Descriptive statistics was used to compare answers to each question when applicable including percentages and ranges.

RESULTS

SL-SRS was performed at 8/10 institutions, (5 out of 6 US institutions and 3 out of 4 international institutions). Only 2 institutions had established clinical indications for SL-SRS (one in the US and one internationally) and one additional US institution reported clinical trials that require SL-SRS to study efficacy of CNS penetrating targeted therapies. One program reported research protocols for untreated brain metastases that would take priority over SL-SRS (program outside the US). Size of the lesion was cited as the most important factor (90%) when deciding to treat any single lesion. Next, lesion location and focal signs/symptoms were both considered moderately important. 80% ranked distance from prior SRS as the least important factor. Perilesional edema was also less important at most programs (90%). Lesion location and presence of symptoms were also considered important. There were several factors that would encourage providers to consider SL-SRS in a patient. Prior WBRT; progressing systemic disease and CNS-penetrating drug option available; and progressing systemic disease and immunotherapy option available were the most common responses. Most respondents cited "specific request by medical oncology" as well as "cooperative studies in this topic" as factors that might push them towards SL-SRS. Several institutions specified factors beyond the listed options. One institution reported that for patients with >20 lesions, they treated the largest lesions with SRS then follow with WBRT, termed the "pre-WBRT boost." Progression of untreated lesions was the most common reason why providers would bring back patients for additional treatment.

CONCLUSION

The responses to this survey demonstrate that patients with >15-20 intracranial lesions, prior WBRT, and worsening systemic disease with CNS penetrating systemic therapies available are being considered for SL-SRS.

Acute hydrocephalus due to a primary malignant peripheral nerve sheath tumor of the cervicothoracic junction: A case report and review of the literature

BACKGROUND

The estimated incidence of malignant nerve sheath tumors is 0.001% per year, and only 2-3% of those tumors involve the spinal nerves. We present a rare case of acute hydrocephalus caused by primary malignant peripheral nerve sheath tumor of the cervicothoracic junction.

CASE DESCRIPTION

A 29-year-old previously healthy male patient, except for a history of two previous surgeries for ulnar nerve entrapment and progressive left upper extremity weakness, presented with acute onset somnolence. The CT and MRI revealed hydrocephalus and periventricular edema. The patient underwent ventriculoperitoneal shunt surgery. Postoperative MRI of the spine revealed a 6×3×3cm intra-extradural lesion at C7-T1 level and multiple metastases in other spinal segments. The patient underwent combined surgical excision and the tumor was diagnosed as a malignant peripheral nerve sheath tumor based on pathological and immunohistological findings. Radiation therapy and chemotherapy were initiated.

CONCLUSION

Primary malignant peripheral nerve sheath tumor of the spine is a very aggressive tumor with a very high recurrence rate, significant potential for metastasis and very poor overall prognosis. They may present with features of more frequent diseases, such as peripheral neuropathies and may be overlooked as in our case. Thus, suspected cases should undergo a more detailed examination.