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Metastatic Brain Tumors
David
Black PA-C
Oct.10, 2003
Cerebral mets are the most common brain tumor seen clinically,
comprising slightly more than half of all brain tumors.
In the U.S., the annual incidence of new cases of cerebral mets is
>100,000, compared to 17,000 for primary tumors.
15-30% of cancer patients develop cerebral mets.
15% of patients who present with cerebral mets & unknown primary
43-60% have an abnormal chest x-ray.
Mets occur in only 6% of pediatric cancers
Solitary mets
At the time of diagnosis, 50% are solitary on CT
If the above patients have an MRI, >70% will have multiple
lesions
Increasing Incidents of Mets
 | Increased length of survival in cancer patients |
| greater ability to diagnose CNS tumors |
| Many chemo drugs do not cross BBB |
| Newer chemo drugs may weaken the BBB |
Primary CA’s
Lung 44%
Breast 10%
Kidney (Renal Cell) 7%
GI 6%
Melanoma 3%
Undetermined 10%
Location
80% are located in the cerebral hemispheres
Trigone most common site (MCA terminus)
Grey/white junction
16% occur in cerebellum
mets are the most common posterior fossa tumor in adults
Presentation
68% - Progressive Neurological Deficit
45% - Motor Weakness
54% - Headache
26% - Seizures
Workup
| metastatic workup
 | a. done prior to obtain tissue biopsy |
| b. CXR, CT chest, abd, & pelvis |
| c. Heme test stool |
| d. Bone scan |
| e. Mammogram |
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Management
| 11% of patients with abnormalities on CT or MRI and with a history
of CA (within the past 5 yrs) do not have cerebral mets. |
Medical Management
| a. Dilantin – for mid-brain or large tumors |
| b. Steroids
| i. Many symptoms are due to tumor vasogenic edema. |
| ii. Should respond to steroids within 24-48 hrs. |
| iii. Improvement is not permanent |
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| c. H2 Blocker |
Chemotherapy
| a.. BBB effectively excludes many chemotherapeutic agents from the
brain |
| b. In mets, the brain may serve as a "safe haven".
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| c. Intrathecal and direct contact chemo agents are being
developed, but no yet promising |
Radiation
| a. Steroids and radiation usually help head ache symptoms, and
resolve symptoms in 50% of patients |
| b. With usual dose (30Gy in 10 divided doses over 2 wks), 11% at
1 year and 50% at two year survivors develop severe dementia |
| c. Radio-resistant tumors |
| d. Large Cell Carcinoma
| i. Melanoma |
| ii. Renal Cell |
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| e. Radio-sensitive Tumors
| i. Small cell Lung Carcinoma |
| ii. Germ Cell Tumors |
| iii. Lymphoma |
| iv. Leukemia |
| v. Multiple Myeloma |
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| f. Prophylactic WBR
| i. WBRT after resection of a SCCL reduces cerebral relapses, but
does not affect overall survival. |
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Post-Op Radiation
| a. WBRT is has traditionally been administered following surgery,
especially with SCCL where "micro-metastasis" are presumed
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Surgical Management
| a. Solitary Lesions
| i. Indications favoring surgical excision
 | 1. Primary Disease controlled |
| 2. Lesion accessible |
| 3. lesion is symptomatic or life-threatening |
| 4. primary tumor known to be radio-resistant |
| 5. primary unknown
| a. Multiple Lesions |
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| ii. Usually treated with XRT |
| iii. If total surgical resection of all mets is possible, then
survival is comparable with solitary met. |
| iv. Indications for surgical excision of multiple mets
| 1. one particular and accessible lesion is clearly symptomatic
and/or life threatening (including posterior fossa and large
temporal lobe lesions). This is a palliative treatment to reduce
symptoms |
| 2. Multiple lesions that can be completely removed at one
surgery through same incision. |
| 3. no identifiable primary (excisional biopsy)
| a. Stereotactic biopsy
| i. Considered for:
| 1. lesions not appropriate for surgery
| a. deep lesions in eloquent cortex |
| b. multiple small lesions |
| c. no identified diagnosis |
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| 2. Patients not candidates for resection
| a. Poor medical condition |
| b. Poor neurologic condition |
| c. Active or wide-spread systemic disease |
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| 3. To ascertain diagnosis
| a. When another diagnosis is possible
| i. No other sites of metastasis |
| ii. Long interval between primary |
| iii. If non-surgical treatment modalities are
planned |
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Outcomes
| a. With optimal treatment, median survival of patients with
cerebral mets is 26-32 weeks after diagnosis. |
| b. By the time neurological findings develop, median survival
among untreated patients ~1 month. |
| c. Using steroids alone doubles survival to 2 months |
| d. WBRT + steroids increases survival to 3-6 months |
| e. iv. 50% of deaths are due to progression of the intracranial
disease. |
| f. Factors associated with better prognosis
| i. Karnofsky score >70 |
| ii. Age <60 |
| iii. Mets to brain only (no systemic mets) |
| iv. Absent or controlled primary disease |
| v. >1 year since primary diagnosed |
| vi. female gender |
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| g. Surgery + WBRT
| i. Recurrence of tumor was significantly less frequent and
more delayed with the use of post-op WBRT. |
| ii. There is also an additional loss of cognitive function
after WBRT, and patients are rarely independent after WBRT. |
| iii. In 33 patients treated with surgical resection of
solitary met and post-op WBRT, median survival was 8 months, with
44% 1 year survival.
| 1. If no evidence of systemic cancer1 year survival is 81%
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| 2. If systemic cancer is present, whether active or
inactive, 1 year survival is 20%
| iv. Surgical mortality is 4% (same as 30 day mortality in
the XRT group only) |
| v. Following surgical resection & WBRT, 22% of patients
will have recurrent brain met within 1 year.
| 1. surgery without XRT recurrence rate is 46-85)% |
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