What is the treatment approach for a brain mass?

Treatment Approach for Brain Mass

The treatment of a brain mass requires immediate tissue diagnosis through either surgical resection or biopsy, with the specific approach determined by whether the lesion is a primary brain tumor, metastasis, or other pathology—and MRI with chest CT should be obtained urgently to guide biopsy site selection. 1, 2

Initial Diagnostic Workup

Obtain brain MRI and chest CT immediately as these two studies together identify the appropriate biopsy site in 97% of patients with newly detected brain masses. 2 This streamlined approach avoids unnecessary diagnostic delays and expensive testing. The average time to biopsy should be 4-6 days, which can be reduced by at least 10% with this focused strategy. 2

• Do not order extensive systemic imaging (CT chest/abdomen/pelvis) in all patients—this is only necessary if metastatic disease is suspected based on initial imaging or clinical presentation. 3 In patients ultimately diagnosed with primary brain tumors, reducing unnecessary CT imaging from 47% to 12% of cases has been achieved through protocol implementation. 3

• Lung cancer accounts for 82% of brain metastases in patients presenting with brain mass as their first cancer manifestation, making chest CT particularly high-yield. 2

Surgical Decision-Making

Surgery (craniotomy for resection) is indicated for: 4, 1

• Lesions >3 cm in diameter (too large for stereotactic radiosurgery)
• Symptomatic mass effect causing midline shift, obstructive hydrocephalus, or steroid-dependent symptoms
• Diagnostic uncertainty when tissue diagnosis is needed
• Solitary accessible lesions in surgically favorable locations
• Posterior fossa lesions with significant edema and impending brainstem compression, even if <3 cm

Factors favoring stereotactic radiosurgery (SRS) over surgery: 4

• Lesions <3 cm in solid, homogenously enhancing tumors
• Deep locations (basal ganglia, brainstem)
• Multiple lesions (1-4 metastases), all amenable to radiosurgery
• Medical contraindications to craniotomy
• Patients requiring concurrent chemotherapy or anti-angiogenesis therapy (which impairs wound healing)

Treatment by Diagnosis

Primary Brain Tumors (Gliomas)

For IDH-mutant, 1p/19q-codeleted oligodendrogliomas (WHO grade 2): 4

• Surgery is the primary treatment modality
• Watch-and-wait is justified after gross total resection, particularly in patients <40 years old without neurological deficits beyond epilepsy
• If further treatment is needed: radiotherapy followed by PCV chemotherapy is standard of care
• Chemotherapy alone remains investigational

For IDH-mutant, 1p/19q-codeleted oligodendrogliomas (WHO grade 3): 4

• Extent of resection is prognostic
• Watch-and-wait can be considered for patients <40 years after gross total resection without homozygous CDKN2A/B deletion
• Standard of care: radiotherapy followed by PCV chemotherapy, which approximately doubles overall survival 4

For newly diagnosed glioblastoma multiforme: 5

• Maximal safe surgical resection followed by focal radiotherapy (60 Gy/30 fractions)
• Concomitant temozolomide 75 mg/m² daily during radiation (up to 49 days), followed by 6 cycles of adjuvant temozolomide 150-200 mg/m² on days 1-5 of each 28-day cycle 5
• This regimen increases median survival by 2.5 months with hazard ratio 0.63 (p<0.0001)
• Pneumocystis pneumonia prophylaxis is required during concomitant chemoradiation

Brain Metastases

For 1-4 unresected brain metastases (excluding small cell lung cancer): 4, 1, 6

• Stereotactic radiosurgery alone is the standard of care to avoid neurocognitive decline associated with whole brain radiation therapy (WBRT)
• SRS achieves local control rates of 75-95% 4

For 1-2 resected brain metastases: 4, 1, 6

• SRS to the surgical cavity should be offered rather than WBRT
• Postoperative radiation reduces tumor recurrence from 70% to 18% and neurologic deaths from 44% to 14% 4

For solitary brain metastasis: 4

• Surgical resection followed by radiation therapy is superior to radiation alone
• Combination reduces local recurrence from 52% to 20% and increases survival from 15 to 40 weeks 4

Whole brain radiation therapy is now reserved for: 4, 1, 6

• Multiple large brain metastases not amenable to surgery or SRS
• Patients with survival expectancy of at least several months
• If WBRT is used, offer memantine and hippocampal avoidance for patients with ≥4 months expected survival and no hippocampal lesions 1

Systemic therapy as monotherapy: 1, 6

• Now considered first-line for asymptomatic patients with certain tumor types (particularly NSCLC with targetable mutations)
• Efficacy depends on primary tumor type and presence of targetable mutations

Symptomatic Management

Dexamethasone dosing for cerebral edema: 1, 6

• 4-8 mg/day for moderate symptoms
• 16 mg/day for severe symptoms with marked mass effect
• Taper dose after surgical resection of lesions with mass effect, particularly when immunotherapy is planned 4

Seizure management: 1, 6

• Do not use anticonvulsants prophylactically
• Only treat patients who have experienced seizures
• Prefer agents that don't impact hepatic metabolizing enzymes

Monitoring and Follow-up

For watch-and-wait strategies without histological verification: 4

• Initial MRI intervals of only 2-3 months due to risk of underestimating malignancy grade
• Use Response Assessment in Neuro-Oncology (RANO) criteria for evaluation

After completion of therapy: 4

• Initial scan intervals of 2-6 months depending on histology
• For suspected progression, short-term control MRI within 4-8 weeks to confirm
• Pseudoprogression most likely occurs in first 3 months after chemoradiotherapy or immunotherapy
• Perfusion MRI and amino acid PET help distinguish pseudoprogression from true progression

Critical Pitfalls to Avoid

• Do not delay biopsy with extensive systemic workup—brain MRI and chest CT are sufficient to identify biopsy site in 97% of cases 2
• Do not use WBRT routinely—it causes neurocognitive decline and SRS alone is now standard for limited metastases 4, 1, 6
• Do not assume extent of systemic disease precludes neurosurgical intervention—the decision for craniotomy should be based on brain lesion characteristics, not systemic burden 4
• Do not start anti-angiogenesis agents (like bevacizumab) perioperatively—these interfere with wound healing 4
• Implement specialized admission pathways to reduce length of stay (from 7 to 5 days) and time to surgery (from 3.5 to 2.7 days) 3