What is the recommended management approach for oligometastatic breast cancer?

Management of Oligometastatic Breast Cancer

Oligometastatic breast cancer should be managed with a multimodality treatment approach combining systemic therapy with local ablative treatments (surgery, radiotherapy, or ablation) to all metastatic sites, discussed in a multidisciplinary setting, as this offers the potential for long-term remission and survival benefit. 1

Definition and Patient Selection

Oligometastatic breast cancer is characterized by single or few detectable metastatic lesions (typically ≤5), usually limited to a single organ, representing 1-10% of newly diagnosed metastatic breast cancer patients. 1

Key prognostic factors for optimal candidate selection include: 2

• Solitary or limited number of metastases (≤5 lesions)
• Disease-free interval >24 months from primary diagnosis
• Limited or no axillary lymph node involvement at primary diagnosis
• Hormone receptor-positive disease
• Bone-only metastases
• Age <55 years
• Good response to initial systemic therapy 1

Core Management Algorithm

Step 1: Multidisciplinary Evaluation

All patients with suspected oligometastatic disease must be discussed in a multidisciplinary tumor board before treatment decisions. 1 This is a Level V, Grade B recommendation but represents the foundation of appropriate care.

Step 2: Comprehensive Staging

• Biopsy confirmation of metastatic disease when appropriate 1
• Complete imaging history review to assess disease dynamics 1
• Systemic imaging staging, preferably with PET scan 1

Step 3: Treatment Strategy

Multimodality treatment combining local and systemic therapies is recommended, tailored to individual disease presentation: 1

Local Ablative Therapy Options:

• Surgery for resectable metastases (particularly lung, liver, or isolated lesions) 1
• High conformal radiotherapy including stereotactic body radiation therapy (SBRT) 1
• Image-guided ablation (radiofrequency or cryotherapy) 1
• Selective internal radiotherapy for liver metastases 1

Systemic Therapy:

Document tumor response with systemic treatment before suggesting local ablative therapy—this sequence appears most reasonable. 1 The specific systemic therapy depends on:

• Hormone receptor status (endocrine therapy ± CDK4/6 inhibitors for HR+/HER2- disease)
• HER2 status (anti-HER2 therapy if positive)
• BRCA mutation status (PARP inhibitors for germline BRCA mutations)
• PD-L1 status (immunotherapy combinations in triple-negative disease)

Site-Specific Considerations

Primary Tumor Management

Locoregional treatment of the intact primary tumor in asymptomatic stage IV disease does NOT lead to overall survival benefit and is not routinely recommended. 1 This is a Level II, Grade D recommendation.

However, surgery of the primary tumor may be considered for: 1

• Bone-only metastasis
• HR-positive/HER2-negative tumors
• Patients <55 years
• Patients with oligometastatic disease
• Those with good response to initial systemic therapy

Bone Metastases

Bone-modifying agents (zoledronate or denosumab) are recommended for all patients with bone metastases regardless of symptoms. 1 Denosumab is more effective than zoledronate in delaying skeletal-related events. 1

Critical Evidence Limitations

The most important caveat: Local ablative therapy to all metastatic lesions may be offered on an individual basis, but it remains unknown if this leads to improved overall survival. 1 This is a Level II, Grade C recommendation from the most recent ESMO 2021 guidelines.

The evidence base consists primarily of:

• Large retrospective series showing associations between surgical removal and improved outcomes 1
• No prospective randomized trials demonstrating survival benefit 1
• Selection bias inherent in all available data 3

Practical Implementation

Despite the lack of Level I evidence, the combination of optimized systemic therapy with local ablative treatment offers: 1

• Rapid disease control
• Potential survival benefit in selected patients
• Improved quality of life
• Possible delay of subsequent systemic treatment progression 4

The ideal candidates are young women with limited disease burden, favorable biology (HR+/HER2-), long disease-free interval, and excellent performance status who can tolerate an aggressive multidisciplinary approach. 1, 2