How often should a patient with a malignant neoplasm (cancer) of the breast undergo a Positron Emission Tomography (PET) scan routinely?

PET Scan Surveillance in Breast Cancer Patients

Recommendation Summary

PET scans are NOT recommended for routine surveillance in breast cancer patients. 1

Evidence-Based Guidelines for Breast Cancer Surveillance

When PET Scans Should NOT Be Used

• PET scans should not be used for routine surveillance in asymptomatic breast cancer patients 1
• PET/CT is not indicated in the routine staging of clinical stage I, II, or operable III (T3N1) breast cancer 1
• The NCCN panel specifically recommends against routine systemic imaging (including PET scans) in patients with early-stage breast cancer without signs/symptoms of metastatic disease 1
• The American Society of Clinical Oncology (ASCO) explicitly states that [18F]fluorodeoxyglucose-PET scanning is not recommended for routine breast cancer surveillance 1

Appropriate Surveillance Schedule for Breast Cancer Patients

The recommended surveillance approach for breast cancer patients includes:

1. Regular History and Physical Examination:

   • Every 3-6 months for the first 3 years
   • Every 6-12 months for years 4-5
   • Annually thereafter 1

2. Mammography:

   • Post-treatment mammogram 1 year after initial mammogram
   • At least 6 months after completion of radiation therapy
   • Yearly mammographic evaluation thereafter 1

When PET Scans May Be Appropriate

PET/CT may be considered in specific clinical scenarios:

1. Suspected Recurrence:

   • When conventional imaging methods are equivocal 1
   • In patients with signs or symptoms suggestive of metastatic disease 1
   • In patients with rising serum tumor markers 1

2. Treatment Response Assessment:

   • May play a role in monitoring treatment response in metastatic breast cancer 1
   • Particularly useful for assessing bone metastases and enabling early response evaluation 1

3. Other Limited Applications:

   • To guide site of biopsy 1
   • To improve radiation therapy planning 1
   • As a substitute for CT and/or bone scan in the detection of bone metastases 1

Rationale Against Routine PET Scans

The recommendation against routine PET scanning is supported by:

• High false-negative rate in detecting small (<1 cm) and/or low-grade lesions 1
• Low sensitivity for detecting axillary nodal metastases 1
• Low prior probability of early-stage patients having detectable metastatic disease 1
• High rate of false-positive scans 1
• No evidence of impact on survival, quality of life, or cost effectiveness 1

Common Pitfalls and Caveats

1. False Positives: PET scans can show increased uptake in benign conditions including:

   • Benign breast lesions (fibroadenomas, papillomas)
   • Inflammatory conditions (mastitis, fat necrosis)
   • Post-surgical changes
   • Recent vaccinations (particularly COVID-19)
   • Physiological uptake (brown fat, lactational changes) 1

2. False Negatives: May occur with:

   • Small tumors due to partial volume effect and limited resolution 2
   • Low-grade tumors with less metabolic activity 1

3. Timing Considerations:

   • PET/CT should be performed at least 10 days (preferably 15 days) after the last dose of systemic therapy to avoid flare phenomenon or stunning reaction 1
   • Wait at least 3 months after radiotherapy to search for recurrence in the radiotherapy field 1

Conclusion

The evidence consistently shows that routine PET scanning is not recommended for surveillance of breast cancer patients. Standard follow-up should consist of regular history, physical examination, and mammography at appropriate intervals. PET scans should be reserved for specific clinical scenarios where conventional imaging is equivocal or there are signs/symptoms suggesting recurrence or metastatic disease.