From the Guidelines
To assess breast cancer metastasis, a whole body bone scan is the most sensitive test for detecting early bone metastasis, with a sensitivity of 98% in symptomatic patients, and should be used in conjunction with other imaging studies like CT scans and PET/CT scans. When evaluating breast cancer metastasis, it is essential to consider the most common sites of metastasis, including bone, lungs, liver, and brain. According to the study by 1, bone is the most common site for breast cancer metastasis, with up to 70% of women with stage IV disease having bone metastasis. The study also highlights the importance of whole body bone scans in detecting early bone metastasis, particularly in symptomatic patients.
Some key points to consider when assessing breast cancer metastasis include:
- The sensitivity of whole body bone scans for detecting bone metastases in patients with late-stage breast cancer ranges from 62% to 100%, regardless of tumor subtype 1
- The presence of peripheral metastasis almost always (>99%) occurs in the context of extraosseous or central osseous metastasis, and detection of additional peripheral metastases does not typically result in a change in management 1
- CT scans and PET/CT scans can detect metastases to organs like the lungs, liver, and lymph nodes, and are useful in conjunction with whole body bone scans
- Brain MRI should be performed if neurological symptoms are present or in aggressive subtypes like HER2-positive or triple-negative breast cancer
In terms of treatment planning and prognosis, early detection of metastasis is crucial, and the use of whole body bone scans, CT scans, and PET/CT scans can provide valuable information to guide treatment decisions. As noted in the study by 1, the incidence of stage IV disease increases with higher T stage, highlighting the importance of accurate staging and assessment of metastasis. Therefore, a combination of imaging studies, including whole body bone scans, CT scans, and PET/CT scans, is recommended to assess breast cancer metastasis and guide treatment decisions.
From the Research
Tests to Assess Breast Cancer Metastasis
- CA15-3: a tumor marker that can be used to detect bone metastases in breast cancer patients, with a sensitivity of 81.5%, specificity of 66%, and positive predictive value of 92% 2
- Bone scan: a diagnostic test that can detect bone metastases, but its use as a standalone investigation for systemic staging is not recommended 3
- CT-TAP (CT staging of the thorax, abdomen, and pelvis): a satisfactory stand-alone investigation for systemic staging in patients with breast cancer 3
- FDG-PET/CT (18F-fluorodeoxyglucose positron emission tomography/computed tomography): a diagnostic test that is superior to bone scan for detecting bone metastases, with a sensitivity of 97.6% 4
Comparison of Tests
- CA15-3 vs bone scan: CA15-3 is a simple, reliable, and inexpensive screening method for detecting bone metastases, while bone scan is more sensitive but also more expensive and time-consuming 2, 5
- FDG-PET/CT vs bone scan: FDG-PET/CT is superior to bone scan for detecting bone metastases and can also identify additional metastases in other organs 4
- CT-TAP vs bone scan: CT-TAP is a satisfactory stand-alone investigation for systemic staging, while bone scan plays a limited role in staging early breast cancer 3, 6
Clinical Applications
- CA15-3: can be used as a simple method to reflect the presence of bone metastases in association with bone scan 5
- FDG-PET/CT: can be used to detect bone metastases and identify additional metastases in other organs 4
- Bone scan: may be reserved for patients with clinical stage III and IV disease, or those with skeletal pain or high levels of CA15-3 5