In 1 large multidecade study, 82% of patients with breast cancer who developed bone metastases had either ER and PR or ER positivity in the primary tumor [115]. A landmark study 2 decades ago transformed our field by discovering 5 distinct composite molecular portraits using quantitative analysis of breast cancer gene expression patterns; luminal A, luminal B, HER2-enriched, basal-like, and normal-like, providing a new type of disease characterization [116]. The molecular subtypes were linked to pattern and type of metastatic spread, as well as disease-specific survival [117,118]. For example, luminal cancers have a propensity to give rise first to bone metastases, HER2-enriched cancers to liver and lung metastases, and basal type cancers to liver and brain metastases [119,120]. These molecular subtypes share similarities with ER/PR expression and HER2 gene amplification but are not synonymous. Luminal subtypes more commonly have ER expression, HER2-enriched cancers more commonly exhibit HER2 expression, and triple-negative breast cancers are most often the basal breast cancer subtype. Although luminal subtypes have significantly better overall and relapse-free survival [118], they carry a long-term risk of recurrence, especially to bone, whereas basal and HER2 subtypes have a higher rate of recurrence in the first 4 years [121], which can be considered when planning frequency and type of surveillance imaging. Bone Scan Whole Body Bone is the most common site for breast cancer metastasis; up to 70% of women with stage IV disease have bone metastasis, with the predilection for bone metastases not applying to basal-like tumors [117]. Up to 13.6% of women diagnosed with early stage breast cancer will develop bone metastasis within 15 years of diagnosis [122], even if the parent tumor is low grade [123].
Imaging of Invasive Breast Cancer. In 1 large multidecade study, 82% of patients with breast cancer who developed bone metastases had either ER and PR or ER positivity in the primary tumor [115]. A landmark study 2 decades ago transformed our field by discovering 5 distinct composite molecular portraits using quantitative analysis of breast cancer gene expression patterns; luminal A, luminal B, HER2-enriched, basal-like, and normal-like, providing a new type of disease characterization [116]. The molecular subtypes were linked to pattern and type of metastatic spread, as well as disease-specific survival [117,118]. For example, luminal cancers have a propensity to give rise first to bone metastases, HER2-enriched cancers to liver and lung metastases, and basal type cancers to liver and brain metastases [119,120]. These molecular subtypes share similarities with ER/PR expression and HER2 gene amplification but are not synonymous. Luminal subtypes more commonly have ER expression, HER2-enriched cancers more commonly exhibit HER2 expression, and triple-negative breast cancers are most often the basal breast cancer subtype. Although luminal subtypes have significantly better overall and relapse-free survival [118], they carry a long-term risk of recurrence, especially to bone, whereas basal and HER2 subtypes have a higher rate of recurrence in the first 4 years [121], which can be considered when planning frequency and type of surveillance imaging. Bone Scan Whole Body Bone is the most common site for breast cancer metastasis; up to 70% of women with stage IV disease have bone metastasis, with the predilection for bone metastases not applying to basal-like tumors [117]. Up to 13.6% of women diagnosed with early stage breast cancer will develop bone metastasis within 15 years of diagnosis [122], even if the parent tumor is low grade [123].