Common Breast Cancer Subtypes and Metastasis Locations
Breast cancers can be made of any combination of estrogen receptor-positive (ER) genes, progesterone receptor-positive (PR), and human epidermal growth factor receptor 2 positive (HER2) genes. Many, but not all, cases of inflammatory breast cancer (IBC) are HR-/HER2+. HR stands for hormone receptor. Knowing your subtype can provide information that doctors can use to treat you.1,2
Metastasis patterns are associated with subtypes
Breast cancer commonly spreads to the bones, brain, liver, and lungs. A 2018 study suggests metastasis sites are not random. One study looked at 295,213 people with breast cancer and found that subtypes influence where the cancer spreads. This, in turn, could impact survival rates.3
The study compared breast cancer subtypes and classified them as HR and HER2 positive or negative. They did not designate if HR+ refers to ER+, PR+, or both. Overall, the best long-term survival outcomes were found with HR+/HER2+ subtypes while triple-negative subtypes had the worst outcomes. Bone metastasis was most common (3.3 percent), followed by lung (1.5 percent), liver (1.2 percent), and brain (0.4 percent). The results also found3:
- Triple-negative subtypes – higher rates of liver, brain, and lung metastasis, but lower rates of bone metastasis compared to HR+/HER2-.
- HER2+ subtypes – higher risk for liver, brain, lung, and bone metastasis. The highest risk was liver metastasis. Compared to HR-/HER2+, HR+/HER2+ had a higher risk for bone metastasis.
- Age-related risk – it was least likely for breast cancer in people over 65 years old to spread to the liver. There was also a higher risk for lung metastasis. Brain metastasis was higher in people ages 40 to 65.
- Site-related risk – cancers spreading to the brain had worse survival outcomes. In terms of metastasis sites, the best outcomes were seen when the cancer spread to the bone instead of the brain, liver, or lungs.
This study looked at all breast cancers, not just IBC. It also reviewed overall survival outcomes for metastatic breast cancers. Each person and each breast cancer is different. Survival outcomes depend heavily on many factors such as other health issues, not just where the cancer has spread (metastasis sites).
Using your subtype to your advantage
This study suggested that breast cancer subtypes have different patterns of (cancer spread) metastasis. Using the subtype may help doctors detect metastasis early since they know where to look. You may need a series of tests to look for metastasis. These include3,4:
- Computed tomography (CT) scans
- Positron emission tomography (PET) scans
- Magnetic resonance imaging (MRI)
- Understanding the link between subtypes and treatments
HR+ breast cancers thrive on hormones. Hormone therapy lowers the level of hormones in your body so the cancer growth slows down. HER2+ cancers can be treated with drugs that target HER2. Triple positive cancers respond to hormone therapy and HER2 therapy. Triple-negative cancer treatments may be limited as these therapies do not work well on it.1
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