Figure 1: HER2 distribution in diagnosed incident cases of breast cancer in the 8MM, ages ≥18 years, 2015
Breast cancer starts when cells in the breast multiply at excessive rates. These cells usually form a tumor that can invade nearby tissues or spread to distant areas of the body. All newly diagnosed breast cancer patients are tested for human epidermal growth factor receptor 2 (HER2), a molecule that facilitates uncontrolled growth of cancer cells.
It’s important for patients to know their HER2 status, because HER2-positive cancers are more likely to benefit from HER2-targeted therapy. The three HER2 categories are HER2-positive (HER2+), HER2-negative/hormone receptor (HR) positive (HER2-/HR+), and triple negative (TN) (Figure 1).
In urban China, the majority of incident cases fall into the HER2-/HR+ category; this pattern is consistent within each of the seven major pharmaceutical markets (7MM: US, 5EU [France, Germany, Italy, Spain, UK] and Japan). However, in each of the 7MM, HER2-/HR+ breast cancer makes up roughly three quarters of all incident cases, whereas this same HER2 category only makes up a little over half of all incident cases in urban China (Figure 1).
Additionally, urban China stands out because TN breast cancer, the most aggressive HER2 type, is roughly double the amount of TN breast cancer observed in the 7MM. These HER2 variations are likely due to the distribution of risk factors in urban China compared to the 7MM (for example, age, menopausal status, socio-economic status, access to screening), and future treatment strategies and guidelines should be evaluated with these variations in mind.
GlobalData (2016). EpiCast Report: Breast Cancer (HER2+, HER2-) – Epidemiology Forecast to 2025, December 2016, GDHCER133-16