According to the Chinese Tumor Registry Annual Report, there are two peak incidences of breast cancer in China: 45 to 50 years of age and 70 to 75 years of age. about 10% to 15% of patients are under 35 years of age.
An important risk factor for developing breast cancer is age. A woman’s risk of developing breast cancer increases with age. Most invasive breast cancers (with progression at the site of origin) are common in women 55 years of age and older.
For Chinese women, the incidence of breast cancer is low until age 20, after which the incidence rises rapidly with age and peaks in the 55-year-old age group, but after age 55, the incidence of breast cancer tends to decline with age instead.