Breast cancer
Epidemiology

Breast cancer is the most common invasive cancer in women in most countries, accounting for 30% of cancer cases in women. In 2022, an estimated 2.3 million women were diagnosed with breast cancer, and 670,000 died of the disease. The incidence of breast cancer is rising by around 3% per year, as populations in many countries are getting older.

Rates of breast cancer vary across the world, but generally correlate with wealth. Around 1 in 12 women are diagnosed with breast cancer in wealthier countries, compared to 1 in 27 in lower income countries. Most of that difference is due to differences in menstrual and reproductive histories – women in wealthier countries tend to begin menstruating earlier and have children later, both factors that increase risk of developing breast cancer. People in lower income countries tend to have less access to breast cancer screening and treatments, and so breast cancer death rates tend to be higher. 1 in 71 women die of breast cancer in wealthy countries, while 1 in 48 die of the disease in lower income countries.

Breast cancer predominantly affects women; less than 1% of those with breast cancer are men. Women can develop breast cancer as early as adolescence, but risk increases with age, and 75% of cases are in women over 50 years old. The risk over a woman's lifetime is approximately 1.5% at age 40, 3% at age 50, and more than 4% risk at age 70.
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