What is Breast Cancer?
Breast cancer is a group of diseases in which cells in breast tissue change and divide uncontrolled, typically resulting in a lump or mass. Most breast cancers begin in the lobules (milk glands) or in the ducts that connect the lobules to the nipple.
USA 2020 Statistics:
- About 1 in 8 U.S. women (about 12%) will develop invasive breast cancer over the course of her lifetime.
- In 2020, an estimated 276,480 new cases of invasive breast cancer are expected to be diagnosed in women in the U.S., along with 48,530 new cases of non-invasive (in situ) breast cancer.
- About 2,620 new cases of invasive breast cancer are expected to be diagnosed in men in 2020. A man’s lifetime risk of breast cancer is about 1 in 883.
- About 42,170 women in the U.S. are expected to die in 2020 from breast cancer. Death rates have been steady in women under 50 since 2007, but have continued to drop in women over 50. The overall death rate from breast cancer decreased by 1.3% per year from 2013 to 2017. These decreases are thought to be the result of treatment advances and earlier detection through screening.
- For women in the U.S., breast cancer death rates are higher than those for any other cancer, besides lung cancer.
- As of January 2020, there are more than 3.5 million women with a history of breast cancer in the U.S. This includes women currently being treated and women who have finished treatment.
- Besides skin cancer, breast cancer is the most commonly diagnosed cancer among American women. In 2020, it’s estimated that about 30% of newly diagnosed cancers in women will be breast cancers.
- In women under 45, breast cancer is more common in Black women than white women. Overall, Black women are more likely to die of breast cancer. For Asian, Hispanic, and Native-American women, the risk of developing and dying from breast cancer is lower. Ashkenazi Jewish women have a higher risk of breast cancer because of a higher rate of BRCA mutations.
- Breast cancer incidence rates in the U.S. began decreasing in the year 2000, after increasing for the previous two decades. They dropped by 7% from 2002 to 2003 alone. One theory is that this decrease was partially due to the reduced use of hormone replacement therapy (HRT) by women after the results of a large study called the Women’s Health Initiative were published in 2002. These results suggested a connection between HRT and increased breast cancer risk. In recent years, incidence rates have increased slightly by 0.3% per year.
- A woman’s risk of breast cancer nearly doubles if she has a first-degree relative (mother, sister, daughter) who has been diagnosed with breast cancer. Less than 15% of women who get breast cancer have a family member diagnosed with it.
- About 5-10% of breast cancers can be linked to known gene mutations inherited from one’s mother or father. Mutations in the BRCA1 and BRCA2genes are the most common. On average, women with a BRCA1 mutation have up to a 72% lifetime risk of developing breast cancer. For women with a BRCA2 mutation, the risk is 69%. Breast cancer that is positive for the BRCA1 or BRCA2 mutations tends to develop more often in younger women. An increased ovarian cancer risk is also associated with these genetic mutations. In men, BRCA2 mutations are associated with a lifetime breast cancer risk of about 6.8%; BRCA1 mutations are a less frequent cause of breast cancer in men.
- About 85% of breast cancers occur in women who have no family history of breast cancer. These occur due to genetic mutations that happen as a result of the aging process and life in general, rather than inherited mutations.
- The most significant risk factors for breast cancer are sex (being a woman) and age (growing older).
Source: Breastcancer.org, U.S. Breast Cancer Statistics, https://www.breastcancer.org/symptoms/understand_bc/statistics, June 25, 2020