Breast cancer is an uncontrolled growth of breast cells. To better understand breast cancer, it helps to understand how any cancer can develop.
Cancer occurs as a result of mutations, or abnormal changes, in the genes responsible for regulating the growth of cells and keeping them healthy. The genes are in each cell’s nucleus, which acts as the “control room” of each cell. Normally, the cells in our bodies replace themselves through an orderly process of cell growth: healthy new cells take over as old ones die out. But over time, mutations can “turn on” certain genes and “turn off” others in a cell. That changed cell gains the ability to keep dividing without control or order, producing more cells just like it and forming a tumor.
A tumor can be benign (not dangerous to health) or malignant (has the potential to be dangerous). Benign tumors are not considered cancerous: their cells are close to normal in appearance, they grow slowly, and they do not invade nearby tissues or spread to other parts of the body. Malignant tumors are cancerous. Left unchecked, malignant cells eventually can spread beyond the original tumor to other parts of the body.
The term “breast cancer” refers to a malignant tumor that has developed from cells in the breast. Usually breast cancer either begins in the cells of the lobules, which are the milk-producing glands, or the ducts, the passages that drain milk from the lobules to the nipple. Less commonly, breast cancer can begin in the stromal tissues, which include the fatty and fibrous connective tissues of the breast.
Over time, cancer cells can invade nearby healthy breast tissue and make their way into the underarm lymph nodes, small organs that filter out foreign substances in the body. If cancer cells get into the lymph nodes, they then have a pathway into other parts of the body. The breast cancer’s stage refers to how far the cancer cells have spread beyond the original tumor (see Breast Cancer Stages for more information).
Breast cancer is always caused by a genetic abnormality (a “mistake” in the genetic material). However, only 5-10% of cancers are due to an abnormality inherited from your mother or father. Instead, 85-90% of breast cancers are due to genetic abnormalities that happen as a result of the aging process and the “wear and tear” of life in general.
There are steps every person can take to help the body stay as healthy as possible, such as eating a balanced diet, maintaining a healthy weight, not smoking, limiting alcohol, and exercising regularly (learn what you can do to manage breast cancer risk factors). While these may have some impact on your risk of getting breast cancer, they cannot eliminate the risk.
Developing breast cancer is not your or anyone's fault. Feeling guilty, or telling yourself that breast cancer happened because of something you or anyone else did, is not productive.
Here are some of the most current statistics about breast cancer in the United States.
About 1 in 8 U.S. women (about 13%) will develop invasive breast cancer over the course of her lifetime.
In 2022, an estimated 287,850 new cases of invasive breast cancer are expected to be diagnosed in women in the U.S., along with 51,400 new cases of non-invasive (in situ) breast cancer.
About 2,710 new cases of invasive breast cancer are expected to be diagnosed in men in 2022. A man’s lifetime risk of breast cancer is about 1 in 833.
About 43,250 women in the U.S. are expected to die in 2022 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% per year from 2013 to 2018. 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 2022, there are more than 3.8 million women with a history of breast cancer in the U.S. This includes women currently being treated and women who have finished treatment.
Breast cancer is the most commonly diagnosed cancer among American women. In 2022, it's estimated that about 30% of newly diagnosed cancers in women will be breast cancers.
Breast cancer became the most common cancer globally as of 2021, accounting for 12% of all new annual cancer cases worldwide, according to the World Health Organization.
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 0.5% 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 BRCA2 genes 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).
Here at Breastcancer.org, we run into some of the same myths year after year. Many of them are included in the list below. We also polled our online Community to ask them what they find to be the most persistent myths about breast cancer that need correcting.
Read the myths and learn the truth about them.
— Last updated on March 10, 2022, 9:04 PM
By submitting my email, I agree to receive newsletters from Breastcancer.org
A confirmation has been sent to your email address.
Get in touch
You can help