Thursday, October 14, 2010
Breast Cancer Awareness Month
About 1 in 8 women in the United States (between 12 and 13%) will develop invasive breast cancer over the course of her lifetime.
In 2010, an estimated 207,090 new cases of invasive breast cancer are expected to be diagnosed in women in the U.S., along with 54,010 new cases of non-invasive (in situ) breast cancer.
About 1,970 new cases of invasive breast cancer will be diagnosed in men in 2010. Less than 1% of all new breast cancer cases occur in men.
From 1999 to 2006, breast cancer incidence rates in the U.S. decreased by about 2% per year. 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.
About 39,840 women in the U.S. are expected to die in 2010 from breast cancer, though death rates have been decreasing since 1991. These decreases are thought to be the result of treatment advances, earlier detection through screening, and increased awareness.
For women in the U.S., breast cancer death rates are higher than those for any other cancer, besides lung cancer.
Besides skin cancer, breast cancer is the most commonly diagnosed cancer among U.S. women. More than 1 in 4 cancers in women (about 28%) are breast cancer.
Compared to African American women, white women are slightly more likely to develop breast cancer, but less likely to die of it. One possible reason is that African American women tend to have more aggressive tumors, although why this is the case is not known. Women of other ethnic backgrounds — Asian, Hispanic, and Native American — have a lower risk of developing and dying from breast cancer than white women and African American women.
In 2010, there are more than 2.5 million breast cancer survivors in the U.S.
A woman’s risk of breast cancer approximately doubles if she has a first-degree relative (mother, sister, daughter) who has been diagnosed with breast cancer. About 20-30% of women diagnosed with breast cancer have a family history of breast cancer.
About 5-10% of breast cancers can be linked to gene mutations (abnormal changes) inherited from one’s mother or father. Mutations of the BRCA1 and BRCA2 genes are the most common. Women with these mutations have up to an 80% risk of developing breast cancer during their lifetime, and they are more likely to be diagnosed at a younger age (before menopause). An increased ovarian cancer risk is also associated with these genetic mutations. In men, about 1 in 10 breast cancers are believed to be due to BRCA2 mutations and even fewer cases to BRCA1 mutations.
About 70-80% of breast cancers occur in women who have no family history of breast cancer. These occur due to genetic abnormalities 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 gender (being a woman) and age (growing older).