The risk of breast cancer per age group, how mastectomy affects it, and more

If a woman’s risk of developing breast cancer throughout her lifetime is 1 in 8, how high is it in her 30s? Does breast size affect risk? Does a mastectomy mean that it is impossible for a breast tumour to develop?

Many of these questions hide myths that are worth examining. Let’s find out more about the risks, statistics and more about the tumour type affecting millions of women worldwide.


“Every woman has a 1-in-8 chance of getting breast cancer”

Where does the myth come from?

Based on studies on the current incidence rates in the United States, 12.4% women will develop breast cancer at some time during their lifetime. This estimate, from the most recent SEER Cancer Statistics Review (a report published annually by the National Cancer Institute’s [NCI] Surveillance, Epidemiology, and End Results Program), is based on breast cancer statistics between 2007-2009.

This estimate means that, assuming the current incidence rate stays the same, a woman born today has about a 1 in 8 chance of being diagnosed with breast cancer at some time during her life.

The reality behind the myth

Your relative risk starts low, and increases as you get older. For instance, when a woman is in her 30s, she has a 1 in 233 chance of being diagnosed with breast cancer.


“If my breasts are smaller than normal, I have lower risk of cancer”

Where does the myth come from?

Many studies have examined the association of different body types and breast cancer risk. Body type characteristics that have been examined include breast size, height, and a number of different features of body weight.

The reality behind the myth

No connection has been found between the size of a woman’s breasts and her breast cancer risk. While very large breasts are considered harder to examine clinically than small ones the best way for every woman to manage her personal risk is to follow guidelines on regular screenings, regardless of her breast size.


“All breast cancers come in the form of a lump”

Where does the myth come from?

It is true that for the vast majority of women, the first sign of breast cancer is the discovery of a lump. Yet in up to 15% of the cases there are different symptoms.

The reality behind the myth

A lump may or may not indicate breast cancer (as it may be benign in nature). However, other signs of cancer exist and should not be ignored. Such signs are changes in the normal texture or appearance of the breasts or nipples, and they include swelling, irritation of the skin, “dimpling”; pain in the breast or nipple; the nipple turning inward, swelling of the lymph nodes in the underarm, redness, scaliness, or thickening of the nipple or the breast skin, or a discharge other than breast milk.

In thousands of cases of breast cancer diagnosed every year there is no palpable lump.




“If I have a mastectomy, I have no risk of breast cancer”

Where does the myth come from?

Mastectomy is surgery to remove a breast. A mastectomy is usually carried out to treat breast cancer. However, in hope of avoiding future disease, some women at high risk of developing breast cancer elect to have both breasts surgically removed. This is done through a procedure called bilateral prophylactic mastectomy or preventive mastectomy. This surgery aims to remove all breast tissue that potentially could develop breast cancer.

The reality behind the myth

Some women actually do get breast cancer after a mastectomy. The reason is that, even though the highest proportion of breast tissue is in the mammary glands, it is not possible to completely remove all such tissue from the woman’s chest. It should be noted that the risk of developing breast cancer after prophylactic mastectomy is reduced by 90% on average.

Other sources include

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