Five Myths About Breast Cancer

There’s a broad range of news and information about breast cancer online, which creates opportunities to learn about prevention, treatment, cures and recurrence. But it also means you may run into confusing misinformation and oversimplifications.

Here are some popular misconceptions about breast cancer.

Mehra Golshan, MD, director of Breast Surgical Services with the Susan F. Smith Center for Women's Cancers at Dana-Farber, speaks with a patient.
Mehra Golshan, MD, director of Breast Surgical Services with the Susan F. Smith Center for Women’s Cancers at Dana-Farber, speaks with a patient.


Most breast cancer is hereditary. While it’s true that a woman’s risk factor for developing breast cancer doubles if a first-degree relative has the disease, this statistic doesn’t tell the whole story.

  • In the vast majority of cases, breast cancer is not caused by an inherited gene defect (or mutation).
  • Only 5 to 10 percent of breast cancer is associated with a gene that can be identified, such as a mutation in the BRCA1 or BRCA2 gene.

If you’re concerned about your risk level and are considering genetic testing, learn more through Dana-Farber’s Center for Cancer Genetics and Prevention.


You shouldn’t eat sugar or soy if you have breast cancer. There is no evidence that if you stop eating sugar or soy, cancer will disappear. In fact, there are no data that consumption of sugar or soy has any clinical effect on breast cancer. If you want to keep soy and sugar in your diet, there are some choices that are better than others.

  • Sugar is a natural substance that feeds all of our body’s cells. Replacing processed sugary foods with fruits, which have sugar and cancer-fighting nutrients, is a smart choice.
  • Swap concentrated or highly processed forms of soy (such as soy protein isolate) for more healthful kinds (such as tofu, edamame, soy milk).

Read more about sugar and cancer cells, healthy diet tips and soy milk and breast cancer.


Self-screening is the most important factor in early diagnosis. There has been debate over the value of breast self-exams to detect breast cancer in its first stages. Many guidelines do recommend self-exams, but they should complement and not replace appropriate screenings from your doctor.

Read more about screening recommendations for breast cancer.


Exposure of the tumor to air during surgery can cause the cancer to spread. This is untrue. The idea likely springs from a related highly circulated concern about needle biopsies spreading cancers.

There is no evidence in breast cancer or breast disease that air causes spread of cancer or that needle core biopsy causes cancer to spread. In fact, needle core biopsy is the preferred method of diagnosing breast cancer or breast abnormalities that are felt or seen on imaging.

For information about how breast cancer does spread in the body, visit the Susan F. Smith Center for Women’s Cancers webpage.


A mastectomy is the best therapy. Many women who have a choice in their treatment struggle to decide between conservative and more radical options.

  • Evidence shows that mastectomy rates and prophylactic mastectomy rates are rising regardless of age.
  • Seven large randomized prospective studies with 35 years of follow-up show that the survival between lumpectomy and radiation is the same as mastectomy.

Read about how breast cancer is treated and hear what Dana-Farber geneticists say about a preventive mastectomy. 

For more information on breast cancer, visit the website for the Susan F. Smith Center for Women’s Cancers at Dana-Farber.