For Women Facing a Breast Biopsy

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Appendix A: What is breast cancer?

Breast cancer starts when cells in the breast begin to grow out of control. These changed cells form tumors and can spread to other parts of the body. Breast cancer cells are very different from normal, healthy cells in the breast.

Breast cancer develops over time, starting with one tiny, abnormal cell. In most cases this process takes a long time, but some types of breast cancer grow very fast and spread quickly.

Likelihood of having breast cancer

Breast cancer is the most common cancer in women (other than skin cancer). It can develop at any age, but the chance of having breast cancer increases as women get older. Some women – because of certain risk factors – may have a greater chance of developing breast cancer than other women.

Some risk factors for breast cancer include:

  • A personal history of breast cancer (You had it before.)
  • Inherited changes (or mutations) in breast cancer-related genes (called BRCA1 and BRCA2 genes) and changes in other genes
  • Radiation treatments to the chest before age 40
  • A relative (mother, sister, grandmother, or aunt) on either side of the family with breast cancer
  • Male relatives with breast cancer
  • Having certain benign (non-cancer) breast changes, such as
  • Usual ductal hyperplasia
  • Fibroadenoma
  • Sclerosing adenosis
  • Several papillomas (called papillomatosis)
  • Radial scars
  • Atypical ductal hyperplasia (ADH)
  • Atypical lobular hyperplasia (ALH)

Women who have any of these risk factors should talk to their health care providers about their breast cancer risk. They should find out if they should have an MRI along with their mammograms.

Some risk factors may increase the chance of having breast cancer by only a small amount, such as:

  • Starting your menstrual periods at an early age (before age 12)
  • Going through menopause at a late age (after age 55)
  • Having no children
  • Having your first pregnancy after age 30
  • Alcohol use (more than 1 drink a day)
  • Being overweight or obese, especially after menopause

But most breast cancers occur in women who have none of these risk factors, other than getting older. This means all women should get routine screening mammograms and should watch for any breast changes.

Last Medical Review: 07/21/2014
Last Revised: 10/20/2015