Myth: A breast cancer tumor must be removed immediately or it will spread.

Truth: Only in rare instances involving very fast-growing cancers do you need to act immediately. Breast cancer develops more slowly than most other cancers. When detected, it has typically been in the breast for anywhere from 3 to 15 years, says Gabriel Hortobagyi, M.D., a professor of medicine at the MD Anderson Cancer Center, in Houston, and president of the American Society of Clinical Oncology.
What It Means for You: “In most cases, there’s no harm in waiting a few weeks to investigate your options, such as breast-conservation therapy versus mastectomy,” says Ted Gansler, M.D., director of medical content for the American Cancer Society. You can also use the time to get a second opinion, find a surgeon, and fully process the diagnosis to prepare for the emotional journey.

Myth: The majority of women who get breast cancer have a family history of the disease.

Truth: Only about 15 to 20 percent of women who get breast cancer have a family history. Even among that group, the cause isn’t necessarily genetic, says Harold P. Freeman, M.D., senior adviser to the director of the National Cancer Institute. Sometimes the shared risk factors are relatives’ similar lifestyles and exercise and eating habits.
What It Means for You: Having relatives with breast cancer doesn’t mean you carry a genetic mutation or that an inherited gene will cause a cancer to develop someday. But it’s still important to know your family history and to be diligent about screening.