In the past it was assumed that the most lethal part of breast cancer was the malignant cells that may have spread to the rest of the body before diagnosis. This notion led to high-dose chemotherapy and stem-cell rescue in an effort to kill every cancer cell when, in actuality, regular dose chemotherapy could have sufficed. Today we know that “there are at least five or six different molecular subtypes of breast cancer and each probably develops from a different step in the evolution of a tumor stem cell,” says Susan Love, MD, in her book, Dr. Susan Love’s Breast Book. With this improved understanding, patients are able to receive more personalized treatments, which lead to better results and less negative side effects. 

More than a mutated cell is needed to get actual cancer, says Love in her book. A nourishing environment is required. Otherwise, a bad cell in a good environment can stay dormant for years. “But if the environment changes,” says Love, “there is likely to be trouble.”

“Breast size has nothing to do with vulnerability to breast cancer or other breast diseases,” says Love. While the proportions may differ, all breasts, including men’s breasts, are made up of fat tissue, milk ducts and supportive fibrous tissues. Breast cancer is thought to arise from changes in a breast’s lining cells, says Love. That change can occur in anyone for reasons still being researched.

Nipples that invert when aroused are normal, but newly inverted nipples that become permanent could be an early sign of cancer and should be investigated, says Love.

The rumor about bras causing breast cancer was started by a husband and wife who said wearing a bra all day compressed the lymphatic system of the breast, resulting in an accumulation of toxins that caused breast cancer. However, there are no scientific studies that deem this belief true, according to the American Cancer Society. “This is total nonsense,” says Love in her book. “It makes no difference medically if your bra has wires or not, opens in the front or back, is padded or not padded, is made of nylon, cotton, or any other material, or gives much support or little support.”

Before jumping to conclusions, visualize what your breasts may be like inside—from butter to gravel to bubble wrap—suggests breast surgeon Ellen Mahoney, MD, in Dr. Susan Love’s Breast Book. None pose reason for concern unless there is an area that is different. Malignant lumps are not normally small and differ from their surrounding area. Since they’ve most likely had time to develop, they are usually at least a centimeter or two, almost an inch or the size of a grape.

Oftentimes cysts, which tend to appear overnight, are mistaken for cancerous lumps. While the fluid-filled sacs are normally easy to distinguish from hard, malignant lumps, they can be deceptive when located deep below the surface. If you detect a sudden lump, make an appointment with your doctor. Chances are it’s a harmless cyst that can easily be aspirated in the office. They’re common in women in their 30s, 40s and early 50s.

“At least two critical factors are necessary for any cancer to develop and flourish,” says Love. Genetics does plays a part in breast cancer development, but if the surrounding area—known as stroma, including fat cells, immune cells and blood cells—of an affected cell is healthy, the two can coexist without the disease ever developing. Only 5-10 percent of breast cancer cases are due to breast cancer genes BRCA 1 and 2.

You know your breasts best. If you feel strongly like something is wrong, but it goes against your doctor’s diagnosis, get a second opinion or insist on a biopsy anyway, says Love. “[A biopsy] is a minor procedure with low risks and potentially high gains.” It’s not uncommon for a woman to suspect she has a lump and it not be detected on a mammogram until years later.

Monthly self-exams help women become familiar with their bodies and can set off an alarm for medical attention. But by the time a woman detects a lump in her breast, it is likely that it has existed and perhaps spread, says Debbie Saslow, PhD, director of breast and gynecologic cancer for the American Cancer Society. Research shows that breast self-exams play a small role in finding breast cancer compared with finding a lump by chance, according to the American Cancer Society (ACS). The ACS recommends that women get yearly mammograms starting at age 40. However this advice has been questioned for women at low risk. Talk to you doctor to decide what’s right for you. 

New research suggests that computer-aided mammography (CAD) doesn’t detect cancer sooner, but rather increases the chances a woman will be called in for further testing. "For every 200 women who are screened with CAD who have a second mammogram, one additional woman is called back unnecessarily for further testing," says study author Joshua J. Fenton, MD, MPH, an assistant professor of family and community medicine at the University of California, Davis. Some believe the extra $12 a mammogram for computer-aided screening outweigh the potential benefits—it has cost Medicare $30 million, according to one study published last year in the Journal of the American College of Radiology.

Related: Celebs Who Survived Breast Cancer

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