Breast Cancer

What it is

Breast cancer starts in the breast. It can start in one breast or both. NCI describes it as cells that grow without control and form a mass called a tumor, which may spread to other parts of the body.

It is the second most common cancer in women, after skin cancer. Men get breast cancer too, though far less often.

What to watch for

NCI is direct about the beginning: "Early breast cancer often has no symptoms, which is why breast cancer screening is important."

When there are changes, these are the ones NCI lists:

• A lump in or near the breast, or under the arm
• A thick or firm area that feels different from the rest
• A change in the size or shape of a breast
• Fluid or discharge from the nipple that is not breast milk
• A nipple that turns inward, flattens, or changes direction
• Skin on the breast or nipple that is scaly, swollen, red, or darker
• Itching or tingling of the nipple
• Dimples or puckering in the skin

None of these means cancer on its own. Breasts change with age, with hormones, and with the menstrual cycle. What makes a change worth reporting is that it is new, and that it stays.

What raises the risk

NCI splits this into what a person can change and what they cannot.

Things nobody can change

Getting older. Being female. Having had breast cancer before, or a condition called DCIS. Certain benign breast changes. Dense breast tissue. High-dose radiation to the chest, especially when young. Starting periods early or reaching menopause late. Having a first child later, never carrying a pregnancy to term, or never breastfeeding. A family history of breast cancer. Inherited changes in genes such as BRCA1, BRCA2, PALB2, CHEK2, and others.

Things that can change

Alcohol. NCI puts it plainly: the more alcohol you drink, the greater your risk. Not being physically active, particularly after menopause. Carrying extra weight, especially after menopause. Combination hormone replacement therapy.

None of this works like a switch. Plenty of people with several risk factors never get breast cancer, and plenty with none of them do.

Is there a test before symptoms start?

Yes, and this is one of the cancers where federal guidance is clear.

NCI says the mammogram is the standard screening test. Breast MRI picks up more than a mammogram does. Ultrasound is also used.

The US Preventive Services Task Force recommends screening mammography every two years for women aged 40 to 74. That is a grade B recommendation, which means the Task Force found at least moderate benefit. For women 75 and older, and for extra scans in women with dense breasts, the Task Force says there is not enough evidence to weigh the benefits and harms either way.

When to start, and how often, is a conversation to have with a clinician who knows your history and your family's. This page cannot make that decision, and it is not trying to.