Breast Cancer Screening

The Basics

What is breast cancer screening?

Screening looks for signs of cancer in people who feel completely well. The goal is to catch a cancer while it’s small and hasn’t spread, when treatment is simpler and far more likely to succeed. This is different from a diagnostic test, which is done to look into a specific symptom or finding.

Why does it matter?

Breast cancer is common, and in its early stages it usually causes no lump, pain, or change you can feel. A mammogram can spot a cancer years before it would ever be noticeable. That head start is why regular screening lowers the chance of dying from breast cancer.

Who is screening for?

Routine mammogram screening is for people with breast tissue, which is most people assigned female at birth. Screening is based on your anatomy and hormone history rather than gender identity, so recommendations for transgender and gender-diverse people are individualized, and we’re always glad to talk it through. Breast cancer in men is rare but possible, and is evaluated based on symptoms or known genetic risk rather than routine screening.

Who & When

Expert groups agree on the big picture and differ a little on the details. Here’s where the major guidelines land for people at average risk:

• U.S. Preventive Services Task Force (2024) — a mammogram every 2 years from age 40 through 74. This is a recent change; the previous guidance started routine screening at 50.
• American Cancer Society — the option to begin annual mammograms at 40, annual screening from 45 to 54, then every 1 to 2 years from 55 onward, for as long as you’re in good health.
• American College of Obstetricians and Gynecologists — offer screening at 40, begin by no later than 50, and repeat every 1 to 2 years.
• Age 75 and older — there isn’t enough evidence for a blanket rule, so the decision is individualized based on your overall health and preferences.

People at higher-than-average risk often start earlier and screen more intensively (see Higher Risk).

The Mammogram

What is it like?

A mammogram uses a very low dose of radiation to take pictures of the breast. Each breast is briefly compressed between two plates so the tissue spreads out and the images are clear. It can feel like firm pressure for a few seconds, and the whole visit usually takes about 15 to 20 minutes.

2D versus 3D (tomosynthesis)

Many centers now offer 3D mammography, which takes a series of thin image “slices” through the breast. Compared with traditional 2D, it can improve cancer detection and reduce the chance of being called back for extra pictures, and it’s especially helpful for dense breasts.

A couple of practical tips

• Skip deodorant, powder, and lotion on the day of the exam, since they can show up on the images.
• If you have prior mammograms from another facility, bringing them (or having them sent over) helps the radiologist compare.
• Screening mammograms are one of the few preventive services that most insurance plans cover at no cost to you.

Your Results

Mammogram results are summarized with a standard score called BI-RADS, from 0 to 6, that tells you and your care team what the images showed and what happens next:

• 0 — incomplete; more images or an ultrasound are needed before a final read.
• 1 — negative; nothing to report.
• 2 — benign; a normal, non-cancer finding (like a cyst).
• 3 — probably benign; a short-interval follow-up (often 6 months) is recommended just to be sure.
• 4 & 5 — suspicious to highly suggestive; a biopsy is usually advised.
• 6 — a cancer already confirmed by biopsy.

Dense Breasts

Nearly half of women have dense breast tissue, which means more glandular and fibrous tissue relative to fat. It’s completely normal and is graded on your mammogram, but it matters for two reasons: dense tissue can make cancers harder to see on a mammogram, and it’s associated with a modestly higher risk of breast cancer.

In the United States, mammogram reports now include a note about your breast density. If yours are dense, we may talk about whether additional screening, such as an ultrasound or MRI, makes sense for you. There’s no one-size-fits-all answer, so we’ll weigh it against your other risk factors together.

Higher Risk

Some people benefit from starting earlier and screening more thoroughly. You may be at higher risk if you have:

• A known inherited gene change such as BRCA1 or BRCA2, or a close relative who carries one.
• A strong family history of breast or ovarian cancer, especially at a young age.
• A personal history of breast cancer or certain high-risk breast biopsy findings.
• Radiation therapy to the chest at a young age (for example, for lymphoma).
• Dense breasts combined with other risk factors.

For higher-risk people, screening often begins in the 30s and may add an annual breast MRI alongside the mammogram. It can also be worth meeting with a genetic counselor and considering testing. A good first step is a family-history review, which we can do at a routine visit to see whether extra screening or genetic evaluation is right for you.

Signs to Watch

Screening is for people without symptoms, but it helps to know what’s normal for you so you notice a change. Have any of the following checked, even if you’re up to date on mammograms:

• A new lump or thickening in the breast or underarm
• Dimpling, puckering, or other changes in the skin’s texture
• Nipple changes, including pulling inward or new discharge (especially if bloody)
• Persistent, unexplained breast pain in one spot
• Swelling, redness, or warmth of the breast

These findings are far more often caused by something benign than by cancer, but they should be evaluated. A symptom is looked into with a diagnostic mammogram or ultrasound rather than a routine screening exam, so let us know and we’ll arrange the right test.

Useful Links

• Breast Cancer Screening — American Cancer Society
• Breast Cancer: Screening — U.S. Preventive Services Task Force
• Breast Cancer Screening — Centers for Disease Control and Prevention
• Annual Check-Ups — 617 Primary Care