The short answer
Possible breast cancer signs include a new lump, changes in breast size or shape, skin dimpling, nipple changes, or discharge. Many of these have non-cancer causes, but any new or lasting change should be checked by a doctor.
A new lump in the breast or underarm is a key sign, but not all lumps are cancer.
Other signs include changes in breast size or shape, skin dimpling, or redness.
Nipple changes, such as turning inward or new discharge, can also be signs.
Many breast changes have non-cancer causes, but new or lasting ones should be checked.
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The whole article, with every detail and caution.
This page is for anyone who has noticed a breast change or wants to know the signs of breast cancer. It covers common and less common signs, and when to get checked.
The simple version
Breast cancer can cause a lump or other changes in the breast. But many breast changes are not cancer. Knowing the possible signs helps you notice changes and get them checked. Screening can also find breast cancer before any symptoms appear.
A key sign: a new lump
A lump in or near the breast is a main sign of breast cancer. It can be in the breast or under the arm. Lumps can feel different from person to person. Because of this, any new lump should be checked. You cannot tell by touch alone whether it is cancer.
Other breast changes to watch for besides a lump
Breast cancer can also cause changes that are not a lump:
- Swelling, or a change in the size or shape of a breast
- Skin that dimples or puckers, sometimes called puckering
- Redness, scaling, or swelling of the skin on the breast, nipple, or areola
- A nipple that turns inward, or fluid coming from the nipple that is not breast milk
- A rash on the breast skin that does not clear up
Pain is usually not the main clue
Breast cancer does not usually cause pain, especially early on. NCI says non-cancer conditions, such as cysts and hormonal changes before your period, can cause breast soreness or pain. This matters because it is easy to assume that "no pain" means "no problem." A painless lump deserves the same attention as a painful one.
Symptoms of cancer that has spread
If breast cancer spreads beyond the breast, it can cause other symptoms. These depend on where it spreads. They can include back pain, a bone that breaks, trouble breathing, a cough that does not go away, belly pain, jaundice, headaches, seizures, or vision problems. These symptoms have many other causes too. But if you have a breast cancer history and notice new symptoms like these, tell your doctor right away. For trouble breathing, a seizure, or sudden vision loss, call 911.
Many breast changes are not cancer
Many breast changes come from non-cancer causes, such as cysts, normal hormonal shifts, or infection. This is genuinely reassuring — most lumps and changes turn out to be benign. But because some changes are signs of cancer, any new or lasting change should still be evaluated by a doctor. Do not wait for it to go away on its own. Get it checked.
Follow up with your doctor when you notice a breast change, even if you had a recent normal mammogram. A mammogram is a picture taken at one point in time. It cannot rule out a change that shows up later.
Screening finds it early
Screening mammograms are an important way to find breast cancer before it causes any symptoms. NCI says cancer found early may be easier to treat. Talk with your doctor about when to start screening and how often, based on your age and your personal risk factors.
What to ask your team
If you notice a change, you might ask:
- Does this need a mammogram, an ultrasound, or a biopsy (a small tissue sample checked under a microscope)?
- When should I start or resume regular screening?
- Does my family or personal history put me at higher risk?
- Which symptoms should prompt me to call before my next visit, rather than wait?
For more detail on specific next steps, see these pages:
- Is a Breast Lump a Sign of Cancer?
- What Does BI-RADS 3 Mean?
- What Does BI-RADS 4 Mean?
- Breast Cancer Treatment by Stage
Sources
Common questions
What is a key sign of breast cancer?
A new lump or mass is a key sign in the breast or underarm. Lumps can feel different from person to person, so any new lump should be checked.
What other symptoms can occur?
Other possible signs include swelling or a change in breast size or shape, skin dimpling or puckering, redness or scaling of the skin, nipple pain or turning inward, and nipple discharge other than breast milk.
Do all breast changes mean cancer?
No. Many breast changes are caused by non-cancer conditions. But because some are signs of cancer, any new or lasting change should be evaluated by a doctor.
Can breast cancer be found before symptoms?
Yes. Screening mammograms can find breast cancer early, before it causes any symptoms, which is why regular screening is recommended for many people.
When should I see a doctor?
See a doctor if you notice a new lump, a change in the size or shape of a breast, skin or nipple changes, or nipple discharge. Getting new changes checked promptly is important.
Questions to ask your doctor
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Last updated: 2026-10-02Next planned review: 2027-07-07
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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