Breast cancer does not always cause noticeable symptoms, especially in its early stages. In fact, some breast cancers are discovered through screening before a person feels or sees any changes.

When symptoms do occur, they can vary considerably. A new lump is one of the best-known warning signs, but it is not the only possible symptom.

At the same time, most breast changes are not caused by cancer. Cysts, infections, hormonal changes, benign breast conditions, and other problems can produce similar symptoms.

1. A New Lump or Thickening

A new lump in the breast or underarm is one of the most important changes to have evaluated.

A cancerous lump may feel:

• Firm or hard
• Different from the surrounding tissue
• Irregular in shape
• Relatively fixed in place

However, these characteristics cannot reliably determine whether a lump is cancerous.

Many benign lumps can also feel firm or unusual.

Don’t try to diagnose a lump by touch alone.

2. A Change in Breast Size or Shape

Breast cancer can sometimes cause one breast to look different from its usual appearance.

You might notice:

• New swelling
• A change in contour
• One breast becoming noticeably different from the other
• A localized area that looks or feels fuller

Breast asymmetry is common and can be completely normal. The concern is a new, persistent change.

3. Skin Changes on the Breast

Changes to the skin can sometimes be a warning sign.

Look for:

• Dimpling or puckering
• Thickening
• Redness
• Swelling
• Scaling
• An area that looks unusually irritated
• Skin that develops an orange-peel appearance

An orange-peel texture is sometimes called peau d’orange.

These changes can also occur with infections or other breast conditions, so they require evaluation rather than self-diagnosis.

4. Changes to the Nipple

Pay attention to a new change in the nipple, particularly if it affects only one breast.

Possible warning signs include:

• A nipple that newly turns inward
• Persistent crusting or scaling
• A sore that does not heal
• New changes in the nipple’s appearance
• Persistent irritation

Some people naturally have inverted nipples, so a nipple that has always looked this way is different from a newly inverted nipple.

5. Unusual Nipple Discharge

Nipple discharge has many possible causes and is often not cancer.

However, discharge deserves medical assessment when it is:

• Bloody
• Clear and persistent
• Occurring without squeezing or stimulation
• Coming from only one breast
• Associated with a lump or other breast change

Breast milk or other discharge associated with pregnancy, breastfeeding, or certain medications can have entirely different explanations.

6. Persistent Breast Pain

Breast pain by itself is not usually a typical sign of breast cancer.

Hormonal changes, injuries, infections, cysts, medications, and other benign conditions can cause breast pain.

However, persistent or unexplained pain—especially when accompanied by a lump, skin change, swelling, or nipple change—should be evaluated.

Don’t assume that pain automatically means cancer, but don’t ignore a persistent unexplained symptom.

7. Swelling in the Breast or Armpit

Sometimes breast cancer can affect lymph nodes under the arm or around the collarbone.

This may appear as:

• A lump in the armpit
• Swelling around the collarbone
• A feeling of fullness or thickening

Swollen lymph nodes can also result from infections and many other conditions.

A new persistent swelling should therefore be checked by a healthcare professional.

8. Changes That Resemble an Infection

Some forms of breast cancer, particularly inflammatory breast cancer, can cause rapid changes in the breast.

Possible symptoms include:

• Rapid swelling
• Redness
• Breast warmth
• Skin thickening
• A heavy or enlarged feeling
• Orange-peel-like skin
• Tenderness

Inflammatory breast cancer is uncommon, and these symptoms can also occur with mastitis or other infections.

But if breast redness and swelling develop rapidly or don’t improve as expected, medical evaluation is important.

9. An Area That Looks or Feels Different

You don’t necessarily need to find a distinct lump to notice a breast problem.

You may simply notice that one area feels:

• Thicker
• Firmer
• Swollen
• Unusually different from the surrounding tissue

Knowing what is normal for your own breasts can make it easier to recognize a new change.

10. Symptoms in More Advanced Breast Cancer

Breast cancer can spread beyond the breast and nearby lymph nodes.

When that happens, symptoms depend on where the cancer has spread and may include:

• Persistent unexplained bone pain
• Shortness of breath
• Persistent cough
• Severe or unexplained fatigue
• Neurological symptoms
• Unexplained weight loss

These symptoms have many possible causes and do not mean someone has advanced breast cancer.

Nevertheless, persistent unexplained symptoms deserve medical attention.

Not Every Breast Lump Is Cancer

This is extremely important.

Breast lumps can result from many noncancerous conditions, including:

• Cysts
• Fibroadenomas
• Fibrocystic breast changes
• Hormonal changes
• Infections
• Injuries

A healthcare professional may use a clinical breast examination and imaging—such as diagnostic mammography or ultrasound—to determine what is happening. A biopsy may be needed when imaging or examination indicates that tissue needs to be examined.

What About a Lump That Doesn’t Hurt?

A painless lump should not be ignored simply because it doesn’t hurt.

Breast cancer can be painless, but benign lumps can also be painless.

Pain—or the lack of pain—is not a reliable way to determine whether a breast lump is cancerous.

What Should You Do If You Notice a Change?

Don’t panic, but don’t put it off indefinitely.

Make an appointment with a healthcare professional if you notice:

• A new breast lump
• A new underarm lump
• Persistent skin changes
• New nipple inversion
• Unusual nipple discharge
• Persistent swelling
• A significant change in breast size or shape
• A breast change that doesn’t go away

If you are already enrolled in a recommended breast-cancer screening program, continue your scheduled screening even when you feel healthy.

Screening is important because some breast cancers cause no symptoms at all.

When Should You Seek Urgent Help?

Most breast changes do not require emergency treatment.

However, seek prompt medical attention for rapidly developing breast swelling, significant redness or warmth with fever, severe illness, or other symptoms suggesting a serious infection.

A new breast lump generally requires a medical appointment rather than an emergency-room visit unless it is accompanied by another serious condition.

How Can You Reduce Your Risk?

Not every breast cancer can be prevented, and some risk factors—such as age and inherited genetics—cannot be changed.

However, several healthy habits can reduce risk for many people:

• Avoid smoking.
• Maintain a healthy body weight.
• Stay physically active.
• Limit alcohol consumption.
• Follow recommended breast-cancer screening guidance.
• Discuss significant family history with a healthcare professional.
• Ask about genetic counseling when there is a strong family history of breast or related cancers.

The Bottom Line

Breast cancer can cause a new lump, breast or armpit swelling, skin dimpling or thickening, nipple changes, unusual discharge, or changes in the size and shape of the breast.

But these symptoms are not proof of cancer. Many are caused by benign conditions.

The safest approach is to become familiar with what is normal for you and have new, persistent, or unusual changes evaluated by a healthcare professional.

And remember: breast cancer can exist without obvious symptoms, which is why appropriate screening remains important.