Found a Breast Lump: How Likely Is It to Be Cancer?

Many breast lumps turn out to be benign, such as cysts or fibroadenomas, but a new lump cannot be judged by feel alone, so it needs a clinician's evaluation. Features such as a hard, irregular lump, skin dimpling, nipple changes or a lump in the armpit raise concern. This article explains what a breast lump may be, what makes cancer more or less likely, how imaging and biopsy sort it out, and when to seek care.

What a breast lump usually turns out to be

Finding a breast lump is frightening, and the first thought for most people is cancer. MedlinePlus (NIH) notes that many breast lumps are not cancer and that several non-cancer conditions can cause them. That is reassuring, but it is not a reason to wait and see. Only a proper evaluation can tell which kind of lump you have, and the chance of cancer depends on your age, your history and what the lump looks like on imaging.

Common benign explanations include:

• Cysts: fluid-filled sacs that often feel smooth and may become tender or larger before a period.
• Fibroadenomas: solid, benign growths that often feel firm, rubbery and movable. They are seen more often in younger women.
• Fibrocystic breast changes: lumpy, tender tissue that can fluctuate with the menstrual cycle, as described in the MedlinePlus premenstrual syndrome overview of cycle-related breast tenderness.
• Fat necrosis: a firm area that can follow an injury or surgery to the breast.
• Infection or abscess: a warm, red, painful lump, sometimes during breastfeeding. Our article on breast pain and fever while nursing covers that situation in detail.
• Normal breast tissue: the natural ridge of tissue along the lower edge of the breast, or the breast buds that develop during puberty, which are described on the MedlinePlus teen development page.

Cancer is also on the list. Breast cancer can present as a lump, though it can also be found on a mammogram before any lump can be felt.

How likely is a breast lump to be cancer?

There is no single number that applies to everyone, and a figure from a website cannot replace an exam. Several factors shift the odds in either direction, and clinicians weigh them together with imaging and, when needed, tissue sampling.

Factors that may make cancer less likely

• A lump that is smooth, soft or rubbery and moves easily under the skin.
• A lump that changes in size or tenderness with your menstrual cycle.
• A younger age. Breast cancer becomes more common as people get older, although it can occur in younger adults.
• A lump that imaging identifies as a simple cyst.

Factors that may raise concern

• A hard, irregular lump that feels fixed in place.
• A lump that is new, persists through a full menstrual cycle, or keeps growing.
• Older age, a personal history of breast cancer, or a strong family history of breast or ovarian cancer.
• Skin changes over the lump, nipple changes, or a swollen lump in the armpit.

Be cautious with both lists. Cancerous lumps are sometimes painless and sometimes tender, and some benign lumps feel hard. Feel alone cannot sort one from the other, which is why a lump that is new or different for you deserves an exam.

Other breast changes to report along with a lump

A lump is only one of the changes that can be associated with breast cancer. According to MedlinePlus on breast cancer, other changes may include:

• Swelling of all or part of a breast, even without a distinct lump.
• Skin dimpling that can look like the surface of an orange.
• Redness, scaling or thickening of the breast skin or nipple.
• A nipple that turns inward or changes shape.
• Nipple discharge other than breast milk, especially if it is bloody or comes from only one breast.
• Pain in the nipple or breast that is new and persistent.

Breast cancer can spread to lymph nodes under the arm, so a firm lump or swelling in the armpit or near the collarbone is worth reporting even when the breast itself feels normal. Men have breast tissue too, and a lump in a man's chest should be evaluated in the same way.

What happens at the appointment

Most evaluations follow a similar path. Your clinician will ask when you noticed the lump, whether it has changed, how it relates to your cycle, and about your personal and family history, including hormone use and prior breast problems. They will examine both breasts and the lymph nodes in the armpits and above the collarbone. Many people feel nervous before the visit. Writing down your questions and the date you first noticed the lump can help.

Imaging

The next step is usually imaging, and the type depends on your age and what the exam finds. As MedlinePlus explains on its mammography page, a mammogram is an x-ray picture of the breast. When it is done to evaluate a symptom such as a lump, it is often called a diagnostic mammogram and may include extra views of the area of concern. Ultrasound uses sound waves and is good at showing whether a lump is a fluid-filled cyst or a solid mass. In younger people, whose breast tissue is denser, ultrasound is often used first or together with a mammogram. MRI may be added in some situations, such as when other tests are unclear or when the risk is high.

A normal mammogram does not rule out a problem when a lump can be felt. Clinicians combine your history, the exam and the imaging, and a lump that still concerns them may be sampled even when the picture looks reassuring.

Biopsy

If the lump is solid, or if anything on the exam or imaging is suspicious, the usual way to know what it is involves removing a small sample of tissue to be examined under a microscope. A needle biopsy is commonly done in the office or imaging center with numbing medicine, and the sample may be guided by ultrasound or mammography. Fluid from a cyst can sometimes be drained with a thin needle. Results usually take some days, and waiting is hard. It can help to ask when and how you will hear the results.

If the lump turns out to be cancer

A cancer diagnosis does not describe one single disease. The biopsy sample is tested to see what type of cancer it is and whether it has hormone receptors, which are proteins that can respond to estrogen or progesterone. The ASCO and College of American Pathologists guideline for estrogen and progesterone receptor testing addresses how that testing is done. Other tests may check for additional features of the tumor and look at the lymph nodes. Together these findings, along with the size of the tumor and your overall health, help your care team plan treatment. Treatment options may include surgery, radiation, hormone-blocking medicines, chemotherapy or targeted therapy, and sometimes medicine is given before surgery, as covered in the ASCO neoadjuvant therapy guideline. Which of these apply depends on the individual case, and outcomes vary. Many people with breast cancer found at an earlier stage do well, and your oncology team can discuss what to expect in your situation.

If the lump is benign

Many benign lumps need no treatment. Your clinician may recommend watching the area, repeating imaging after a set interval, draining a cyst, or removing a fibroadenoma that is growing or causing worry. Some benign findings, such as certain changes seen on biopsy, may call for closer follow-up or a different screening plan, so ask your clinician what follow-up they recommend for your result. An infection may be treated with antibiotics or drainage as your clinician decides.

What you can do while you wait for an appointment

• Note the date you found the lump, its approximate size and location, and whether it changes with your cycle.
• Write down any other changes in the skin, nipple or armpit.
• Gather your family history of breast, ovarian and other cancers, if you know it.
• List the medicines and hormones you take, and tell your clinician about them.
• Avoid squeezing or repeatedly pressing the lump, which can cause irritation and make it harder to examine.

If you are due for routine screening, mention it. Routine screening mammograms are done for people without symptoms, while a lump needs the diagnostic evaluation described above. Do not wait for a scheduled screening date if you have found something new.

Breast lumps during pregnancy, breastfeeding and puberty

Breasts change a great deal during pregnancy and breastfeeding, and a blocked milk duct or infection can cause a tender lump. The MedlinePlus breastfeeding page covers common nursing concerns. Cancer is much less common than these everyday causes in this group, and a lump alone does not establish it. Even so, a lump that does not go away after a few days of ordinary measures, or one that keeps coming back in the same place, should be examined. Ultrasound is often the first imaging test because it can be used during pregnancy and nursing. In teens, firm tissue under the nipple is often normal breast development, but a clinician can confirm that.

When to Seek Medical Care