Cancer or Infection? How Can I Tell?

by Phyllis Johnson Patient Advocate

“My doctor says I have an infection, but when I Googled my symptoms, I saw that I have all the symptoms of inflammatory breast cancer. Is my doctor wasting my time with an antibiotic? Should I insist on a biopsy?”

We frequently get variations on this question here at HealthCentral. How can you tell whether you have an infection or a rare type of breast cancer called inflammatory breast cancer (IBC)? The short answer is you cannot without a doctor. However, understanding the similarities and differences between breast infections and IBC may help you decide what steps you need to take to get a proper diagnosis.

Breast infections include lactational mastitis, non-lactational mastitis, and abcesses.** Lactational mastitis**. When a woman is breast feeding, bacteria can get into her milk ducts. Usually the constant flow of milk washes the bacteria right out, but sometimes a duct becomes blocked, and bacteria multiply causing an infection. According to the Mayo Clinic, “In most cases, you'll feel ill with flu-like symptoms for several hours before you recognize that there's a sore red area on one of your breasts. As soon as you recognize this combination of signs and symptoms, it's time to contact your doctor.”

Mastitis symptoms include fever, pain, a lump, and a swollen, tender breast that may feel warm or hot to the touch. The red, inflamed area often forms a wedge shape.

Your obstetrician or lactational consultant will be familiar with mastitis. He or she may prescribe warm compresses, emptying as much milk as possible out of the breast, and an antibiotic that won’t hurt the baby. It is fine to keep on breastfeeding in most cases. In fact, it will help clear the milk ducts.

Non-lactational mastitis**.** The symptoms for non-lactational mastitis are the same as for lactational, but this form of mastitis is much less common. Women who get mastitis when they are not breastfeeding often are diabetic, have had recent breast surgery, or have a condition that suppresses their immune system. They will often run a high fever.

Subareolar Abscess. According to Dr. Susan Love’s Breast Book, an abscess can form behind the nipple and need draining. Symptoms are similar to mastitis, but the red, swollen area will be in the areola area, not spread across the breast. These abcesses can be a complication of mastitis or can form on their own when ducts in the milk glands or nipples are blocked. Dr. Love says these infections can recur about 40% of the time, especially in women who smoke, so once you are diagnosed with a subareolar abscess, you will need to be vigilant in case it comes back.

Redness and breast rashes can also signal other sorts of skin issues, such as a fungal infection, so the above list is not a complete catalog of every possible problem. If you have any of the above symptoms or other breast changes, you need to see your doctor for two reasons: you will probably need an antibiotic, and you need to have inflammatory breast cancer ruled out.

Inflammatory breast cancer shares symptoms with breast infections.

Inflammatory breast cancer represents about 1%-5% of all breast cancer cases, so the chances are that your symptoms that look like an infection are an infection. IBC symptoms overlap with mastitis symptoms although the red area with IBC is likely to cover a larger area, usually at least a third of the breast. In addition, fever is not an IBC symptom. So suppose you have no fever and you are not breastfeeding. Why might your doctor still be giving you an antibiotic instead of a biopsy?

First of all, not all people run a fever when they have an infection, so the absence of fever is not a sure indication of cancer. Secondly, even though non-lactational mastitis is rare, so is IBC. My own primary care doctor told me that in 15 years of practice, she has diagnosed one case of each. From your doctor’s point of view, it makes sense to treat the simplest problem first. While you are waiting to see if the antibiotic works, a diagnostic mammogram and ultrasound may give your doctor more information.

Although most patients with IBC do not have a lump that shows up on a mammogram, imaging tests do often show changes in breast density, symmetry, and other features. If the antibiotic clears up the symptoms, the problem is an infection. Antibiotics do not cure cancer.

Be a proactive patient.

If the antibiotic does not work, then what? The next step is to ask for a referral to a breast surgeon for a biopsy. Some doctors may want to try a second antibiotic at this point, but most experts on inflammatory breast cancer say waiting to see if another type of antibiotic will work is not a good idea. IBC is an aggressive form of breast cancer, so it is important to start treatment as quickly as possible.

If you are nursing and have mastitis-like symptoms that do not improve with the first round of antibiotics, it may be harder to decide what to do next. Because you are nursing, it is more likely that you have an infection, not cancer. However, women who are nursing have been diagnosed with IBC, usually after a delay because their doctors were convinced that they had mastitis. At the very least, I would recommend seeing a breast specialist familiar with IBC. Because my frame of reference is IBC, I would lean towards biopsy rather than more antibiotics, but a breast specialist can help you weigh the risks and benefits of a biopsy in your specific situation.

Sorting out the difference between an infection and cancer requires a knowledgeable doctor who pays attention to your symptoms and uses all the diagnostic tools available to get definitive answers. If it turns out that you do have IBC, don’t despair. New treatments are helping more people survive this form of cancer.


Breast Infections and Inflammations. Health Library. John Hopkins Medicine. Dec. 9, 2015.

Diseases and Conditions: Mastitis. Mayo Clinic. Accessed from Dec. 9, 2015.

Love S with K Lindsey. Dr. Susan Love’s Breast Book, 6th ed. 2015; 40-44.

Subareola Abscess. Medline Plus. NIH: US Library of Medicine. Accessed from Dec. 9, 2015.

Phyllis Johnson
Meet Our Writer
Phyllis Johnson

Phyllis Johnson is an inflammatory breast cancer (IBC) survivor diagnosed in 1998. She has written about cancer for HealthCentral since 2007. She serves on the Board of Directors for the Inflammatory Breast Cancer Research Foundation, the oldest 501(3)(c) organization focused on research for IBC. Phyllis attends conferences such as the National Breast Cancer Coalition’s Project LEAD® Institute. She tweets at @mrsphjohnson.