How Breast Cancer Can Be Misdiagnosed

Why It Happens and What to Do

Breast cancer is the most common non-skin cancer, but sometimes, it’s misdiagnosed, missed, or overdiagnosed. 

A missed or delayed breast cancer diagnosis may result in more advanced cancer, more aggressive treatment, and a worse outlook. On the other hand, diagnosing cancer or a noncancerous condition as more dangerous than it is can lead to unnecessary invasive testing or treatments.

There aren’t too many studies on the rate of misdiagnosis of breast cancer in real-world scenarios. Some studies suggest that misdiagnosis of any illness happens about 5% of the time. Overdiagnosis of breast cancer may be as high as 31%. Mammograms miss about 12% of breast cancers. 

Healthcare provider holds hand of person seeking care

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Common diseases that a healthcare provider may misdiagnose as breast cancer include:

  • Breast cysts
  • Fibrotic breast tissue
  • Pregnancy-related breast changes
  • Mastitis

This article reviews what we know about breast cancer misdiagnosis statistics, how symptoms of breast cancer and the conditions above overlap, and where the diagnosis process can go wrong, leading to misdiagnosis, missed diagnoses, and overdiagnosis. 

How Often Does Breast Cancer Misdiagnosis Occur?

Healthcare providers can make several mistakes when diagnosing breast cancer: 

  • Misdiagnosis is when a healthcare provider has diagnosed breast cancer as another disease or condition. Perhaps they mistook a breast lump for a benign cyst instead of cancer.
  • A missed diagnosis is when your symptoms don't lead to a diagnosis. Perhaps a radiologist (a physician specializing in interpreting medical imaging) determines that your regular screening mammogram is normal when you have cancer.
  • Overdiagnosis is when a healthcare provider misdiagnoses a benign condition as cancer or diagnoses early stage cancer as more advanced than it is. Overdiagnosis may lead to unnecessary treatments or tests.

In these instances, you end up getting the wrong treatment, too much treatment, or not enough treatment. These can lead to death, debilitation, side effects, or aggressive treatment when a healthcare provider later diagnoses breast cancer.

Generally, misdiagnosis and missed diagnoses (of all kinds) seem to be around 5% when people see a healthcare provider in an outpatient setting (outside of a hospital setting).

Healthcare providers diagnose over 280,000 cases of breast cancer a year—that's about 15% of all cancers. Over 43,000 people die from breast cancer in a year; that's only about 7.1% of all cancer deaths. The five-year relative survival rate for breast cancer is 90.6%, based on data from 2012 to 2018.

Getting a Second Opinion

You should consider getting a second opinion if you’re worried your healthcare provider has missed or misdiagnosed breast cancer. Consider getting a second opinion about a breast lump if you’re over 40, have breast cancer symptoms, or are at a heightened risk of breast cancer.

In addition, consider requesting a second opinion on your breast biopsy (a sample of the suspected tumor analyzed in the lab). A second opinion can help catch many staging (determining how far cancer has spread) mistakes, a 2016 study said.

Getting an accurate diagnosis of breast cancer is important. Breast cancer is much easier to treat and has much higher survival rates when diagnosed early. 

The five-year survival rate for breast cancer that hasn’t spread to other tissues is 99.1%. Five-year survival drops to 86.1% if it has spread to other nearby tissues (or the lymph nodes). If it has spread to other organs, the five-year survival rate for breast cancer is 30%.

Conditions That May Appear Like Breast Cancer 

In addition to the risk of over- or underdiagnosing breast cancer, your doctor may also misdiagnose or dismiss your symptoms. A few specific conditions have symptoms similar to breast cancer. They may cause lumps or lead to swelling, redness, heat, tenderness, or pain — all common breast cancer symptoms.

Fibrocystic Breast Changes

Lumps are often cysts or fibrosis in the breast. These two types of growth are often discussed together as fibrocystic changes. These growths are common in females of childbearing age but can develop at any time in life. Fibrocystic changes are typically benign.

Cysts are fluid-filled pockets that feel round and moveable. They can grow up to 2 inches across. Fibrosis, on the other hand, is scar tissue and feels rubbery and firm. 

Fibrocystic changes are common in younger females under 40. Those who are menstruating may feel cysts or fibrotic lumps grow and become more painful just before their period. 

Fibrocystic breast changes can make the breast swell and cause tenderness or pain. They often form a lump in the breast and may cause nipple discharge. These are all common symptoms of breast cancer as well. But breast cancer is less common in these younger females. 

A healthcare provider who feels a lump in a menstruating person under 40 may initially assume it is a cyst or fibrosis. If they are concerned about it being cancer, they may order a breast ultrasound to test if the lump is solid or fluid-filled. 

Some cysts carry a risk of being cancerous. A complicated cyst is unlikely to be cancer, but your healthcare worker may suggest having it biopsied to be sure. 

A complex cystic and solid mass has a solid part or a thick outer wall. These complex cysts have a higher risk of being cancerous. Your healthcare provider will order a biopsy if you have a complex mass with both cystic and solid characteristics.

Pregnancy-Related Breast Changes

Normal pregnancy and breastfeeding can cause many changes to the breasts. These changes may make pregnancy-related breast cancer harder to diagnose. Often diagnoses of these cancers are delayed and pregnancy-related breast tumors end up larger and at a higher stage than those in people who are not pregnant.

Developing breast cancer during pregnancy is rare; only about 1 in 3,000 pregnant people get a diagnosis of pregnancy-related breast cancer. Some cases of pregnancy-related breast cancer may be misdiagnosed as pregnancy-related breast changes or missed altogether if a person assumes these changes are normal.


In addition to general pregnancy changes in the breasts, people are more likely to develop mastitis when breastfeeding, which may look like inflammatory breast cancer (IBC).

Mastitis is swelling of the breast due to an infection from a clogged duct or through broken skin of the nipple. The breast may develop a hard lump, look red, feel hot, and itch. You may also have flu-like symptoms.

IBC may make the breast feel swollen, red, hot, and itchy. It is rare but occurs more often in females under 40—those still likely to be pregnant and breastfeeding. It usually doesn’t cause a traditional lump seen on a mammogram. Mastitis is much more common than IBC. Less than 5% of breast cancers are inflammatory.

Especially if you’re breastfeeding, your healthcare provider may treat you first with antibiotics to rule out mastitis before ordering additional testing for cancer.

Contributing Misdiagnosis Factors 

Many factors are at play when getting a breast cancer diagnosis. Wrong diagnoses can happen in stages of the breast cancer diagnostic process: in the healthcare provider's office for a physical exam, at the radiologist's for a mammogram, or during the biopsy process. 

A 2020 study of 562 breast cancer malpractice claims analyzed the most common reasons diagnosis was delayed, with more than one factor noted in some claims. They found that:

  • In 49% of the malpractice claims, diagnostic studies were misinterpreted.
  • In 27% of the claims, diagnostic tests were either delayed or not ordered.
  • In 17% of the claims, there was a failure or delay in a consultation or referral.
  • In 16% of the claims, miscommunication between the person seeking care and the healthcare providers caused the delay.
  • In 12% of the claims, the delay was due to miscommunication among healthcare providers.

In your healthcare provider's office, they may dismiss symptoms of breast cancer as a benign condition. They may misdiagnose a lump as a cyst or swelling as mastitis. 

During a mammogram, a radiologist may misclassify what they're seeing. Radiology isn't perfect—the radiologist may not always be able to tell if what they're seeing is cancer or not.

For example, mammograms aren't 100% accurate in showing if a female has breast cancer. They can miss some cancers, and sometimes they find things that turn out not to be cancer (but that still need further testing to be sure).

A 2012 study of breast cancer and mammograms estimated that about 31% of cases of breast cancer in 2008 were overdiagnosed.

Conversely, mammograms can look free of cancer even when cancer is present. Overall, screening mammograms miss about 1 in 8 breast cancers.

Mammograms are even more of an issue with females with dense breast tissue. Consider a follow-up mammogram or other breast imaging study if you have dense breasts. Some radiology practices specialize in addressing the needs of people with denser breasts.

If you're having symptoms of breast cancer, you may need additional tests such as a diagnostic mammogram, breast ultrasound, or breast magnetic resonance imaging (MRI) to look more closely at the area. Some cancers can be seen better with alternate screening methods.

If something shows up on a mammogram or an ultrasound, you'll likely have a biopsy to confirm a cancer diagnosis. During a biopsy, the surgeon may miss the tumor while taking the sample.

Or the pathologist (a physician specializing in laboratory and anatomical medicine) may analyze your biopsy sample incorrectly. They may under-interpret early and precancers and over-interpret some samples as more cancerous than they are. 

There are many steps to getting an accurate breast cancer diagnosis, and misdiagnosis, missed diagnosis, or overdiagnosis can happen at any time. 

If You Suspect You’ve Been Misdiagnosed 

If you think your healthcare provider has missed a breast cancer diagnosis or are unsure about the diagnosis you received, you may wonder what you can do about it. 

Depending on which step you think the misdiagnosis happened, you can:

  • Ask your healthcare provider why they think your symptoms aren’t cancer.
  • Ask them what they should do if they notice changes in your symptoms.
  • Ask for a referral to a cancer specialist (oncologist).
  • Ask for a second opinion from a physician.
  • Ask for a repeat mammogram.
  • Ask for additional screening with breast ultrasound or MRI.
  • Visit a mammogram center that specializes in dense breasts.
  • Ask for a second opinion on your biopsy sample.
  • Ask for another biopsy.

If you want a second opinion, call your health insurance representatives to see if they would cover it and help you find another physician. Second opinions are common, and often your new physician needs only to review your existing records to form their opinion.


When being diagnosed with breast cancer, there are many ways that things can go wrong. Your healthcare provider may miss your symptoms or think another disease caused them. This is a misdiagnosis.

A mammogram may miss your cancer if the radiologist reading the results interprets them as benign, not cancerous. This is a missed diagnosis.

The pathologist who analyzes your biopsy sample may misread your results, leading them to label a precancer as cancerous. This is overdiagnosis. 

It isn't known how often breast cancer is missed, misdiagnosed, or overdiagnosed. General figures for misdiagnosis of all conditions tend to be around 5%. Overdiagnosis by screening mammograms may be much higher. If you think your breast cancer case was misdiagnosed, missed, or overdiagnosed, ask for a second opinion.

A Word From Verywell 

If you think your healthcare provider has misdiagnosed your breast cancer or if you think they have missed some signs of cancer, know you're not alone. They are human beings, and they make mistakes.

Trust your gut if you think something isn't right. If your symptoms persist and you think they're worsening, go back to your healthcare provider or ask for a second opinion. If you have cancer and were misdiagnosed, you won't regret the extra effort. 

Frequently Asked Questions

  • Can a healthcare provider misdiagnose breast cancer from a biopsy?

    A healthcare provider may analyze your breast cancer biopsy sample wrong. A 2015 study put pathologists to the test interpreting breast biopsies.

    In many cases, the pathologists’ interpretation did not match the actual condition presented in the test slides.

    Some underdiagnosed cases of precancers, stage 0 cancers, and stage 1 cancers. Others overdiagnosed these cancers as more advanced than they were.

  • Do breast scans have a margin for error?

    Mammograms aren’t perfect. Overall, screening mammograms miss about 1 in 8 breast cancers. They also can lead to overdiagnosis and treatment of abnormal breast tissue that isn’t necessarily cancer or precancer. This number may have been as high as 31% of cases of breast cancer in 2008, according to a 2012 study.

  • What actions should you take if your breast cancer was misdiagnosed?

    If a healthcare provider has misdiagnosed or delayed your breast cancer diagnosis, talk to your oncologist as soon as possible to see how this may impact treatment. If breast cancer is more advanced because of the diagnosis delay, treatment will likely be more aggressive. 

    A misdiagnosis may negatively impact your life, treatment options, or prognosis. Consider filing a complaint about the healthcare provider; reporting them to the hospital, practice manager, or the state medical board; and hiring an attorney to file a malpractice suit.

    A malpractice attorney can tell you if you have a claim and help you file a report with the state medical board. A malpractice suit requires:

    • That the treatment given was not consistent with the standard of care
    • That the person sustained an injury as a result of inappropriate treatment
    • That the injury resulted in significant loss or other difficulties
14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Jennifer Welsh
Jennifer Welsh is a Connecticut-based science writer and editor with over ten years of experience under her belt. She’s previously worked and written for WIRED Science, The Scientist, Discover Magazine, LiveScience, and Business Insider.