When it comes to treating almost any kind of cancer, early detection is crucial. The sooner you start getting treatment, the better your prognosis will be. Yet research has shown that doctors misdiagnosed cancer with alarming frequency. Unfortunately, these are precisely the cancers in which a delay in treatment is often deadly.

These five cancers are among the most commonly misdiagnosed cancers in the U.S.

1. Lymphoma

According to research conducted by the National Coalition on Health Care and Best Doctors, physicians in the U.S. believe that lymphoma is “the most misdiagnosed cancer,” Boston Magazine reported.

Lymphoma is cancer of the cells that make up the body’s immune system. Both Hodgkin lymphoma and non-Hodgkin lymphoma begin in the white blood cells known as lymphocytes. It’s also possible to develop lymphoma of the skin.

Why does lymphoma go undetected so frequently? One major reason why doctors misdiagnosed cancer of this type so commonly is because the symptoms – such as fever, weight loss, fatigue, and drenching night sweats – are also common in other, less severe conditions.

Even the enlarged lymph nodes that characterize lymphoma are a nonspecific symptom. When doctors misdiagnosed cancer, it’s often because they attributed these signs to the common cold or an infection.

2. Breast Cancer

Breast cancer is so commonly misdiagnosed that the delayed detection of breast cancer is “the most frequent reason for lawsuits against doctors,” the National Association of Science Writers reported.

As many as 31 percent of breast cancers are overdiagnosed, according to the New England Journal of Medicine. This means that doctors misdiagnose precancerous cells that won’t cause clinical problems or endanger the patient’s life as full-fledged cancer. Overdiagnosis causes healthy patients to undergo drastic cancer treatments for no reason.

On the other hand, mammograms miss about 16 percent of breast cancer cases, the Susan G. Komen organization reported. For these patients, the delay in detecting and treating breast cancer could be deadly.

Early stage breast cancer has a survival rate of nearly 100 percent. However, when breast cancer progresses to stage IV, just 28 percent of patients survive for five years or longer. When doctors misdiagnosed cancer of the breast, the consequences can be deadly.

3. Colon Cancer

Another of the cancers doctors most commonly miss is colorectal cancer.

Doctors usually detect cancer of the colon, rectum, or bowel by performing a colonoscopy. This procedure, recommended for both men and women ages 50 and older, uses tubes and cameras to allow doctors to view the inside of the colon while the patient is sedated.

A colonoscopy is one screening test that doesn’t just identify cancer, but can actually prevent it. Most colon cancers begin as noncancerous tumors called polyps. During a colonoscopy, doctors can biopsy or even remove polyps, so they never get the chance to develop into cancer.

Anytime doctors misdiagnosed cancer of the colon is a serious situation. The colon cancer survival rate drops from 91 percent at stage I to just 14 percent at stage IV.

4. Lung Cancer

Another type of cancer that is devastating when misdiagnosed is lung cancer. Among both men and women, lung cancer is the second most common cancer in America. Unfortunately, many patients don’t learn they have lung cancer until it’s too late.

Why not? For one thing, lung cancer often grows slowly. While that’s good in the sense that you can treat the cancer if caught early, it also makes the condition difficult to detect. Lung cancer presents few symptoms in the early stages.

Even the symptoms that patients do experience often get misdiagnosed as something else. Doctors who misdiagnosed cancer may mistake shortness of breath from lung cancer for asthma or COPD. They may confuse the chronic cough that lung cancer causes with pneumonia or bronchitis. If you’re coughing up blood, doctors might assume you have tuberculosis when you really have lung cancer.

The longer lung cancer goes undiagnosed, the worse the patient’s prognosis becomes. At stage 0, your lung cancer survival rate is 73 to 90 percent, but that rate drops to less than 10 percent when the cancer advances to stage IV.

5. Skin Cancers

Research has shown that melanoma – a rare but deadly form of skin cancer – is also among the most commonly misdiagnosed cancers in the U.S. At early stages, skin cancer may mimic eczema, and other non-cancerous conditions. Doctors who dismiss suspicious skin marks and growths without further testing could allow cancer to progress to life-threatening stages.

Besides attributing cancer symptoms to benign causes, one of the biggest – and most surprising – reasons for cancer misdiagnosis is an error in the lab. Biopsies, the collection of body tissue samples for testing and analysis, are widely used in cancer detection. They’re also a lot more fallible than most people realize, especially when it comes to diagnosing skin cancers.

The people who work in laboratories analyzing these samples – typically by looking at slides of them under a microscope – are called pathologists. While pathologists can specialize in interpreting a certain kind of cancer, many don’t. Those who do specialize in one kind of cancer may sometimes have to weigh in on samples that they’re not experts in.

When pathologists try to look for a kind of cancer they haven’t specialized in, “many mistakes” occur, ABC News reported. Skin cancer is among the types of cancer most prone to pathologist errors.

Dealing With a Delayed Cancer Diagnosis

When doctors misdiagnose cancer, they prevent patients from getting the treatment they need when they need it. This mistake allows treatable early-stage cancer to advance to late-stage or even terminal cancer.

As soon as you find out that you have cancer – no matter what stage it is – you should speak with a doctor about your options. It’s often a good idea to seek a second opinion, even if you think your doctor is competent, because diagnostic errors are far too common.

Remember that any further delay could make your bad prognosis even worse. It’s important that you’re getting the care you need right now.

However, no matter how quickly you act, it doesn’t change the delay in getting your treatment in the first place or how much your condition has worsened as a result of that delay.