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Seemingly every medical condition has myths surrounding it. Cancer is no exception.

One such myth is that the fungus Candida causes cancer or that cancer cells are actually a form of fungus. Research has revealed neither to be true.

Keep reading to find out how this rumor likely started and what researchers know about connections between cancer and fungus.

The myth that cancer is a fungus likely began with an Italian physician named Dr. Tullio Simoncini.

Simoncini is responsible for several unproven theories related to cancer, including that cancer is a fungus and should be treated with intravenous sodium bicarbonate.

Because his claim was so different from what traditional medicine knows about cancer, some news outlets, message boards, and social media platforms began paying attention to it. This allowed the theory to spread unchecked.

Why people believe this

Although his theories have been widely disproven, simply having Simoncini’s statements out there is enough to spread the myth.

So what would cause him — or anyone, really — to believe that cancer is a fungus?

Some people say the presence of the Candida fungus triggers an immune response in the body that leads to cancer. Other people believe that on imaging studies, cancerous tumors look like fungus.

But, again, there are no pathology, imaging, or research studies that would indicate in any way that cancer is a fungus.

And just to be clear: Cancer is not a fungus — this is one myth that needs to be permanently put to rest.

Armed with the knowledge that cancer isn’t a fungus, it’s time to further determine what cancer is. At its most basic definition, cancer is an illness that causes cells to grow uncontrolled in the body.

Our bodies thrive on order and maintaining homeostasis or balance. When something is imbalanced — such as body temperature, metabolism, or even a broken bone — the body works to return to normal.

Because cancer cells multiply in an uncontrolled fashion, they start to crowd out normal cells. The body puts energy toward making these cancer cells, which doesn’t leave energy for other functions.

Ultimately, the uncontrolled cells can spread to other body parts, which makes it harder for organs to maintain their everyday functioning. If left unmanaged or untreated, this can lead to death.

As for what causes cancer, the answer is not a fungus, but likely multiple potential causes. Doctors have found a combination of the following factors could cause cancer:

Sometimes, doctors can’t identify why cancer cells spontaneously grow.

Despite an overwhelming lack of evidence that cancer is a fungus, the two are still connected.

Recent research is examining the connection between fungal infections and cancer. A 2022 study found small amounts of fungal cells and DNA in variety of different cancer tissue samples.

While this new data raises new questions, it’s important to remember that correlation does not equal causation, and much more research is needed to learn how cancers and fungal infections may be interrelated.

Having cancer may make some individuals more vulnerable to fungal infections. But having cancer doesn’t mean you will have a fungal infection, just as having a fungal infection doesn’t mean you will have cancer.

Cancer treatments such as chemotherapy and radiation can naturally lower the body’s immune system. This can make for an opportune time for fungal infections to occur.

Cancer isn’t a fungus. This myth has been widely debunked.

But while this is the case, some people who are undergoing cancer treatments may be at increased risk for fungal infections. Doctors are also researching whether there’s a connection between fungal infections and cancer.

If you have a question about fungal infections and cancer, talk with your doctor to make sure you’re getting the most accurate information available.