Is GcMAF a Potential Cancer Treatment?

Medically Reviewed by Laura J. Martin, MD on June 23, 2020

In 2008, a group of studies appeared in medical journals claiming that a treatment called GcMAF had wiped out breast, colorectal, and prostate cancers in small groups of people. But more than a decade later, scientists have raised questions about the research, and three of the studies have been retracted.

GcMAF isn't approved for cancer, but some researchers are still investigating it as a possible treatment.

What Is GcMAF?

GcMAF is short for "Gc protein-derived macrophage-activating factor." It's a type of immunotherapy, a treatment that revs up the immune system -- your body's defense against germs -- to kill cancer.

Macrophages are white blood cells the immune system sends out to gobble up foreign cells like bacteria and cancer. Our bodies make the protein GcMAF to activate macrophages. But cancer cells are thought to release an enzyme called nagalase that blocks the making of GcMAF to protect themselves against attack.

GcMAF treatment aims to activate more macrophages so they can fight cancer.

GcMAF Research

A 1997 study tested GcMAF on mice with cancer. It found that GcMAF improved their survival from 16 days to 32 days.

A few years later, the researchers tested the treatment on people with breast, colorectal, and prostate cancers. They gave them shots of a tiny amount of GcMAF once a week. After a few months, all of the patients were cured, according to the studies. Four to 7 years later, their cancers hadn't come back.

These results sound impressive, but there were some big problems with the studies. For one thing, they were very small -- just eight to 16 people each. Everyone in the studies had already been on standard cancer treatments like surgery, chemotherapy, or radiation. So it was hard to tell whether these treatments, or GcMAF, caused the cancers to shrink.

Also, doctors usually use imaging and lab tests to stage cancers -- in other words, to see how big the cancer is and whether it has spread. The researchers didn't do this. Instead, they took blood tests to check nagalase levels, which isn't a proven way to check for cancer or to see if it has gotten smaller.

Finally, the researchers never tested whether GcMAF actually activated macrophages in the patients' blood. So they couldn't be sure that the treatment was working at all.

Three doctors from the Anticancer Fund, a nonprofit group that promotes cancer research, published a letter in 2014 that outlined many of the concerns with the studies. They found several mistakes in the studies' claims and said that its conclusions "make no sense."

Future of GcMAF

A few researchers are still investigating GcMAF as a possible cancer treatment. Some early studies suggest that it may be helpful for people with late-stage cancers.

It's hard to know whether GcMAF works. The studies that have been done so far looked at very small numbers of people. Some of them included only one person. Larger studies are needed to prove that this treatment works on cancer and that it's safe.

Macrophages may still hold promise. Researchers are trying to learn whether monoclonal antibodies or other drugs might help macrophages kill cancer cells.

Until we know more, doctors stick to other immunotherapies, like checkpoint inhibitors, that have more evidence behind them. If you have questions about GcMAF or any other cancer treatment you've read about online, your cancer doctor is the best person to answer them.

Show Sources


American Cancer Society: "What are the Phases of Clinical Trials?"

Cancer Immunology, Immunotherapy: "Immunotherapy of Metastatic Colorectal Cancer With Vitamin D-binding Protein-Derived Macrophage-Activating Factor, GcMAF," "Inconsistencies and questionable reliability of the publication 'Immunotherapy of Metastatic Colorectal Cancer With Vitamin D-binding Protein-Derived Macrophage-Activating Factor, GcMAF' by Yamamoto et al."

Cancer Research UK: "'Cancer cured for good?' -- Gc-MAF and the miracle cure."

Clinical Cancer Research: "The Promise of Targeting Macrophages in Cancer therapy."

International Journal of Cancer: "Retracted: Immunotherapy of metastatic breast cancer patients with vitamin D-binding protein-derived macrophage activating factor (GcMAF)."

Journal of Clinical & Cellular Immunology: "Management of Metastatic Colorectal Carcinoma with GcMAF Forte and Thymus Peptides: A Case Report."

National Cancer Institute: "Cancer Staging," "Immune Checkpoint Inhibitors."

Natural News: "The War on Independent Media Has Begun."

Oncoimmunology: "GC Protein-Derived Macrophage-Activating Factor Decreases alpha-N-acetylgalactosaminidase Levels in Advanced Cancer Patients."

Retraction Watch: "Yet another study of widely touted cancer "cure" retracted."

The DCA Site: "Updating You on DCA and Cancer."

Translational Oncology: "Immunotherapy for Prostate Cancer with Gc Protein-Derived Macrophage-Activating Factor, GcMAF."

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