Do Stem Cells Hold the Key to Tumor Regrowth?

Cancer that has been seemingly eradicated through chemotherapy and other therapies can return—but why? New studies suggest that dormant cancer stem cells may be the reason some tumors make a comeback.

Stem cells are considered undifferentiated cells, in that they can become another type of cell, such as a muscle cell or skin cell. Because of that potential, they’re used to repairing areas in the body that have been damaged, such as tissue or other cells.

A recent study in the journal The Lancet gave details on a groundbreaking procedure in which doctors constructed a vein for a 10-year-old girl made from her own stem cells.

Despite the good they can do, there’s also a downside. Some scientists believe that cancer stem cells, a specific type of cancer cell, may be able to grow and produce the various types of cells located in a tumor. Even after treatment, they can lie undetected, only to grow new tumors later.

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The Washington Post reports that some previous studies have discovered signs of cancer stem cells in breast and colon cancers, but the cancer cells scientists studied were often human cells transplanted into mice without immune systems, and they may not provide the best model.

In an online study released this week in the journal Nature, researchers focused on brain tumor cells developed in mice.

Study co-author Luis Parada said in a news release that the research team identified a subgroup of brain tumor cells that are “are slower growing or remain at rest, and appear to be the source of cancer recurrence after standard therapy in which the drug temozolomide is given to stop the tumor’s growth.” (Temozolomide is a drug used to treat human brain tumors.)

Current forms of therapy, Parada said, zero in on tumor cells that grow quickly, but not on those that can form new tumors. “To the best of our knowledge,” he added, “this is the first identification of a cancer stem-like cell in a spontaneously forming tumor inside a mammal.” In this and other studies, certain cells were labeled so they could be better found when the tumor regrew.

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Other studies released this week—another in Nature and one in the journal Science—also found evidence of cancer stem cells in mice, both in precursors to skin cancer and intestinal cancer.

Parada, chairman of developmental biology at the University of Texas Southwestern Medical Center in Dallas, admits that the idea of cancer stem cells isn’t embraced by everyone in the scientific community—some are skeptical and others don’t believe in the concept at all.

One of those skeptics, CBS News said, is Scott Kern of the Sidney Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University in Baltimore, who said that since the tumors were developed in mice, the findings might not hold relevance to humans.

How important do you think stem cell research is in finding cures for diseases? Let us know in the comments.

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Jeannine Stein, a California native, wrote about health for the Los Angeles Times. In her pursuit of a healthy lifestyle she has taken countless fitness classes, hiked in Nepal, and has gotten in a boxing ring. Email Jeannine |