Radiation and chemotherapy may help create dangerous cancer stem cells

Common cancer treatments such as radiation therapy and chemotherapy may have the undesirable effect of helping to create cancer stem cells, which are thought to be particularly adept at generating new tumors and are especially resistant to treatment, according to researchers.

The finding might help explain why late-stage cancers are often resistant to both radiation therapy and chemotherapy, and it could point to new strategies to fight tumors.

Past studies hint that cancer stem cells give rise to new tumors and researchers suggested that they are ultimately responsible for the recurrence of cancers and the dangerous spread of a cancer throughout the body.

Scientists also have found that cancer stem cells are more likely than other cancer cells to survive chemotherapies and radiation therapies, probably because their "stemness" allows them to self-replenish by repairing their damaged DNA and removing toxins.

The exact origin of cancer stem cells is debated. One possibility is that normal stem cells which are valued for their ability to give rise to other cell types in the body mutate to become cancerous. Another is that regular cancer cells somehow acquire stem cell properties.

The new study suggests regular cancer cells can indeed give rise to cancer stem cells, and that the radiation commonly used to treat cancer can trigger their stemness.

"Radiotherapy has been a standard treatment for cancer for so long, so we were quite surprised that it could induce stemness," Live Science quoted study researcher Dr. Chiang Li, of Harvard Medical School in Boston, as saying.

The scientists exposed regular cancer cells to gamma-rays, one form of ionizing radiation. They found that under the conditions that normally foster stem cell growth, regular cancer cells formed balls of cells a hallmark of cancer stem cells.

Additionally, analysis of these irradiated cancer cells revealed activity of genes linked with stem cell behaviors, according to the findings the scientists detailed online in the journal PLoS ONE.

Chemotherapy may have similar effects, according to previous findings that Li and his colleagues detailed in July in the journal Cell Cycle.

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Radiation and chemotherapy may help create dangerous cancer stem cells