Chemotherapy can cause damage to healthy cells, which triggers them to secrete a protein that sustains tumor growth and makes cancer more resistance to any further treatment. We are beginning to see clinical evidence across the board show that what happens to healthy cells during cancer treatment determines much if not the entire outcome of treatment.
“Cancer cells inside the body live in a very complex environment or neighborhood. Where the tumor cell resides and who its neighbors are influence its response and resistance to therapy,” said senior author Dr. Peter S. Nelson, a member of the Hutchinson Cancer Center’s Human Biology Division. “Our findings indicate that the tumor microenvironment also can influence the success or failure of these more precise therapies.” In other words, the same cancer cell, when exposed to different “neighborhoods,” may have very different responses to treatment.
Researchers at the center tested the effects of a type of chemotherapy on tissue collected from men with prostate cancer, and found “evidence of DNA damage” in healthy cells after treatment, the scientists wrote in Nature Medicine in August of 2012.
The scientists found that healthy cells damaged by chemotherapy secreted more of a protein called WNT16B, which boosts cancer cell survival. The researchers observed up to 30-fold increases in WNT production! “The increase in WNT16B was completely unexpected,” said Dr. Nelson. The protein was taken up by tumour cells neighboring the damaged cells. “WNT16B, when secreted, would interact with nearby tumor cells and cause them to grow, invade, and importantly, resist subsequent therapy,” said Nelson.
Rates of tumor cell reproduction have been shown to accelerate between chemotherapy treatments. “Our results indicate that damage responses in benign cells… may directly contribute to enhanced tumor growth kinetics,” wrote the team. The researchers said they confirmed their findings with breast and ovarian cancer tumors.
Dr. Nelson describes chemotherapy saying, “In the laboratory we can ‘cure’ most any cancer simply by giving very high doses of toxic therapies to cancer cells in a petri dish. However, in people, these high doses would not only kill the cancer cells but also normal cells and the host.” Therefore, treatments for common solid tumors are given in smaller doses and in cycles, or intervals, to allow the normal cells to recover. This approach may not eradicate all of the tumor cells, and those that survive can evolve to become resistant to subsequent rounds of anti-cancer therapy.