Circulating Tumor Cells in Long-Term Cancer Survivors

Researchers have found circulating tumor cells (CTCs) in long-term breast cancer survivors, who may have some innate mechanisms to keep the cancer from progressing. The findings were reported in the December 2004 issue of Clinical Cancer Research.

The investigators collected blood from 36 women who had mastectomies and had been clinically cancer-free for at least seven years. Of those, 13 were found to have CTCs, but the number was low and remained low. Since CTCs are short-lived, they must constantly be replenished, possibly from tiny tumors somewhere in the body. CTCs were found in women up to 20 years after having a mastectomy, who have a very low risk of recurrence. After 20 years, the risk rises to 20% of survivors.

"Dormancy is a mysterious phenomenon that occurs in certain types of cancer,” said lead author Dr. Jonathan Uhr, professor in the Cancer Immunobiology Center at the University of Texas Southwestern Medical Center (Dallas, USA; www.utsouthwestern.edu). He said there appears to be a precise balance between tumor cell replication and cell death. Those women who stay healthy may have developed a way of keeping the size of the tumor cell population in check, making breast cancer a chronic illness in those patients.

The next step, according to Dr. Uhr, is to investigate the mechanisms for how the body and cancer cells peacefully coexist. The answers could reveal new ways to control cancer. "If patients at risk for impending relapse can be identified, it may be possible to prevent recurrence with appropriate therapy,” added Dr. Uhr.






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