Immune System May Make or Break Cancer
Cancer Researchers Note Immune System's Role in Cancer Growth
Nov. 19, 2007 -- Cancer researchers today reported that the body's
immune system may be the tipping point toward or away from cancer.
Their findings may help scientists develop new cancer treatments that
harness the immune system's cancer-fighting powers.
Here's an overview of the studies, published in today's advance online
editions of Nature and Proceedings of the National Academy of
In Nature, scientists show that a healthy immune system may hold some
cancers in check.
The results may pave the way for the development of new therapies to
"convert cancer into a controllable chronic disease," write the
They injected a cancer-causing substance into mice. Some mice developed
growing tumors, while other mice developed tumors that stayed small.
But those small, stable tumors started to grow when the scientists
suppressed the mice's immune systems.
The bottom line: A healthy immune system helps prevent cancer, though
it didn't stop every small tumor from growing.
The researchers included graduate student Catherine Koebel and Robert
Schreiber, PhD, of the pathology and immunology department at Washington
University School of Medicine in St. Louis.
Their findings are "startling" and "demonstrate that considering
cancer as a fatal disease is not always appropriate," writes Cornelius
Melief, MD, PhD, in a Nature editorial.
Melief works at Leiden University in the Netherlands.
Cancer Defies Immune System
Sometimes, cancer flies under the immune system's radar, a British study
The study focuses on immune system
cells called regulatory T-cells (T-regs) and their effect on
macrophages in test tubes.
Macrophages normally help the body
get rid of threats. But under the sway of T-regs, macrophages act the opposite
way. Instead of going on defense, the macrophages chill out, as if there were
no cause for concern.
That process could open the door for tumor growth, note the researchers, who
included Leonie Taams, PhD, of King's College London.
"We hope to be able to use this new knowledge about the relationship
between regulatory T-cells and macrophages to find more effective treatments
for tumors," Taams says in a news release.