New research has shown for the first time that the human immune system can stop the growth of a cancerous tumor without actually killing it. These results help explain why some tumors suddenly stop growing and go into a long period of dormancy.
The study‘s authors call this cancer-suppressing state “equilibrium.” During equilibrium, the immune system decreases the cancer‘s ability to grow, and kills some cancerous cells, although not enough to eliminate or shrink the tumor.
Researchers injected mice with small doses of a chemical carcinogen and observed those who developed small, stable masses at the site of the injections. When certain components of the animals‘ immune systems were disabled, the growths became full-blown cancers. This suggests that the immune system had been holding the tumors in check.
"We may one day be able to use immunotherapy to artificially induce equilibrium and convert cancer into a chronic but controllable disease," suggests co-author Mark J. Smyth, Ph.D., professor of the Cancer Immunology Program at the Peter McCallum Cancer Centre in Melbourne, Australia.
"Proper immune function is now appreciated as another important factor in preventing the development of some cancers. Further research and clinical validation of this process may also turn established cancers into a chronic condition, similar to other serious diseases that are controlled long-term by taking a medicine," he added.
According to a scientific theory called cancer immuno-surveillance, your immune system can discern malignant cells, and attack tumors with the same weapons it uses to eliminate invading microorganisms. Current immunotherapy efforts use pharmaceutical agents to increase the chances that the immune system will recognize and attack tumor cells.
The cancer immuno-surveillance theory however fell out of favour, and in 2001 a new model known as cancer immuno-editing was established.
The cancer immuno-editing theory suggests that conflict between cancers and the immune system takes place naturally, but with three different potential outcomes.
- Your immune system can eliminate cancer, destroying it completely
- Your immune system can form a balance with cancer, by checking its growth but not destroying it
- The cancer can escape from your immune system, and become more malignant