A new study published this month in the Journal of Experimental Medicine has discovered an example of the Law of Unintended Consequences that has potentially serious implications for cancer patients undergoing chemotherapy: the treatment may exacerbate the disease.
According to research carried out at Boston’s Beth Israel Deaconess Medical Center, the dead and dying cancer cells left behind after chemotherapy can cause inflammation that in turn, results in new tumor growth and the spread of malignancy. Fortunately, there is a solution, involving certain molecules produced by the patient’s own body.
Chemotherapy is the use of specific drugs, either alone or in combination with other treatments, for killing cells that grow and multiply quickly. Although cancer cells are the target, there is no practical way to confine the effects to cancer cells specifically. As a result, chemotherapy drugs can also affect healthy hair follicles, skin cells and bone marrow, resulting in some of the side effects (such as hair loss) associated with the treatment. When cancer cells are killed off, they leave debris behind that appears to stimulate the growth of new cancer cells. It is the reason that lead author Dr. Dipak Panigrahy says, “Conventional cancer therapy designed to kill tumor cells is inherently a double-edged sword.”
Although clinical observations over the past 60 years have noted a connection between cellular debris left in the wake of radiation treatments and chemotherapy and cancer recurrence, this is one of the first studies to examine the mechanism behind the phenomenon. As part of the study, Panigrahy and his colleagues injected cellular debris from chemotherapy patients into laboratory mice. After more than a year, the animals showed no sign of cancer. Next, the test animals were injected with debris in combination with a small number of live cancer cells that by themselves, would not have caused the disease. The combination resulted in the rapid growths of tumors. They found that lipid (fatty acid) molecules on the surface of dead or dying cancer cells caused the release of cytokines, a type of signaling protein that can cause an inflammatory response. This results in a “cytokine storm” that stimulates the growth of new tumors.
Panigrahy describes the process as “a positive feedback loop that is difficult to overcome with more aggressive cytotoxic therapy” – i.e., chemotherapy and radiation treatment. He adds, “This may explain the inherent therapeutic limit to cancer treatments available today.”
There is good news, however. A group of recently-discovered molecules known as resolvins that are produced by omega-3 fatty acids (one of the “good fats” found in walnuts and fish such as salmon and mackerel) have anti-inflammatory properties. They also stimulate immune cells that are able to absorb the debris left by dead tumor cells. When the research team injected resolvins into mice with cancer, they discovered that it suppressed the growth and spread of tumors.
The best part: resolvins are non-toxic and have little in the way of serious side effects. This new line of research is paving the way for new cancer treatments as well as possible treatments for other inflammatory disorders.