Even with today’s safer and more targeted anti-cancer drugs, scientists have been unable to satisfactorily explain the phenomenon of why treated cancers so often recur. The common theory is that the cancer cell develops “Internal resistance to treatment,” and overrides the toxic effects of the drug.
Now, findings by a team of scientists led by Professor Yuval Shaked of the Technion-Israel Institute of Technology Faculty of Medicine and the Technion Integrated Cancer Center could provide the key for reducing recurrence, and allowing anti-cancer drugs to do work as intended.
In their study published in The Journal of Pathology, the team shows that tumor relapse occurs when the body, in effect, mobilizes itself in favor of the tumor, causing recurrence of the disease, increasing its aggressiveness and creating metastases or tumor spread. Even selective, highly focused treatments that harm cancer cells almost exclusively lead to a similar response.
“The administration of an anti-cancer drug is very aggressive intervention in the body,” explains Prof. Shaked.
“Therefore, the body responds to chemotherapy the way it responds to trauma. This creates the effect of a double-edged sword: although chemotherapy kills cancer cells, it also causes the secretion of substances that confer resistance to the tumor. Even more selective treatments, with fewer side effects, cause physiological reactions that increase the aggressiveness of the disease.”
In this specific study, among other studies the group has published in this area, mice with multiple myeloma – a malignant disease of the plasma cells produced in bone marrow and spread throughout the body via the circulatory system – were treated with the selective anti-cancer drug Velcade. The researchers found that treatment with Velcade led to a physiological reaction that actually reinforced the intensity of the myeloma in the mice. According to Prof. Shaked, the drug caused inflammatory cells in the bone marrow to enhance the aggressiveness of the disease and provide the cancer cells with resistance to treatment.
“It is important to clarify that treatment with Velcade is essential and necessary,” says Prof. Shaked, “but its disadvantage is that along with the benefit there is damage.”