Considering the fact that cancer is one of the leading causes of death worldwide, it is also one of the most researched topics by doctors and scientists. With the advancement in biomedical engineering and medical studies, there are new technologies and medicines to help fight this disease better. Despite the fact that the survival rate for this disease has increased, there are many cases of relapses. This fact has intrigued doctors for decades, as patients who seem to have recovered 100 % from cancer have experienced the disease resurfacing after years.
Studies done in Washington this year have shown that the cancer cells which seem to have disappeared post treatment may seek the help of the defense system of the body to recur a few years later. The cancer cells can lie in a dormant (inactive) state within the immune system for years at a stretch. As per the researchers, this could be the reason for the tumors to come back in the body, after a few rounds of toxic chemotherapy.
The situation turned out to be ironical as the immune system is the major defense system of the body which protects it from all major disorders. This system protects the body from foreign substances and pathogenic microbes but in the case of cancer relapse, it fails to recognize the cancer cells and houses them.
To study the reason for recurring cancers, doctors did some studies on rats and came to the conclusion that during chemotherapy, the cancer cells are under a lot of stress. Due to this some of the tumor cells are driven into the thymus. Thymus is the gland which produces immune cells which are also known as the T- cells.
As these tumor cells enter the glands, they are enveloped with protective agents and as a result the body is not able to kill them. As per theses findings, experts believe that now they need to come up with cancer treatments which can attack these hidden tumor cells.
One of the researchers believe that to successfully cure cancer, the therapy should be able to kill tumor cells along with components which block the pro-survival signals.
The current cancer therapies, despite being the most advanced and effective fail to target this survival response. In the preclinical studies, the researchers tested mice who were suffering from a type of cancer called Burkitt’s lymphoma. These small animals were put under a therapy that consisted of doxorubicin which is a standard chemotherapy drug. The drug was effective and the tumors relapsed. The mice were killed and an internal examination of their organs revealed that the lymph nodes, spleen and bone marrow were free of cancer cells. However, the thymus contained more tumor cells after the administration of doxorubicin than before. This proved that the thymus was protecting the tumor cells against chemotherapy.
The researchers also genetically engineered mice with dysfunctional thymus and it was found that they survived better which proved the fact that thymus played a major role in protecting tumor cells.