For patients diagnosed with lung cancer or mesothelioma,
chemotherapy is the most commonly prescribed treatment for managing symptoms and slowing the growth of the disease. But both diseases have shown to become chemo-resistant, eventually rendering the treatments ineffective. Now, researchers report they have uncovered a clue to the cause of the chemo-resistance.
In an April 4 press release, researchers from the Medical University of Vienna report that, initially, lung cancer patients respond “very well to platinum-based therapy,” but within a year tumors begin to resist the drugs and continue to grow. Additional rounds of chemotherapy using a different drug are often inadequate as well. However, the researchers believe the reason that cancer cells thrive is that some of them escape into the bloodstream where they circulate and migrate to other organs in the body.
These break-away circulating tumor cells (CTCs) join together to form “cancer clusters,” according to the researchers. The clusters resist chemotherapy, according to the findings, because the drugs cannot penetrate the group of cells, and because many of the cells are oxygen-starved and have gone dormant. Oxygen radicals are necessary to destroy the cancer cells.
The researchers report they found “ground-breaking proof” chemo-resistance and radiotherapy resistance both are due to the CTCs forming clusters.
“Completely new therapeutic approaches must therefore be developed to prevent the formation of these cancer clusters or to break them up,” the researchers report. “Small cell lung cancer follows the model of an aggressively metastasizing cancer – so that these findings could equally well apply to other malignant diseases.”
Pleural mesothelioma, an asbestos-caused cancer that affects the lining of the lungs, is extremely aggressive with limited treatment options and no cure. Treatment for pleural mesothelioma and lung cancer is often similar, with chemotherapy being one of the primary treatment modes. Stopping tumor growth and preventing metastasis is critical for increasing survival in patients.
This new insight into the reason for cancer’s continued growth may lead researchers to attack cancer clusters. Finding a treatment that fights back at chemo-resistant cancer cells could mean the difference in survival for some mesothelioma patients.
The study was published in the Feb. 26 issue of Cell Adhesion and Migration.