Cancer was recently declared the second leading cause of death worldwide. Compared to other conditions, the global killer shows up virtually out of nowhere and attacks your body, forcing you to fight back with chemotherapy or radiation or surgery. These treatments can last weeks or even months, and have lasting effects on your body. One way of fighting cancer is through immunotherapy, which pits your body’s immune system against the cancer cells, and researchers have now found a way to make immunotherapy even more effective in cancer sufferers.

Francis Crick Institute researchers, funded by Cancer Research UK, have found that aspirin is effective in the immunotherapy treatment of skin, breast, and bowel cancer cells. These cells often produce large amounts of prostaglandin E2 (PGE2), which dampens down the immune system’s normal response to attack faulty cells. These faulty cells help the cancer to hide within them. The hiding method in turn allows tumors to grow and may be one of the reasons immunotherapy is not as effective in some cases.

COX inhibitors — a group of molecules of which aspirin is a part of — stop the production of PGE2 and help wake up the immune system to get back to work. The combination of immunotherapy and aspirin or other COX inhibitors slowed bowel and melanoma cancer growth in mice when compared to immunotherapy alone.

"Giving patients COX inhibitors like aspirin at the same time as immunotherapy could potentially make a huge difference to the benefit they get from treatment,” said study author Professor Caetano Reis e Sousa, senior group leader at the Francis Crick Institute said in a press release. “It's still early work, but this could help make cancer immunotherapy even more effective, delivering life-changing results for patients."

Sousa went on to say that the team added to the growing evidence that some cancer cells produce PGE2 to escape the immune system. If researchers are able to remove the cancer cell’s ability to produce PGE2, then they will be able to use the full power of the immune system to fight the cancer cells, thus making immunotherapy more effective.

"PGE2 acts on many different cells in our body, and this study suggests that one of these actions is to tell our immune system to ignore cancer cells,” said Professor Peter Johnson, Cancer Research UK's chief clinician. “Once you stop the cancer cells from producing it, the immune system switches back to 'kill mode' and attacks the tumor.”

Unfortunately, this study was conducted on mice, so it will still be a while before we see how COX inhibitors work in human cancer patients. Nonetheless, it is an exciting step forward in the battle against cancer.

Source: Zelenay, S. et al, Cyclooxygenase-dependent tumor growth through evasion of immunity. Cell. 2015.