The 2018 Nobel Prize in Physiology or Medicine has been awarded to James P. Allison and Tasaku Honjo by the Nobel Committee for advances in discovering how the body's immune system can fight off the scourge of cancer.

"Allison and Honjo showed how different strategies for inhibiting the brakes on the immune system can be used in the treatment of cancer," the Nobel Assembly at Sweden's Karolinska Institute said, on awarding the prize of 9 million Swedish crowns ($1 million).

Medicine is the first of the Nobel Prizes awarded each year. The prizes for achievements in science, literature and peace were created in accordance with the will of dynamite inventor and businessman Alfred Nobel and have been awarded since 1901.

The literature prize will not be handed out this year after the awarding body was hit by a sexual misconduct scandal.

Both laureates studied proteins that prevent the body and its main immune cells, known as T-cells, from attacking tumor cells effectively.

Allison, professor at the University of Texas MD Anderson Cancer Center, studied a protein that functions as a brake on the immune system and realized the potential for unleashing immune cells to attack tumors if the brake could be released.

"I'm honored and humbled to receive this prestigious recognition," Allison said in a statement. "A driving motivation for scientists is simply to push the frontiers of knowledge. I didn't set out to study cancer, but to understand the biology of T cells, these incredible cells that travel our bodies and work to protect us."

Honjo, professor at Kyoto University since 1984, separately discovered a second protein on immune cells and revealed that it too operated as a brake, but with a different mechanism.

"The seminal discoveries by the two Laureates constitute a landmark in our fight against cancer," the institute said.

In 2014, Allison and Honjo received the first "Tang Prize for Biopharmaceutical Science" for their research in cancer immunotherapy, a type of treatment that allows for the immune system to fight cancer effectively.

Both researchers were awarded with $1.3 million cash and a $334,000 research grant.

Last year's prize went to three Americans for work in identifying genes and proteins that work in the bodytarget="_blank"'>