"The seminal discoveries by the two Laureates constitute a landmark in our fight against cancer,"the Nobel Assembly at Sweden's Karolinska Institute said as it awarded the prize of 9 million Swedish crowns ($1.4 million).
"Allison and Honjo showed how different strategies for inhibiting the brakes on the immune system can be used in the treatment of cancer,"it said.
The treatments,often referred to as"immune checkpoint therapy",have"fundamentally changed the outcome for certain groups of patients with advanced cancer",it added.
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 washit by a sexual misconduct scandal.
Allison and Honjo's work had both worked on proteins that act as brakes on the immune system - preventing the body and its main immune cells,known as T-cells,from attacking tumour cells effectively.
Allison,a professor at the University of Texas MD Anderson Cancer Centre in the United States,worked on a protein known as CTLA-4 and realised during his work that if this could be blocked,a brake would be released,unleashing immune cells to attack tumours.