Cancer patients are less capable of fighting off cancer cells because of their weakened immune response. It is proven that people, whose NK cells are more active, have a lesser possibility of suffering from cancer. Additionally, an experiment showed that the cancer occurrence doubled for people with less active NK cells by comparing a group with highly-active NK cells to a group with less active NK cells.
Ability to remove cancer cells
J.Korean Aced Fam Med, 2008, 29(4),Suppl.
Immune response in cancer patients is 25% of that of healthy people.
Cancer incidence according to NK activity
'NK cytotoxic activity of peripheral-blood lymphocytes cancer incidence' lmai K, Matsuyama S, Miyake S, Suga K, Nakachi K, Lancet 2000)
When NK activity is low, the incidence of cancer is doubled.