Biologics Appear Safe for Some Rheumatoid Arthritis Patients Who’ve Had Cancer. The immune system is at the root of the problem in people with RA. Instead of defending the body from unwanted invaders, like viruses and bacteria, and watching out for mutations that may turn into cancer, the faulty immune system creates inflammation and directs attacks on the joints and organs. Biologic medications control the disease and its damage by interrupting the rogue immune activity at specific points in the process.