Cancer will be the most deadly disease world wide.o doubt we have made huge strides in medicine, yet cancer continues to be a formidable disease, which is slated to become the leading cause of death worldwide.In the United States, medical advances and education campaigns have helped slash the death rate from cancer by nearly 16 percent in 20 years, American Cancer Society epidemiologist Susan Gapstur told reporters at the launch of a cancer-themed edition of the Journal of the American Medical Association.