We've seen a lot of ingenuity in bioengineering attacks on cancer with viruses or the immune system. Here's an example of a mixed method - a little of both: "Researchers zeroed in on immature T-cells from bone marrow, programming them to respond to specific threats to the immune system while delivering a cancer-destroying virus to the tumor cells. To deliver the virus, researchers removed T-cells from a healthy mouse, loaded them with the virus and injected the T-cells back into the mouse. Researchers found that once the T-cells returned to the lymph nodes and spleen, the virus detached itself from the T-cells, found the tumor cells, selectively replicated within them and extracted tumor cells from those areas. ... In mice with lung cancer metastasis, cancer cells were significantly reduced in one-third of mice and completely eradicated in two-thirds of mice. Efforts to clear metastases from colorectal tumors were similarly effective. Lung and colorectal tumor cells were purged from lymph nodes. Also, the spleens of mice that had lung cancer developed immunity to the cancer after the treatment."