A German biotech company has announced positive results from a genetically engineered herpes virus that is designed to kill cancer cells. It not only kills the cancer cells but leaves healthy tissue unharmed. Results from clinical trials has showed promise.

Being injected with a virus might seem strange but researchers believe that viruses could one day become a valuable addition to conventional cancer treatments.

The results have shown in animal testing and limited human testing the ability to kill colorectal and liver cancer cells.

Once upon a time there were two groups of mice, all genetically engineered to develop prostate cancer. Each group was fed the same amount of calories. One group of mice lived in cages warmed to 80.6 degrees. The other group lived in cages kept at 71.6 degrees. The mice in the cooler quarters burned more calories to keep warm. And after three weeks, they weighed less than the toasty warm mice. They were also less likely to develop prostate cancer.

Then there were two other groups of mice, also genetically engineered to develop prostate cancer. Both groups were kept in cages with temperatures 80.6 degrees and 71.6 degrees -- like above. But these mice got to eat whatever their little hearts desired. The mice in cooler cages ate 30 percent more than the mice in warmer cages. They got just as fat as the warm mice. And they all got prostate cancer at the same rate, despite the extra calories.

The moral of the story is this -- being lean rather than obese has a greater protective effect against cancer. Excess calorie retention, rather than consumption, raises cancer risk. This moral stands in contrast to what most researchers believe -- that a restricted diet cuts the risk of and slows the growth of cancer and this is directly related to calorie intake.

Tim Nagy, Ph.D. and professor of nutrition sciences at the University of Alabama, Birmingham and lead researcher on the mice story says when you eat more calories than you burn, you store the extra calories as fat. It's the fat cells -- not the extra calories themselves -- that affect cancer risk.

It's not a good idea for humans to chill themselves to avoid cancer, Nagy says. But perhaps people could get the same effect by exercising more since that, too, burns calories.

Nagy's study appears in the January 1 issue of the journal Cancer Research.

Researchers from the National Cancer Institute announced Thursday that two cancer patients with rapidly growing melanoma were successfully treated with gene therapy. The patients -- both men -- were given immune system cells from their own blood that were engineered to attack their tumors. This took place 18 months ago -- and they are still surviving with no evidence of cancer. This success comes after a three-decade effort by surgeon Steven Rosenberg to find ways to use the immune system to fight cancer. This approach is not always successful, however, and 15 other patients who got this same treatment did not survive. Still, Rosenberg believes this small-scale success is proof that the principle of gene therapy can work. And others agree -- calling his work an important landmark, even though the response rate of two out of 17 is not ideal.

Rosenberg does not claim the two surviving patients are cured. If they survive for five years, he might classify them as possibly cured -- but even after five years, cancer can come back. He does consider this a huge breakthrough for these two men who are still alive and well. And he says he has every expectation that he can get the process to work even better in the future.

It's kind of like karma. Engineered karma. In a what goes around comes around karmic fate, researchers have created a virus designed to turn cancer cells cannibalistic -- turning on each other -- eating each other. It's about time. University of Texas M. D. Anderson Cancer Center researchers explain that they engineered the virus to track down and infect the most common and deadly form of brain cancer and then kill tumor cells by forcing them to devour themselves. The result was a huge difference in tumor volume among mice with subcutaneous malignant glioma. It works in the laboratory. The research group will be following up the malignant glioma findings by studying ways to improve the efficiency of viral infection of cancer cells.