The problem with trying to treat cancer has always been that the body does not accept cancer as something foreign. It is hard to target a tumor for destruction if you don't recognize cancer as an invader. So traditional chemotherapies have been based on the idea that cancer is rapidly growing. Powerful drugs that destroy rapidly growing cells do well against cancer, unfortunately they also damage rapidly growing normal cells, especially the hair, stomach lining, and bone marrow - hence the usual side effects from Chemo, hair falling out, nausea, and anemia.

But the latest treatments are clever - they are based on genetic differences that lead to the production of certain abnormal proteins that promote cancer growth. They take into account that certain cancers, such as melanoma, are antigenic, meaning they have surface proteins that can be used to trigger our body's immune system in ways that can shrink the cancer.

These treatments which are less toxic and more focused are generally better tolerated and cause less side effects. Once you convince the body that cancer is foreign, you can then provoke the immune system to fight it.

Three targeted therapies for cancer made very exciting news at the annual meeting of the American Society of Clinical Oncology this past week. First, with stomach cancer, a breakthrough treatment with the use of Herceptin, a very successful drug already in regular use for breast cancer. Herceptin targets an abnormal protein found in 1/4 of women with breast cancer and decreases recurrence in 50 percent.

This protein, (HER2) was now found in high amounts in 22 percent of patients with stomach cancer. There are 21,000 new cases a year of stomach cancer in the U.S. one million new cases worldwide. In a study out of Belgium, Herceptin used in stomach cancer patients with high amounts of this abnormal protein lived three months longer than those who weren't treated. The risk of death decreased by 26 percent.

Second, in women with extensive breast cancer, another new option was found to be useful. PARP inhibitors are chemicals which keep cancer from repairing its damaged genes. Breast cancer patients who received this lived twice as long, an average of 9.2 months, even with extensive cancer. This treatment is exciting because it stops only the cancer from repairing itself, NOT normal tissue. It may be especially useful in patients where breast cancer is linked to specific genetic abnormalities such as BRCA gene.

Third, a cancer vaccine has been developed against lymphoma, using the body's own immune cells to fight the cancer, was shown with a small group of patients to keep them in remission for 44 months compared to 31 months for those who didn't receive it.

These are all preliminary studies, but they together show progress in using technology, genetics, and specific therapies to help patients based on their characteristics and not just bombing cancer with a one-size-fits-all, kill-the-cancer-before-you-kill-the-body approach.

In contrast, by using tailored treatments that take into account the specifics of a patient's cancer, you may get a better result than the shotgun poisons of chemotherapy. The research here is early but promising.

Dr. Marc Siegel is an internist and associate professor of medicine at the NYU School of Medicine. He is a FOX News medical contributor and writes a health column for the LA Times, where he examines TV and movies for medical accuracy. Dr. Siegel is the author of "False Alarm: The Truth About the Epidemic of Fear"and "Bird Flu: Everything You Need to Know About the Next Pandemic." Read more at www.doctorsiegel.com

Dr. Marc Siegel, a practicing internist, joined FOX News Channel (FNC) as a contributor in 2008..