New Strategies in the Cancer War

By David Chorney

More than thirty years after President Richard Nixon declared war on cancer, we are finally beginning to see results. In 1971, cancer researchers were barely able to discern the characteristics of cancer cells. The war is finally beginning to pay off, with the last ten years yielding promising results from drug research. Now, therapies that target cancer are coming to the market. Overall, survival rates have risen from 50 percent to 64 percent. New drugs in trials have saved some people with no hope.

The traditional therapy regimen of surgery, chemotherapy and radiation has proven indiscriminant. The hope in traditional therapy is that the cancer cells will be destroyed faster than healthy cells and that the cancer will be killed before the patient. There are other drawbacks. Surgery, ironically, can speed the spread of cancer, cancer cells are able to adapt to chemotherapy and radiation is often ineffective. The patient suffers severe side effects and will likely live with chronic health problems. Traditional chemotherapy drugs are derivatives of mustard gas. Traditional therapies will nonetheless still be used for the foreseeable future, since improved radiation techniques and chemotherapy agents have increased survival rates.

To find safer and more effective therapies, researchers must improve their understanding what differentiates cancer from normal cells. Why do cancer cells reproduce endlessly? Why do they mutate uncontrollably? What enables cancer cells to divide at such a rapid rate? What other factors contribute to the growth and spread of cancer? It is now known that telomeres, genes at the end of a cell’s DNA chain, control the number of times that a cell can divide. Cancer suppressor genes have been discovered, such as P53 that correct mutations during cell division. The answers found so far open the door to other types of drugs.

New classes of drugs now target cancer cells. Some drugs target enzymes that control cell growth. Gleevec works by stopping a protein called tyrosine kinase. While generally having fewer side effects than traditional therapies, the newer drugs are not miracle cures. Currently, the majority of these new drugs increase life expectancy by only weeks or months. And drug companies have more incentive to develop “blockbuster” drugs that are taken over a lifetime.

Genetic factors are being studied to use the newer drugs more effectively. The newer drugs target specific genes, requiring that they be tailored accordingly. In the future, cancers will be described according to genetic factors, rather than location. For the time being, the newer drugs are given using a hit-or-miss approach.

An unlikely individual, Dr. Judah Folkman, conceived another class of drugs. Not being an oncologist, he nonetheless observed the growth of blood vessels that nourish cancer cells, leading to the theory that cancer cells caused their growth. If cancer cells secrete a substance to cause blood vessel growth could this process be disrupted? Angiogenesis inhibitors are being developed and tested as a class of drugs that do not attack cancer cells, but rather prevent the proliferation of blood vessels that cancer needs to grow.

Vaccines unleash the body’s immune system against cancer in the same manner as against viruses. Unlike a virus, cancer consists of the patient’s own cells. The immune system is too slow to recognize cancer cells. The cancer cells are taken from the patient, and antigens are extracted from the cancer cells. The antigens are injected into the patient, and the immune system can then target cancer cells. Currently, vaccines cannot stimulate the immune system to kill all cancer cells. Not all cancer cells have antigens that distinguish cancer cell from healthy cells.

Gene therapies are

Improved and earlier detection are paying off in a big way. Survival rates have improved the most for breast, colon, prostrate and lung cancers.

The science of oncology has made much progress since Nixon’s declaration of war on cancer, but there is still much work to be done. But the outlook is encouraging, with many new drugs in trials.