• 7/1/2005
  • Houston, TX
  • Waun Ki Hong, M.D. & Edward Kim, M.D.
  • MD Anderson’s CancerWise (www.cancerwise.org)

For decades, scientists have increasingly explored the possibilities of preventing cancer. This field of study, known as “chemoprevention,” involves the use of agents such as aspirin and aspirin-like drugs, as well as foodstuffs like green tea, spices and vitamins.

A number of recent large-scale chemoprevention trials throughout the world have failed, however, challenging the value of such studies.

Two M. D. Anderson scientists commented in a recent issue of the Journal of the National Cancer Institute that although a great amount of work needs to be done to improve design and development of chemoprevention trials, there is no need to give up hope.

Defining the road ahead in improving future trials

“The field of chemoprevention still remains an exciting area of research, yet many challenges are ahead,” write Waun Ki Hong, M.D., head of the Division of Cancer Medicine, and Edward Kim, M.D., an assistant professor in the Department of Thoracic/Head & Neck Medical Oncology.

Hong and Kim say that many of the failed chemoprevention studies were unsuccessful because researchers had not yet established risk models that can best define which patients will be helped by chemoprevention.

Chemoprevention trials are “large, time-consuming and expensive,” they write. In order for them to serve patients best, scientists need to establish a set of criteria that includes biomarkers, genetic signposts that can predict which agents will work, to prevent a second or even a first cancer from developing.

The best examples of successful chemopreventive agents are the hormonal drugs used in patients with early stage breast cancer to prevent recurrence or development of new cancers in a healthy breast, the researchers say. Women who benefit are those who carry the appropriate biomarker that indicates their cancer is fueled by hormones.

Authors involved in roots of chemoprevention

It was at M. D. Anderson, under Hong’s leadership, that the scientific search for cancer chemoprevention agents began three decades ago. Reasoning that cancer doesn’t begin with the appearance of a tumor, just as cardiac disease doesn’t start with a heart attack, Hong began investigating whether vitamin A could prevent head and neck cancers.

His research, along with that of his M. D. Anderson colleagues, provided some hope that chemoprevention could work. The scientists were the first to show that a form of Vitamin A, 13 cis-retionic acid (13-cis-RA), can reverse oral leukoplakia, a precancerous condition that can lead to head and neck cancer.

But the studies also provided some lessons, because some of the agents proved to be toxic, or less effective than expected.

Historic theories of chemoprevention may be viable today

Hong and Kim began their commentary with a short history of chemoprevention, mentioning origins dating back to the Greek physician Hippocrates, whose favorite natural remedies were apples, dates and barley mush (porridge).

The authors conclude by saying that only when researchers are able to identify, in advance, which patients will benefit from chemoprevention “will we be able to discover that elusive ‘golden apple’ of chemoprevention.”