BUFFALO, NYThe 1990s have seen a new focus on cancer
prevention, particularly chemoprevention. Researchers must use
results of basic, clinical, and translational chemoprevention studies
to design more effective trials to further this field, Scott M.
Lippman, MD, said at the New Horizons in Cancer Prevention Symposium,
hosted by Roswell Park Cancer Institute.
For the first time in our history, we know that we can use a
pill to decrease cancer risk, ie, tamoxifen [Nolvadex] to decrease
breast cancer risk. As we focus on these exciting changes in cancer
prevention, we need to look closely for targeted agents with
decreased risks and increased benefits, said Dr. Lippman,
chairman, Department of Clinical Cancer Prevention, M.D. Anderson
Many drugs have epidemiologic data supporting their ability to
decrease cancer risk. However, epidemiologic evidence cannot
substitute for large-scale clinical trials, he said. For the best
results, clinical trials of chemopreventive agents should be based on
strong evidence of potential efficacy and molecular observations.
Chemoprevention is the pharmacologic prevention of invasive
cancer. However, at this time, many chemopreventive agents, such as
tamoxifen, also present risks to the people who want to use them.
Trials of such agents generally target high-risk patients who can use
and benefit from chemoprevention and may accept greater side
effects, Dr. Lippman said.
One important new chemoprevention trial is the Study of Tamoxifen and
Raloxifene (STAR), which is currently accruing patients. This study
is the first definitive randomized trial to compare a new cancer
chemopreventive agent (raloxifene, Evista) directly with standard
chemopreventive therapy (tamoxifen).
In addition to testing raloxifenes potential benefit in
decreasing risk of breast cancer, this trial is designed to address
one of the important secondary observations that came from the first
randomized trial of tamoxifen as primary chemoprevention, ie, an
increased risk of endometrial cancer.
We must analyze all the data that we receive from current
trials. These trials take too long not to use all of the data that
come from them, Dr. Lippman said.
He noted that many investigators believe that phase III trials
now have better levels of rationale. Future phase III clinical and
translational trials will continue to provide valuable data on drug
mechanisms and biomarkers. However, he added, chemoprevention
trials must also focus on the interplay of age, diet, and other