St.Petersburg Times, 05-29-06
Dr. Tim Byers, a professor in the department of preventive medicine and biometrics at the University of Colorado Cancer Center, spoke at a recent meeting of the Association of Community Cancer Centers.
He said that the American Cancer Society's goal of achieving a 50 percent drop in cancer mortality by 2015 may not happen. However, he predicted that by 2015 there will be a 25 percent decrease in the death rates for the four leading cancers: breast, lung, prostate and colorectal.
--Breast cancer: Byers said the decline in mortality started in 1990 and has been continuing at an annual rate of 2 percent. He attributed this to early detection and improved treatment.
Byers cautioned against neglecting screening mammography and treatment for elderly women, who are at a greater risk. Because a woman age 79 might live another 10 to 15 years, he advises against age discrimination. He estimated that 10 percent of breast cancer deaths are due to failure to have mammograms and ineffective treatment.
Since the Women's Health Initiative study revealed a causal relationship between hormone replacement therapy (HRT) and breast cancer, most postmenopausal women are avoiding HRT. This will further decrease the incidence of postmenopausal breast cancer.
--Prostate cancer: Mortality has been falling by an annual rate of 2 percent since 1994. It is tempting to attribute this drop to PSA (prostate-specific antigen) testing, but there is no definite proof. Besides, the mortality rates from prostate cancer started falling before PSA testing was widely applied.
Byers cited randomized clinical trials that show reduction in the incidence of prostate cancer in people taking vitamin E and selenium, but predicted that selenium will emerge as a more potent preventive agent.
He also suggested that genetic and molecular footprints of biopsy and blood tests may prove to be better predictors of cancer and aggressiveness of these cancers than PSA.
--Colorectal cancer: Byers estimates a greater than 50 percent reduction in colorectal cancer death rates by 2015. He stated that the death rate peaked around World War II and started declining since 1950.
The reason for this decrease is unknown, but it could be due to the availability of refrigeration for safe storage of fruits and vegetables.
It is estimated that, of the 57,000 deaths due to colorectal cancers each year in the United States, 35 percent could be attributed to patients who did not undergo screening as per recommendations. If screening guidelines were adopted as recommended, an additional 19,000 deaths could be avoided.
--Lung cancer: Death rates have been coming down for both men and women. It is estimated that, of the 161,000 deaths per year due to lung and larynx cancers, 80 percent are due to tobacco.
If strict tobacco control policy is enforced, as in California, a substantial decrease in the death rates attributed to lung cancer and all tobacco-related cancers can be realized.
Employment of early detection techniques and application of adjuvant chemotherapy and targeted therapies, where indicated by randomized control trials, will further enhance the declining mortality effect.
--Reversal of the obesity epidemic: The American Cancer Society's "Nutrition and Physical Activity Guidelines for Cancer Prevention" prominently mentions increasing access to healthy foods in schools, workplaces, and communities and safe, enjoyable access to physical activity.
Obesity has either a proven or implied relationship to cancer and heart disease, both of which account for the majority of deaths in the United States.
Simple measures such as behavior modification, smoking cessation, weight control, a diet rich in fruits and vegetables, regular physical activity and application of current guidelines for screening can prevent a sizable number of cancers.
Employment of currently effective treatments such as surgery, radiation, chemotherapy and targeted therapies can cure a good fraction of the early detected cancers.
So, it seems the goal of decreasing the cancer death rate by 25 percent to 50 percent by 2015 is achievable.
--V. Upender Rao, M.D., FACP, practices at the Cancer and Blood Disease Center in Lecanto.
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