Hormone Therapies Offer Breakthrough Against Some Cancers
Prostate, breast tumors not as lethal, thanks to new approaches
TUESDAY, Sept. 23, 2003 (HealthDayNews) -- Therapies that interfere with the effects of hormones have helped usher in an era of plummeting death rates from prostate and breast cancers.
Paired with advances in tumor detection, early use of these treatments has slashed the 10-year death rate associated with budding prostate cancer by as much as one-third in the United States and Europe, compared with the 1980s, says a new study.
The effect is approximately as large for early-stage breast cancer.
"The drop is big," says study co-author Sir Richard Peto, a professor of medical statistics at the University of Oxford. "It's quite clear that in terms of preventing deaths you do better starting hormonal treatment immediately rather than waiting until" the cancer spreads.
Nearly 221,000 American men will be diagnosed with prostate cancer this year, and 29,000 will die of the disease, according to the American Cancer Society. Prostate cancer is the second leading cancer killer of men in the United States, behind lung cancer. Even so, the survival rate for men with the disease now hovers above 90 percent.
Breast cancer will strike about 211,000 American women this year, killing nearly 40,000, according to the cancer group. As with prostate cancer for men, breast cancer trails only lung cancer in causing the most cancer deaths for U.S. women.
Death rates from each disease were on their way up in the 1970s and 1980s, says Peto, who presented his group's findings Sept. 23 at the European Cancer Conference in Copenhagen, Denmark.
"Suddenly they dropped about a quarter to a third in the 1990s," he says, adding that early detection efforts were joined at that time by the increasing use of hormonal therapies.
The death rate from prostate cancer in the United States dropped sharply between 1990 and 2000, figures show, falling by one-third in men aged 50 to 74, and by one-quarter among those aged 75 to 84.
While surgery can remove cancers, the scalpel is only so fine a tool. It sometimes leaves behind a few cancerous cells that over time can spawn return tumors. The trick to successful cancer care is to eradicate all the cancerous cells at once.
Both prostate and breast tissue grow in response to contact with sex hormones -- testosterone in the case of the prostate and estrogen in the case of the breast. So scientists reasoned that depriving the organs of these hormones would prevent any cancerous cells in them from growing.
Removing the testes was an obvious --but undesirable -- way to suppress testosterone in men. Drugs such as Lupron were developed that could do the same thing.
The drug tamoxifen, which suppresses estrogen, has become a crucial player in the prevention and treatment of breast cancer.
To gauge the effect on mortality of hormone-based therapies, Peto's group pooled evidence from many previous studies of prostate and breast cancer patients. One, for example, looked at the impact of surgical castration and chemical castration -- the use of male hormones to protect the prostate -- on 10-year survival rates in 5,000 men with early-stage prostate tumors.
Another followed 10,000 women with early-stage breast cancer to see if initial treatment with tamoxifen bettered their chances of surviving five years.
The pooled analyses -- called "meta-analyses" -- looked at patients in middle age. Early-stage disease was defined as cancer that hadn't spread beyond its initial site.
Taken together, the studies found initial hormone treatments were significantly more effective than waiting to start the treatments until signs of advanced disease appeared.
Thanks to the advent of hormone-suppressing therapies, Peto says, by 2010 death rates from breast and prostate cancer will be about half what they otherwise would have been.