Early chemotherapy offers unprecedented prostate cancer survival benefits

c.2014 New York Times News ServiceJune 2, 2014 

CHICAGO -- Many men with prostate cancer put off using chemotherapy as long as possible, fearing its side effects.

But a new study has found men given chemotherapy early in their treatment for the advanced disease lived a median of nearly 14 months longer than those who did not get early chemotherapy. The result could upend the established treatment practice, researchers said here Sunday.

"We haven't seen survival benefits like that for any therapy in prostate cancer," said Dr. Michael Morris, an associate professor at the Memorial Sloan-Kettering Cancer Center, who was not involved in the study but was selected to publicly comment on it at the annual meeting of the American Society of Clinical Oncology.

Another study presented Sunday found drugs called

aromatase inhibitors might be better than the standard drug tamoxifen in preventing a recurrence of disease in premenopausal women with early breast cancer.

Both studies were featured in the plenary session Sunday, meaning they were deemed among the most noteworthy of the more than 5,000 studies presented at the meeting. In a conference that typically celebrates the latest and greatest drug, all four studies chosen for the plenary session this year are about better ways of using older drugs, showing there can be a lot to learn even after drugs get to market.

Dr. Nicholas Vogelzang, an author of the study on prostate cancer, said the findings would change practice and he had already started discussing this option with patients. The challenge, he said, is getting men to agree.

"Not many of them want to do chemotherapy, even though the numbers are convincing," said Vogelzang, who works at the Comprehensive Cancer Centers of Nevada.

The study's findings apply to a fairly narrow group of patients -- men whose cancer has already spread beyond the prostate gland at the time of diagnosis, or whose cancer has come back after surgery or radiation treatment and still remains susceptible to hormone therapy.

Only a small fraction of men have metastatic prostate cancer at the time of the initial diagnosis because prostate cancer screening using a blood test typically detects the disease before it spreads.

But screening is expected to become less common because a government advisory committee, the U.S. Preventive Services Task Force, has recommended against routine screening, saying more men are harmed by unnecessary treatments for prostate cancer than are saved from death by screening. That could lead to an increase in men whose initial diagnosis is metastatic cancer, Vogelzang said.

The study, sponsored by the National Cancer Institute, involved 790 men who received either hormone therapy only or hormone therapy in addition to at most six infusions of docetaxel spaced three weeks apart.

Those who received the chemotherapy lived a median of 57.6 months, compared with 44.0 months in the control group, a difference of 13.6 months. The difference in survival was even greater - 17 months - for the patients whose cancer had spread more extensively. Morris of Sloan-Kettering said those men were the best candidates for early chemotherapy.

Docetaxel is sold under the brand name Taxotere by Sanofi, but generic versions are also available. It was approved for metastatic prostate cancer in 2004. In the last few years, several other drugs have been approved, like Zytiga from Johnson & Johnson and Xtandi from Medivation and Astellas Pharma.

But docetaxel and the newer drugs are typically used after hormone therapy has stopped working. In that setting, each of them has extended median survival by about two to five months in clinical trials.

Dr. Matthew Cooperberg, associate professor of urology at the University of California, San Francisco, said doctors were starting to use the newer agents before docetaxel, pushing chemotherapy further back in the sequence.

So the new study "is, to an extent, bucking the tide," he said. "This trial may be evidence that the role for chemo is earlier, when patients are healthier and the disease burden is relatively low."

The results also raise the question of whether the other prostate cancer drugs would also provide a much greater survival advantage if used earlier. Some trials are underway to determine that.

One issue is early treatment is often handled by urologists, not oncologists. And many urologists do not administer chemotherapy.

Morris said he did not think earlier use of docetaxel would diminish sales of the newer agents. Men will eventually become resistant to hormone therapy, he said, and will need the newer agents.

In breast cancer, women with estrogen-responsive disease typically take drugs for at least five years after their tumor has been removed surgically, to prevent cancer from recurring.

Aromatase inhibitors are generally considered a better choice than tamoxifen for postmenopausal women. But aromatase inhibitors work only when women have low estrogen levels, which usually rules them out for premenopausal women.

The new study -- actually two studies being analyzed together to accumulate nearly 4,700 patients -- involved suppressing the functioning of the ovaries so that the younger women could take an aromatase inhibitor.

Five years of an aromatase inhibitor in addition to ovarian suppression proved superior to five years of tamoxifen in addition to ovarian suppression. After five years, 91.1 percent of those who received the aromatase inhibitor, exemestane, were free of cancer, compared with 87.3 percent of those who received tamoxifen with ovarian suppression. (In the United States, tamoxifen is typically used without ovarian suppression.)

Some experts said they were a bit skeptical that the results would change practice, noting that so far there was no difference between the groups in how long the women lived. And side effects must be evaluated, they said. Those include both the joint pain caused by aromatase inhibitors as well as the hot flashes and bone loss that could come from putting women into early menopause so they could use the aromatase inhibitor.

Ovarian suppression is typically accomplished using drugs like goserelin. Another study presented here Friday showed that goserelin can help preserve fertility in young breast cancer patients.

Exemestane is sold under the brand name Aromasin by Pfizer, although generic versions are commonly used.

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