Study Compares Timing of Hormonal Therapy for Prostate Cancer

SUNDAY, June 3 (HealthDay News) — Men with metastatic prostate
cancer who undergo hormone-deprivation therapy sometimes take breaks from
the treatment to minimize its often difficult side effects.

However, a major new study that tracked more than 1,500 men for almost
a decade finds that opting for intermittent treatment may take a toll on
certain patients, in terms of shortened survival.

The study found that for men with cancer involving “minimal spread,”
adopting a stop-and-start treatment schedule was associated with a
two-year decline in survival compared to men who’d been treated on a
continuous basis.

This gap in survival did not appear for men whose prostate tumors
showed more extensive spread, but the researchers stopped short of
recommending intermittent treatment for this subset of patients, pending
better data.

The study, funded by the U.S. National Cancer Institute, was reported
Sunday at the annual meeting of the American Society of Clinical Oncology
(ASCO) in Chicago.

According to the American Cancer Society, prostate cancer is the second
most common cancer in men after skin cancer, with almost 242,000 new cases
diagnosed in the United States each year.

Doctors have long known that prostate tumors “feed” on circulating male
hormones such as testosterone. So hormonal deprivation therapy — designed
to turn off testosterone production and thereby stop cancer growth —
remains a common first-line approach in keeping the cancer at bay.

But, there’s a big downside to the treatment, since it “is associated
with significant side effects, including loss of libido, erectile
dysfunction, osteoporosis, muscle wasting, hot flashes, depression and
cardiovascular issues,” said Dr. Herbert Lepor, chairman of the department
of urology at New York University School of Medicine in New York City.

He said that in prior studies, “intermittent therapy was equally
effective as continuous therapy with fewer side effects,” and so patients
have sometimes opted for this approach.

But, would the intermittent approach remain equally effective over the
long term?

The new phase 3 trial sought to answer that question. In the study,
researchers tracked outcomes for more than 1,500 men with
hormone-sensitive cancers that had spread beyond the prostate. All of the
men first got seven months of continuous hormone deprivation therapy.
Then, half were randomly chosen for intermittent treatments while the
other half stayed on the continuous regimen.

Overall, the men who got the stop-and-start treatment were exposed to
about half the total amount of hormonal therapy as the men in the
continuous group, the researchers said.

Unfortunately, “survival with intermittent hormone therapy was inferior
to survival with continuous hormone therapy,” reported study author Dr.
Maha Hussain, a professor of medicine and urology at the University of
Michigan Comprehensive Cancer Center.

Speaking at an ASCO press briefing, she concluded that “because of
these findings, continuous therapy continues to be the standard of
care.”

After a median follow-up of more than nine years, overall survival in
men with minimal disease spread (no cancer beyond the spine, pelvis and
lymph nodes) was 7.1 years for those on continuous therapy vs. 5.2 years
for those treated intermittently — a two-year difference.

That gap in survival closed for men with more extensive disease (4.4
years for those on continuous therapy vs. 5 years for those in the
intermittent group). However, Hussain was careful not to recommend
treatments breaks, even for this sicker group of patients, saying that the
finding was “surprising” and more data is needed.

For patients with extensive cancer spread, it’s best to discuss
treatment options with a doctor before embarking on either one of the
regimens, she said.

Dr. Bruce Roth, a professor of medicine in the division of oncology at
Washington University School of Medicine in St. Louis, said experts had
waited a long time for the findings of this “important” trial.

“Prior, underpowered studies suggested that there was no downside to
intermittent therapy, which clearly provides less toxicity,” he said at
the press briefing. “This study for the first time indicates that there is
a price to pay.”

Lepor agreed that, “on the basis of this study, intermittent androgen
[hormonal] deprivation therapy should no longer be recommended for those
men with minimal disease spread.”

Findings presented at medical meetings are typically considered
preliminary until published in a peer-reviewed journal.

More information

There’s more on treatments for prostate cancer at the American Cancer Society.

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