formulations of vitamin D and common, over-the-counter
painkillers can greatly slow the growth of prostate cancer
tumors, U.S. researchers reported Thursday. Combining
the two slowed their growth by up to 70% in a
laboratory dish, the team at the Stanford University
School of Medicine found.
David Feldman and
colleagues are so impressed by the results that they
have started a clinical trial to see if the approach also
works in men. "There is great enhancement when
the drugs are given together, using what we think is a
safe dose in humans," Feldman said in a statement.
"It's hard to make an exact comparison,
as we are talking about cells in a dish and not a
that his team is testing calcitriol, a form of vitamin D
that is efficiently used by the body and different from the
sort found in vitamin pills and fortified milk.
"We don't want the patient to think that
if they take over-the-counter vitamin D, it will work in the
same way," Feldman said.
Writing in the
journal Cancer Research, Feldman and colleagues
said they have seen the effects of calcitriol before
and, based on the cancer-slowing effects seen in some trials
of painkillers, they wanted to see if the two
approaches worked in synergy.
tumor cells in lab dishes, they saw a 25% reduction in
prostate-cell growth using only calcitriol, and about the
same reduction using only ibuprofen and naproxen. When
they combined calcitriol and one of the two
painkillers, they saw growth slow by as much as 70%.
Nearly 30,000 men
die every year in the United States from prostate
cancer, and more than 200,000 are diagnosed. The cancer is
normally slow-growing but becomes aggressive in some
team plans to test the drugs in men whose prostate cancer
has returned after surgery or radiation therapy.