Dr. Huibert Vriesendorp is leery of talking about cures for cancer.
But the radiation oncologist at the M.D. Anderson Cancer Center in Houston, Texas, is optimistic that a radioactive isotope called yttrium-90 will one day be used to kill cancer cells immediately after a patient is diagnosed.
“I would not be surprised to find out yttrium is going to be useful in many kinds of common cancers,” Vriesendorp said. “But we have to do the studies cautiously and carefully.”
Vriesendorp is testing the isotope, extracted from nuclear waste stored at the Hanford nuclear reservation near here, on cancer patients.
“It’s nice because (patients) do appear to respond. Three out of four get shrinkage of their tumor,” Vriesendorp said.
The isotope is not a cure - tumors recur within a year in most patients. But researchers are working to address that.
Sixty patients with Hodgkin’s Disease, a cancer of the lymph system, have participated in Vriesendorp’s study at the Houston center so far. At least six other human clinical trials of yttrium-90 are under way around the country, the National Cancer Institute said.
The Houston cancer clinic has applied for a $5 million NCI grant over five years to expand its study of yttrium-90 as a weapon against brain, ovarian and breast cancer, Vriesendorp said.
But he worries that federal budget problems will mean the cancer institute, the U.S. Department of Social and Health Services and other agencies will cut back support of studies like his.
He believes researchers could be on the verge of a breakthrough involving development of a new protein carrier to deliver yttrium-90 to the tumor.
“We don’t have enough people to do the tests, we don’t have enough funds to buy the animals and do the analysis,” Vriesendorp said.
“But if this new protein works for Hodgkin’s Disease, I think we’ll be close for something that will be useful at the time of diagnosis. I’d love to call it a cure, but I’m not comfortable using that word. We have to be cautious.”
Like other researchers, he noted, “we’re doing it mainly with federal money and if we don’t get it, all our research will be on a backburner.”
He’ll hear about the grant in October.
The yttrium-90 studies involve patients who have failed to respond to more traditional cancer treatments: radiation and chemotherapy and bonemarrow transplants.
“When they come to us, they really don’t have any other treatments available to them,” Vriesendorp said.
In the outpatient treatment, patients receive two injections, the first with a diagnostic isotope that determines whether the protein carrier will deliver the yttrium-90 directly to the cancer.
“If the protein doesn’t arrive in the right spot you know you don’t want to use the yttrium,” Vriesendorp said. “The advantage to the patient is you can just stop if you see you aren’t getting the right pictures.”
Once past that phase, the yttrium-90 is injected. The patient must remain close to the clinic for about two weeks of monitoring, but the treatment is free of the side effects of nausea, vomiting and hair loss associated with chemotherapy and radiation, Vriesendorp said.
The patient then goes home, undergoing weekly blood tests.