Radiation May Not Help Pancreatic Cancer
Drug therapy alone may offer patients best hope, study suggests
WEDNESDAY, March 17, 2004 (HealthDayNews) -- It has been part of standard pancreatic cancer therapy for years, but the combined use of anti-cancer drugs and radiation just after surgery may do little to prolong patients' lives.
In fact, this type of "chemoradiation" therapy may even lower survival rates by delaying patients access to a more powerful drugs-only approach, a new British study contends.
"If chemoradiation was given prior to chemotherapy, the benefit of [tumor-removing] surgery was reduced," says study author Dr. John P. Neoptolemos, head of the department of surgery at the Royal Liverpool University Hospital in Liverpool.
His team's findings appear in the March 18 issue of the New England Journal of Medicine.
Pancreatic tumors remain one of the deadliest forms of cancer, with a five-year survival rate of less than 4 percent. Experts blame this high death rate on the fact that pancreatic cancer tends to grow without symptoms, remaining undiagnosed until it's too late. Once a tumor has spread to adjacent organs, such as the intestines or bile duct, symptoms such as jaundice or abdominal pain can occur. But by this time, surgical removal of the tumor may not be an option.
Dr. Michael Choti of Johns Hopkins Hospital adds the pancreas "is also in a strategic location in the body that's surrounded by a lot of vital structures -- arteries, veins to the intestines and the liver. So it doesn't require very much spread before it can encase or involve vital structures that simply can't be removed."
In fact, just 10 percent of patients diagnosed with pancreatic cancer are deemed eligible for surgery.
Among that 10 percent, nearly all will go on to receive either radiation, anti-cancer drug therapy (chemotherapy) or a combination of both, to help hunt down stray cancer cells lurking in the body.
In their study, Neoptolemos and his team compared the five-year survival rates of 289 pancreatic cancer patients treated with chemoradiation, chemotherapy alone, chemoradiation plus chemotherapy, or no treatment following surgery. The patients were drawn from 30 cancer centers across Europe.
The results: "Chemotherapy increases five-year survival from 10 percent for surgery alone to 30 percent for surgery plus six months of chemotherapy," Neoptolemos says.
However, the results weren't so promising when it came to chemoradiation.
While patients given drugs-only chemotherapy survived an average of nearly two years after surgery, those given either chemoradiation or chemoradiation plus chemotherapy survived just 14 months on average, the researchers found.
How might radiation work to actually lower patient survival? The answer may lie in the relative strengths of chemoradiation and chemotherapy in hunting down and killing rogue cancer cells.
"Pancreas cancer is a systemic disease," explains Neoptolemos, and "cutting out the cancer is good as it removes the bulk of the tumor. However, there are millions of cancer cells that have spread in the blood to many other organs."
"Chemoradiation will not hit these cancer cells," Neoptolemos says. On the other hand, "chemotherapy will hit all cancer cells."
Therefore, "if given before chemotherapy, chemoradiation delays the effective delivery of systemic chemotherapy, enabling cancer cells to grow and grow, making them more resistant to chemotherapy when it is finally introduced," Neoptolemos says.
The result may be a patient with a decided disadvantage in fighting off tumor recurrence, experts conclude.
In his editorial comment on the study, Choti cautions it's still too early to completely rule out chemoradiation as post-operative therapy for patients with pancreatic cancer.
According to Choti, the British researchers were unable to track whether chemoradiation was being administered consistently across the 30 different centers in which the study took place. "It's complicated to give radiation therapy," he says. "If not given carefully, there can also be side effects that increase the [side effects], perhaps even the mortality" of patients taking the therapy.
Choti believes an even clearer picture of the relative risks or benefits of chemoradiation may come with the release of findings from a major U.S. trial, due out soon.
In the meantime, he stresses that the vast majority of patients with pancreatic cancer are not even eligible for surgery. These patients may also receive cancer-killing drugs or radiation, but with little hope of curing their condition. "You could call it palliative chemoradiation therapy. It does prolong one's life and quality of life," he says.
There's better news for the fortunate 10 percent who qualify for surgical removal of the tumor. It's a complex, multi-organ operation called the Whipple Procedure.
"Historically it was considered a very complicated and difficult operation," Choti says. "It still is, but now it can be done extremely safely, rapidly and with very low morbidity than even a decade ago. We've really mastered this operation."