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New treatment option for pancreatic cancer shows early promise
ANN ARBOR, MI - When someone is diagnosed with pancreatic cancer, surgery to remove the tumor offers the greatest potential for survival. But in the vast majority of cases, surgery is not an option, forcing patients and their doctors to look to other, less-effective treatments - often involving radiation together with chemotherapy, or chemotherapy alone. .
Even with these therapies, nearly all pancreatic cancer patients show evidence that the cancer has spread throughout the body within months of diagnosis, making it one of the most deadly and difficult cancers to treat. In 1996, the Food and Drug Administration approved a more effective chemotherapy drug called gemcitabine for use, and several leading medical centers have investigated techniques to combine this drug with radiation. But many of these studies have found the combination causes unacceptable side effects.
Now, a new University of Michigan study has now shown that the drug can be delivered safely in combination with accurately targeted radiation. In fact, the combination could actually be more beneficial than currently available therapy, without an increased risk of severe side effects.
In a paper published today in the Journal of Clinical Oncology, a team of pancreatic cancer specialists at the U-M Comprehensive Cancer Center reports that gemcitabine can be delivered at the recommended standard dose together with carefully aimed radiation without substantial side effects. This clinical study results from years of laboratory research at the U-M to understand the mechanism of interaction between gemcitabine and radiation, and technical advances in the delivery of radiation.
Previous research on this combination has focused on broadly targeted radiation therapy techniques with the addition of relatively low doses of gemcitabine. Although promising, the combination proved to result in unacceptable nausea, vomiting, and excessive weight loss.
The study reported today shows that the U-M technique, co-developed by Cornelius McGinn, M.D., assistant professor of radiation oncology and Mark Zalupski, M.D., clinical associate professor in medical oncology at the U-M Health System, produced relatively modest side effects and allowed the chemotherapy to be kept at a standard dose, rather than a reduced dose.
"Since pancreatic cancer spreads very easily, it is important to attack it throughout the body with effective chemotherapy. But treatment must also target the tumor in the pancreas itself, and that's where focused radiation comes in," McGinn says. "By investigating the appropriate radiation dose using a conformal radiation technique that spares non-cancerous tissue, we have effectively targeted the primary cancer while still delivering systemic therapy for potential spread, something no other study has attempted."
Encouraged by the initial results, the team of researchers will embark on a new trial later this year, testing the approach at the U-M and other medical centers throughout the country. The development of a specific clinic for patients with pancreatic cancer within the U-M Comprehensive Cancer Center is being considered as well, as a means to provide coordinated multidisciplinary care for this special patient population and develop further research efforts.
Pancreatic cancer is the fourth leading cancer killer, claiming almost 30,000 lives every year in the United States. Even more alarming is the fact that by the time pancreatic cancer is diagnosed, it is usually too late for surgical removal, with the average life expectancy being only six to nine months.
But the findings of the study conducted at the U-M Health System offer a glimmer of hope that survival time could be extended while patients enjoy a better quality of life.
The study looked at 37 patients with locally advanced pancreatic cancer, including many with evidence that the cancer had already spread. Over the course of three weeks, gemcitabine was given once a week during a course of radiation therapy delivered every weekday. The radiation was administered by conformal therapy directed at the primary tumor, without targeting any other areas at risk. After a week break, a second three week course of gemcitabine alone was given. Additional chemotherapy was then given to many patients, but not as part of the trial.
During the trial, seven different radiation dose levels were investigated in as many groups of patients. Some patients who received the highest doses of radiation did experience toxic side effects. As a result, the next trial will use a slightly lower radiation dose that was well tolerated.
McGinn says the overall results were promising. On average, patients lost less than 1 percent of their pretreatment body weight. In fact, more than 40 percent of patients were actually able to gain weight during the course of therapy. This is significant achievement when compared to results of previous studies of gemcitabine and radiation, in which patients often experienced substantial nausea, vomiting and weight loss occasionally resulting in hospitalization. The time required for daily radiation (three weeks) was appealing as well, when compared with more conventional course of radiation which requires five to six weeks.
Survival time for patients ranged from five months to longer than two years. Median survival was just over 11 months. Compared to the expected survival time for this group of patients, this result is encouraging. However, McGinn cautions that this doesn't represent a cure and noted that the trial was not designed to investigate outcome as a primary endpoint. It is possible, he says, that this approach represents new strategy which could be built upon for additional gains.
"Pancreatic cancer is a terribly tragic disease. We believe we have made a small step towards giving patients a chance at a longer and better life," he says. "The reality is we're still trying to learn more about pancreatic cancer and ways to treat it, without jeopardizing quality of life."
For more information on cancer care at the U-M contact the UMHS Cancer AnswerLine™ at 1-800-865-1125.