TORONTO - An international team of cancer researchers has found a way to predict which Hodgkin's lymphoma patients won't respond well to therapies, opening the door to using a less aggressive regimen on those more likely to be cured.
The team, led by researchers at the B.C. Cancer Agency in Vancouver, found that high levels of a certain type of white blood cells called macrophages were predictive of poor response to treatment.
The study was published Thursday in the prestigious New England Journal of Medicine, which said in an editorial that advances in Hodgkin's lymphoma have been stagnant for the past 20 years because medicine lacked a way to tease out patients who won't respond from the majority who do.
"If at the time of diagnosis we could identify patients who are destined to have a poor response to treatment, most patients could be spared a combination of therapies or radiotherapy with its attendant long-term toxic effects," said the editorial, written by Dr. Vincent DeVita and Dr. Jose Costa of the Yale Cancer Center, in New Haven, Conn.
This paper "may have provided the necessary tool to do just that," they said.
Hodgkin's disease, as it is also called, is a cancer originating in white blood cells called lymphocytes.
It's one of the more curable forms of cancer; between 75 and 85 per cent of patients are cured after undergoing one round of treatment. About half of patients who relapse are also cured, but a small percentage of people continue to fail treatment.
Medicine hasn't been able to distinguish those tough cases from the ones destined to be cured, meaning many patients likely undergo treatment that is more aggressive than they need, treatment that increase their risk of future serious health problems.
Dr. Joseph Connors, one of the authors and the clinical director of the B.C. Cancer Agency's centre for lymphoid cancer, explained using the example of a woman in her 20s or 30s with Hodgkin's.
Because the tumour is generally located in the chest and neck, the standard response in a case like this is some chemotherapy followed by some radiation, Connors said. But the radiation increases the woman's life-long risk of developing breast cancer. And the radiation can damage her heart, raising the chance she'll develop heart disease.
"Now, if I think the patient has to have this in order to be cured of their cancer, then I'll just tell her to live with it," he said from Vancouver.
"But if I have a test that tells me perhaps somewhat less treatment, perhaps leaving out radiation, will still leave a very high success rate, then I can alter the treatment and not confer that heart and breast cancer risk on the patient."
The potential benefits of the findings don't just extend to patients destined to be cured of the disease.
Finding better treatments for those who have hard-to-treat forms of Hodgkin's has been complicated by the inability to identify those patients early on, Connors said. Findings of studies including the easily cured patients could be skewed by the fact that the majority of patients were going to do well anyway.
Being able to test new therapies only on those who really need them could speed development of new treatments, he suggested. And it would mean patients who don't need additional therapies aren't subjected to the inevitable side-effects of experimental cancer treatments.
"We can actually tailor things much more sensibly," Connors said.
The study isn't the final answer. New treatments are still needed, as are answers to why a small portion of Hodgkin's patients do not respond well to therapy.
Still, Connor said these results, published in this journal, should move the science forward. Asked to describe the import of the findings in baseball terms, he called them "a double."
"If somebody hits a double, everybody pays attention," Connors said. "But the game isn't over."
The research team included scientists from several U.S. and German institutions. Funding came from a number of sources, including the Canadian Institutes of Health Research.
