Cancer researchers in British Columbia have made a new breakthrough in lymphoma treatment, discovering a way to predict which patients will be cured and which ones will likely relapse.
The New England Journal of Medicine celebrated the BC Cancer Agency study as the "breakthrough we have been looking for."
The discovery by a team of 26 scientists from throughout North America and Europe shows a new way to predict the 15 to 25 % of patients who will have a poor prognosis if they aren't treated more aggressively from the time of diagnosis.
Dr. Joseph Connors, study co-author and lymphoma expert, said although 75 to 80 % of patients are cured with initial treatment, the rest relapse.
The study published in the NEJM found that those who relapse have a high number of white cells called CD68-positive macrophages in their tumours.
The macrophage test can be "easily incorporated into a routine diagnostic approach," the researchers said.
In the study, which investigated patient records, the 10-year survival rate in patients with the highest number of the macrophages was 59.6 % compared to 88.6 % in patients with a lower number. The study also examined tissue samples from nearly 300 patients aged 33 to 46.
Although it was formerly believed that macrophages provided a helpful immune system response, scientists now believe that they can create a haven for malignant cells to avoid detection. They can send the signals that tell malignant cells to grow and release chemicals that encourage new blood vessels to grow, providing nourishment for the tumour.
"Despite an overall cure rate of about 80 %, advances in treatment have stagnated for 20 years because we have lacked markers that can reliably predict the response to therapy," the NEJM editorial accompanying the study stated.
"As a consequence, overtreatment with (radiation treatment) and combination chemotherapy is the rule for most patients with Hodgkin's disease," it continued.
Radiation treatment to the chest is associated with a higher risk of heart damage, breast cancer and other secondary cancers which may arise years later.
Decades ago, before the availability of effective chemotherapy agents, Hodgkin's patients almost always had radiation treatment. But now, four cycles of chemotherapy is considered the gold standard for patients with early stage disease and radiation is added only as needed.
Bone marrow transplants are used in relapsed patients, which are successful about 50 % of the time.
Lead author Dr. Christian Steidl said in addition to finding a correlation between the number of macrophages and the outcome of primary treatment, researchers also discovered the number of macrophages could be used to predict success or failure of secondary treatment, including bone marrow transplants, after relapses.
Similar research has been done in animal models of breast, colon and prostate cancers and those studies have also found that high numbers of macrophage cells in tumours is linked to treatment resistance and cancer spread.