Researchers at he BC Cancer Agency will be receiving a $563,000 grant to continue a study on the increasing rates of Non-Hodgkin's lymphoma. While incidence rates for the majority of cancer sites have stabilized or declined since 1988, new cases of non-Hodgkin's lymphoma (NHL) have more than doubled in the last 30 years.
The grant, announced by the Canadian Cancer Society today, will provide an additional three years of funding to a study started in 1999, and previously funded by the Canadian Institutes of Health Research.
The BC Cancer Agency team conducting the research includes Dr. John Spinelli (Cancer Control Research), Dr. Joseph Connors (Medical Oncology), Dr. Randy Gascoyne (Pathology), and Dr. Angela Brooks-Wilson (Genome Sciences Centre).
"Relatively little is known about the risk factors for this disease," says Dr. Spinelli. "But we think that most cases may be caused by an interaction between genetic susceptibility and environmental exposure."
Dr. Spinelli and his team have collected blood samples from 1,100 British Columbians – half of whom have NHL and half of whom do not – and will continue to collect 400 more over the next year. These samples will be used to determine genetic information and to measure exposure to organochlorines, a class of environmental contaminants that includes PCBs and DDT. They will also gather information on the research subjects' exposure to ultraviolet radiation and other possible risk factors.
"Organochlorines are important to study because they are thought to be a risk factor for NHL, and unlike many other chemicals, their compounds accumulate in our body tissues," says Dr. Spinelli. The team is also studying exposure to ultraviolet radiation because there is a link between skin cancer and NHL, as well as evidence that sunlight exposure suppresses the immune system.
The data on sunlight and chemical exposure will be combined with an examination of genes known to metabolize organochlorines and repair or prevent sun damage to identify any connection between all of the factors.
"This study is an important step in understanding the causes of NHL," says Dr. Spinelli. "Through epidemiological research projects such as this, we hope that we will eventually be able to suggest preventive measures that will reduce a person's risk of the disease."
The team hopes to begin publishing results of the study one year after all the data is collected.
For more information, or to arrange an interview, please call:
Nicole Adams
Public Relations Officer
BC Cancer Agency
(604) 877.6272
Backgrounder
What is NHL?
Lymphoma is a general term for cancers that develop in the lymphatic system which is part of the immune system. Hodgkin's disease is one type of lymphoma. All other lymphomas are grouped together and are called non-Hodgkin's lymphoma.
In lymphoma, cells of the lymphatic system become abnormal. They divide and grow without control, or do not die as they normally do.
What is known about the causes of NHL?
We know that the likelihood of getting NHL increases with age and that it is more common in men. We also know that people with a weakened immune system (due to autoimmune diseases or taking immunosuppressant drugs after transplants) are at higher risk. There is some evidence that exposure to some viruses and certain chemicals and pesticides also increases the risk of developing NHL. It is thought that most cases of NHL are caused by an interaction between genetic susceptibility and environmental exposure.
What are the main things this study is looking at?
We have three main hypotheses. The first is that cumulative exposure to organochlorines, and environmental contaminant that includes PCB and DDT, increases the risk of NHL. We also are looking at the possibility that sunlight exposure may also be related to NHL. Finally, we are looking at the impact that genetic susceptibility, in common with environmental and other risk factors influences the risk of NHL.
What is the evidence that sunlight exposure is related to non-Hodgkin's lymphoma?
The is a link between skin cancer and NHL. The incidence of melanoma (a form of skin cancer) and NHL have been increasing at a similar rate, and we know that sunlight is the main cause of melanoma. We also know that people with skin cancer have a higher risk of getting NHL, and vice-versa. Finally, sunlight exposure is known to suppress the immune system.
What is the evidence that organochlorine exposure is related to non-Hodgkin's lymphoma?
Several studies have shown that farmers have an higher risk of NHL, and pesticide exposure was hypothesized as the agent. More recent studies have focussed on types of pesticides, and certain organochlorines were found to be risk factors. Two recent studies also showed an increased NHL risk for individuals with high levels of serum organochlorines.
Why is this study important?
This project is an important step in understanding the causes of NHL. The identification of environmental risk factors (OC, UVR) may ultimately lead to preventive measures that will reduce an individual's risk of NHL. Knowledge about genetic determinants of NHL will increase our understanding of the mechanisms in the development of lymphoma. The identification of the interaction between genetic factors and environmental exposures will increase our understanding of an individual's response to environmental exposures, and improve the precision of risk estimates associated with those environmental exposures.