Cancer patients from poor communities have lower survival rates than those from more affluent neighbourhoods, a new Canadian study has found.
What's more, the research team discovered that the explanation for similar disparities in U.S. research -- that patients from poorer areas are more likely to be diagnosed when their cancer is at a later stage -- did not hold true.
The researchers, led by Dr. Christopher Booth at the Cancer Research Institute at Queen's University in Ontario, found that poorer patients had a greater chance of dying prematurely from their disease even though cancer stage at the time of diagnosis was similar across socioeconomic groups.
"Contrary to what has been reported in studies from the U.S., we have found that stage of cancer at time of diagnosis does not account for any substantial component of the difference in survival across social groups," Booth said in a statement.
The findings, though only gleaned from Ontario data, suggest other factors play a role in survival, including the unique biology of each patient's disease, the presence of other illnesses, access to treatment and overall quality of care.
The study was published Monday in Cancer, the journal of the American Cancer Society.
For the study, the research team compared median household income data from the 2001 Canadian census with diagnosis information from the Ontario Cancer Registry. The team analyzed all cases of breast, colon, rectal, non-small cell lung, cervical and laryngeal cancer diagnosed in the province between 2003 and 2007.
Their findings include:
- The chance a woman from a poor community will be alive five years after a breast cancer diagnosis is 77 per cent, compared to 84 per cent for a wealthy woman.
- Fifty-two per cent of patients with colorectal cancer from poor neighbourhoods are still alive five years after diagnosis, compared to 60 per cent of patients from wealthy communities.
The team said the fact that stage of disease at the time of diagnosis was similar across socioeconomic groups may be explained by universal health coverage in Ontario, "which may facilitate access to primary care physicians and/or cancer screening," Booth said.
However, the disparity in survival rates, while they seem small, "are important and meaningful differences," he told The Canadian Press.
"If we had a form of chemotherapy or cancer treatment that led to an improvement or difference in five-year survival of seven, eight, nine per cent -- the order of magnitude we're seeing with these differences -- it would be a blockbuster home run as far as cancer treatment advances," Booth said.
The team said further research is needed to identify the specific factors that are leading to the disparities in survival, which will then allow experts to devise strategies to reduce those disparities.
