Cancer patients from poorer communities in Ontario have a greater chance of dying prematurely than those from wealthier backgrounds, but the stage of cancer at time of diagnosis made little difference, researchers have found.
Researchers looked at household incomes from the 2001 Canadian census and used the Ontario Cancer Registry to identify patients diagnosed from 2003 to 2007 with breast, colon, rectal, non-small-cell lung, cervical and laryngeal cancer. The patients were divided into household income brackets of $24,000, $31,000, $36,000, $45,000 and $55,000.
Research in the U.S. has shown stage of cancer at time of diagnosis varies across socioeconomic groups and seems to account for much of the difference in survival.
Dr. Christopher Booth of the Queen's University Cancer Research Institute in Kingston, Ont., says the chance of a woman from a poor community being alive five years after a diagnosis of breast cancer is 77 per cent, compared to 84 per cent for affluent women.
"Patients with breast cancer who reside in the poorest communities in Ontario have a 47 per cent increased risk of death compared with patients of the highest quintile," reads the study.
And 52 per cent of patients with colorectal cancer from the lowest income groups are alive five years after diagnosis, compared to 60 per cent of those in the most affluent communities.
'A bit surprising'
Much of the literature on the topic suggests poor people are diagnosed when their cancer is at a later stage, but this particular study didn't find that to be the case.
For example, in Ontario, only modest differences in cancer stage at time of diagnosis were found, Booth and his colleagues reported in Monday's online issue of the journal Cancer.
"That was a bit surprising. But its also reassuring because the next logical thought is that, 'Well, perhaps the difference we're seeing here relates to the presence of universal health care,'" said Booth, an oncologist and the study's lead researcher.
The only other large studies with similar findings to Ontario's were published in the United Kingdom, which also has a large public healthcare component to its medical system, he added.
It's thought that universal health care may allow people to have more equitable access to cancer screening tests and primary care physicians.
But other factors such as tumour biology, presence of other illnesses, access to treatment, quality of care, or differences in nutrition, exercise and smoking may also play a role in survival, the researchers said.
Canadian doctors, researchers and policymakers need to work towards understanding and correcting these disparities, Booth said.
Next, the Kingston team plans to look at breast cancer and colorectal cancer cases in the province to see whether the treatments patients are choosing or have access to explains some of the differences in survival.