Clear disparities in cancer outcomes persist, a large Ontario study comparing First Nations patients and other residents suggested.

Data from a cohort study that included nearly 12 million participants showed that some outcomes for screening-program cancers are improving for First Nations patients in Ontario. Nevertheless, persistent disparities highlight the need to improve prevention and screening and to better understand how Indigenous people experience the healthcare system, according to the authors.

“Although historically, Indigenous peoples in Canada were at lower risk for cancer compared with non-Indigenous people, this is no longer the case,” the authors wrote.

The findings were published on July 10 in JAMA Network Open.

Worse Survival Rates

The researchers assessed cancer incidence (1994-2018), mortality (1994-2017), and survival (2007-2019) trends for breast, cervical, and colon cancers (all of which are the focus of screening programs) in a retrospective study. The cohort included First Nations patients identified from the Indian Registry System linked to the Registered Persons Database and other Ontario residents identified from the Registered Persons Database.

While the incidence and mortality of all three cancers improved for First Nations patients, cancer survival was significantly lower among First Nations patients than among other Ontario residents, even after accounting for cancer stage and comorbidity at diagnosis.

After diagnosis, First Nations patients had a higher risk for death than other Ontario residents (breast cancer: hazard ratio [HR], 1.51; cervical cancer: HR, 1.60; colon cancer: HR, 1.19).

Breast cancer was a notable exception in some measures. Compared with other Ontario women, First Nations women had lower breast cancer incidence (rate ratio [RR], 0.77) and mortality (RR, 0.79).

Cervical cancer trends were also encouraging. While incidence and mortality were higher in First Nations women (RR, 1.47 and 2.26, respectively), over time, both rates declined more rapidly in the First Nations women than in the comparator group.

Improvement in Cervical Cancer

“The good news story, in my mind, is the dramatic change over time for cervical cancer incidence and mortality,” senior author Jill Tinmouth, MD, PhD, a scientist and gastroenterologist at Sunnybrook Research Institute in Toronto, told Medscape News Canada. “There was a really wide gap at the beginning of the study period, with First Nations experiencing much higher incidence and mortality, but that gap has really narrowed to the point that the lines almost cross.”

Human papillomavirus vaccination (which began to be administered to eighth-grade girls in 2007-2008 and to boys in 2016) was instituted too recently to have had a huge impact on the trends, Tinmouth noted. But there has been a considerable effort in Indigenous communities to improve the uptake of cervical cancer screening. “That’s what we think might be playing a role here,” Tinmouth said. The paper mentions efforts such as creating short animated educational videos in Ojibwe and Cree, hosting cervical cancer screening events, and facilitating mobile-center screening.

Among the most concerning results is that survival across all three cancer types is worse for First Nations patients than for other Ontarians, said Tinmouth. “That is quite discouraging. And these are analyses that have been adjusted for age and sex and comorbidity and stage of diagnosis.”

The question, then, is whether there are large disparities in accessing care and having continuity of care, Tinmouth noted. “That’s work we’d like to do in the future — examine care trajectories.”

Colon Cancer at Younger Ages

The researchers also found not only that colon cancer incidence was higher among First Nations patients but also that elevated colon cancer risk was similar between patients aged 40-49 years and those aged 50-74 years (incidence RR, 1.27 and 1.29, respectively). First Nations patients also had higher colon cancer mortality (RR, 1.18).

In Canada, the recommended age to start colon cancer screening for average-risk adults is 50 years, Shahid Ahmed, MD, PhD, professor of medical oncology and interim head of oncology at the University of Saskatchewan in Saskatoon, pointed out.

“This paper helps make the case for lowering the start age for colon cancer screening in Canada,” Ahmed, who did not participate in the study, told Medscape News Canada.

The study highlights that “cancer care or detection does not end with screening,” he added. “We need to have a timely diagnosis and culturally safe treatment. Healthcare is complex, so we need care navigation and, more importantly, continuity of care.”

The cohorts from this study were from a single province, but the findings may have broader implications. “The approach taken and lessons learned in Ontario are expected to be relevant to other countries with distinct Indigenous populations, such as the United States, Australia, and New Zealand,” the authors wrote.

The study was supported by the Canadian Institutes for Health Research and by ICES, which is funded by an annual grant from the Ontario Ministry of Health and the Ministry of Long-Term Care. Tinmouth and Ahmed reported no relevant financial relationships.