Alberta cancer diagnoses dropped sharply early in pandemic, Calgary study shows

New research from the University of Calgary shows the detection of some cancers plummeted and hundreds of diagnoses may have been missed during the early stages of the COVID-19 pandemic in Alberta. That's when screening services were scaled back and health systems scrambled to deal with a deadly new pathogen.

The research, published in the Canadian Medical Association Journal, looked at 10 of the most common types of cancer and diagnosis trends between January 2018 and December 2020.

"The sweeping and unprecedented measures enacted … had an inevitable impact on cancer care," the study's authors wrote.

A total of 42,862 diagnoses were analyzed. Researchers found dramatic reductions in identification of four key cancers as the province began battling COVID-19.

The study shows diagnoses for melanoma dropped 43 per cent during the three months after Alberta's public health emergency went into effect, in mid-March of 2020.

Colorectal and prostate cancer identification fell by 36 per cent and breast cancer diagnoses sank by 33 per cent.

"We really saw the largest drops that were observed in early-stage cancers," said Darren Brenner, the study's lead author.

"Most of this likely relates to disruptions in organized screening programs, and the related diagnostic activities, potentially also difficulty accessing primary care services and fewer in-person appointments."

According to the study, while active chemotherapy and emergency surgery were prioritized early during the pandemic, some cancer services, including non-emergency surgeries and screening programs for breast, cervical and colorectal cancers, were delayed or paused.

Some cancers, including bladder, kidney and lung cancer, were not impacted, according to Brenner, an associate professor in the department of oncology and community health sciences at the University of Calgary.

That's likely because there are no asymptomatic screening programs for them and efforts were made to preserve care for later-stage cancers, he said.

The team's modelling suggests 1,455 diagnoses of the four impacted cancers may have been missed, including 350 breast cancers, 398 colorectal cancers, 484 prostate cancers and 223 melanomas, between March and December 2020.

These cancers can be detected before symptoms arise through screening programs.

"These data show concretely that cancer screening works to catch early-stage cancers," said Brenner.