Screenings for a variety of common cancers have not returned to pre-pandemic levels, potentially leading to diagnoses later in the course of the disease when it may be more difficult to treat successfully, U.S. data published on Thursday suggest.

In 2020 - the first year of the pandemic - average rates of screening for breast cancer fell by 40%, for cervical cancer by 36%, and for colorectal cancer by 45%, compared to the three previous years, according to an analysis of medical claims data from 306 million adults.

Diagnoses of breast, cervical and colorectal cancers dropped by roughly 6% to 7% between 2019 and 2020 and by an additional 5% to 6% between 2020 and 2021, the researchers also found.

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The decrease in diagnoses "does not mean these cancers are suddenly less common," said study leader Allison Oakes of data analytics company Trilliant Health in Brentwood, Tennessee. "Rather, it means there are people with cancer who are going to be diagnosed at a later, more severe stage of the disease."

By the end of 2021, screening rates had rebounded but were still below pre-pandemic levels, researchers reported in JAMA Oncology.

A patient undergoes a breast cancer screening in Nairobi, Kenya, on Jan 23, 2020.  (REUTERS/Njeri Mwangi/File Photo)

Ongoing analysis of 2022 data suggests screening rates in 2022 are unlikely to have improved dramatically, Oakes said.

"We do not see significant changes in behavior when looking quarter-over-quarter," she added.

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The issue appears to go beyond cancer testing, the study found.

Healthcare utilization for non-COVID, non-mental-health issues in the first quarter of 2022 was 6.2% lower than in the first quarter of 2019, Oakes said.

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"Not only are people missing their annual cancer screenings, but they are using less primary care," Oakes said.

"While Americans appear to be getting back to normal everyday life, whether in-office work or leisure travel, many of them are still avoiding the healthcare system."