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Rates of new cancer diagnoses in the United States declined substantially during the early months of the COVID-19 pandemic amid recommendations that screenings be postponed, with potentially significant consequences.

“While residents have taken to social distancing, cancer does not pause,” say the authors of a new analysis published online in JAMA Network Open.

“The delay in diagnosis will likely lead to presentation at more advanced stages and poorer clinical outcomes,” the authors warn.

The National Cancer Institute (NCI) has recently warned of the impact that the pandemic could have on cancer outcomes, predicting more than 10,000 excess cancer deaths during the next decade as a result of missed screenings, delays in diagnosis, and reductions in oncology care caused by the COVID-19 pandemic.

The new analysis was conducted by Harvey W. Kaufman, MD, and colleagues at Quest Diagnostics, Secaucus, New Jersey. The researchers evaluated testing data from the diagnostics company from January 1, 2018, to April 18, 2020. Using ICD-10 codes, they identified patients who had been diagnosed with any of six cancer types (breast, colorectal, lung, pancreatic, gastric, and esophageal).

Two groups of patients were compared ― those diagnosed during the baseline period, from January 6, 2019, to February 29, 2020 (n = 258,598, 92.8%), and those diagnosed during the COVID-19 period, from March 1, 2020, to April 18, 2020 (n = 20,180, 7.8%).

The mean weekly number of patients newly identified as having cancer during the baseline period included 2208 with breast cancer, 946 with colorectal cancer, 695 with lung cancer, 271 with pancreatic cancer, 96 with gastric cancer, and 94 with esophageal cancer.

During the pandemic period, the total mean weekly number for the six cancers combined fell by 46.4% (from 4310 to 2310). There were significant declines in all cancer types.

Mean weekly diagnoses for breast cancer declined by 51.8%, from 2208 to 1064 (P < .001). For pancreatic cancer, diagnoses declined by 24.7%, from 271 to 204 (P = .01).

With regard to age, overall, patients who were diagnosed with cancer during the COVID-19 period were within 1 year in age compared to those diagnosed during the baseline period. Those with esophageal cancer who were diagnosed during the COVID-19 period were slightly older (mean age, 69.5 vs 68.4 years; P = .04). For all other cancers, patients were diagnosed at a younger age during the COVID-19 period.

There were no significant differences in sex distribution of cancer diagnoses during the two periods, with the exception of pancreatic cancer, for which there were fewer women in the baseline group (P = .01).