Patients diagnosed with colorectal cancer after a Covid-19 lockdown may experience worse outcomes than those diagnosed before, according to a new study published in JAMA Network Open.

Study details

In the study, researchers analyzed 80 patients in France who had been diagnosed with metastatic colorectal cancer. Half of the patients received cancer screenings between November 11, 2019, and March 9, 2020, before the country's first 55-day pandemic lockdown. The other half received cancer screenings between May 14, 2020, and September 3, 2020, after the lockdown.

The patients included 48 men and 32 women, with a median age of 62 years old. Patients were initially recruited through the PANIRINOX study, a clinical trial testing a targeted therapy for metastatic colorectal cancer. The patients received care at 18 clinical centers in France and had blood samples collected to identify RAS and BRAF mutations.

The researchers analyzed the tumor burden among patients in the study by measuring the circulating tumor DNA (ctDNA) in their plasma. They then compared the ctDNA in patients who were screened before the lockdown and patients who were screened after.

Key findings

The researchers found that the median ctDNA concentration in patients diagnosed with metastatic colorectal cancer after the lockdown was statistically higher than those who had been diagnosed before the lockdown.

Specifically, the researchers found that the tumor burden for patients diagnosed after the lockdown was nearly seven times higher than patients who had been diagnosed before the lockdown. In addition, they found that higher tumor burden was linked to a lower median survival of 14.7 months compared with 20 months.

"The tumor burden of colorectal cancer varied and appeared to be associated with poor survival for those who received a post-lockdown diagnosis, suggesting that this cancer is a major area for intervention to minimize Covid-19-associated diagnostic delay," the researchers wrote.

Comments and implications for the future

According to the researchers, their study is the first to assess the clinical effects of delayed diagnosis and treatment due to the Covid-19 pandemic for a specific cancer.

"The use of a clinically validated blood test enabled us to present the first quantitative assessment of tumor burden related to a specific cancer during pre- and post-lockdown periods," Alain Thierry, the director of research at INSERM and Institut de Recherche en Cancérologie de Montpellier and the study's lead author, said. "These numbers highlight the lockdown's human cost, since our data suggested median survival decreased by half."

He added, "Our data points first, to the crucial importance of early detection; second, to [the need] to maintain screening programs and diagnostic services during a pandemic; and third, to the need … to minimize patient's fears by ensuring [better] communication."

According to STAT News, earlier studies using models have also suggested the health consequences of missed cancer screenings during the pandemic may be significant. For example, a model from the National Cancer Institute that examined breast cancer and colorectal cancer predicted that there would be 10,000 additional deaths in the United States over the next decade because of delays in tumor diagnosis and treatment during the pandemic.

In addition, data from Quest Diagnostics indicate that screenings still have not returned to their pre-pandemic levels. Specifically, an August analysis from the organization found that while diagnoses of eight cancers, including breast, colorectal, lung, and prostate cancer, returned to pre-pandemic levels during the summer of 2020, they dropped once more from November 2020 through March 2021.

However, the researchers cautioned that the results of their study only show "a snapshot of a situation that continues to evolve." They added that more research and time is necessary before broader conclusions about the impact of delayed diagnosis or treatment can be drawn.

Separately, Quoc-Dien Trinh, of the Dana-Farber Cancer Institute and Brigham and Women's Hospital, who was not involved in the study, said while the number of patients included in the study was relatively small, "we can all agree that the consequences of the Covid-19 pandemic on cancer care are real. It will take years to fully understand the pandemic's impact, but it would not be entirely surprising to find that we are nowadays treating a higher proportion of individuals presenting with late-stage cancers … with downstream effects on cancer mortality." (Cooney, STAT News, 9/8; Carbajal, Becker's Hospital Review, 9/8; Thierry et al., JAMA Network Open, 9/8)