The COVID-19 pandemic has changed the priority of medical care around the globe. In April 2020, Centers for Medicare and Medicaid Services recommended postponing medical services such as routine care and preventive screening in order to triage resources and reduce risk of transmission . The enforcement of public health guidelines, compounded with the fear of infection, dissuaded people from going to hospitals to seek care or undergo routine examinations. Such a trend can be seen in cancer screening across the globe. Numerous studies have reported a precipitous drop in cancer screening since the pandemic began . During the three-month period between March and June 2020, Massachusetts General Brigham (MGB) noted a sharp decline in five common screening tests for cancer: mammography, colonoscopy, Papanicolaou test, low-dose computed tomography (CT) and prostate-specific antigen screening. Compared to the preceding three months, the number of tests administered decreased by 60% to 82% . This phenomenon, dubbed as “The COVID Cancer Effect,” was not singular – locations around the world have reported similar levels of reduction in screenings . This has unsettled the medical community, which worries that those missed or delayed cancer diagnoses might foreshadow worse prognosis and increasing mortality [1, 15]. A statistical model released in July 2020 forecasted almost 10,000 excess deaths caused by breast and colorectal cancer alone due to the effect of COVID-19 on screening .
The situation appeared dire. However, cancer is a long-term and complex disease. Two years are too short to fully evaluate the effect of COVID-19 on cancer. The public health quandary is further complicated by inconclusive evidence supporting the benefits of routine screening for cancer, which has led to disparate conclusions and recommendations. For example, mammography, a non-invasive procedure for breast cancer screening, has long been controversial. Different organizations, such as the US Preventive Services Task Force, the American Cancer Society and the American College of Radiology, offer different or even conflicting recommendations on mammography, especially for people in their 40s . Despite the potential benefits of reducing treatment side effects and prolonging life expectancy, going through a cancer screening may have various side effects. People may have to endure anxiety and even unnecessary procedures due to false positives . Moreover, the amount of missed or delayed diagnoses might be exaggerated because high-risk patients remained being prioritized for screening. According to data reported by MGB, the number of screenings administered decreased more dramatically than the number of diagnoses followed by screening . In other words, a missed screening test does not necessarily equate to a missed cancer diagnosis. Therefore, a projection of cancer mortality simply based on number of screenings may be an overestimation of COVID-19’s effect on cancer detection. In addition, as lockdowns lifted and vaccines rolled out, the number of diagnoses across all major cancers rebounded, although it has fluctuated with surges in COVID-19 cases and has not recovered to pre-pandemic levels [7, 12].
Still, the drop in both diagnosis and screening is significant, and its consequences are concerning for many. In general, earlier detection of cancer allows for more therapeutic interventions, and advanced stage cancer is associated with worse patient outcomes . Davis et al. examined data from two major northeastern cancer centers in the US and found that although similar number of patients were diagnosed with melanoma during the pre-lockdown (August 2019 – March 2020) and post-lockdown period (May – December 2020), the percentage of advanced stage cancer increased from 7.1% to 27.1%, which may be caused by the delay in diagnosis due to the lockdown . A group of researchers in France demonstrated a similar uptick in advanced breast cancer diagnosis post-lockdown: the rate of small tumors decreased compared to pre-lockdown, while the rate of locally advanced cancer grew by 80% . Post-lockdown patients may need to endure more intensive therapeutics and have worse prognoses.
Analyses of potential consequences of the pandemic are also limited by data and metrics currently available. Two studies have considered the socioeconomic status (SES) of the patients and found a more significant decrease in breast and colorectal cancers among patients with higher SES status [7, 14]. However, both studies obtained data of privately or publicly insured individuals, so they might underestimate the effect of SES, which was perceived by clinicians as an important barrier to receiving a colonoscopy . Furthermore, cancer screening has a differential impact on different communities. A study has analyzed over four hundred thousand patients with breast, prostate, colorectal and cervix cancer and discovered that uninsured individuals were more likely to present cancer with more advanced stages in screening . Marginalized populations who may work in hazardous environments can have higher risk of cancer but limited access to health care, and COVID-19 may have enlarged the health care disparities .
As the pandemic continues to unfold, technological solutions such as telehealth and at-home test kits have emerged to remedy the consequences of reduced hospital screenings [4, 11]. One study estimated that increasing usage of fecal immunochemical test (FIT), an at-home screening test for colorectal cancer, will help an additional 20% of eligible individual to complete the screening, decreasing the reduction caused by the prolonged pandemic . In the midst of pessimistic estimations, these technological mitigations have offered hope, yet the future remains unclear until more evidence emerges. The pandemic abates, but the repercussion of COVID-19 on cancer will be long-lasting.
Edited by: Rehan Mehta
Illustrated by: Jenny Yoo