Cancer screening for breast, colorectal and cervical cancers significantly reduced across the world during the COVID-19 pandemic
Cancer screening for breast, colorectal and cervical cancers was significantly reduced during the period of the pandemic compared to pre-pandemic levels according to the results of a systematic review by a group of Italian and US researchers.
According to GLOBOCAN in 2020 there were an estimated 19.3 million new cancer cases and almost 10.0 million cancer deaths and that cancer screening has contributed to a decrease in both cancer morbidity and mortality. As a result, any reduction in screening could potentially lead to a surge in cases. In fact, modelling studies have already indicated a possibly large increase in cases due to the pandemic. For example, one Canadian simulation suggested that the interruption of services to COVID-19 could lead to an additional 310 cases diagnosed at advanced stages and 110 cancer deaths. Moreover, in a UK-based modelling study, the authors estimated that as a consequence of the pandemic, there would be a 7·9-9·6% increase in the number of deaths due to breast cancer up to year 5 after diagnosis and for colorectal cancer a 15·3 – 16·6% increase in additional deaths.
However, because of differences in the start date and duration of lockdown measures across the world, for the present study, the researchers wanted to examine how this variation impacted on screening. They focused on breast, colorectal and cervical cancer screening since the beginning of the pandemic and made a comparison with pre-pandemic levels. The team searched all the major databases for observational studies and articles that reported data from cancer registries and which compared the level of screening tests performed before and during the pandemic and in different areas of the world.
Cancer screening reductions during the pandemic
A total of 39 articles were identified and included in the analysis with 21 related to breast, 22 colorectal and 11 for cervical cancers.
For the period between January and October 2020, there was an overall 46.7% (95% CI -55.5% to -37.8%) decrease in breast cancer screening in comparison the pre-pandemic level.
For colorectal cancer, the overall reduction was 44.9% (95% CI -53.8% to -36.1%) and this included a 52.5% reduction in colonoscopy, a 37.8% decrease in faecal occult blood testing and a 37.8% decrease in immuno-chemical testing.
With cervical cancer, the overall reduction was -51.8% (95% CI -64.7% to -38.9%).
Commenting on their findings, the authors noted that these reductions in screening occurred across the world but that there were some obvious differences. For example, Europe saw the largest reduction in mammography compared to North America. although the decrease for both colorectal and cervical cancer screening was similar in both areas. The authors suggested that the most likely explanation for the reduced screening was the ‘stay at home’ order introduced during the early stages of the pandemic.
They concluded that there was a large reduction in cancer screening as a consequence of the COVID-19 pandemic and which could be associated with an increased number of deaths and called for further work to investigate the relationship between cancer diagnosis and treatment during the pandemic.
Teglia F et al. Global Association of COVID-19 Pandemic Measures With Cancer Screening: A Systematic Review and Meta-analysis JAMA Oncol 2022