Impact of COVID-19 Pandemic on Cancer Incidence
The COVID-19 pandemic caused a substantial decline in cancer diagnoses during 2020, with screening-detected cancers dropping by 75-85% at the pandemic's peak, but incidence rates largely returned to near pre-pandemic levels by 2021 without a compensatory rebound to capture the missed 2020 diagnoses—except for metastatic breast cancer, which showed significantly elevated rates, suggesting delayed diagnoses progressed to more advanced stages. 1
Magnitude of Cancer Diagnosis Decline
The pandemic created an unprecedented disruption in cancer detection:
- Peak screening reductions in April 2020: Breast cancer screening dropped 85%, colorectal cancer 75%, prostate cancer 74%, and lung cancer 56% compared to 2019 baseline 2
- Overall cancer case decline: A cumulative 7.3% year-over-year reduction in total cancer diagnoses following pandemic onset 3
- Screen-detected cancers most affected: Nonmelanoma skin cancer declined 20.2%, breast cancer 14.3%, and prostate cancer 12.8% 3
Timeline of Recovery Pattern
The recovery followed a distinct three-phase pattern:
- Acute decline phase (4 weeks): Precipitous drop of 110 cases per week starting March 4,2020 3
- Moderate recovery phase (10 weeks): Partial rebound of 23.7 cases per week 3
- Gradual normalization: Cancer diagnoses trended slowly back toward pre-pandemic baseline over approximately 12 months 3
Critical Finding: Incomplete Recovery
By 2021, cancer incidence rates returned close to expected pre-pandemic trends but did NOT show a rebound that incorporated the delayed diagnoses from 2020 1. This represents a critical gap—the "missing" cancers from 2020 were not subsequently diagnosed in 2021 at higher-than-expected rates.
Exception: Metastatic Breast Cancer
Metastatic breast cancer showed significantly higher observed rates than expected in 2021 (rate ratio = 1.09,95% CI = 1.04-1.13) 1. This suggests that diagnostic delays allowed earlier-stage cancers to progress to metastatic disease, directly impacting mortality and quality of life.
Clinical Service Disruptions
Beyond screening, the entire cancer care continuum was affected:
- Outpatient visits: Hospital outpatient evaluation and management visits declined 74% in April 2020 2
- New patient encounters: New patient visits dropped 70% 2
- Cancer treatment: Physician-administered oncology products decreased 26% in April and 31% in July 2020 2
- Surgical procedures: Mastectomies reduced consistently April-July, colectomies in April-May, prostatectomies in April and July 2
Long-Term Implications for Mortality and Morbidity
Diagnostic delays longer than 3 months potentially compromise cancer-specific outcomes 4. The Italian College of Breast Radiologists emphasized that while short delays of 6-12 weeks should not affect overall outcomes, delays exceeding 3 months carry risk 4.
The failure to see a compensatory rebound in 2021 diagnoses means:
- Cancers remain undiagnosed in the population
- Stage migration toward more advanced disease at diagnosis (as evidenced by metastatic breast cancer increases)
- Increased future cancer mortality and decreased quality of life
Populations Most Affected
Variations in case volume reductions occurred across:
- Geographic regions
- Age groups
- Gender
- Race
- Insurance coverage status 3
Among cancer patients tested for COVID-19,5.3% had positive results 3, highlighting the dual burden faced by this vulnerable population.
Current State and Ongoing Monitoring Needs
Ongoing monitoring and targeted interventions are needed to address the long-term consequences of the COVID-19 pandemic on cancer care and outcomes 1. The pandemic created an opportunity to reassess early detection programs with explicit prioritization of populations historically experiencing cancer disparities 5.
Priority Populations for Screening Recovery
Target guideline-eligible people who have never been screened or are significantly out of date with screening to maximize benefits 5. This approach focuses resources on populations with the most to gain from screening interventions.
Common Pitfalls to Avoid
- Assuming natural recovery: Do not assume missed diagnoses will automatically present later—the 2021 data shows they did not 1
- Ignoring stage migration: The metastatic breast cancer increase demonstrates real harm from delays 1
- Uniform approach: Screen-detected cancers (breast, colorectal, prostate) were disproportionately affected compared to symptom-detected cancers 3