Table 2. Global institutional elective procedure performance reductions and outcome determinants.

BREAST CANCER
No.:	Authors (year of publication)	Study design	Country	No. of patients, (year)	No. of elective procedures performed (%), (year), p-value	Case performance reduction, (%)	Outcome determinants (qualitative)
1	Fregatti et al. (2020)	Cross-sectional study	Italy	n = 85	n = 71 (83.53%)	16.5%	• Pre-operative SARS-CoV-2 screening (surgery delayed if positive) • Potential information bias: Patients’ responses to coronavirus symptom screen • Healthcare personnel redeployment • Reduced availability of operating theatres
COLORECTAL CANCER
2	Giuffrida et al. (2020)	Case series	Italy	n = 13	n = 13 (2020) vs. Pre-pandemic: n = 25 (2019)	48%	• Local COVID-19 prevalence • Lockdown • Conversion of hospital departments to COVID-19 units • Insufficient hospital bed capacity • Delayed screening and diagnostic tests • Increased care-seeking hesitancy and resultant delays in diagnosis • Disrupted continuity of care (daily changes of practice and workplans)
3	Tejedor et al. (2021)	Case series	Spain	n = 301	n = 259 (86.05%)	13.95%	• Limited study follow-up period • Hospital case volume of COVID-19 • Pre-operative SARS-CoV-2 screening (surgery delayed if positive) • Referral to other facilities • Eligibility for interim NACRT • PPE shortages • Loss to follow-up • Other reasons (unspecified)
4	Matosevic et al. (2021)	Case series	Croatia	n = 116	n = 116 (2020) vs. Pre-pandemic: n = 147 (2019)	21.09%	• Clinical anaesthetic risk assessment • Clinical risk profile overall (age, comorbidities, physical habitus) • Pathologic tumour staging • Eligibility for interim NACRT or ‘watch-and-wait’ approach • Delayed screening and diagnostic tests • Type of procedure required • Hospital resource availability
5	Feier et al (2022)	Case series (Comparative to pre-pandemic period)	Romania	n = 147	n = 29 (from 2020–2021) n = 68 (from 2018–2019) n = 50 (from 2016–2017)	57.3% (compared to 2018–2019) 42% (compared to 2016–2017)	• Delayed presentation: Local public health messaging to patients to present to hospital only in the instance of severe symptoms or (surgical) emergencies • Care-seeking hesitancy among patients due to fear of contagion • Delayed screening and diagnostic tests • Conversion of intensive care unit to COVID-19 unit • National ‘state of emergency’ declaration on 16 March 2020
6	Tarta et al (2022)	Case series	Romania	N = 198 n = 83 (2019) n = 80 (2020) n = 84 (2021)	n = 57 (68.7%) (2019) n = 40 (50.0%) (2020) n = 36 (42.9%) (2021) p = 0.002	25.8% (comparing 2021 to 2019) 7.1% (comparing 2021 to 2020)	• Suspension of elective surgery services • Suspension of screening colonoscopy services • Delayed presentation due to care-seeking hesitancy • Higher number of emergencies due to delayed presentation with resultant development of complications • Elective procedures delayed until patients demonstrated negative SARS-CoV-2 PCR test results
7	Sozutek et al. (2021)	Cohort study	Turkey	n = 99 n = 40 (Colon cancer) n = 59 (Rectal cancer)	n = 99	0%	• No SARS-CoV-2 infections (Healthcare personnel or patients) during study period • Clinical anaesthetic risk assessment • Clinical risk profile overall (age, comorbidities) • Pathologic tumour staging • Eligibility for interim NACRT • Fidelity to standardised treatment algorithms and clinical guidelines • Re-organisation of hospital units, physical distancing of beds • Hospital resource availability
8	Cui et al. (2021)	Case series (Comparative to pre-pandemic period)	China	n = 67	n = 67 (2020) vs. Pre-pandemic: n = 101 (2019) n = 104 (2018)	66.34%	• Adherence to national- and professional epidemic control standards • Decreased number of health consultations • Pathologic tumour staging • Limited bed capacity • Patient avoidance of long-distance traveling to health facilities due to fear of contagion
9	Sobrado et al. (2021)	Cross-sectional study	Brazil	n = 90 (For diagnosis of CRC)	n = 90	0%	• Pathologic tumour staging • Eligibility for interim NACRT • Decreased number of health consultations during COVID-19 pandemic • Local COVID-19 public health policy • Pre-operative SARS-CoV-2 screening test result (surgery delayed if positive) • No SARS-CoV-2 vaccine availability at the time of study
10	Santoro et al. (2021)	Cross-sectional expert survey: Expert respondents reported ‘Delays’ or ‘No delays’ in CRC diagnosis or surgery	Global (84 countries)	Total: n = 1,051 n = 745 (70.9%)–Reported ‘Delays’ n = 306 (29.1%)–Reported ‘No delays’	N/A	70.9% (Affected by delays)	• Local COVID-19 prevalence and public health response • Hospital involvement in COVID-19-care (e.g., Fully- vs. partially dedicated) • Type of hospital (academic vs. non-academic, bed capacity) • Availability of ‘COVID-19-free’ units • Availability of COVID-19 clinical protocols • Delayed diagnostic services (endoscopy, histopathology) • Suspended multidisciplinary meetings • PPE shortages • Pre-operative SARS-CoV-2 screening test result (surgery delayed if positive) • Pathologic tumour staging • Eligibility for interim NACRT • Personnel infection with SARS-CoV-2 • Personnel redeployment
BREAST- OR COLORECTAL CANCER
11	Aguiar et al. (2020)	Research letter: Cross-sectional study	Brazil	Total: n = 540 Breast: n = 88 Colorectal: n = 32 Other: n = 420	n = 454 (84.1%) Breast: n = 83 (94.32%) Colorectal: Not stated (Gastrointestinal: n = 96)	Breast: 5.68% Colorectal: Not stated (Gastrointestinal: 10.42%)	• Pre-operative SARS-CoV-2 screening test result (surgery delayed if positive) • Patient-specific factors: • Voluntary cancellation of procedure • Access to health insurance • Geographic residential proximity to healthcare facilities
12	Nepogodiev et al. (2020) COVIDSurg Collaborative Study	Ecologic, modelling study	Global: 84 countries	CRC: n = 486,583 Benign breast- or ‘other’ cancer: n = 6,760,731	CRC: n = 486,583 Other diagnoses (incl. benign breast conditions): n = 6,760,731 vs. Pre-pandemic: CRC: n = 1,353,952 Other surgery incl. benign breast surgery: n = 8,273,626	CRC: 35.9% Other surgery incl. breast surgery: 81.7%	• Local COVID-19 prevalence • Local public health policy • Fidelity to national or international clinical guidelines, including with respect to suspension of elective surgery

Abbreviations–CRC: Colorectal cancer