Background: During the COVID-19 lockdown, referrals via the 2 Week Wait (2WW) urgent pathway for suspected cancer in England are reported to have dropped by up to 84%. We aimed to examine the impact on cancer survival of different scenarios of lockdown accumulated-backlog. We also aimed to examine by tumour-referral-group and age, survival benefit per referred patient considering survival decrement from delayed referral versus risk of death from nosocomial SARS-CoV-2 infection.
Methods: To construct the underlying models, we used age- and stage-stratified 10 year cancer survival estimates for England 2007-2017 for 20 common tumour-types. We applied per-day hazard ratios for cancer progression generated from observational studies of delay to-treatment. We quantified the annual numbers of cancers diagnosed via the 2WW-pathway using the 2WW age- and stage-specific breakdowns. From these, for per-patient delays of 1- 6 months, we estimated aggregate number of lives lost and life-years lost in England. Using referral-to-diagnosis conversion rates and COVID-19 case fatality rates, we also estimated the survival increment per patient referred. Findings: Per month across England in 2013-2016, on average 6,281 patients with Stage 1- 3 cancer were diagnosed via the 2WW pathway of whom 1,691 would be predicted to die within 10 years from their disease. We estimated 2WW-pathway presentational-delay from three months of lockdown will result in total in 181/361/542 attributable additional deaths (if % reduction in referrals was 25/50/75% respectively). Limited diagnostic capacity to address the backlog may result in additional delays: 401/811/1,231 attributable additional deaths are estimated if additional diagnostic capacity is delayed until months 3-8 post-lockdown. 2-month delay in 2WW investigatory referral results in average loss of life-years per-referred-patient of between 0 and 0.7, depending on age and tumour-type. Interpretation: Prompt provision of additional capacity for ‘catch-up’ in diagnostics will minimise deaths consequent from ‘diagnostic-delay’ accumulated on top of the ‘presentational-delay’. Prioritisation of patient groups for whom delay would result in most life years lost warrants consideration as an option for mitigating the aggregate burden of mortality. Funding: None