Decline in Cancer Diagnoses during the ‘Zero COVID’ Policy in Hong Kong: Indirect Spillover Impact of the COVID-19 Pandemic

Abstract

<p><strong>Aims</strong></p><p>Despite a largely successful ‘zero COVID’ policy in 2020, the COVID-19 pandemic disrupted routine cancer services in the city of Hong Kong. The aims of this study were to examine the trends in cancer incidence before and during the COVID-19 pandemic and estimate missed cancer diagnoses.</p><p><strong>Materials and methods</strong></p><p>We used population-based data from the Hong Kong Cancer Registry 1983–2020 to examine the trends of age- and sex-standardised cancer incidence before and during the COVID-19 pandemic. We applied: (i) the annual average percentage change (AAPC) calculated using the Joinpoint regression model and (ii) the autoregressive integrated moving average (ARIMA) model to forecast cancer incidence rates in 2020. Missed cancer diagnoses in 2020 were estimated by comparing forecasted incidence rates to reported rates. A subgroup analysis was conducted by sex, age and cancer site.</p><p><strong>Results</strong></p><p>The cancer incidence in Hong Kong declined by 4.4% from 2019 to 2020 (male 8.1%; female 1.1%) compared with the long-term AAPC of 0.5% from 2005 to 2019 (95% confidence interval 0.3, 0.7). The gap between the reported and forecasted incidence for 2020 ranged from 5.1 to 5.7% (male 8.5%, 9.8%; female 2.3%, 3.5%). We estimated 1525–1596 missed cancer diagnoses (ARIMA estimate –98, 3148; AAPC 514, 1729) in 2020. Most missed diagnoses were in males (ARIMA 1361 [327, 2394]; AAPC 1401 [1353, 1460]), with an estimated 479–557 missed cases of colorectal cancer (ARIMA 112, 837; AAPC 518, 597) and 256–352 missed cases of prostate cancer (AAPC 231, 280; ARIMA 110, 594).</p><p><strong>Conclusion</strong></p><p>The incidence of new cancer diagnoses declined in 2020 contrary to the long-term increase over the previous decades. Significantly lower diagnoses than expected were observed in males, particularly for colorectal and prostate cancers. Fewer reported cancer cases indicate missed diagnoses and could lead to delayed treatment that could impact future health outcomes.</p>