The projected impact of the COVID-19 lockdown on breast cancer deaths in England due to the cessation of population screening: a national estimation.

BACKGROUND: Population breast screening services in England were suspended in March 2020 due to the COVID-19 pandemic. Here, we estimate the number of breast cancers whose detection may be delayed because of the suspension, and the potential impact on cancer deaths over 10 years. METHODS: We estimated the number and length of screening delays from observed NHS Breast Screening System data. We then estimated additional breast cancer deaths from three routes: asymptomatic tumours progressing to symptomatically diagnosed disease, invasive tumours which remain screen-detected but at a later date, and ductal carcinoma in situ (DCIS) progressing to invasive disease by detection. We took progression rates, prognostic characteristics, and survival rates from published sources. RESULTS: We estimated that 1,489,237 women had screening delayed by around 2-7 months between July 2020 and June 2021, leaving 745,277 outstanding screens. Depending on how quickly this backlog is cleared, around 2500-4100 cancers would shift from screen-detected to symptomatic cancers, resulting in 148-452 additional breast cancer deaths. There would be an additional 164-222 screen-detected tumour deaths, and 71-97 deaths from DCIS that progresses to invasive cancer. CONCLUSIONS: An estimated 148-687 additional breast cancer deaths may occur as a result of the pandemic-related disruptions. The impact depends on how quickly screening services catch up with delays.

Optimum screening mammography reading volumes: evidence from the NHS Breast Screening Programme.

OBJECTIVES: Minimum caseload standards for professionals examining breast screening mammograms vary from 480 (US) to 5000 (Europe). We measured the relationship between the number of women's mammograms examined per year and reader performance. METHODS: We extracted routine records from the English NHS Breast Screening Programme for readers examining between 1000 and 45,000 mammograms between April 2014 and March 2017. We measured the relationship between the volume of cases read and screening performance (cancer detection rate, recall rate, positive predictive value of recall (PPV) and discrepant cancers) using linear logistic regression. We also examined the effect of reader occupational group on performance. RESULTS: In total, 759 eligible mammography readers (445 consultant radiologists, 235 radiography advanced practitioners, 79 consultant radiographers) examined 6.1 million women's mammograms during the study period. PPV increased from 12.9 to 14.4 to 17.0% for readers examining 2000, 5000 and 10000 cases per year respectively. This was driven by decreases in recall rates from 5.8 to 5.3 to 4.5 with increasing volume read, and no change in cancer detection rate (from 7.6 to 7.6 to 7.7). There was no difference in cancer detection rate with reader occupational group. Consultant radiographers had higher recall rate and lower PPV compared to radiologists (OR 1.105, p = 0.012; OR 0.874, p = 0.002, unadjusted). CONCLUSION: Positive predictive value of screening increases with the total volume of cases examined per reader, through decreases in numbers of cases recalled with no concurrent change in numbers of cancers detected. KEY POINTS: • In the English Breast Screening Programme, readers who examined a larger number of cases per year had a higher positive predictive value, because they recalled fewer women for further tests but detected the same number of cancers. • Reader type did not affect cancer detection rate, but consultant radiographers had a higher recall rate and lower positive predictive value than consultant radiologists, although this was not adjusted for length of experience.