ABSTRACT
Background-Physical distancing for COVID-19 led to decreased in-person patient follow up assessments and delayed imaging appointments. Herein we describe for the first time the impact of delays in diagnostic investigations of patients with an history of early-stage breast cancer (BC) in the largest public cancer center of Lombardy, the Italian region most affected by the pandemic. Methods-This single-institution retrospective study included three observational periods. The first pandemic peak period (March-April 2020) corresponding to the interruption of follow up imaging;the post-peak period (May-December 2020);the pre-pandemic period represented by the five previous years (January 2015-December 2019) as control. The flow of diagnostic activities was compared among the different years. Moreover, the number and characteristics of recurrent BC cases (rBC) diagnosed in the post-peak period were compared to the figures observed in pre-pandemic years, when imaging was regularly carried out, using descriptive statistics. A further comparison was performed between the characteristics of scheduled and delayed rBC diagnosed after the first peak. Results-During the first pandemic peak, diagnostic investigations declined by 81.2% (from 1032 in January-February to 194 in March-April), a drop which was not identified in the same period of the pre-pandemic years, before rebounding to 1065 in May-June, 832 July-August (reflecting the Ssummer physiological drop), 1334 September-October, and 879 November-December. The average number of rBC cases of 16 (range 12-25) in March-April of the pre-pandemic period declined to a value as low as 4 during the first pandemic peak. Thereafter, the number of rBC cases began a steady increase, until reaching a total of 27 in September-October 2020, almost doubling the mean of 14.8 (range 11-21) achieved in the corresponding months of 2015-2019. As a result, the absolute number of rBC cases was 76 in 2020 and on average 78.4 (range 70-95) in pre-pandemic years, and the rBC proportion of 1.42% (76/5336;95% exact confidence interval, CI: 1.12-1.78%) in 2020 was slightly higher than the average proportion of 1.26% of the five previous years, though the latter being well included in the CI of the 2020 proportion. No difference in primary tumor presentation and age at initial diagnosis was found among recurrent patients before and after the pandemic. Of the rBC cases reported during 2020, 10 were from 513 patients with postponed follow up who were finally diagnosed between September-December. As compared to patients on schedule, delayed rBC cases did not present with ductal carcinoma in situ, and reported a median tumor size of 18 mm (range 4.3-90 mm), which was 20% higher than the median of 15 mm (3.1-34) observed for scheduled patients. Distribution of luminal-like, triple negative and HER2-overexpressing BC subtypes among evaluable rBC cases was 75%, 12.5%, 12.5% in scheduled and 66%, 11% and 22% in delayed cases, respectively. Conclusions-Our data showed a slight decrease in the absolute number of rBC during 2020 despite a rebound of examinations, and an increased size of invasive recurrence following the 2-month stop of the first pandemic peak. The full impact of the COVID-19 pandemic on recurrent cancer diagnosis will be known when national population-based data become available in the coming years.