Abstract P3-12-29: Effect of the COVID outbreak on detection of second primary breast cancer and breast cancer recurrences
Authors: Eijkelboom Anouk H , de Munck Linda , Wesseling Jelle , Westenend Pieter J , van den Bongard Desirée HJG , Hendriks Mariëlle PWA , Broeders Mireille JM , Strobbe Luc JA , Bessems Maud , Honkoop Aafke H , Lobbes Marc BI , Tjan-Heijnen Vivianne CG , Siesling Sabine ,   NABON-COVID-19 consortium and the COVID and Cancer Care-NL consortium
Published: March 2022

Abstract
Introduction: The COVID-19 pandemic led to a decrease in the incidence of breast cancer diagnoses in the Netherlands. This was due to the encouragement to stay at home, a lack of capacity at the general practitioner (GP) and an increased reluctance of patients to visit the GP. Moreover, from the 16th of March the Dutch breast cancer screening program was halted and gradually restarted from June onwards. Part of the follow-up visits for breast cancer survivors were also postponed or changed to an appointment by phone. However, it is not known how this affected the incidence of second primary breast cancer (SPBC) and pathologically confirmed breast cancer recurrences . Objective: To investigate the effect of the COVID-19 pandemic on the diagnosis of SPBC and breast cancer recurrences. Methods: Women diagnosed with a pathological confirmed SPBC or recurrence (locoregional recurrences (LRR) + distant metastasis (DM)) between January 1st 2017 and February 28th 2021 were selected from the Netherlands Cancer Registry, based on diagnoses of the Nationwide Histopathology and Cytopathology Data Network and Archive (PALGA). Patients with a SPBC or recurrence who had their primary breast tumor diagnosed more than five years ago were excluded. March 1st 2020 till February 28th 2021 was regarded as the COVID-19 period. Incidence was expressed per 100,000 women, who were diagnosed with breast cancer less than 5 years ago, and who were still alive. Incidence of SPBCs and recurrences was calculated for the total COVID-19 period and for four subperiods, and compared with the corresponding periods in 2017/2019 (averaged). Results: A total of 393 patients were diagnosed with a SPBCs in 2017, 340 in 2018, 299 in 2019, 342 in 2020 and 71 up to February 2021. A total of 447 patients were diagnosed with a recurrence in 2017, 520 in 2018, 516 in 2019, 529 in 2020 and 80 up to February 2021. During the COVID-19 period a total of 449 patients were diagnosed with a SPBCs per 100,000 breast cancer survivors, this was comparable to the 445 patients diagnosed per year per 100,000 breast cancer survivors in 2017/2019 (p=0.91) (Table 1). The incidence of SPBCs was significantly lower during March-May 2020 compared to the same period in 2017/2019 (86 vs. 121) (p=0.03), leading to 50 less SPBCs diagnoses. The incidence was higher during June-August 2020 (124 vs. 95), however this was not significant (p=0.09). The incidence of recurrences in the COVID-19 period, and within all four subperiods, was comparable to the incidence in 2017/2019. Conclusion: The COVID-19 pandemic led to a decrease in the detection of SPBCs at the beginning of the pandemic. However, this drop in incidence was caught up in the period thereafter. This might be related to the restart of the regular follow-up visits (partly in real-life consultations), the call to go to the GP in case of complaints and the improved accessibility of the GPs. The incidence of recurrences did not decrease since it includes also DM, which cause worrisome symptoms for which care is sought.
Incidence of pathological confirmed second primary breast cancer and breast cancer recurrencesSPBCP-value1Recurrence2P-value1Reference3445.00.91639.40.63COVID-19 period4448.7658.9March - May reference3120.70.03151.80.64March - May 202085.9142.3June - August reference395.30.09166.40.37June - August 2020124.3185.9September - November reference3125.00.78159.50.54September - November 2020120.5171.8December - February reference3104.80.44166.40.70December 2020 - February 2021117.9159.0Incidence is expressed per 100,000 women who were diagnosed with breast cancer less than 5 years ago and who were still alive SPBC: Second primary breast cancer Bold: incidence in that period of 2020/2021 is statistically significantly lower compared to the incidence in 2017/2019 (averaged) 1. Comparing 2020/2021 with the same period in 2017/2019 2. Recurrence included locoregional recurrences and distant metastasis 3. Reference period: 2017/2019 4. COVID-19 period: March 2020 - February 2021
Citation Format: Anouk H Eijkelboom, Linda de Munck, Jelle Wesseling, Pieter J Westenend, Desirée HJG van den Bongard, Mariëlle PWA Hendriks, Mireille JM Broeders, Luc JA Strobbe, Maud Bessems, Aafke H Honkoop, Marc BI Lobbes, Vivianne CG Tjan-Heijnen, Sabine Siesling, NABON-COVID-19 consortium and the COVID and Cancer Care-NL consortium. Effect of the COVID outbreak on detection of second primary breast cancer and breast cancer recurrences [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-29.