Introduction The dissemination of SARS-Cov2 may have delayed the diagnosis of new cancers. This study aimed at assessing the number of new cancers during and after the lockdown. Methods We collected prospectively the clinical data of the 11.4 million of patients referred to the Assistance Publique Hôpitaux de Paris Teaching Hospital. We identified new cancer cases between January 1 st 2018 and September 31 st 2020, and compared indicators for 2018 and 2019 to 2020 with a focus on the French lockdown (March 17 th to May 11 th , 2020), across cancer types and patient age classes. Results Between January and September, 21,681, 20,778 and 16,764 new cancer cases were identified in 2018, 2019 and 2020, respectively. The monthly median number of new cases reached 2,520 (interquartile range, IQR, 2,328; 2,586), 2,322 (IQR 2,307; 2,399) and 1,949 (IQR 1,586; 2,045) in 2018, 2019 and 2020, respectively. From March 1 st to May 31 st , new cancer decreased by 33% in 2020 compared to the 2018-19 average; then by 19% from June 1 st to September 31 st . This evolution was consistent across all tumor types: -33% and -19% for colon, -30% and -8% for lung, -29% and -13% for breast, -30% and -18% for prostate cancers, respectively. For patients aged < 70 years, the decrease of colorectal and breast new cancers in April between 2018-2019 average and 2020 reached 46% and 44%, respectively. Conclusion The SARS-Cov2 pandemic led to a substantial decrease of new cancer cases. Delays in cancer diagnoses may affect clinical outcomes in the coming years.

The SARS‐Cov2 may have impaired care trajectories, patient overall survival (OS), tumor stage at initial presentation for new colorectal cancer (CRC) cases. This study aimed at assessing those indicators before and after the beginning of the pandemic in France. In this retrospective cohort study, we collected prospectively the clinical data of the 11.4 million of patients referred to the Greater Paris University Hospitals (AP‐HP). We identified new CRC cases between 1 January 2018 and 31 December 2020, and compared indicators for 2018‐2019 to 2020. pTNM tumor stage was extracted from postoperative pathology reports for localized colon cancer, and metastatic status was extracted from CT‐scan baseline text reports. Between 2018 and 2020, 3602 and 1083 new colon and rectal cancers were referred to the AP‐HP, respectively. The 1‐year OS rates reached 94%, 93% and 76% for new CRC patients undergoing a resection of the primary tumor, in 2018‐2019, in 2020 without any Sars‐Cov2 infection and in 2020 with a Sars‐Cov2 infection, respectively (HR 3.78, 95% CI 2.1‐7.1). For patients undergoing other kind of anticancer treatment, the percentages are 64%, 66% and 27% (HR 2.1, 95% CI 1.4‐3.3). Tumor stage at initial presentation, emergency level of primary tumor resection, delays between the first multidisciplinary meeting and the first anticancer treatment did not differ over time. The SARS‐Cov2 pandemic has been associated with less newly diagnosed CRC patients and worse 1‐year OS rates attributable to the infection itself rather than to its impact on hospital care delivery or tumor stage at initial presentation.

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