COVID-19 impact on incidence and stage at diagnosis of five prominent cancers: A French cancer registry-based study.

Background: The French healthcare system has been affected by the COVID-19 pandemic in 2020, including cancer care.

Methods: In order to evaluate the impact of this pandemic on cancer incidence, the Isere Departmental Cancer Registry compared the actual 2020 incidence of melanoma, breast, colorectal, prostate and lung cancers with the expected 2020 incidence based on data collected by the Registry between 2015 and 2019, taking into account periods of lockdown and reopening. When available, cancer stages and/or prognostic scores were recorded.

Results: During the period of initial confinement, a 54%, 50% and 36,8% drop in incidence was observed for breast, prostate and colorectal cancer respectively. Although their annual incidence remained stable, a worsening trend emerged as a decline in the number of low stages/scores at diagnosis in favour of higher stages/scores towards the end of 2020. In contrast, a significant 17,8% drop was observed in annual incidence of melanoma, particularly for Breslow scores < 1 (-27,4%). However, this trend was noticeable before the lockdown, as well as the 14% reduction in the incidence of lung cancer in women, but not in men.

Conclusion: The incidence of certain cancers was caught up over the year but the COVID-19 pandemic seems to be associated with a change in their severity at diagnosis throughout 2020. The downward trends in female lung cancer and melanoma incidence point to complex underlying phenomena. Further analysis is still needed to assess the global impact of the COVID-19 pandemic on cancer incidence.