Why Did Breast Cancer Diagnoses Decline in 2020? The Impact of COVID-19 in Japan

Introduction

While breast cancer incidence in Japan has generally increased over the years, 2020 saw an unexpected decline. This article explores the reasons behind this drop, focusing on the impact of the COVID-19 pandemic on cancer screening and diagnosis.

Incidence Trends

According to data from the National Cancer Center Japan and e-Stat, the number of newly diagnosed breast cancer cases in 2020 was approximately 94,500, down by about 2,300 cases compared to the previous year.

Main Reasons for the Decline

• Suspension and postponement of cancer screenings
  Many municipalities and medical institutions canceled or scaled down group screenings. Individual screenings were also limited due to reduced capacity and public health restrictions.
• Avoidance of medical visits
  Fear of infection and public messaging around “non-essential outings” led many individuals to delay or skip medical consultations—even when symptoms were present.
• Reduced opportunities for diagnosis
  Experts suggest that the actual incidence rate did not decrease, but rather, fewer cases were diagnosed due to missed screenings and delayed visits.

Expert Insights

Reports from the Japan Cancer Society indicate a drop in early-stage breast cancer diagnoses and a rise in later-stage detections, suggesting that delays in screening may have led to more advanced disease at the time of diagnosis.

Conclusion

The decline in 2020 was likely a temporary statistical effect caused by pandemic-related disruptions. Since 2021, breast cancer diagnoses have resumed an upward trend. Continued public awareness and access to screening remain essential for early detection and improved outcomes.

Note: This website is not a medical institution. For medical decisions or treatment options, please consult a qualified healthcare provider.

Sources

Sources: Ministry of Health, Labour and Welfare – Impact of COVID-19 on Cancer Screening and Care, Japan Cancer Society – 2020 Cancer Diagnosis Survey, National Cancer Center Japan – Cancer Statistics: Breast