Fewer breast and colorectal cancer diagnoses have been made in the Netherlands due to the COVID-19 crisis this spring. The decline in the number of diagnoses was more abundant in age groups invited to national population screening programmes, as compared to other age groups.
More specifically, there was a drop of approximately one-third in breast cancer diagnoses (including its precursor) among 50-74-year-old women and approximately one-fifth in colorectal cancer diagnoses among 55-75-year-old men and women.
These are the age groups that are invited to national population screening programmes in the Netherlands. Avinash Dinmohamed, Sabine Siesling, and coauthors described these findings in the Journal of Hematology & Oncology based on data from the Netherlands Cancer Registry (NCR) that relies on pathological cancer notifications via the Nationwide Histopathology and Cytopathology Data Network and Archive (PALGA).
Sabine Siesling, Professor of the University of Twente is involved in monitoring the effects of the Covid outbreak on the care of cancer patients, together with the Integral Cancer Centre Netherlands (IKNL) and the "Pathological-Anatomical National Automated Archive (PALGA) and experts from the field she has looked at the effects of the outbreak on the diagnosis of bowel and breast cancer.
The temporary halt of national population screening programmes during the early stages of the COVID-19 epidemic this spring, along with alterations in healthcare-seeking behaviour and referral practices to hospitals, resulted in fewer breast and colorectal cancer diagnoses among individuals eligible for national population screening programmes.
The number of breasts and colorectal cancer diagnoses gradually increased to the expected level during the summer. This increase can be accounted for by more diligent health-seeking behaviour and the gradual restart of national population screening programmes.
Notwithstanding, there is still a backlog of approximately 2,000 breast cancer diagnoses (including its precursor ductal carcinoma in situ) and approximately 1,000 colorectal cancer diagnoses in the age groups eligible for cancer screening.
The researchers, therefore, emphasize the importance of visiting the general practitioner in case of symptoms and accept the invitation of the cancer screening programmes.
The backlog of cancer cases
At the peak of the COVID-19 crisis this spring, the number of breasts and colorectal cancer diagnoses dropped sharply. This drop was most pronounced in the age group eligible for cancer screening programmes; that is, among women aged 50 to 75 years for breast cancer and men and women aged 55 to 75 years for colorectal cancer.
The steady decrease in the need for critical COVID-19 cares in the Netherlands since early April paved the way forward to restart various components of regular health care services. Also, cancer screening programmes gradually restarted in mid-May for colorectal cancer and in early-mid June for breast cancer. As a result, the number of breasts and colorectal cancer diagnoses gradually increased.
The number of diagnoses ultimately reached the level of the expected number of diagnoses. This level was reached for colorectal cancer around late June and for breast cancer around early-mid July. Nevertheless, the accrued backlog of cases has not yet been cleared.
This notion can be explained, in part, because a proportion of the target group for cancer screening has not yet received an invitation, especially among those eligible for breast cancer screening.
The figures below show the number of breast and colorectal cancer diagnoses per calendar week. The top panels show the age groups that are not eligible for cancer screening. The bottom panels show the age groups that receive an invitation for cancer screening.
Early detection of cancer
Cancer screening programmes aim to detect cancer at an early stage. Early detection of cancer substantially increases the chances of successful treatment and better prognosis.
Since most of the tumours detected through cancer screening programmes are often precancerous or small tumours, it can be reasoned that a slight delay in diagnosis will not have significant consequences for progression to a higher stage of the (premalignant) cancer and an increased risk of mortality for most individuals.
Individuals who will eventually receive an invitation for cancer screening, or whenever they visit their general practitioner with troublesome symptoms, will be ultimately diagnosed. It is imperative during the second wave of COVID-19 to avoid further delays in cancer diagnoses and hospital referrals. Therefore, cancer screening programmes are as yet not halted during the second wave of COVID-19.
With the currently available data, it is not yet possible data to assess whether the decreased diagnostic scrutiny of cancer during the early stages of the COVID-19 epidemic resulted in a diagnosis of cancer in an advanced stage.
Once cancer has advanced to a higher stage, the outlook for patients is generally worse because more aggressive treatment approaches are required and survival chances can be reduced. Research with more detailed data from the Netherlands Cancer Registry is ongoing to assess whether a shift towards a higher disease stage has occurred.
Dinmohamed, A. G., et al. (2020) The impact of the temporary suspension of national cancer screening programmes due to the COVID-19 epidemic on the diagnosis of breast and colorectal cancer in the Netherlands. Journal of Hematology & Oncology. doi.org/10.1186/s13045-020-00984-1.