Degree of coverage and data quality for the Breast Cancer Registry of Norway

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Degree of coverage and completeness

All women with invasive breast cancer in Norway should be included in the registry. The inclusion criteria for the registry are patients with breast cancer (C50 according to ICD-10) and precursor to breast cancer (Ductalt carcinoma in situ/DCIS, D05). Tumors in the breast due to sarcoma, lymphoma, Phyllodestumor and Paget disease are not included in the registry. Lymphoma is included in the Norwegian Registry for Lymphoma and Lymphoid Leukaemias.

The Cancer Registry's basic registry contains information on 99.99 per cent of all patients diagnosed with breast cancer. The coverage rate for assessment reports for breast cancer in 2022 is 91.8 per cent.

The degree of coverage of clinical reports for each hospital is specified in the annual report (Norwegian only).

The Cancer Registry of Norway has had a strong focus on increasing the degree of coverage in recent years, which has resulted in improved reporting for all quality registries.

Reporting of breast cancer oncology reports remains low and absent at some hospitals. Measures to change this have been the revision of clinical reports for oncology, which will result in a reduction in the number of reports and variables. At the same time, INSPIRE (data collection on drug cancer treatment) has been introduced for breast cancer, and results for systemic treatment are referred to in this year's report.

The forms for radiotherapy and chemotherapy will be discontinued and replaced with automated data collection from the radiation machines and the cytodose/CMS systems, respectively. Revised oncology reports will be published in fall 2023.

Data quality

Quality assurance of data is done as an integral part of the coding and registration process. In addition, the following examples help to ensure data quality in the Cancer Registry:

  • Several independent sources report information 
  • The information is reported at several points in the course of the disease
  • The employees have unique expertise in coding cancer cases according to the Cancer Registry's own code book and international coding systems
  • IT systems have rules and barriers for illogical combinations, incorrect information and more 
  • The Cancer Registry of Norway conducts analyses and control runs that reveal inconsistency in the data
  • Data extraction for researchers makes it possible to check a smaller data set of information that can reveal individual errors (e.g. incorrect entry of hospital codes) or systematic differences due to different interpretations of coding systems and rules