Neoplasms

Skin and Connective Tissue Diseases

All Conditions

Breast Neoplasms

Non-proportional stratified sample of women diagnosed with interval or screen-detected breast cancers after participation in BreastScreen Norway. This sample will include under- or overdiagnosed cancers, as well as cancers that were not under- or overdiagnosed.

Women residing in Norway, born between 1927 and 1934 (inclusive). This cohort will include women who have attended screening and who have not attended screening.

Women aged 50-69, and practising family doctors aged 25-75, currently living in Norway.

Diagnosed with a cancer that was visible on prior mammograms

Under- or overdiagnosed cancer

Screening

Solveig Hofvind, PhD

This PhD project will describe tumour characteristics and survival associated with of under- and overdiagnosed breast cancers, the rate of overdiagnosis in BreastScreen Norway, and whether women and family doctors are aware of, and knowledgeable about, under- and overdiagnosis in breast cancer screening.

Mammographic screening among women aged 50-69 reduces breast cancer mortality but also carries some risk. This PhD project will study under- and overdiagnosis, two risks associated with mammographic screening, in BreastScreen Norway. Underdiagnosis can occur when a tumour is present but not detected as a result of screening, while overdiagnosis can occur when a woman is diagnosed with a slow growing cancer that would not become symptomatic during her lifetime.

This project will address the following topics and research questions using observational study methods.

Study 1: To determine whether tumour histopathology and survival differentially associated with potentially under- or overdiagnosed interval and screen-detected breast cancers.

* Do women with potentially underdiagnosed interval cancers have different tumour histopathology and survival than those whose interval cancers showed no signs at the prior screen?
* Do women with potentially overdiagnosed screen-detected cancer have different tumour histopathology and survival than those whose screen-detected cancer showed no signs at the prior screen?

Study 2: To estimate overdiagnosis in the screening program using individual-level data:

* What was the rate of overdiagnosis for women screened in the program during 1996-2003?
* How does adjusting for sociodemographic factors affect estimates of overdiagnosis?

Study 3: To describe awareness and knowledge about under- and overdiagnosis and breast screening in general:

* Are women aware of and knowledgeable about under- and overdiagnosis in breast screening?
* Are family doctors aware of and knowledgeable about breast screening, and under- and overdiagnosis? Are they confident in their ability to relay this information to their patients?

Study 1 is a quality improvement study and has approval from Personvernombudet (PVO 2016-4696). Study 2 has research ethics board (REK) approval (REK 2013/795), while REK approval will be sought for Study 3.

Under- and Overdiagnosis in BreastScreen Norway

Using a self-administered web-based questionnaire designed for this study, the investigators will analyse survey responses to determine whether self-reported age (categorised into 5-year age groups) is associated with awareness and knowledge of overdiagnosis. This will be done separately for women and family doctors.

Using a self-administered web-based questionnaire designed for this study, the investigators will analyse survey responses to determine whether self-reported formal education (none; primary school; high school; up to 4 years postsecondary; more than 4 years of postsecondary education) is associated with awareness and knowledge of overdiagnosis among women.

- Histopathological type (Ductal carcinoma in situ, invasive carcinoma of no special type, invasive lobular carcinoma)

- Crude and adjusted measures of overdiagnosis will be presented to show the amount and direction of confounding resulting from sociodemographic factors.

Agreement between awareness (yes versus no/incomplete) and knowledge (yes versus no/incomplete) of overdiagnosis

Study title	NCT ID	Conditions	Interventions	Eligibility	Organization	Link
Under- and Overdiagnosis in BreastScreen Norway	NCT03852953	Breast Cancer	Under- or overd... Screening	25 Years - 75 Years	Cancer Registry of Norway
Under- and Overdiagnosis in BreastScreen Norway	NCT03852953	Breast Cancer	Under- or overd... Screening	25 Years - 75 Years	Cancer Registry of Norway

Spots Global Cancer Trial Database for quantitative methods