In Norway, women aged 50 to 69 years are invited to breast cancer screening biennially. The goal is to detect breast cancer at an early stage to provide less aggressive treatment and reduce the mortality from the disease.
Breast cancer survivors can experience a wide range of complications and late treatment effects, which can affect their long-term quality of life. These may include side effects related to heart and lung function, altered pregnancy and childbirth opportunities, development of arm lymphedema, neuropathy, skin changes and/or chronic pain and fatigue. Various psychosocial consequences, such as depression and anxiety, can also be caused by breast cancer treatment.
The current evidence on relationships between breast cancer detected by screening and long-term effects of treatment in the form of various late effects and the impact on women’s long-term quality of life is insufficient. Breast tumors detected by screening are often smaller and have less frequently spread to other parts of the body than breast tumors detected due to symptoms such as breast lump. It may be that the less aggressive treatment of screen-detected breast cancer can result in a lower extent of serious and long-lasting late effects for women compared to the treatment of breast cancer detected due to symptoms.
To the best of our knowledge, no breast cancer survivor studies have been conducted to investigate whether women’s long-term quality of life differs between women with breast cancer detected by screening and women with breast cancer detected due to symptoms.
The aim of this project is to investigate the long-term effects of breast cancer diagnosis and subsequent treatment for women with screening detected versus symptomatic breast cancer.
We will also examine the effect of the mode of detection; whether breast cancer is screen-detected, detected between two screening examinations/appointments (so-called interval cancer) or detected outside of the screening program. In addition, we will investigate whether tumor characteristics (tumor diameter, histological grade and lymph node and receptor status) are associated with women’s long-term quality of life.
The project is carried out as a retrospective study. Information from a random sample of women aged 50-69 years, both with breast cancer (n = 7500) and without breast cancer (n = 4000), will be retrieved from the Cancer Registry database. The women with breast cancer will either have the disease diagnosed and treated after attendance in BreastScreen Norway (n = 2500 for breast cancer detected at screening and n = 2500 for interval cancer), or have it detected due to symptoms, outside of the screening program (n = 2500).
We will use a self-reported questionnaire to obtain information on treatment, quality of life and any long-term effects of the treatment from 1 to 12 years after diagnosis. The results of the questionnaire and data on tumor characteristics will be compared between the groups and with women without breast cancer.
Quality-adjusted life years will be used to measure the burden of long-term effects. Quality-adjusted life years encompass the length of life and are often measured as the person’s ability to perform daily life activities without pain and mental disturbance.
Planned studies and status
In 2020, the project group sent out questionnaires to 11,500 women in the target group of BreastScreen Norway. The questionnaires were collected and registered at the Cancer Registry, and data have been analyzed. Writing for the first two sub-studies is in progress.
Study 1: Long-term quality of life among breast cancer survivors with screen-detected breast cancer - a review study. In progress.
Study 2: Long-term quality of life after breast cancer treatment among women with screen-detected versus symptomatic breast cancer. In progress.
Study 3: Quality of life after breast cancer treatment among women who attended screening versus women who were invited but did not attend. Not yet started.
Study 4: Detection method versus tumor characteristics as the main predictor of long-term quality of life among breast cancer survivors. Not yet started.
Information from the women who provide their written consent to participation will be used in the study. The consent form is attached to the questionnaire that the women receive.
Women who have expressed their willingness to participate in the study have the right to access the information we have registered about them. These women also have the right to correct any errors in the information we have recorded. Only information processed in the study can be accessed. This means information from the questionnaire may be accessed. Other information included in the study will not be available, such as detailed health information on cancer treatment and biological properties of tumors, as it will demand a disproportionate amount of effort. In these cases, access to information would have to be requested from the primary source in accordance with the rules that apply to access data from the Cancer Registry.