About PERMS

Background

All women aged 50 to 69 are invited to mammography every other year in the Mammography Program. The risk of developing breast cancer varies among women in the target group; some have a lower risk than average, while others have a higher risk.

Both in Norway and most European countries, women are offered mammography screening at the same interval between exams, regardless of their risk for developing the disease. This "one-size-fits-all" approach is now being discussed in the professional community because studies have shown that tailored mammography screening, where the offer is based more on individual risk of developing breast cancer, can increase benefits and reduce disadvantages for participating women.

One of the risk factors discussed in this context is "false alarm" - that is, a false positive screening result. The term is used for a woman who undergoes additional examinations due to suspicious findings on the screening images, without breast cancer being found. Studies, including those from the Mammography Program, have shown that women with a "false alarm" have an increased risk of later being diagnosed with breast cancer, either between screening rounds (interval cancer) or at subsequent screening visits. It is therefore discussed whether more frequent mammography than every other year may be beneficial for these women.

Another risk factor discussed is mammographic density. Mammographic density concerns how the breast appears on a mammogram. The breast consists of different types of tissue: Milk glands, milk ducts, fatty tissue, and connective tissue. When a mammogram is taken, the different tissues appear differently on the images. Fatty tissue appears dark, while milk glands, milk ducts, and connective tissue appear light. If there is relatively much of the light tissue, the woman is said to have mammographically dense breasts. If there is more fatty tissue and less of the light tissue, the breast has low mammographic density.

It is known that the risk of developing breast cancer increases with higher density. Dense breast tissue can also make it harder to detect cancer on mammograms, because both the dense breast tissue and any cancerous tumors are light areas in the image. Cancerous tumors may therefore be hidden within the dense tissue. This means that mammography is a less suitable examination for women with very high density.

Organizations like the European Society of Breast Imaging (EUSOBI) therefore recommend an additional examination for women with high mammographic density as part of a personalized screening program. Nevertheless, no screening programs in Europe have established this to date, partly due to lack of capacity.

Although there is currently increased knowledge about the scientific basis for offering personalized mammography screening, few studies have investigated the practical aspects of providing this. There is also little knowledge about how such an offer would potentially be received by the target group.

Purpose

The purpose of the project is to gain more knowledge about practical aspects of providing a more personalized screening offer in the Mammography Program. This knowledge will be used for further planning of a possible personalized screening program in Norway in the future.

The main goal is to gain knowledge about what proportion of women who receive a "false alarm" or have very high mammographic density will take advantage of an offer of additional examination.

The project will also investigate results for other quality indicators related to the Mammography Program, such as the proportion of women who are called for additional examinations and the proportion who are diagnosed with breast cancer.

Implementation

PERMS consists of two sub-studies. The sub-studies will be carried out in collaboration with the breast centers at Oslo University Hospital HF (OUS), Vestre Viken HF and Akershus University Hospital HF (Ahus). The results will be compared with historical data from the Mammography Program.

Sub-study in Oslo and Vestre Viken:

Here, women who receive a "false alarm" will be invited to an additional examination with mammography one year after their original screening examination.

Sub-study at Ahus:

Here, women attending screening will have their mammographic density measured. Those found to have high mammographic density will be offered an extra examination with tomosynthesis within six months of the original appointment.

Privacy and data basis

All those considered for inclusion in PERMS have the right to opt out of being invited to the study, and in both sub-studies participants must give consent before they can take part.

In the sub-study at OUS and Vestre Viken, we will register and use information about the additional examinations performed. In addition, the sub-study will use information related to attendance and findings from current and previous screening examinations, which are stored in the Cancer Registry when you participate in the Mammography Program. This also includes information about radiologists’ assessments, as well as the outcome of screening examinations (screening information).

In the sub-study at Ahus, we will register and use information about the additional examinations performed, and screening information registered in the Cancer Registry from the current and previous attendances in the Mammography Program. We will also use information from density measurements at the current screening attendance.

In both sub-studies, women are followed for two years to include information about the subsequent screening round in the analyses. It will be impossible to identify individuals in published results.

We will process personal information in the study based on public interest (GDPR 6.1.e and 9.2.j).

The Regional Ethical Committee (REK) has approved the study (REK #585149).

Organization

The Cancer Registry at FHI is the coordinating institution and data controller for the study. This means responsibility for obtaining necessary approvals, data collection, study monitoring, quality assurance and analysis of the data material, as well as publication and reporting of results.

Both the Cancer Registry and the collaborating health trusts are responsible research institutions under the Health Research Act. The parties have an independent responsibility to organize and conduct the part of the study carried out at their own institution, and to ensure this takes place in accordance with relevant regulations and formal approvals.

Funding

The study is supported by funds from the Pink Ribbon campaign.

Status

Necessary approvals have been obtained, agreements are signed, and both sub-studies are underway.

Contact information

Solveig Hofvind at the Cancer Registry, FHI, is the project leader for the study. For practical questions related to the project, contact senior adviser Gunvor Gipling Wåde at the Cancer Registry, FHI.