Selection of Breast Cancer Patients with Low-risk Tumors using MR Imaging

Every year more than 13.000 Dutch women are diagnosed with breast cancer. This
makes breast cancer the cancer with the highest incidence in Dutch women.
Screening programs have allowed detection of breast cancer at earlier stages,
but also contributed to the detection of more indolent cancers [1]. Although
not every breast cancer is the same, they are treated uniformly depending on
stage.

Each step may cause side effects such as infection and bleeding, poor cosmetic
outcome, toxicity and fatigue. Hence, breast-conserving therapy pursues a
delicate balance between achieving local tumor control and minimizing side
effects. Large excision volumesand large radiation doses will improve local
control, but will also increase therapy-induced mutilation, resulting in
decreased quality of life after treatment.

Patients with more indolent type of cancers will suffer from the same treatment
side effects and psychosocial aspects, but are far less likely to die from
their disease had they been treated less aggressively. As a result, concern has
arisen about potential overtreatment in subgroups of patients with early breast
cancer.

To address this concern, minimally or non-invasive techniques have been
developed as a substitute for open surgery.
Examples are of such techniques are RF ablation and MRI-guided focused
ultrasound39 (MR-HIFU). Their anticipated advantage is reduction of side
effects. There are, however, three pitfalls at the moment: 1) It is unknown
which patients are at low risk prior to therapy; 2) No resected tissue becomes
available to verify that the cancer has been completely removed and 3) No
resected tissue is present to examine risk factors that determine if additional
systemic drug therapy is necessary.

As a result of these uncertainties, clinical research in non-invasive local
therapy of breast cancer has stalled in recent years, and a new impulse is
required to make this technique available to the growing population of patients
with early-stage breast cancer.

Primary objective:
To establish the accuracy of pretreatment 7T MRI to identify low-risk breast
cancers. This will be done by identifying preoperative imaging-based
characteristics related to risk factors of cancer relapse in the resection
specimens: 1) the risk of imaging-occult disease components that may lead to
tumor-positive resection margins, 2) the risk of cancer relapse and mortality
based on established prognostic models.

Secondary objective:
Comparison of pre-treatment dynamic contrast-enhanced MRI, MR
diffusion-weighted imaging, and magnetic resonance spectroscopy (MRS) at 7T to
identify low-risk breast cancers.

Tertiary objective:
Comparison of known prognostic markers from core biopsy in combination with 7T
MRI on the one hand with the resection specimen on the other hand.

This is a prospective cohort study aimed at establishing the pre-treatment
accuracy of 7T MRI to identify low-risk breast cancers compared with the
clinical standard (prognostic markers derived from the resection specimen).
Consecutive consenting patients will be included, and the duration of the
project will be two years.

One single contrast-enhanced MRI examination at 7T prior to surgery. Potential
benefits: Preoperative local tumor staging may be improved by MRI, detection of
positive surgical resection margins may be improved with more detailed analysis
of resection specimens. Potential risks: Improved local staging may lead to
additional diagnostic testing and therapy changes that have not yet been proven
to improve patient survival. Allergic reaction to MRI contrast agent may occur
in rare cases.