MRI of the breast for optimal selection of patients with a preoperative diagnosis of ductal carcinoma in situ for a sentinel node biopsy procedure

Since the implementation of mammographic breast cancer screening the incidence
of ductal carcinoma in situ (DCIS) has risen dramatically. A further increase
is projected as a consequence of the introduction of digital mammography in the
screening population, as was recently done in the Netherlands. In a portion of
patients, a diagnosis of DCIS on a core needle biopsy (CNB) may represent a
DCIS and invasive ductal carcinoma (IDC) on an excision, a sampling problem
known in the literature as the *underestimate rate.* The presence of IDC
warrants a sentinel node biopsy procedure in these patients. Decision trees
have been developed to identify those patients with only DCIS on CNB with a
high risk of IDC in the excision specimen and these patients are offered a
SNP. In the Dutch national guidelines these patients have high grade DCIS on
CNB and/or a large (> 2,5 cm ) area of calcifications on mammography or an age
under 55 years. Ablation of the breast (for oncological reasons or at the
request of the patient) is another reason for a SNP. However, these criteria
are imperfect and a considerable number of patients have a SNP while not having
a IDC on excision and others do not have a SNP yet an IDC is found in their
excision specimen. Therefore, optimization of patient selection is needed to
better allocate available resources and give more relevant preoperative
information to patients.

The aim of the study is to optimize the selection of patients with ductal
carcinoma in situ (DCIS), diagnosed on core needle biopsy (CNB), for a sentinel
node biopsy procedure (SNP). In addition to the usual work up patients included
in this study will have an extra MRI of the breast and additional markers will
be tested on the tissue obtained by CNB.

In this study patients will have the usual diagnostic procedure for a breast
lesion consisting of physical breast examination, digital mammography and
ultrasound examination of the breast and if necessary also of the axilla.
Guided CNB will be taken.

Patients with biopsy proven DCIS will have an additional MRI of the breast
before the operative procedure. Extra tissue slides of the CNB wil be stained
for markers that potentially predict aggressive behaviour.

All patients will have the standard treatment for biopsy proven DCIS consisting
of breast conserving surgery or ablation.

According to the Dutch guidelines, all patients with proven high grade DCIS
and/or a large (> 2.5cm) area of calcifications and/or an age < 55 years and
those patients that will have an ablation, will have a SNP, independent of the
MRI or pathological results.

Tissue obtained from breast surgery will be wil examined at the department of
pathology acording to standard procedures as outlined in the Dutch guidline

The positive and negative predictive value of MRI for the presence of invasive
carcinoma in the excision specimen will be calculated. The same will be done
for the results of Her2neu and oestrogen receptor staining. These predictive
values will be compared to the predictive values of pathological and other
radiological features.

Besides normal patient care, patients participating in this study will undergo
MR mammography. The extra time required to undergo MR mammography is 45
minutes. There is a very small risk risk of an allergic reaction associated
with MR mammography.