Magnetic tracer in the sentinel node procedure in breast cancer: the non-radioactive alternative for radio-isotopes

In breast cancer, a sentinel node procedure is performed to investigate
whether malignant cells have spread to the axillary lymph nodes. This is an
important part of determining the stage of breast cancer and the final
treatment plan.
In current practice the lymph nodes are localized with the radio-isotope
Technetium (in combination with a blue dye). Due to the half-life of
Technetium, the nuclear medicine physician usually injects this tracer one day
preoperatively. Subsequently a nuclear scan is made to evaluate the route of
the tracer. In the operation theatre the surgeon will detect the radioactive
Technetium signal with a gamma-probe. A concomitant blue dye can be used for
visual detection of the sentinel nodes.
Magtrace is an alternative for Technetium. It consists out of iron oxide
nanoparticles, covered in a carboxydextran coating. After injection, it spreads
to the lymph vessels and the sentinel node, just as Technetium.
With the Sentimag-probe the sentinel nodes can be magnetically localized. The
brown colour of the Magtrace will cause a concomitant visual marking. In
contrast to Technetium, with Magtrace no preoperative nuclear scan is required
one day preoperatively. Nor is concomitant injection of blue dye necessary.
A disadvantage of the sentinel node procedure with Technetium is that it is
performed using radioactive tracing with concomitant radiation exposure for the
patients and all medical personnel involved. In addition, the use of
radioactive tracing puts high demands on the logistics in the operation
theatre: the capacity of the number of patients that can be treated in one day
is limited and the radio-active tracing leads to many time-consuming
precautionary measures.
A radiation free alternative would therefore be advantageous. Not only with
respect to radiation exposure for the patients and health care workers, but
also by reducing the waiting time for operation for the patients, as it will
make the planning of patients for operation more efficient.

This study aims to analyse the feasibility and internal validity of Magtrace in
the sentinel node procedure in breast cancer; with the ultimate goal to make
the sentinel node procedure a radiation free process.

The primary objective of this study is to analyse the feasibility and internal
validity of Magtrace in the sentinel node procedure in breast cancer in the
Breast Care Centre in Zuyderland Medical Centre; with the ultimate goal to make
the sentinel node procedure a radiation free process.

A prospective cohort of 40 patients with breast cancer and an indication for
the sentinel node procedure will be injected with both Technetium
(radioisotope) and Magtrace (magnetic). All patients in this study will receive
both tracers.

Intervention group

This is a prospective cohort of all patients with breast cancer and an
indication for a sentinel node procedure. These patients will be injected with
the magnetic tracer (Magtrace) and the Technetium tracer preoperatively.
Perioperatively the sentinel node procedure will be performed using the
Sentimag-probe to localize the Magtrace. The Technetium tracer will be used to
check if the removed sentinel nodes are Technetium positive and with the
gamma-probe it is checked if there are sentinel nodes in the axilla that were
not detected by the Magtrace.

The goal of this project is proving the feasibility and internal validity of
Magtrace in the sentinel node procedure. To establish that Magtrace is a
non-inferior and a non-radioactive alternative for Technetium with respect to
reliability in detecting metastases. The ultimate goal is to make the sentinel
node procedure a radiation free process.