Gamma Probe and Ultrasound Guided Fine Needle Aspiration Cytology of the Sentinel Node Trial

Sentinel node biopsy (SNB), which is a surgical operation, is the gold standard
for staging of melanoma and breast cancer patients. Given the invasive nature
of this staging procedure, there is a morbidity rate of up to 10% associated
with SNB, mostly consisting of seroma and wound infection / dehiscence, and
rarely lymph edema. Targeted ultrasound (US) of the sentinel node (SN), with or
without fine needle aspiration cytology (FNA) have recently been investigated
as minimally invasive alternatives. However, reported sensitivity rates so far
are too low to replace SNB, due to a low identification rate of the SN and a
high false negativity rate. Our hypothesis is that additional use of a handheld
gamma-detection probe can aid in transcutaneous identification of the SN for
FNA or core needle biopsy (CNB), thereby providing a minimally invasive SN
procedure which ultimately even may replace surgical SNB.

To study the sensitivity of the combined gamma probe and US guided FNA compared
to the gold standard histology of the surgically removed SNB. Secondary aims 1)
to study the identification rate of this technique 2) to study possible
differences in outcome of FNA vs CNB.

Open single arm observational study with invasive measurements.

All patients will undergo intervention in addition to standard care. The
intervention consists of preoperative gamma probe and US guided detection of
the SN to perform FNA. The first 10 patients additionally receive placement of
a titanium marker in the SN for identification rate control. Separately,
additional CNB is performed in the first 10 breast cancer patients to study
histological compatibility of CNB vs SNB.

Only minimal risks are associated with participation in this study. Minimal
burden to the patient is caused by undergoing US and FNA (which takes 20
minutes) in the time frame between preoperative lymphoscintigram and SNB. The
first 10 patients will additionally receive placement of a titanium marker for
SN identification rate control (10 more minutes). Separately, the first 10
breast cancer patients receive an additional CNB (10 more minutes). No extra
visits or repeat visits are needed. Both FNA and CNB are known as minimally
invasive procedures, as the most frequent complications are minor (haematoma or
minimal prolonged bleeding at the puncture site) and occur in less than 1%, and
both FNA and CNB are preferred procedures for staging primary breast cancer
tumours and metastases of both breast cancer and melanoma. Titanium marker
placement is minimally invasive as well, being increasingly applied in
combination with CNB for localization of the primary tumor in breast cancer.
Concluding, we feel that the extra burden for these patients is outweighed by
the possible benefit for future patients who can be spared a SNB and its
complications.