Minimal invasive Microwave Ablation in early stage breaST cancER, a feasibility study

In the Netherlands approximately one out of seven women will develop breast
cancer during her life [1]. Most of these breast cancers are early stage, 40%
of the women have stage 1 [2]. Stage 1 breast cancer means that the cancer is
small (size <2cm) and only in the breast tissue or it might be found in lymph
nodes close to the breast [3]. The standard treatment for stage 1 breast cancer
is breast conserving surgery (BCS), sentinel lymph node procedure (SLNP) and
additional radiotherapy [4]. When BCS is performed, pathologic evaluation of
the margins is required, because residual (in situ) breast cancer in the
resection margins is the most important predictive factor for local recurrence.
Between 11% and 30% re-excisions are performed after BCS, which can result in a
poor cosmetic outcome, higher burden for the patient, sometimes conversion to
mastectomy and higher health care costs [5-8]. This standard treatment
protocol results in a10 years survival rate of 95% for stage 1 disease [3].
However, nowadays there is a discussion whether these early stage breast cancer
could be treated less invasively[10-14].
To reduce the invasiveness of breast cancer treatment, without compromising
breast cancer specific survival, minimally invasive nonsurgical ablation
procedures of breast cancer have been investigated for small breast lesions
[15-19]. Ablation of the tumor can be achieved by using extreme hyperthermia to
destroy the tumor cells. This ablation technique can ablate an area up to 3 cm
with a single probe. This is one of the reason that this technique is suitable
for the treatment of breast tumors<2 cm, because a margin of 0.5-1.0 cm should
be included in the ablation volume [20]. Furthermore, there are several
advantages of ablation procedures: it is a minimal invasive technique, with a
small or absent cutaneous scar and thereby potentially improving patient
quality of life. There is the ability to image the tumor intraoperatively and
thereby reducing the surgical excision rate. In addition, adjuvant therapy may
be administrated faster after ablative treatment, in the absence of a wound
requiring healing. Furthermore, ablative treatment can be done under local
anesthesia and/or conscious sedation instead of general anesthesia and in
daycare setting, which can reduce treatment cost [21,22]. In a recent
meta-analysis of Van de Voort et al. the overall complete ablation rate of
thermal ablation of tumors<2 cm was 86% in 1266 patients [20]. This suggest
that 14% of the patients will need a re-ablation which is at the low end of the
estimates for the re-excision rates of 11-30% after BCS [5-8]. An important
challenge of the ablation procedure is to determine whether the ablation
procedure of the tumor volume is complete. A well-established technique would
be a post procedural MRI which can determine complete necrosis and residual
disease. There is a strong correlation between postprocedural MRI and
pathological outcomes [23-25]. Microwave ablation is already being used in
liver, kidney and lung tumors at the UMCG.

To assess whether minimally invasive nonsurgical microwave ablation (MWA)
followed by postprocedural MRI scan can be an alternative treatment for
breast surgery in early stage breast cancer: a non-inferiority study .

Is the quality of life, cosmetic outcome, fear of breast cancer recurrence, and
costs in patient treated with MWA non-inferior compared to patients treated
with breast surgery?

Clinical, consecutive, prospective feasibility study.

All 15 patients will undergo ultrasound guided minimally invasive nonsurgical
MWA under local anesthesia. The patient will undergo a MRI scan on the day of
admission to the hospital for standard breast surgery.

Breast surgery (breast conserving surgery or mastectomy with a sentinel node
procedure) as standard care and gold standard is performed in all patients
within a maximum of 35 days from diagnosis (conform guidelines). The results of
the MWA have no influence on the surgical procedure.

For the assessment of the cosmetic outcome, the breast Q preprocedure will be
used before the microwave ablation. For breast cancer recurrence fear, the
Lerman Breast Cancer Worry scale will be applied and for overall QoL the
EuroQol 5D5L and for cosmetic outcome the breast Q postprocedure. These three
evaluation will be done 4 days and 2 weeks after the MWA and 4 days, 2 weeks
and 2 months after surgery.

Micorwave ablation:
Complications of the ablation treatment were reported in 9.8% of all patients
(123/1258) [22]. The most common complications were skin burns (3.5%) and
pectoralis major muscle damage (1.1%). The change of pneumothorax was 0.2%
[22]. In the meta-analysis of Mauri et al. the minor (local discomfort and
grade-1 skin burns) and major (grade 2 or 3 skin burns and skin necrosis)
complications pooled rate was 8% and 6%, respectively [21]. To avoid these
complications, administration of saline between the tumor and skin/musculus
pectoralis major will be applied to create an adequate buffer spacing to avoid
any unwanted warmth effects of the microwave needle. In literature a margin of
2 mm between tumor and adjacent tissue was used to protect the adjacent
tissue[26]. However to further decrease the risk for complications we use a
hydrodissection for all patients regardless of the distance between tumor and
skin/muscle.

MRI: Until now, no hazardous effects of MRI are documented. The burden for the
patient is an extra MRI scan of 20 minutes. This MRI is scheduled on day that
the patient is admitted to the hospital for the standard breast surgery.

Burden for the patient:
Questionnaires: one questionnaire, Breast Q preprocedure, should be filled in
before the MWA. This will take 5 minutes.
After the MWA three questionnaires (Breast Q postprocedure, Lerman Breast
Cancer Worry scale and EuroQol 5D5L) at 2 different time points (4 days and 2
weeks after MWA) should be filled in by the patient this will take 15 minutes
(5 minutes per questionnaire) at each time point.
After the standard surgery the same three questionnaires (Breast Q, Lerman
Breast Cancer Worry scale and EuroQol 5D5L) at 3 different time points (4
days, 2 weeks and 2 months) should be filled in by the patient this will take
15 minutes (5 minutes per questionnaire) at each time point.