Rationale: In breast cancer (BC) patients, lymph node status is a key prognostic indicator. At present, axillary ultrasound (US) with subsequent fine needle aspiration cytology (FNAC) of suspicious lymph nodes (US+FNAC) is widely used as a pre-operative staging method. When US+FNAC is negative, a sentinel node procedure (SNP) is performed during breast surgery. Nowadays, an axillary lymph node dissection (ALND) is generally performed if one of the abovementioned diagnostic entities reveals lymph node metastases. However, the extensive role of ALND in BC patients with lymph node metastases may change or diminish in upcoming years due to emerging evidence that completion ALND (cALND) does not affect disease-free survival and overall survival in early BC patients with (sentinel) node-positive disease. Whether ALND is needed in these patients, should be based on (axillary) tumour load. Because of the fact that tumour load can only be reliably evaluated by SNP and not by US+FNAC, the role of SNP might become even more important in upcoming years.

Ideally, the status of this sentinel lymph node is known prior to breast surgery, so a patient tailored treatment plan can be made and discussed with the patient before breast surgery. In this context, it would be very logical to perform a SNP under local anaesthesia (LA), prior to breast surgery. This might not only lead to significantly less two-step surgical procedures under general anaesthesia (GA), but might also lead to a reduction of depressive symptoms and anxiety and improved quality of life (QoL) of BC patients, because BC patients are in particular risk for psychological distress in the first three months after diagnosis of BC. Knowing lymph node status and the complete treatment plan as soon as possible (by performing a SNP under LA), might reduce this psychological distress. To investigate which BC patients would benefit most from SNP under LA, the investigators recently analysed 1132 BC patients retrospectively. Both prevalence of axillary lymph node metastases and prevalence of false negative results of US+FNAC were directly associated with age <60 years and with primary breast tumour size >20 mm. Hence, these BC patients might benefit most from SNP under LA. In the present study, the value of SNP under LA in these BC patients (i.e. <60 years with a breast carcinoma >20 mm) will be analysed.

Objectives: Reduction of the mean number of operations under general anaesthesia per patient. Improvement of QoL. Reduction of depressive symptoms and experienced anxiety.

Study design: Prospective single centre randomised controlled clinical trial. Study population: Women aged 18 to 60 years who are diagnosed with BC AND with a tumour size of >20 mm ultrasonographically AND with a negative or inconclusive pre-operative US+FNAC.

Intervention: Sentinel Node Procedure under Local Anaesthesia (SNP under LA) Control: Traditional Sentinel Node Procedure under General Anaesthesia (SNP under GA) Main study parameters: Primary outcome parameters are the number of operations under GA per patient and the number of operations under LA per patient. Secondary outcome parameters are QoL, experienced depressive symptoms and anxiety.

Timeline and statistics: The inclusion period will be conducted from the 1st of July 2014 to the 1st of August 2015, and 80 patients will be enrolled in this study (alpha 0.05; power 0.8). Inclusion of 80 patients will be sufficient to reduce the number of two-stage surgical procedures under general anaesthesia with 30%. Data will be analysed using descriptive statistics, Chi-squared test, Fisher's exact test, Mann-Whitney U test, Kruskall-Wallis test, students t-test, ANOVA, paired t-test, Wilcoxon signed-rank test, Friedman test, Pearson's and Spearman's rank correlation coefficients and finally logistic and linear regression analysis.

Inclusion Criteria:

• Female
• Age 18-60 years
• Diagnosis of invasive BC (established with core needle biopsy of the breast lesion)
• Breast carcinoma measures > 20 mm ultrasonographically
• Pre-operative US+FNAC is negative or inconclusive
• No evidence of distant metastases
• ASA Classification I-III
• Signed informed consent

Exclusion Criteria:

• History of previous breast surgery in the affected breast
• History of previous axillary surgery in the ipsilateral axilla
• History of radiation therapy (ipsilateral breast or axilla)
• History of neo-adjuvant therapy (for the BC)
• Known allergy to lidocain