In this prospective trial, Stage 1-3 patients having mastectomies or isolated lumpectomy with axillary node dissection will be randomly assigned to general anesthesia with opioids combined with a Pecs II block or to general anesthesia with opioids combined with a placebo Pecs II block. Participants will be followed postoperatively during their entire hospital stay to determine the effectiveness of Pecs II block and opioids versus placebo Pecs II block and opioids as postoperative pain treatment.

Each year, 9400 new cases of breast cancer are diagnosed in Belgium. It makes breast cancer the most common cancer in women, good for more than one third of all cancer cases in women.

Surgical excision of the tumour is a necessary and effective step to cure from the disease. Recent studies have demonstrated the positive effects of regional anesthesia on peroperative and postoperative pain. Paravertebral blocks have become popular as an alternative to the analgesia provided by the 'gold standard' of thoracic epidural analgesia. However, both regional techniques have complications and slow learning curves that make them unsuitable for the large proportion of breast surgery patients who are treated on a day-stay basis. Recently, Rafael Blanco introduced the Pecs and Pecs II blocks, a practical alternative to both paravertebral and epidural blockade in the management of pain after breast surgery.

The investigators introduced the Pecs II block in their clinical practice. This study compares general anesthesia with a Pecs II block to general anesthesia with a placebo Pecs II block for breast surgery. The objective is to evaluate analgesic effectiveness and changes in opioid consumption when applying a Pecs II block versus a placebo Pecs II block.

Stage 1-3 patients having mastectomies or tumourectomies with axillary clearance will be randomly assigned to general anesthesia with a Pecs II block or to general anesthesia with a placebo Pecs II block. Enrolling 140 patients over an anticipated time frame of 2 years will provide an 90% power and a p-value of 0.05 for perioperative and postoperative opioid consumption as well as pain scores (NRS). Confirming the hypothesis will indicate that a minor modification to the anesthetic procedure will reduce the opioid consumption (including it's unwanted side effects) during and after surgery while maintaining or reducing patients' indicated pain scores (NRS).

Inclusion Criteria:

• Primary breast cancer without known extension beyond the breast and axillary nodes (i.e. believed to be Tumor Stage 1-3, Nodes 0-2)
• Scheduled for unilateral or bilateral mastectomy with or without implant (isolated "lumpectomy" will not qualify)
• Isolated "lumpectomy" with axillary node dissection (anticipated removal of at least five nodes)
• Written informed consent, including willingness to be randomized to opioids or regional analgesia
• Dutch speaking

Exclusion Criteria:

• Previous surgery for breast cancer (except diagnostic biopsies)
• Inflammatory breast cancer
• Scheduled free flap reconstruction
• ASA Physical Status ≥ 4
• Any contraindication to locoregional analgesia (including coagulopathy, abnormal anatomy)
• Any contraindication to midazolam, propofol, sevoflurane, sufentanyl, tramadol or piritramide
• Other cancer not believed by the attending surgeon to be in long-term remission
• Systemic disease believed by the attending surgeon to present ≥ 25% two-year mortality
• Obesity defined as BMI ≥ 30 kg/m2
• Chronic use of pain medication (started > 3 months ago)
• Allergic to Chirocaine
• Chronic drug or alcohol abuse
• INR > 1.4
• Thrombocytopenia < 70,000 platelets
• Dementia
• Pregnancy
• Kidney or liver failure