Rhomboid intercostal block is used to block lateral cutaneous branches of intercostal nerves between T3 and T9 dermatomes. RIB has been reported to be successful in attenuating acute pain following breast surgeries. However, it's effect on chronic pain has not been evaluated yet. The primary hypothesis of the study is that the incidence of chronic pain of the patients who will receive Rhomboid intercostal block (RIB) following breast cancer surgery will be lower than the patients who will receive no block intervention at the postoperative 3rd month. The secondary hypothesis is that the incidence ofchronic pain of the patients who will receive Rhomboid intercostal block (RIB) following breast cancer surgery will be lower than the patients who will receive no block intervention at the postoperative 6th month. An other secondary hypothesis is that the total BPI-SF scores will be lower in the RIB group than control group at the postoperative 3rd and the 6th months.

The study is designed as a prospective, double-blinded, randomize controlled study. The patients who will undergo mastectomy surgery with or without axillary dissection will be included in the study. Anesthesia will be inducted with intravenous (iv) thiopental 5 mg/kg, fentanyl 2 mcg/kg and rocuronium bromide 0.6 mg/kg. Following intubation, patients will be allocated into two groups according to a randomization table created by a professional statistician. In the study group, patients will receive a single shot Rhomboid Intercostal Block (RIB) with 30 milliliters of %0.25 bupivacaine and in the control group no block procedure will be performed. All patients will receive a standard analgesia protocol which will include an intraoperative intravenous (iv) infusion of dexketoprofen 50 mg and iv tramadol 1 mg/kg 15 minutes prior to the end of the surgery. Postoperative pain intensity of the patients will be evaluated by Numerical Rating Scale (NRS) which is a scale ranges between 0 (no pain) and 10 (the worst pain that a person can stand). Pain scores of the patients will be recorded at the postoperative 15. and 30. min in the recovery room and if the NRS score is 4 or more, iv fentanyl 1 mcg/kg will be applied. At the surgical ward, pain scores will be evaluated at the postoperative 1st, 2nd, 6th, 12th and 24th hours and if the NRS score is 4 or more, iv tramadol 50 mg will be applied as rescue analgesia. Opioid consumptions of the patients will be recorded at the postoperative 24th hour. At the postoperative 3. and 6. months, a pain doctor will evaluate all patients by using Brief Pain Inventory Short Form (BPI-SF) and Douleur Neuropathique 4 (DN4) questionnaire.

Inclusion Criteria:

• ASA I-II patients
• Female
• Ages between 18-65
• Patients who will receive breast cancer surgery under general anesthesia

Exclusion Criteria:

• Alcohol or substance or chronic opioid consumption story
• Any pain killers intake in the last 24 hours prior to surgery
• Body mass index over 35 kg/m2
• Infection at the injection sites
• Known allergy to local anesthetics
• Known psychiatric diseases which prevents communication
• Operations longer than 3 hours

IPD will not be shared with anyone

The patients will be under general anesthesia and will not be aware if they receive a block procedure or not.

The investigator, the data collector and the outcome assessor will be completely blind to the study groups. Only the care provider who will perform the block procedures will know the study groups, but she will not involve in data collection.