Compare the effect of ropivacaine versus placebo pectoral nerve block (Pecs 1 and 2) on acute pain after tumorectomy plus sentinel lymph node dissection on one day surgery.

Before surgery, the 3rd interpectoral space will be identified. After aspiration, half of the solution of Ropivacaine 5 mg/ml not exceeding 3 mg/kg of maximal dose and 30 ml of maximal volume or saline (not exceeding 30 ml of maximal volume) will be injected into the interpectoral space underneath the pectoralis major muscle for the Pecs 1 block. The other half of the solution will be injected above the serratus anterior muscle at the third rib.

Evaluation of the percentage of patients treated with step 2 or 3 analgesics during the three postoperative hours.

Inclusion Criteria:

1. Women with non-metastatic invasive breast carcinoma or breast carcinoma in situ treated by breast-conserving surgery (tumorectomy) with sentinel node technique on one day surgery.
2. Age between 18 and 85 years.
3. ASA class 1, 2 or 3
4. Signed informed consent form.

Exclusion Criteria:

1. Ongoing neoplasm or history of neoplasm other than breast cancer with the exception of: basal cell carcinoma, cervical carcinoma in situ, other treated cancer that has not relapsed during the 5 years preceding inclusion in the trial.
2. Axillary dissection planned during surgery planning
3. All bilateral surgery the day of Pecs administration
4. Metastatic breast carcinoma at diagnosis (M1).
5. Allergy to local anesthetics and morphine.
6. Use of analgesics during the 12 hours preceding the surgical procedure.
7. History of ipsilateral surgery during the previous 6 months.
8. History of substance abuse.
9. Pregnant woman or breastfeeding.
10. Subjects deprived of their liberty or under guardianship (including temporary guardianship).
11. Subjects no covered by social security scheme
12. Experiencing any psychiatric condition or major cognitive impairment that may hamper completion of self-reported questionnaires.

There is no prohibition for people to take part simultaneously in another search and there is no exclusion cause at the end of the research period

Sponsor will share de-identified data sets. Documents generated under the project will be disseminated in accordance with Institut Curie policies.

Data requests can be submitted starting 9 months after last article publication and will be made accessible for up to 12 months.

Access to trial individual participant data can be requested by qualified researchers engaging in independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a data sharing agreement (DSA).

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