 Patients will be recruited among patient refered to our department for a breast cancer and needing an axillary dissection. Enrolled patients will have an injection of Lanreotide or placebo the day before surgery when they arrive in their room. The quantity of lymph in axillary drain will by daily noted until day 4. The patient will be evaluated at D15, D30 and M6 for pain, lymphocele and adverse events. 