This is a prospective, non-randomized and multicenter study designed to compare biological features between pN0 triple negative breast cancer (TNBC) with size ≤ 10 mm (pT1a/b) versus pT1c T2 ≤ 30 mm.

All consecutive patients will be recruited by each investigator after completion of surgery. No modification of standard management according to each investigator center will be done. All patients will then be followed each year during 5 years in order to collect the following events: local and loco regional recurrence, metastatasis, second cancer, death or not and the cause.

At initial visit, a 10 mL blood sample will be collected (= study intervention) and immediately processed for serum storage; all serum samples will be stored at -80°C and may be used for the purpose of further scientific research.

A representative formalin-fixed paraffin-embedded tumor block of all 200 samples will be addressed at the Institut Claudius Regaud for central collection which will consist of one haematoxylin-eosin stained slide for central histological review, up to 15 unstained slides for DNA extraction (after microdissection), and construction of a tissue micro-array (TMA).

Extracted DNA from 100 samples (50 in each group) will then be transferred to Institut Paoli Calmettes, Marseille; extracted DNA will be subjected to array-CGH analysis in order to detect gene copy number alterations such as gains/amplifications/deletions, and to next generation sequencing (NGS; MiSeq, Illumina) using a panel of ~400 genes for mutation detection.

Inclusion Criteria:

1. Woman with age ≥ 18 years.
2. Patient who completed surgery for his breast cancer and for which definitive histo-pathological analysis of surgical specimen is available.
3. Invasive breast carcinoma pN0 or pN(i+) with histological tumor size ≤ 10 mm (pT1a/b subgroup) or invasive breast carcinoma with histological tumor size > 10 mm and ≤ 30 mm (pT1c T2 ≤ 30 mm control group).
4. Patient with HER2-negative breast carcinoma: immuno-histochemistry (IHC) score = 0, 1+ or 2+ and in situ hybridization (FISH, CISH, or SISH) negative (local laboratory testing).
5. Patient with ER and PR negative invasive carcinoma (< 1% stained cells by immuno-histochemistry assay) (local laboratory testing).
6. In case of multifocality, the histological size of the largest tumor must be ≤ 10 mm or ≤ 30 mm according to the inclusion subgroup. All lesions must be ER, PR and HER2-negative.
7. In case of breast conserving surgery, clear margins are required.
8. Patient affiliated to a Social Health Insurance in France.
9. Patient information and written informed consent form signed prior to any study specific procedures.

Exclusion Criteria:

1. Patients with any previous malignancy of the breast or other site, with the exception of adequately treated basal or squamous cell carcinoma, non-melanomatous skin cancer totally resected.
2. Non-invasive breast carcinoma (i.e. ductal carcinoma in situ exclusively).
3. Inoperable breast invasive carcinoma.
4. Synchronous bilateral breast cancer.
5. Patients who received neo-adjuvant treatment (radiotherapy or chemotherapy or other before surgery).
6. Pregnant or breast-feeding women.
7. Any psychological, familial, geographic or social situation, according to the judgment of investigator, potentially preventing the provision of informed consent or compliance to study procedure.
8. Patient who has forfeited his/her freedom by administrative or legal award or who is under guardianship.