The purpose of this study is to evaluate the quality criteria of the SLN detection technique in breast cancer patients with a tumor size (clinical measurement) greater than 2 centimeters (rate of false negatives, rate of detection).

Eligible patients will only be registered (no randomization). The estimated inclusion period is approximately 24 months. The duration of the research is 25 months (24 months for patient inclusion + 1 month for reception of results). The maximum participation duration of each patient is 1 month.

The number of patients required in this multicentric and prospective study is 240 (16 participating centers).

Axillary node extension is one of the major prognostic factors in breast cancer. Axillary dissection of Berg level I and II nodes is the validated method to obtain information on lymph node invasion, but it is associated with important morbidity.

Sentinel lymph node assessment (SLN) was developed to select patients likely not to have axillary node extension using a technique less invasive than conventional dissection. Axillary dissection is restricted to patients with undetected or metastatic SLN.

SLN detection involves subareolar or peri-tumoral injection of lymphotropic contrast agents which map the regional lymphatic drainage pattern of the tumor.

This technique allows an optimization of histopathological analysis: the pathologist must analyze only two nodes on average (instead of 10-15), allowing the examination of numerous tissue sections and the development of specific techniques such as immunohistochemistry.

The principal indicators of success for the technique are the detection rate, the false negative rate and the number of SLN sampled.

The assessment of feasibility is based on concomitant histopathological analysis of the SLN and of complementary lymph nodes.

There is no consensus in the literature on the SLN technique to be used for tumors with clinical size superior to 2 cm in diameter.

The aim of this prospective, multicentric study is to evaluate the performance of the SLN technique, in terms of detection rate and false negative rate, for patients with tumors greater than 2 cm (clinical measurement).

A homogeneous technique with "combined", colorimetric and isotopic SLN detection with subareolar or peri-tumoral injection will be used. This consensus "combined" technique has been validated by all investigators. The histopathological procedure will also be homogeneous, and validated within the group of pathologists of the Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC). Breast surgery will either be a mastectomy or conservative treatment.

The primary objective of the study is to evaluate the quality criteria of the SLN detection technique in breast cancer patients with a tumor size (clinical measurement) greater than 2 centimeters (rate of false negatives, rate of detection).

The secondary objectives are:

• Evaluation of the number of SLN sampled per patient,
• Lymphoscintigraphic evaluation of the pattern of lymphatic drainage in breast tumors > 2 centimeters,
• Precise histopathological description of the SLN sampled and of axillary nodes of levels I and II.

Evaluation criteria:

The primary criterion is the rate of false negatives, determined by the ratio of the number of patients with detected but negative SLN to the total number of positive non-sentinel nodes at the time of axillary dissection of levels I and II (patients classified as N+ according to the TNM system).

This rate will be determined after calculation of the detection rate, determined by the ratio of the number of patients evaluated on the total number of patients.

In agreement with international recommendations, the expected rate of false negatives should be < 5 % with a detection rate > 85 %.

Secondary criteria include:

• Total number of sampled SLN per patient,

• Lymphoscintigraphy: detection of SLN by means of extra-axillary markings,

• Histopathological results:

  • SLN: metastases, capsular breach, micro metastases, isolated cells,
  • Dissection: number of positive nodes.

Inclusion Criteria:

• Female, age ≥ 18 years
• Patient with invasive unifocal breast cancer with tumor size > 2 cm at initial examination (clinical examination and/or imaging)
• Preoperative histological diagnosis of infiltrating mammary carcinoma
• No lymph node at clinical examination
• No treatment for this cancer before surgery
• Mandatory affiliation with a social security system
• Written, signed informed consent

Exclusion Criteria:

• No invasive breast cancer
• Breast tumor =< 2 cm
• Preoperative histological diagnosis other than infiltrating mammary carcinoma
• Multifocal breast cancer
• Inflammatory breast cancer
• Metastatic cancer
• History of homolateral breast surgery
• History of allergic disorders
• History of homolateral breast cancer
• Difficult follow-up
• Pregnant or lactating woman
• Previous inclusion in the trial