The investigators conducted a prospective cohort study to assess the safety, quality of life and cosmetic sequelae of prepectoral breast reconstruction in women with breast cancer and high risk. The study's main objective is to assess the safety of prepectoral breast reconstruction in terms of postsurgical complications and the feasibility of reconstruction (loss of implants). The secondary objectives are to evaluate oncologic safety (local relapses, residual glandular tissue) and to identify factors related to quality of life and cosmetic sequelae. The evaluation of residual tissue will be conducted by magnetic resonance imaging 12 to 18 months after the surgery, and the quality-of-life assessment will be performed using the BreastQ questionnaire. An initial patient evaluation will be conducted 12-18 months after the surgery, and a second evaluation will be performed at 5 years. The estimated sample size is 81 patients.

1. Mastectomy technique. The breast removal will be performed using a mastectomy adapted to the breast and optimizing the preservation of the breast's original elements (inframammary fold, skin envelope, fat transitions, nipple-areolar complex) according to each patient's anatomical and oncologic possibilities.
2. Reconstruction technique. The reconstruction will be performed by placing a silicone implant coated with polyurethane foam in the prepectoral position.
3. Preoperative assessment. All patients will be assessed by a surgeon of the breast unit. The decision for the mastectomy will be made in consensus with the multidisciplinary committee. Before the surgery, the patients will undergo a mammography and magnetic resonance imaging to confirm the tumor size and rule out multifocality/multicentricity, as well as an evaluation of the distribution of glandular tissue and transitions between the breast and chest wall.
4. Breast magnetic resonance imaging. This study will employ the first magnetic resonance imaging during the postoperative period (between 12 and 18 months) to assess the residual glandular tissue following the mastectomy.
5. BreastQ questionnaire. The BreastQ questionnaire is aimed at evaluating patient-reported satisfaction and quality of life through the use of breast reconstruction modules. The preoperative format, which is delivered to patients before the surgery, and the postoperative format, which is delivered to them 12-18 months after the surgery. Likewise, we will conduct a second postoperative assessment at 5 years of the surgery.

d. Images. The evaluation of the cosmetic sequelae requires taking photographs of the patient's chest (from the suprasternal notch to navel). Photographs will be taken prior to the surgery (frontal, right and left lateral), then again at 12-18 months and finally at 5 years of the surgery.

Inclusion Criteria:

• We will include all women operated on in the Breast Unit through skin sparing mastectomy/Nipple skin sparing mastectomy (unilateral or bilateral) and immediate reconstruction with prepectoral implantation.

The study population will include 2 patient groups:

1. Women with breast carcinoma. This group consists of patients with a histological diagnosis of in situ or infiltrating breast carcinoma, either primary or metachronic, which requires mastectomy as the surgical treatment.

2. Women at high risk for breast cancer. This group consists of women evaluated at a high-risk consultation and whose reducing risk mastectomy has been approved by the tumor committee of the Breast Unit of University Hospital Complex of A Coruna. For this procedure, the patients should meet at least one of the following criteria:

   • Hereditary breast and ovarian cancer syndrome, either by demonstrated genetic mutation or through their family history.
   • Histological diagnosis of high-risk lesions (atypical hyperplasia, ductal carcinoma in situ, lobular carcinoma in situ) associated with family history.
   • High-risk criteria (genetic, histological, family) during the breast cancer follow-up.

Exclusion Criteria:

• Inability to undergo magnetic resonance imaging during the diagnosis and follow-up.
• Inability to fill out the BREAST-Q questionnaire.
• Unwillingness by the patient to participate in the study.
• Breast sarcomas.
• Benign breast tumors.
• Prepectoral breast reconstruction using expanders.
• Prepectoral reconstruction with mesh