The goals of this clinical trial are:

• demonstrate the safety of REGENERA breast implant in patients undergoing lumpectomy of malignant breast lesions
• demonstrate the safety and performance of REGENERA in terms of investigator's satisfaction, potential interference with current standard-of-care imaging techniques and occurrence of device-related serious adverse events.

Participants will perform 13 study visits, and at each visit, all necessary study procedures will be performed according to the clinical investigation plan:

• Screening
• Pre-surgery treatment
• Surgery and study device implant
• Post-surgery follow-up up to 5 years

Inclusion Criteria:

• Female adult subject aged 40-70 years.
• Subject diagnosed with malignant breast lesion:
• monolateral nodular infiltrative carcinoma,
• without microcalcification,
• single or multifocal,
• included in an area with a maximum diameter of 4 cm,
• non-metastatic (M0).
• Subject with clinically negative axilla.
• Subject considered eligible for conservative breast surgery - BCS (Breast-Conserving Surgery, lumpectomy or quadrantectomy), leaving a volume deficit compatible with a REGENERA implant (available in two dried sizes) volume of 70 ml or 100 ml.
• Confirmation of malignant lesion (pT1, pT2, pN0, pN1) with no discordance between biopsy and radiological imaging.
• Adequate hematopoietic functions.
• Good general health and mentally sound.
• Subject able and willing to give written informed consent form.

Exclusion Criteria:

• Subject with actual concomitant benign breast lesion (B2 and B3), unless present in the same mammary quadrant or in the contralateral breast.
• Subject with actual concomitant malignancies, lobular neoplasm, metastatic breast carcinoma, sarcoma, malignant phyllodes lesions, or Paget's disease.
• Axillary dissection planned as part of the breast lesion surgery.
• History of surgery, chemotherapy, neoadjuvant chemotherapy, or irradiation of the breast parenchyma object of the study.
• Skin retraction at the breast to be operated.
• Infection of the surgical site confirmed pre-operatively by clinical examination.
• Abnormal blood sugar and glycosylated hemoglobin.
• Hard smoker (more than 10 cigarettes a day).
• Acute or chronic severe renal insufficiency (creatinine values >180 μmol/l).
• History of severe asthma or allergies (including allergy to anesthetics or contrast media).
• Autoimmune disease.
• Subjects who are known to be carriers of BCRA mutation.
• Inability to undergo MRI or allergy to contrast media.
• Systemic infections in an active phase.
• Immunocompromised patients (HIV).
• Pregnant or breastfeeding woman or woman who has nursed a child within 3 months prior to enrolment in the study.
• Subject who has participated in another interventional study within the past 3 months.
• Subject who received immunosuppressant therapy in the last 3 months.
• History of substance abuse (drug or alcohol).
• Non-collaborative patients (severe physical disabilities or psychiatric disorders, as per specialist opinion).