Breast reconstruction is the surgical process of rebuilding the shape and look of a breast, most commonly in women who have had surgery to treat breast cancer. It involves using autologous tissue, prosthetic implants, or a combination of both with the goal of reconstructing a natural-looking breast. This process often also includes the rebuilding of the nipple and areola, known as nipple-areola complex (NAC) reconstruction, as one of the final stages.

Generally, the aesthetic appearance is acceptable to the woman, but the reconstructed area is commonly completely numb afterwards, which results in loss of sexual function as well as the ability to perceive pain caused by burns and other injuries.

Breast reconstruction can be performed either immediately following the mastectomy or as a separate procedure at a later date, known as immediate reconstruction and delayed reconstruction, respectively. The decision of when breast reconstruction will take place is patient-specific and based on many different factors. Breast reconstruction is a large undertaking that usually requires multiple operations. These subsequent surgeries may be spread out over weeks or months.

Breast reconstruction is termed "immediate" when it takes place during the same procedure as the mastectomy. Within the United States, approximately 35% of women who have undergone a total mastectomy for breast cancer will choose to pursue immediate breast reconstruction. One of the inherent advantages of immediate reconstruction is the potential for a single-stage procedure. This also means that the cost of immediate reconstruction is often far less to the patient. It can also reduce hospital costs by having fewer procedures and requiring a shorter length of the stay as an inpatient. Additionally, immediate reconstruction often has a better cosmetic result because of the preservation of anatomic landmarks and skin. With regards to psychosocial outcomes, opinions on timing have shifted in favor of immediate reconstruction. Originally, delayed reconstruction was believed to provide patients with time to psychologically adjust to the mastectomy and its effects on body image. However, this opinion is no longer widely held. Compared to delayed procedures, immediate reconstruction can have a more positive psychological impact on patients and their self-esteem, most likely due to the post-operative breast more closely resembling the natural breast compared to the defect left by mastectomy alone.

Delayed breast reconstruction is considered more challenging than immediate reconstruction. Frequently not just breast volume, but also skin surface area needs to be restored. Many patients undergoing delayed breast reconstruction have been previously treated with radiation or have had a reconstruction failure with immediate breast reconstruction. In nearly all cases of delayed breast reconstruction tissue must be borrowed from another part of the body to make the new breast. Patients expected to receive radiation therapy as part of their adjuvant treatment are also commonly considered for delayed autologous reconstruction due to significantly higher complication rates with tissue expander-implant techniques in those patients. While waiting to begin breast reconstruction until several months after radiation therapy may decrease the risk of complications, this risk will always be higher in patients who have received radiation therapy. As with many other surgeries, patients with significant medical comorbidities (e.g., high blood pressure, obesity, diabetes) and smokers are higher-risk candidates. Surgeons may choose to perform delayed reconstruction to decrease this risk.

There are several techniques for breast reconstruction. These options are broadly categorized into two different groups:

This is the most common technique used worldwide. Implant-based reconstruction is an option for patients who have sufficient skin after mastectomy to cover a prosthetic implant and allow for a natural shape. For women undergoing bilateral mastectomies, implants provide the greatest opportunity for symmetrical shape and lift. Additionally, these procedures are generally much faster than flap-based reconstruction since tissue does not have to be taken from another part of the patient's body.

Implant-based reconstruction may be one- or two-staged. In one-stage reconstruction, a permanent implant is inserted at the time of mastectomy. During two-stage reconstruction, the surgeon will insert a tissue expander underneath the pectoralis major muscle of the chest wall at the time of mastectomy. This temporary silastic implant is used to hold tension on the mastectomy flaps. In doing so, the tissue expander prevents the breast tissue from contracting and allows for use of a larger implant later on compared to what would be safe at the time of the mastectomy. Following this initial procedure, the patient must return to the clinic on multiple occasions for saline to be injected into a tube inside the tissue expander. By doing this slowly over the course of several weeks, the space beneath the pectoralis major muscle is safely expanded to an appropriate size without causing too much stress on the breast tissue. A second procedure is then necessary to remove the tissue expander and replace it with the final, permanent prosthetic implant.