Clinical case: Breast cancer development after prophylactic subcutaneous mastectomy

History

The patient was a 46-year-old premenopausal woman who was concerned about a mass she felt in the left breast. Five years prior she had undergone bilateral prophylactic mastectomy because of a family history of breast cancer. The patient also had breast reconstruction via bilateral breast implants (Figure 2).

Physical examination

The patient, who had annual follow-up exams with ultrasound imaging, became aware of a mass in the lower quadrant of her left breast during the last month. The physical examination revealed a mass in the lower outer quadrant of her left breast near the edge of the implant in that breast.

Imaging

An ultrasound exam revealed an irregularly contoured solid lesion with dimensions of 1.3 x 1.5 cm. Follow-up MR imaging confirmed the presence of the lesion (Figure 3).

Histopathology and management

And, because the imaging was suggestive of a malignancy, a biopsy was ordered. The results of the excisional biopsy confirmed invasive ductal cancer. Based on this finding, an incision of 4 cm was made on the left lower quadrant, and the cancerous area was removed. Frozen section was performed during the surgery, and the surgical margins were found to be negative. An incision of about 5 cm long was also done in the axilla and the axillary lymph nodes were dissected and removed.

Evolution

The patient recovered well and was discharged and referred to the oncology department. The pathology report indicated invasive ductal carcinoma and reactive lymph nodes.

Breast cancer risk and prophylaxis

In order to reduce their risk of developing breast cancer, prophylactic mastectomy is an option for high-risk women who have not yet been diagnosed with breast cancer. High risk factors for breast cancer include:

• a strong family history of breast and/or ovarian cancer
• a disease causing mutation in the BRCA1 gene or the BRCA2 gene
• a high-penetrance mutation in one of many other genes associated with the development of breast cancer.

Bilateral prophylactic mastectomy may include removal of both nipples (total mastectomy) or removal of breast tissue as far as possible while excluding the nipples (subcutaneous or nipple- sparing mastectomy). The latter procedure results in a more natural appearing breast than the total mastectomy procedure. However, total mastectomy is more preventive than the subcutaneous procedure because more breast tissue is removed. The patient in this case chose nipple and areola sparing mastectomy, which was one of the surgical options presented to her.

Prior to a prophylactic mastectomy a patient must be made aware of the associated possible risks inherent in this surgery:

• Bleeding or infection.
• Fluid accumulation under the scar.
• Delayed wound healing.
• Loss of breast sensitivity.
• Body image anxiety or depression.

Thus, even though the patient may avoid cancer, she still may suffer some debilitating consequences if she chooses prophylactic mastectomy.
Further, as shown by this case, mastectomy does not guarantee that breast cancer will never occur. Clearly, in this patient, the remaining breast tissue surrounding the implant became malignant. Even in total mastectomy, accessory breast tissue (e.g., in the axilla; see below) may develop cancer.
In this patient, the axillary lymph nodes were reactive, implying that the tumor was confined to the primary site and there was no metastasis to the lymph nodes.

Prophylactic surgical procedure is typically the simple mastectomy, which removes only the primary breast tissue and leaves behind the axillary lymph nodes and anterior chest wall muscles. Therapeutic surgery for breast cancer is the radical mastectomy, which removes breast, related lymph nodes and pectoralis major and minor muscles (Figure 2). If the tumor does not involve the muscle layer, a modified radical mastectomy is performed, which removes only breast and related lymph nodes.

Sentinel node biopsy

Lymph from the breast drains to the axillary lymph nodes, draining first to the pectoral group, which is one of five axillary groups. Lymphatic system collects the lymph, which is derived from the interstitial fluid in all organs. Lymphatic capillaries are more permeable to large molecular weight proteins and large particles including bacteria and tumor cells compared to venous capillaries. This fluid eventually passes to lymph nodes for filtering. Lymph nodes thus are useful in determining whether cancer cells have metastases to other parts of the body.

In current breast cancer therapy a sentinel biopsy is done to determine if removal of the axillary nodes are necessary (Figure 5).

A sentinel lymph node is considered to be the first lymph node to which cancer cells would most likely to spread from a primary tumor. Sometimes, there can be multiple sentinel lymph nodes. A sentinel lymph node biopsy (SLNB) is a procedure in which the sentinel lymph node is identified, removed, and examined to determine whether cancer cells are present. A negative SLNB result suggests that cancer has not spread to nearby lymph nodes or other organs. A positive SLNB result suggests that cancer is present in the sentinel lymph node and may have metastasized to other nearby lymph nodes (called regional lymph nodes) and, possibly, other organs.

To determine the sentinel node the surgeon injects into the intercellular space near the tumor a radioactive substance or a blue dye, or both. This material flows to the sentinel lymph node. The surgeon then uses a device that detects radioactivity to find the sentinel node or searches for blue-stained lymph nodes that are stained. Once the sentinel lymph node is identified, a small incision (about 1 cm) is made in the overlying skin and the node is removed (Figure 5).

The sentinel node then undergoes a pathological examination. If cancer is found, the surgeon may remove additional lymph nodes, either during the same biopsy procedure or during a follow-up surgical procedure.
SLNB is usually done when the primary tumor is removed. However, the procedure can also be done prior to or after the excision of the tumor. SLNB may help some patients avoid more extensive lymph node surgery.