Jessica M. Bensenhaver
Tara M. Breslin
Presentation
A 50-year-old female presents with a new finding of clustered microcalcifications discovered on her annual screening mammogram. She has an unremarkable medical history and denies a history of previous breast biopsies or breast conditions. She reports a family history significant for breast cancer in a maternal grandmother and aunt. Her breast exam is unremarkable with symmetric, moderate-sized breast, without skin changes and with no erythema, dimpling, or nipple inversion. On palpation, there is no dominant mass or nipple discharge from either breast. She has undergone image-guided core biopsy and has a pathology report that reveals ductal carcinoma in situ (DCIS), nuclear grade 3 with associated comedonecrosis, estrogen receptor (ER) positive by immunohistochemistry.
Differential Diagnosis
DCIS falls along a spectrum of benign, preinvasive, and invasive breast histologies that include ductal hyperplasia, atypical ductal hyperplasia, DCIS, DCIS with microinvasion, and invasive carcinoma. Mammographic lesions can represent one of these conditions in isolation or different combinations.
Workup
This patient presented with new clustered microcalcifications on screening mammogram, a common presentation of DCIS. Further evaluation included in-depth history with risk assessment and thorough physical exam of BOTH breasts and lymph node basins.
A complete imaging evaluation consists of diagnostic mammography to address the characteristics (calcifications, soft tissue density) and extent (focal, multifocal, or multicentric) of ipsilateral disease, and rule out bilateral disease (Figures 1A and 2). Review of prior images is helpful for determining stability of probably benign findings. The information from these imaging studies is essential for planning surgery.
FIGURE 1 • A: Mammogram images of clustered microcalcifications. B: Wire localization image after core biopsy with clip placement. Note hooked portion of wire adjacent to biopsy clip. C: Intraoperative specimen radiograph. Note radiographic wide margins and calcifications and clip adjacent to reinforced portion of wire. D: Postsurgery comparison mammography showing complete removal of all calcifications. Note incision marker and metallic clips marking lumpectomy bed.
FIGURE 2 • Example of soft tissue density.
Diagnosis
Diagnosis requires tissue biopsy. Core biopsy is the preferred method. It is minimally invasive, accurate, and can be performed in office under local anesthesia. Image guidance, either stereotactic or ultrasound, is employed for accuracy and allows placement of a marking clip in the biopsy site. It must be noted that core biopsy represents just a portion of the lesion, and there is a 10% to 15% chance of associated invasive carcinoma being present with a core biopsy diagnosis of DCIS.
Treatment Principles
DCIS treatment is multimodal, including a combination of surgery, radiotherapy, and hormone therapy. DCIS without invasive cancer is unlikely to cause death. Therefore, the focus of DCIS treatment is prevention of local recurrence, unlike most cancer treatments that focus on survival.
Surgical options include breast conservation (BC) or simple (total) mastectomy. BC is feasible if the following conditions are met: (1) the patient is a candidate for postpartial mastectomy radiation and (2) the size of disease allows for partial mastectomy with negative margins without sacrificing cosmesis. Simple mastectomy is indicated in cases of true multicentric disease or multifocal disease for which partial mastectomy would compromise cosmesis. Patient preference can play a role in choosing mastectomy in disease otherwise amenable to BC, usually seen in highly motivated women with genetic predisposition (BRCA mutation). These patients must understand that mastectomy offers a risk reduction benefit, but no survival benefit. Patients undergoing mastectomy should also be considered for reconstruction and undergo preoperative evaluation by a plastic surgeon.
Pathologic evaluation confirms diagnosis; addresses tumor size and extent; characterizes the nuclear grade, tumor architecture, and presence or absence of comedonecrosis; evaluates for microinvasion (focus of invasion <0.1 cm) or occult invasive disease; establishes receptor status; and assesses surgical margins with measurements. The optimal DCIS margin width is unknown, but a width of 1 mm or more is associated with a decreased chance of recurrence. DCIS is upstaged (from stage 0) by the presence of microinvasion or occult invasive disease and should be treated according to recommendation for invasive disease.
Radiotherapy is not routine after mastectomy, but is routine after BC as literature shows a 50% risk reduction in local recurrence with radiotherapy. However, no DCIS trial has ever demonstrated that radiation offers a survival benefit when compared with excision alone; therefore, omitting radiotherapy in low-risk patients is an area of active investigation. To date, however, there are no prospective trial data or established pathologic selection criteria for identifying appropriate patients.
Hormone therapy with tamoxifen has a role for risk reduction in patients with ER-positive DCIS. When used for 5 years, tamoxifen therapy reduces the risk of ipsilateral recurrence and contralateral disease. Therefore, noting no contraindications to tamoxifen exist, hormonal therapy should at least be considered for ER-positive DCIS.
Surgical Approach for BC
Partial mastectomy is performed with the patient supine, under general anesthesia or IV sedation (Table 1). Wire localization is preformed preoperatively for nonpalpable lesions (Figure 1B). Incision planning is strategic and based on lesion location and depth. It is preferable to plan the incision close to the lesion with an orientation (circumareolar, curvilinear, or radial) based on the breast anatomy, recognizing the possibility for future mastectomy if margin status is inadequate (Figure 3). Include the skin overlying superficial lesions. Large skin excisions can affect cosmesis by causing a mastopexy-type effect. If using wire localization, it is ideal to include the location of skin penetration by the wire with the incision, unless doing so will result in excessive tunneling during the dissection. If the incision does not incorporate the wire, be careful to note its location and then deliver it through the center of the incision once encountered.
TABLE 1. Key Technical Steps and Potential Pitfalls of Breast Conservation (BC)
FIGURE 3 • Orientation of incisions for lumpectomy/partial mastectomy excision procedure. (From Bland KI, Klimberg VS, Master Techniques in General Surgery: Breast Surgery. Philadelphia, PA: Lippincott Williams & Wilkins, 2011.)
In cases performed under IV sedation, local anesthesia is utilized prior to incision. The incision is made and dissection is aimed directly down to the lesion, avoiding thin skin flaps if possible. Excise the tissue around the specimen that creates margins grossly appearing to be around 1 cm. Amputate, orient the specimen, and sent it to mammography to confirm removal of the lesion, margins, radiopaque clip if placed at biopsy, and the localizing wire (Figure 1C). Palpate the lumpectomy cavity to ensure removal of all suspicious tissue. Place marking clips on the borders of the specimen cavity (helpful for radiation planning and identification on future breast imaging). Ensure hemostasis and close.
The most common pitfall associated with partial mastectomy is inadequate margin status requiring reexcision or possibly mastectomy. Intraoperative specimen mammography and frozen section of the margins potentially avoids a second operation by providing an opportunity to identify and address margin issues at the primary operation. Re-excision to achieve negative margins is necessary; however, the resultant cosmesis may be compromised and ultimately result in the need for a mastectomy for adequate local control.
Surgical Approach for Mastectomy
Mastectomy is performed under general anesthesia with the patient in the supine position (Table 2). Prepping and draping includes the anterior arm, breast, ipsilateral thorax, and lower neck. An elliptical incision includes the nipple–areolar complex, the biopsy site, and the skin anterior to the tumor (Figure 4). Skin-sparing mastectomy is often utilized in cases with planned immediate reconstruction. The incision is chosen with input from the reconstructive surgeon and traditionally is adjacent to the areolar border (Figure 5). This smaller skin opening does somewhat limit exposure, but the rest of the procedure is performed similarly to standard mastectomy.
TABLE 2. Key Technical Steps and Potential Pitfalls of Mastectomy
FIGURE 4 • Mastectomy incision. (From Bland KI, Klimberg VS. Master Techniques in General Surgery: Breast Surgery. Philadelphia, PA: Lippincott Williams & Wilkins, 2011.)
FIGURE 5 • Skin-sparing mastectomy incision. (From Bland KI, Klimberg VS. Master Techniques in General Surgery: Breast Surgery. Philadelphia, PA: Lippincott Williams & Wilkins, 2011.)
After incision, skin flaps are created by gently handling and retracting the skin edges at a right angle to the chest wall (retractors are avoided to prevent pressure necrosis). Downward countertraction on the breast parenchyma toward the chest exposes the connective tissue layer that separates the adipose tissue of the breast and the adipose tissue of the skin. The skin flaps are developed along this connective tissue plane to the chest wall superiorly, inferiorly, and medially and laterally to the latissimus dorsi. Close attention to flap thickness is important as overly thin flaps are at risk for necrosis and infection. Throughout dissection and removal, any encountered vessels should be isolated and ligated.
The breast is amputated from the chest wall with the pectoralis fascia. Breast tissue is reflected laterally while traveling parallel to the muscle fibers, so that just before amputation is complete, gentle tension on the breast allows visualization of the tissue plane of the axillary fascia. This technique results in amputation of the breast, including the tail of Spence without penetrating the axilla. Ensure hemostasis, place a drain, and close. The patient is either observed overnight or discharged the same day with the drain in place. Drains are often removed once output is 30 to 40 mL/d.
The most common intraoperative complications are inadequate surgical margins and subsequent wound complications. The goal of surgical therapy is local control with complete excision of disease both grossly and microscopically. If extensive superficial disease requires a large skin resection to ensure margins, skin closure can be compromised. Undermining the subcutaneous tissues inferiorly and superiorly can better mobilize the flaps. Skin grafting is rarely necessary but also an option.
Special Operative Considerations in DCIS
The role of axillary surgery in DCIS is controversial. Sentinel lymph node biopsy (SLNB) is recommended for women undergoing mastectomy for DCIS, and should be considered in women with lesions at higher risk for occult invasive disease including those that are clinically palpable, large (>4 cm on imaging), or have aggressive features on biopsy (e.g., comedonecrosis, microinvasion).
Oncoplastic surgical techniques are an emerging technology offering more choices for patients with tumor characteristics that would require generous partial mastectomy to achieve negative margins. These techniques are especially beneficial as an alternative to mastectomy in women with a generous amount of breast tissue. Contralateral reduction is often necessary for symmetry.
Postoperative Management
Common complications of both partial mastectomy and simple mastectomy are infection, hematoma, seroma, chronic incisional pain, and lymphedema. Preoperative prevention practices include prophylactic antibiotics especially in high-risk patients (obese, elderly, diabetic) and cessation of anticoagulants 10 to 14 days before scheduled surgery. Adequate postoperative counseling with PT/OT referral when necessary can address incisional pain and lymphedema. Although rare, brachial plexopathy from positioning can also occur. Two unique complications of BC are the rare potential for pneumothorax from wire placement and Mondor’s disease. Postoperative flap necrosis can occur after mastectomy, seen most often with thin flaps and in smokers. This complication sometimes requires debridement and chronic wound management and/or delayed closure techniques.
Partial mastectomy follow-up starts with a postsurgical mammogram 1 to 3 weeks after surgery to compare with preoperative images and confirm complete excision of calcifications (Figure 1D). Surveillance mammography resumes 6 months after completion of radiation to evaluate treatment-associated changes and establish a new baseline. Annual bilateral screening is then reestablished. Clinical breast exam is recommended every 6 months for 2 years, then annually with screening mammography. Interim self–breast exam is always encouraged.
After mastectomy, surveillance includes clinical exam (ipsilateral chest wall, contralateral breast, and bilateral nodal exam) every 6 months for 2 years, then annually. Contralateral breast screening with mammogram continues annually. Interim self-exam is encouraged.
Case Conclusion
The patient underwent successful wire-localized partial mastectomy (Figure 1B). Intraoperative specimen mammogram included the calcifications, biopsy clip, and wire (Figure 1C). Final pathology revealed high-grade DCIS with comedonecrosis, no microinvasion, and ER-positive receptor status, and all surgical margins were greater than 2 mm. At 3 weeks post-op, mammogram confirmed complete excision of the all the suspicious calcifications (Figure 1D). The patient has been referred to radiation oncology for whole breast irradiation. Following completion of radiotherapy, she will be evaluated for tamoxifen therapy for risk reduction due to her ER-positive DCIS.
TAKE HOME POINTS
· Screening mammography has increased the preclin-ical identification and overall incidence of DCIS.
· Preoperative diagnostic imaging is mandatory to evaluate the extent of ipsilateral disease, to rule out contralateral disease, and guide surgical planning.
· Diagnosis requires tissue biopsy.
· Pathologic evaluation confirms the diagnosis; addresses the size, extent, and presence/absence of invasion; characterizes the disease features; and evaluates margins.
· BC or mastectomy candidacy is based on disease extent with regard to surgical margin, anticipated cosmetic result, suitability for radiotherapy, and patient preference.
· The two surgical options have equal long-term survival benefits.
· Goal of surgery is local control with clear margins. Once the specimen is amputated, it must be oriented for appropriate margin evaluation. Re-excise as necessary to obtain negative margins, realizing that re-excision often affects cosmesis.
· SLNB is recommended for patients undergoing mastectomy for DCIS and in lesions at high risk for occult invasive disease (palpable lesion, large lesion >4 cm, aggressive features, microinvasion).
· Adjuvant radiation therapy results in 50% recurrence risk reduction in BC. Omission in low-risk patients treated with excision only is a controversial area of investigation.
· Adjuvant hormonal therapy with tamoxifen for 5-year duration should be considered for risk reduction in ER-positive DCIS patients.
SUGGESTED READINGS
Burstein HJ, Polyak K, Wong JS, et al. Ductal carcinoma in situ of the breast. N Engl J Med. 2004;350:1430–1441.