After Breast Conservation Therapy

Overview

This chapter will review the definition of breast conservation therapy, indications for this therapy, principles of preoperative tumor localization and surgical specimen radiography, surveillance after breast conservation therapy, expected changes after breast conservation therapy, and typical imaging findings of residual disease or recurrent cancer .

The optimal therapy for breast cancer is based on a multidisciplinary approach and collaborative effort of breast radiologists, surgeons, oncologists, pathologists, breast reconstructive surgeons, and radiation oncologists who together develop the best treatment plan for each patient. The aims of treatment are to completely excise the tumor using the appropriate surgical option (i.e., the option that optimizes locoregional control and overall survival while ensuring an acceptable cosmetic outcome) and to eradicate any possible microscopic tumor deposits with radiation therapy and/or systemic therapy. The choice of treatment plan depends on multiple factors, including cancer stage, hormonal subtype, local disease extent, tumor multicentricity and multifocality, contraindications to radiation therapy, and the patient’s own preference. Tumor excision is achieved with either mastectomy, which is surgical removal of the whole tumor-harboring breast, or lumpectomy, also referred to as breast conservation surgery (BCS), which is excision of the tumor with a safe margin. BCS is usually followed by whole-breast radiation therapy.

Radiologists play an important role in the care of patients who undergo breast conservation therapy (BCT) and thus must be familiar with the principles of this treatment approach. Specifically, radiologists play an important role in patient selection, presurgical planning, and intraoperative imaging guidance in patients undergoing BCT. Furthermore, radiologists must have knowledge of the imaging appearance and evolution of benign posttreatment changes in the breast after BCT to ensure appropriate posttreatment surveillance and timely detection of residual or recurrent disease.

This chapter will review the definition of BCT, indications for BCT, principles of preoperative tumor localization and surgical specimen radiography, post-BCT surveillance, expected post-BCT changes, and typical imaging findings of residual or recurrent cancer.

Breast Conservation Therapy

Definition and History

BCT includes tumor excision followed by adjuvant whole-breast radiation therapy ( Box 16.1 ). Surgical staging of the axilla usually is also performed. Additionally, systemic hormonal therapy or cytotoxic therapy may be administered after surgery to eradicate microscopic residual disease (“adjuvant systemic therapy”) or before surgery to downstage the primary malignancy (“neoadjuvant systemic therapy”).

Box 16.1

Breast Conservation Therapy: Definition and Requirements

Definition

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Surgical excision of the primary tumor (breast conservation surgery) followed by whole-breast radiation therapy

Requirements for Successful BCT

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Surgical excision of the primary tumor with negative margins
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Acceptable postsurgical cosmetic appearance of the breast
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Patient’s ability to receive radiation therapy
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Ability to perform follow-up breast imaging

BCS was first described by Sir Geoffrey Keynes, an English surgeon at St. Bartholomew’s Hospital in London in 1924. BCS is defined as the removal of a breast cancer with clear surgical margins. It has also been referred to as “lumpectomy,” “wide local excision,” “segmental resection,” “partial mastectomy,” “quadrantectomy,” and “tylectomy.”

Studies showed that whole-breast radiation therapy after BCS significantly improved outcomes of breast cancer patients. Multiple randomized trials have been conducted showing similar overall survival after mastectomy and BCT. In 1990, a National Institutes of Health consensus panel advised that BCT is an appropriate primary therapy for the majority of women with early (stage I or II) breast cancer. More recently, neoadjuvant systemic therapy has increasingly been used for preoperative treatment of patients with more advanced breast cancer, rendering some patients eligible for BCT rather than total mastectomy, depending on the response to the treatment.

Oncoplastic BCS

The term “oncoplastic surgery” was introduced by a German surgeon, Dr. Werner Audretsch, in 1993, when he first described the technique of repairing defects from BCS using plastic surgery. Oncoplastic BCS gained popularity, since it provided patients with better cosmetic results than simple BCS. Oncoplastic BCS encompasses a variety of techniques that allow resection of a breast cancer with wide surgical margins while preserving the shape and appearance of the breast. Oncoplastic BCS usually includes excision of the primary tumor with clear margins, immediate soft tissue rearrangement, and if needed, contralateral breast procedures to achieve symmetry. The two most commonly used oncoplastic techniques are (1) repair of the defect by transposition of tissue from elsewhere in the breast and (2) filling of the defect with local tissue or with autologous fat grafting. Collaboration between breast surgery and plastic surgery teams is necessary to achieve the best oncological and cosmetic outcomes.

Surgical Management of the Axilla

The initial site of metastatic disease for breast cancer patients is usually axillary lymph nodes. Therefore correct assessment of axillary nodal status is of outmost importance for breast cancer patients. For patients undergoing BCT who have a clinically negative axillary nodes (i.e., by physical examination and/or imaging), sentinel lymph node biopsy during BCT is generally the standard initial approach. Intraoperative injection of blue dye, radioactive tracer, or both is traditionally used to identify the sentinel lymph node. At some institutions, presurgical lymphoscintigraphy following radioactive tracer injection, usually in the peritumoral or periareolar region, is used to localize the sentinel lymph node before surgery ( Fig. 16.1 ). Axillary lymph node management, including sentinel lymph node biopsy, targeted axillary dissection, and indications for complete axillary dissection are covered in detail in Chapter 15, Chapter 17 .

Fig. 16.1, Lymphoscintigraphy for sentinel lymph node localization.

Patient Selection for BCT

Careful patient selection for BCT is very important to minimize risk of recurrence. In order to achieve successful BCT, it must be possible to excise the primary tumor with negative margins and acceptable cosmetic results, the patient typically must be able to receive radiation therapy, and the patient must be amenable to performing follow-up imaging of the breast to detect local recurrence (see Box 16.1 ).

Patients who are generally not candidates for BCT include those with a high probability of recurrence, those with contraindications to radiation therapy, those at risk for a poor cosmetic outcome, and those who prefer mastectomy.

Contraindications to BCT

Patients with extensive malignant microcalcifications occupying the majority of the breast are not suitable candidates for BCT ( Box 16.2 ). This mammographic presentation suggests diffuse ductal carcinoma in situ (DCIS), which precludes achievement of negative margins. In addition, patients in whom negative surgical margins are not achievable without compromising the cosmetic appearance of the breast are not candidates for BCT. A history of prior therapeutic radiation therapy delivered to the breast region or mediastinum/lung also often excludes BCT as a treatment option. This category includes patients with Hodgkin disease who received chest wall radiation during adolescence or early adulthood. Pregnancy is a major contraindication to radiation therapy, which cannot be administered during any gestational period because of scatter exposure to the fetus. However, BCS may be performed during the third trimester of pregnancy, with radiation therapy deferred to after delivery.

Box 16.2

Contraindications to Breast Conservation Therapy

Absolute

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Diffuse, malignant microcalcifications on the preoperative mammogram
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Inability to achieve negative surgical margins with satisfactory cosmetic result
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Pregnancy (possible if radiation performed after delivery)

Relative

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Multicentric disease
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Collagen vascular disease (e.g., active scleroderma and active systemic lupus erythematosus)
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Prior radiation therapy delivered to breast or chest wall
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Large primary tumor size relative to breast size

Multifocal and multicentric breast cancers are no longer absolute contraindications to BCT. However, the number of lesions, their size, location, and relationship to each other determine whether it is possible to resect all tumors with negative margins and an acceptable cosmetic outcome and thus influence whether BCT is feasible ( Fig. 16.2 ). Specific types of collagen vascular disease, including active scleroderma and, to a lesser degree, active systemic lupus erythematosus, are relative contraindications because of the risk of radiation toxicity (see Box 16.2 ). Tumor size relative to breast size is another important consideration in selecting patients for BCT. A large tumor in a small breast is a relative contraindication, since an adequate resection would result in poor cosmetic outcome. Neoadjuvant chemotherapy or hormonal therapy can reduce tumor size significantly and allow for BCT with acceptable rates of local recurrence. Eligibility for BCT depends on the extent of tumor after, not before, neoadjuvant systemic therapy.

Fig. 16.2, Breast conservation therapy (BCT) in multicentric breast cancer.

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