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Technique of Lumpectomy and Radiation

A discussion of proper technique is available as a consensus statement: the NCCN guidelines, a Consensus Statement, and a discussion of sentinel nodes and chemotherapy , and other information, on line.   In general terms, lumpectomy means that the cancer is excised (removed) with a small margin of normal tissue (rather than having the whole breast removed, i.e. mastectomy.) The role of the boost field is somewhat controversial. There are three components to the procedure:

Elements in the Technique of Irradiation      (from the Consensus Report) ( the NCCN guidelines are a little different)
There is a general consensus regarding some but not all of the elements in the technique of irradiation. As soon as the patient has healed adequately from the surgical procedure, radiation therapy should begin. Therefore, irradiation usually can begin within two to four weeks of uncomplicated breast conserving surgery.

Each field should be treated on a daily basis, Monday through Friday. Bolus should not be used. In order to minimize the risk of radiation pneumonitis, not more than 3 to 3.5 cm of lung as projected on the beam radiograph at isocenter should ordinarily be treated, and a minimum of 1 to 1.5 cm of lung is required. For left-sided lesions, efforts should be made to minimize the amount of heart in tangential fields. Whole breast radiation therapy is delivered using opposed tangential fields to a dose of 4,500 to 5,000 cGy at 180 to 200 cGy per fraction.
Although controversy has existed concerning the need for delivering an additional boost dose to the primary site, there is growing consensus about its utility. Although boost irradiation generally is used, the precise indications for its use are not well defined. However, research indicates that a boost should be used in patients with focally positive or close margins of resection.

Boost irradiation usually is delivered using electron beam or interstitial implantation. The total dose to the primary tumor site is increased to approximately 6,000 to 6,600 cGy. Selection of the boost dose and volume should be based on knowledge of the surgical procedure and the pathologic findings. In situations where an electron beam boost and an interstitial implant boost are judged to be equally effective, an electron beam is generally preferred because of considerations of cost, patient convenience, and cosmesis.

A boost may not be required for patients who have been treated with more extensive breast resections and have margins of resection that are clearly negative. If the breast boost is omitted in these patients, the only available data indicate that the standard whole breast radiation therapy dose is 5,000 cGy at 200 cGy per fraction.
Techniques To Be Avoided
Although there is a lack of consensus concerning the advisability of treating nodal areas with irradiation, there is agreement on the need to avoid certain radiation therapy techniques for the treatment of regional lymph nodes:

1. Axillary irradiation usually is unnecessary following a complete axillary dissection (Levels I to III). Irradiation of the supraclavicular fossa and contiguous apical region may be considered if extensive numbers of lymph nodes (e.g., greater than or equal to four) contain tumor. The benefit of radiation in patients with one to three positive nodes is unknown.
2. Overlap between adjacent fields should be avoided.
3. Techniques that result in cardiac irradiation should be avoided given the known increase in late cardiac mortality with inadvertent irradiation of the heart. The use of computed tomography (CT) simulation is encouraged for patients with left-sided breast cancer to aid in minimizing cardiac irradiation.