Radiation Therapy for Axillary Control

NSABP-B04 demonstrated that radiation, in lieu of axillary dissection, for patients with clinical N0 or N1 breast cancer was adequate treatment and secured local control in the majority of patients.

Currently, most patients require axillary staging to direct systemic therapy. In the case of elderly patients who are not medially fit for chemotherapy, and in cases when the primary tumor, upon excision, is demonstrated to be hormone-receptor positive and, therefore, utilization of hormonal therapy is indicated, axillary dissection is not necessary. For patients who will undergo radiation as a component of their therapy, it is technically quite simple to include levels 1 and 2 of the axilla. In this circumstance, the inferior aspect of the humoral head is the desired superior border of the radiation field. This represents a very minor alteration in the standard radiation field and should be considered as an appropriate alternative to axillary surgery in this select population.

Postmastectomy Radiation Therapy

Among patients who undergo mastectomy for early-stage breast cancer (StageI and Stage II) the role of postmastectomy radiation is currently in evolution. At one point in time, this was the only adjuvant therapy available and it was clearly effective in diminishing local failure.

With longer follow-up on the rather simple radiation techniques from the 1950s and 60s, however, it has become evident that cardiovascular deaths, particularly for patients treated for left-sided tumors, were a significant cause of long-term mortality. Therefore, postmastectomy radiation therapy fell out of favor as chemotherapy became more commonly utilized among patients with breast cancer.

It has become evident that chemotherapy alone has little impact upon local failure rates in certain patients with a variety of unfavorable prognostic factors. Local control in the chest-wall region clearly benefits from the addition of radiation to combined-modality treatment.

At our institution, patients with primary tumors 5 cm or greater in dimension, four or more positive axillary lymph nodes or positive margins of resection are referred for postmastectomy radiation therapy. Recent randomized studies from Canada and Europe suggest that the indications for postmastectomy radiation should be extended to all node-positive patients.

These studies have certain flaws in as much as the local failure rate among patients who underwent mastectomy alone is considerably higher than one would expect. The number of axillary lymph nodes removed is considerably lower than one would expect, and the adequacy of local surgical managemen in these studies is called into question. Nevertheless, the investigators did demonstrate an improvement in survival among patients who underwent postmastectomy chest-wall radiation and further investigation on this topic is merited.