Risk of lymphedema after regional nodal irradiation with breast conservation therapy.

PURPOSE: To evaluate the risk factors for lymphedema in patients receiving breast conservation therapy for early-stage breast cancer. METHODS AND MATERIALS: Between 1982 and 1995, 727 Stage I-II breast cancer patients were treated with breast conservation therapy at Massachusetts General Hospital. A retrospective analysis of the development of persistent arm edema was performed. Lymphedema was defined as a >2-cm difference in forearm circumference compared with the untreated side. The median follow-up was 72 months. Breast and regional nodal irradiation (BRNI) was administered in 32% of the cases and breast irradiation alone in 68%.
RESULTS: Persistent arm lymphedema was documented in 21 patients. The 10-year actuarial incidence was 4.1%. The median time to edema was 39 months. The only significant risk factor for lymphedema was BRNI. The 10-year risk was 1.8% for breast irradiation alone vs. 8.9% for BRNI (p = 0.001). The extent of axillary dissection did not predict for lymphedema even within the subgroups of patients defined by the extent of irradiation. Most patients underwent Level I or II dissection. In this subgroup, the lymphedema risk at 10 years was 10.7% for BRNI vs. 1.0% for breast irradiation alone (p = 0.0003).
CONCLUSION: Nodal irradiation was the only significant risk factor for arm lymphedema in patients receiving breast conservation therapy for early-stage breast cancer. Our data suggest that this risk is low with Level I/II dissection and breast irradiation. However, even after the addition of radiotherapy to the axilla and supraclavicular fossa, the development of lymphedema was only 1 in 10, lower than generally recognized.