Background: Post-mastectomy loco-regional radiation to the chest wall and draining lymphatics, combined with adjuvant chemotherapy and hormonal therapy, significantly improve survival in patients with node-positive breast cancer. However, the actual benefit of post-mastectomy radiotherapy and the desired extent of treatment are still debatable.
Objectives: To examine the effect of postoperative loco-regional radiotherapy on local and regional recurrence and survival in breast cancer patients with four or more involved lymph nodes or extracapsular tumor extension.
Methods: This controlled clinical trial included 258 breast cancer patients with four or more involved nodes or ECE[1]. Eighty-nine patients in the control group had modified radical mastectomy and received adjuvant chemotherapy with melphalan and 5FU, but no radiation therapy. The 169 patients in the study group (87 with MRM[2] and 82 with lumpectomy and axillary dissection) received various adjuvant chemotherapy regimes and radiation therapy to the chest wall/breast, supraclavicular region and full axilla.
Results: With an average follow-up of more than 5 years, loco-regional radiation significantly reduced local and regional disease recurrence. The median disease-free survival was significantly longer in radiated patients (59.2 months and 63.3 months in the MRM and L+AXLND[3] groups, respectively, vs. 28.4 months in the control group; P < 0.01). There was no difference in the rate of systemic recurrence and overall survival. The median overall survival was 71.2 and 67.5 months in the study groups (MRM and L+AXLND, respectively) and 70.5 months in the control group (P = 0.856).
Conclusions: Radiotherapy to the breast/chest wall and to the draining lymphatics, in addition to surgery and adjuvant therapy, significantly reduced the risk of local and regional recurrence in high risk breast cancer patients with four or more involved lymph nodes or ECE.