Interim Results of a Phase I/II Trial of 3D-conformal External Beam Accelerated Partial Breast Irradiation in Patients with Early Breast Cancer

Article Outline

• Purpose/Objective(s)
• Materials/Methods
• Results
• Conclusions
• Copyright

Back to Article Outline

Purpose/Objective(s) 

Only a few studies using 3D-Conformal External Beam for accelerated partial breast irradiation (3-DCAPBI) have been reported, all with limited patient numbers and short follow-up (FU). We present our initial experience with this approach for patients in the first cohort of a prospective IRB approved Phase I-II dose-escalation clinical trial.

Back to Article Outline

Materials/Methods 

From 10/2003 through 11/2005, 99 patients with Stage I breast cancer were treated at MGH (78 patients), BIDMC (16 patients), or BMC (5 patients). Eligibility criteria included infiltrating ductal cancer; pT1N0; no EIC or LVI; margins 2 mm or wider. The median age was 60; the median tumor size was 0.9cm; 91% had invasive ductal carcinoma; 88% of tumors were ER+. A dose of 32 Gy was given in 8 fractions BID over 4 consecutive days, prescribed to a PTV encompassing a 1.5-2 cm margin around the excision cavity. Techniques used were: mixed photons and electrons (PH/E), usually with 2 mini-tangents and en face electron field delivering about 20% of the dose, for 63 pts; photons alone (PH) for 16 pts; and protons for 20 pts. 3 patients received adjuvant chemotherapy and 27 took hormonal therapy. Patients were followed at 3-8 weeks, and every 6 months thereafter for evaluation for recurrent disease, cosmetic outcome, toxicity, and patient satisfaction.

Back to Article Outline

Results 

Median FU was 36 months (range, 2-50 months); 10 pts had more than 4 years of FU. Two pts had local failures at 30 and 36 months (1 inside and 1 outside the original quadrant). At last FU, grade 2 and 3 (>2 square cm) telangiectasia occurred in 5%, 7% and 25% of pts treated with mixed PH/E, PH, or protons, respectively, and moderate fibrosis occurred in 8%, 7% and 5%, respectively. No severe fibrosis occurred. Global breast cosmesis at last FU was judged excellent or good for 97% of patients by their physicians and by 95% of patients themselves. Other complications included rib fracture (1 patient) and rib tenderness (3 patients). At last follow-up, 94% (92/98) of pts reported total satisfaction with this treatment.

Back to Article Outline

Conclusions 

3-D conformal accelerated partial breast irradiation as used in our study resulted in high local control and cosmesis rates at 3 years median follow-up, with near-universal patient satisfaction. Additional follow-up is needed to asses the long-term efficacy and toxicity of this approach.