LOS ANGELES—Partial breast irradiation (PBI) with concurrent chemotherapy is feasible and is associated with an acceptable rate of toxicity, finds a phase I/II trial presented at the 49th annual ASTRO meeting (abstract 44). In addition, this treatment produces good-to-excellent cosmetic outcomes in most patients.
Delivering chemotherapy and radiation therapy for breast cancer at the same time has several potential benefits, said lead author Richard C. Zellars, MD, of Johns Hopkins Kimmel Cancer Center. These benefits include shortening of the overall duration of therapy, initiation of both therapies closer to surgery, and possibly better local control through a radiosensitizing effect of the chemotherapy.
"Unfortunately, whole-breast radiation and concurrent chemotherapy has been associated with prohibitive toxicities," he commented, with more than 40% of women experiencing grade 4 radiation dermatitis in one study. "But today, with the advent of PBI, the toxicity may no longer be prohibitive."
In the trial, women with resected early-stage breast cancer were treated with dose-dense doxorubicin and cyclophosphamide (AC) every 14 days for four cycles with growth factor support, along with concurrent PBI consisting of 2.7 Gy daily for 15 days (total dose, 40.5 Gy) by external beam.
In terms of dosimetric limitations set for various tissues, Dr. Zellars said, "Please note they were very similar to [NSABP] B-39, except for the heart. In our trial, no more than 10% of the heart received more than 5% of the dose."
Analyses were based on the first 22 consecutive patients. Ten received AC only while 12 received AC plus paclitaxel. Four patients discontinued chemotherapy (mainly because of febrile neutropenia), and four had a delay in chemotherapy. All patients completed radiation therapy.