Treatment with accelerated partial-breast irradiation (APBI) versus conventional whole-breast irradiation for women with early-stage breast cancer resulted in similar tumor recurrence rates and overall survival, but APBI was associated with less toxicity, according to a report published in the European Journal of Cancer.
“There was no evidence of significant differences regarding the true incidence of recurrence nor new-onset ipsilateral tumors. [Overall survival] did not differ between the two treatment groups, with the same number of deaths related to” breast cancer, wrote Dr. Lorenzo Livi, a radiation oncologist at the University of Florence, Italy, and his colleagues (Eur. J. Cancer 2015;51:451-63).
Six of the 520 patients, three in each study arm, had ipsilateral breast tumor recurrence. No significant differences were observed in contralateral breast cancer occurrence, distant metastases, or overall survival. The low rate of events at the median 5-year follow up “underlines the importance of longer follow up in addition to an appropriate selection of patient candidates for APBI,” they wrote, urging caution in interpreting the results because longer follow-up is required.
Most of the patient cohort had tumor grade G1-2 (89%), positive estrogen-receptor status (95%), negative nodal status (86%), and were human epidermal growth factor receptor 2 negative (96%).
The APBI group had significantly fewer adverse events than the whole-breast irradiation (WBI) group (P < .0001). Erythema was the most frequently observed event in both arms of the study, at 20% for APBI and 66.5% for WBI. The most represented late skin adverse event was grade 1-2 fibrosis (11% in WBI, 4.5% in APBI). No grade-3 toxicity was recorded in either study arm.
Potential advantages of APBI include shorter treatment time, lower costs, and improved cosmesis, compared with convention treatment. Cosmetic results for both groups in the study were rated excellent/good in greater than 90% of patients, with APBI having slightly better outcomes (P = .045).
The randomized, phase III trial was conducted at the radiation-oncology department of the University of Florence (Italy) between 2005 and 2013 and compared APBI using intensity-modulated radiotherapy (IMRT) with conventional, tangential-field WBI. For the WBI arm, a total dose of 50 Gy was given in 25 fractions, followed by a radiation boost of 10 Gy in five fractions. For the APBI group, a dose of 30 Gy in five fractions at 6 Gy/fraction was given (treatment time, 2 weeks), which is equivalent to 54 Gy in a standard 2-Gy fractionation.
Compared with conformal techniques, IMRT produces optimal dosimeter results while allowing easier, less time-consuming treatment delivery. Additionally, APBI appears to be more cost effective than conventional WBI radiation therapy. The trial “demonstrated excellent results in terms of safety, with a very low rate of local recurrences. APBI using the IMRT technique with the administration of 30 Gy in five non-consecutive fractions should be part of the multidisciplinary discussion to offer a tailored treatment for the patient,” Dr. Livi and his colleagues wrote.
The investigators did not declare any outside funding or conflicts of interest.