Survival and recurrence rates were similar among patients with breast cancer who either received accelerated partial breast irradiation or whole breast irradiation.
Accelerated partial breast irradiation (APBI) may be as effective as whole breast irradiation (WBI) in preventing recurrence in patients with low risk early breast cancer, according to the findings of a phase 3 clinical trial presented during the 2019 San Antonio Breast Cancer Symposium (SABCS).
Following a lumpectomy, patients with early-stage disease are treated with radiation to lower their risk of the disease coming back. WBI is radiation delivered to the entire breast whereas APBI only delivers radiation to the area of the breast where the cancer was located. APBI also has a shorter treatment schedule than WBI.
In the APBI IMRT trial, which was led by Dr. Icro Meattini of the University of Florence, Italy, 520 women over age 40 were randomly chosen to either receive APBI (260 patients) or WBI (260 patients). The patients enrolled had stage 1 or stage 2 breast cancer, and most had hormone receptor-positive, HER2-negative breast cancer.
Ten-year follow-up data presented at SABCS showed that 3.3% of patients experienced breast cancer recurrence after APBI compared with 2.6% who received WBI. These results were comparable to the five-year follow-up results, noted the researchers, in which the group that received APBI had a 2.4% recurrence rate versus 1.2% in the WBI group.
Although there were slight differences between groups, the study authors said those differences were not statistically significant, meaning they were not greater than the difference that would be expected by chance.
“These results reinforce the initial promising results from the previous study,” Meattini said in a press release. “Accelerated partial breast irradiation can produce excellent disease control.”
In addition to cancer recurrence, researchers examined overall survival. Among patients who received APBI, 92.7% survived their breast cancer compared with 93.3% who received WBI. Breast-cancer specific survival was 97.6% for those who received APBI and 97.5% for those who received WBI.
The results of this study could help health care professionals in selecting between procedures. Clinicians may recommend that patients at lower risk of recurrence choose to receive APBI, while those at a higher risk of recurrence may be recommended for WBI, Meattini explained.
“In well-selected cases, there is no difference in patients’ outcomes whether they are treated with APBI or WBI,” Meattini said. “A once-daily regimen of external APBI might also produce an improved quality of life, with less toxicity, and can potentially reduce the overall treatment time.” He added that APBI may also be less likely to cause cosmetic changes and carries a lower cost of administration than WBI.