In addition to the highlighted articles on possible toxicity from 3D Conformal APBI, several interesting breast cancer-related abstracts were presented. The following were selected by one of our editors (MK) for inclusion due to direct or potential implications for partial breast irradiation techniques. The 10-year update of the Massachusetts General Hospital (MGH) interstitial APBI dose escalation trial was presented. The data again showed significant toxicity and poor cosmetic results using LDR brachytherapy, especially in the group receiving 60 Gy. Local control remains excellent at 88% (Abstract 14).  Another paper presented showed the long-term results out to a minimum of 8 years for the Harvard DCIS trial examining wide local excision in a favorable subset (1 cm margin). The median follow-up was 10 years. You may recall that the trial closed early due to excessive local failures. At eight years, 27% of patients had events, including 19/36 local recurrences and 13/36 contralateral breast cancers. One third of the local failures were invasive at the time they were discovered (Abstract 63). Still another intriguing abstract presented from MGH described the incidence of local failure for patients undergoing breast conservation based upon approximated Luminal subtypes and HER2 status compared to age at treatment. Although patients in the lowest age quartile (23-46 years) had somewhat higher local failure rates than the older patients, they were still quite low and deemed acceptable by the authors. The median follow-up was 85 months, and 1,434 patients were included in the study. Overall local failure was 3.1% and 6.5% in the youngest group. Comparing the HER2 positive patients (n=55) failure in the entire group was 10.9%, compared to 13.3% in the youngest quartile. Comparing the triple negative patients (n=171) local failure was seen in 8.8% vs. 10.2% for the whole group and youngest patients, respectively.

Another interesting group of presentations included a panel looking at the ASTRO APBI Breast Cancer Consensus, questioning the timing of a review and potential revision. Dr. Vicini discussed the growing body of data suggesting a lack of discrimination among different ASTRO subgroups and local failure rates. He also suggested that the original intent was to review the guidelines on a regular basis. Other panelists stated that they did not feel the data he presented was “practice changing” and did not see the need for review. As a reminder, this statement was first written 3 years ago and published more than 2.5 years ago. Numerous single institution series and the ASBrS Registry publications were not included in the study leading to the Consensus Statement. Some of these data, including the Registry Trial and the William Beaumont Hospital dataset, were presented at this year’s ASTRO as well.