Frank A. Vicini, MD, radiation oncologist, GenesisCare, discusses the potential utility of using the DCISionRT test to determine treatment benefit in the phase 3 NRG-NSABP-B43 trial (NCT00769379) in HER2-positive ductal carcinoma in situ (DCIS) of the breast.

Previous research on HER2-positive versus HER2-negative DCIS has elucidated an association between HER2 status and increased risk of local recurrence. The prospective, randomized NRG-NSABP-B43 trial evaluated whether the efficacy of whole breast radiation therapy increased with 2 doses of trastuzumab (Herceptin) in patients with HER2-positive DCIS who had previously undergone breast conservation surgery, Vicini begins. Although primary data from this trial did not show a statistically significant reduction in ipsilateral breast recurrence (IBR) with the regimen, a modest improvement in local control was observed.

In a poster presented at the 2022 San Antonio Breast Cancer Symposium, researchers assessed the rate of IBR in a large, multicenter population of HER2-positive patients to determine clinical benefit from radiation therapy after breast conserving surgery, Vicini explains. The DCISionRT biomarker test was used to evaluate a patient’s residual risk subtype and predict an individual’s invasive 10-year recurrence risk after breast conserving surgery with or without radiation therapy.

Patients identified as low risk were expected to achieve similar rates of recurrence with radiation therapy while those in the high-risk group were expected to have significantly lower recurrence rates with radiation therapy, Vicini continues. Clinicopathologic features associated with recurrence risk were also accounted for and were used as a comparison to the DCISionRT biosignatures. The results showed that DCISionRT was a better predictor of 10-year prognosis and radiation therapy benefit vs clinicopathologic criteria alone.

This classification of patients based on residual risk suggests that further analysis with the predictive 7-gene biosignature DCISionRT test could help clarify the impact of trastuzumab on patient outcomes and predict which patient subtypes will benefit most from the investigational regimen explored in NRG-NSABP-B43, he concludes.

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Frank A. Vicini, MD, discusses the potential utility of using the DCISionRT test to determine treatment benefit in the phase 3 NRG-NSABP-B43 trial in HER2-positive ductal carcinoma in situ of the breast.
 

Dr. Vicini on the Potential Utility of the DCISionRT Test in HER2+ DCIS of the Breast

Frank A. Vicini, MD, radiation oncologist, 21st Century Oncology of Michigan, compares the use of partial breast irradiation (PBI) with that of whole breast irradiation (WBI) in women with early-stage breast cancer at the 2018 San Antonio Breast Cancer Symposium.

Primary results of the NSABP B-39/RTOG 0413 trial were presented at the symposium, in which 4216 women who had received a lumpectomy with 0 to 3 positive axillary nodes were randomized to treatment with WBI or PBI. Of these patients, 25% had ductal carcinoma in situ, 65% had stage I disease, and 10% had stage II disease. Additionally, 81% of patients were hormone receptor—positive and 61% were postmenopausal.

Ipsilateral breast tumor recurrence (IBTR) occurred in 90 women and 71 women who received PBI and WBI, respectively. The percentage of patients who were IBTR-free at 10 years was 95.2% in those who received PBI and 95.9% in those who were given WBI. The difference in the 10-year relapse-free interval was 1.5%, demonstrating statistical significance. Although the trial could not declare equivalence in controlling local in-breast tumor recurrence, Vicini says there are subsets of patients for whom PBI may be appropriate.

Dr. Vicini on Partial Breast Irradiation Versus Whole Breast Irradiation in Women With Early-Stage Breast Cancer

Frank A. Vicini, MD, radiation oncologist, 21st Century Oncology of Michigan, discusses a European study that examined the efficacy of accelerated partial breast irradiation (APBI) versus conventional whole breast irradiation (WBI) in patients with low-risk breast cancer.

The multicenter European noninferiority phase III study demonstrated noninferiority of APBI compared with WBI for select patients with early-stage breast cancer. It is also the first large trial that addresses this topic, Vicini adds. Patients were closely followed, and techniques were done consistently.

Data from this study show that the paradigm for treating these select patients should change in centers beyond Europe, Vicini explains.

Frank A. Vicini, MD, radiation oncologist, 21st Century Oncology of Michigan, discusses a European study that examined the efficacy of accelerated partial breast irradiation versus conventional whole breast irradiation in patients with low-risk breast cancer.


Frank A. Vicini, MD

Articles

Dr. Vicini on the Potential Utility of the DCISionRT Test in HER2+ DCIS of the Breast

Dr. Vicini on Partial Breast Irradiation Versus Whole Breast Irradiation in Women With Early-Stage Breast Cancer

Dr. Vicini on Accelerated Partial Breast Irradiation in Low-Risk Breast Cancer