"Standard" Fractionation for Breast Cancer is No Longer Standard

Prospective Comparison of Hypofractionated Versus Normofractionated Intensity-Modulated Radiotherapy in Breast Cancer: Late Toxicity Results of the Non-Inferiority KOSIMA Trial (ARO2010-3)

Purpose

To compare the late toxicity profile of hypofractionation and normofractionation for whole-breast radiotherapy in breast cancer (BC) patients after conserving surgery.

Methods

Sixty-year-old or older patients with pTis-pT3, pN0-pN1a, M0 BC were recruited and stratified to hypofractionated (arm R-HF) or normofractionated (arm L-NF) intensity-modulated radiotherapy (IMRT), for right- and left-sided BC, respectively, in this single-center, non-randomized, non-inferiority trial. A boost was allowed if indicated. The primary outcome was the cumulative percentage of patients developing grade III fibrosis, grade I telangiectasia, and/or grade II hyperpigmentation after 2 years, with a pre-specified non-inferiority margin of 15% increase from an expected 2-year toxicity rate of 20%.

Results

The Median follow-up was 4.93 (0.57-8.65) years for R-HF and 5.02 (0.65-8.72) years for L-NF (p=0.236). The median age was 68 (60-83 and 60-80) years, respectively. In total, 226 patients were recruited (107 for R-HF and 119 for L-NF), with 100 and 117 patients suitable for assessment, respectively. A boost was delivered in 51% and 53% of each arm, respectively. Median PTV volumes were 1013.6 (273-2805) cm3 (R-HF) and 1058.28 (315-2709) cm3 (L-NF, p=0.591). The 2-year primary endpoint rate was 6.1% (95% CI 1.3-11.7, n=5 of 82) and 13.3% (95% CI 7-20.2, n=14 of 105), respectively (absolute difference -7.2%, one-sided 95% CI ∞ to -0.26, favoring R-HF). No local recurrence-free- or overall-survival differences were found.

Conclusion

In this prospective non-randomized study, hypofractionation did not have higher toxicity than normofractionated whole-breast IMRT.

Hypofractionated Whole-Breast Irradiation Focus on Coronary Arteries and Cardiac Toxicity-A Narrative Review

Breast cancer is the most common cancer among women worldwide, which is often treated with radiotherapy. Whole breast irradiation (WBI) is one of the most common types of irradiation. Hypo-fractionated WBI (HF-WBI) reduces the treatment time from 5 to 3 weeks. Recent radiobiological and clinical evidence recommended the use of HF-WBI regardless of the age or stage of disease, and it is proven that hypo-fractionation is non-inferior to conventional fractionation regimen irradiation. However, some studies report an increased incidence of heart-related deaths in the case of breast irradiation by hypo-fractionation, especially in patients with pre-existing cardiac risk factors at the time of treatment. Due to the new technical possibilities of radiotherapy techniques, HF-WBI can reduce the risk of cardiac toxicity by controlling the doses received both by the heart and by the anatomical structures of the heart. The radiobiological “double trouble”, in particular “treble trouble”, for hypo-fractionated regimen scan be avoided by improving the methods of heart sparing based on image-guided irradiation (IGRT) and by using respiration control techniques so that late cardiac toxicity is expected to be limited. However, long-term follow-up of patients treated with HF-WBI with modern radiotherapy techniques is necessary considering the progress of systemic therapy, which is associated with long-term survival, and also the cardiac toxicity of new oncological treatments. The still unknown effects of small doses spread in large volumes on lung tissue may increase the risk of second malignancy, but they can also be indirectly involved in the later development of a heart disease. It is also necessary to develop multivariable radiobiological models that include histological, molecular, clinical, and therapeutic parameters to identify risk groups and dosimetric tolerance in order to limit the incidence of late cardiac events. MR-LINAC will be able to offer a new standard for reducing cardiac toxicity in the future, especially in neoadjuvant settings for small tumors.

Association of the Oncology Care Model with Value-Based Changes in Use of Radiation Therapy

PURPOSE

Radiation utilization for breast cancer and metastatic bone disease varies in modality, fractionation and cost, despite evidence demonstrating equal effectiveness and consensus recommendations such as Choosing Wisely that advocate for higher value care. We assessed whether the Oncology Care Model (OCM), an alternative payment model for practices providing chemotherapy to patients with cancer, impacted the overall use and value of radiation therapy in terms of Choosing Wisely recommendations.

METHODS AND MATERIALS

We used CMS administrative data to identify beneficiaries enrolled in traditional fee-for-service Medicare who initiated chemotherapy episodes at OCM and propensity-matched comparison practices. Difference-in-difference (DID) analyses evaluated the effect of OCM on overall use of post-operative radiation for breast cancer, use of intensity-modulated radiation therapy (IMRT) and hypofractionation for breast cancer, and fractionation patterns for treatment of metastatic bone disease from breast or prostate cancer. We performed additional analyses stratified by the presence or absence of a radiation oncologist in the practice.

RESULTS

Among 27,859 post-operative breast cancer episodes, OCM had no effect on overall use of radiation therapy following breast surgery (DID percentage point difference=0.4%, 90%CI=-1.7%, 2.4%), or on use of IMRT in this setting (DID=-0.6, 90%CI=-3.1, 2.0). Among 19,366 metastatic bone disease episodes, OCM had no effect on fractionation patterns for palliation of bone metastases (DID for ≤10 fractions=-1.1%, 90%CI-2.6%, 0.4% and DID for single fraction=-0.2%, 90%CI=-1.9%, 1.6%). Results were similar for practices with and without a radiation oncologist. We did not evaluate the effect of OCM on hypofractionated radiation after breast-conserving surgery due to evidence of differential baseline trends.

CONCLUSIONS

OCM had no effect on use of radiation therapy after breast-conserving surgery for breast cancer, or fractionation patterns for metastatic bone disease. Future payment models directly focused on radiation oncology providers may be better poised to improve the value of radiation oncology care.