Patterns of Fractionation and Boost Usage in Adjuvant External Beam Radiotherapy for Ductal Carcinoma in Situ in the United States.

BACKGROUND

While the roles of hypofractionated (HFxn) radiotherapy and lumpectomy boost in the adjuvant management of invasive breast cancer are supported by the results of clinical trials, randomized data supporting their use for ductal carcinoma in situ (DCIS) are forthcoming. We sought to evaluate current national trends and identify factors associated with HFxn and boost usage using the National Cancer Database.

PATIENTS AND METHODS

We queried the National Cancer Database for women diagnosed with DCIS from 2004 to 2014 undergoing external beam radiotherapy after breast conservation surgery. Patients were categorized as receiving either conventional fractionation (CFxn) or HFxn and as either receiving or not receiving a boost. Multiple logistic regression was performed to identify demographic, clinical, and treatment factor associations.

RESULTS

A total of 101,615 women were identified, with 87,641 (86.2%) receiving CFxn, 13,974 (13.8%) receiving HFxn, and most patients in each group (84.9% and 57.7%, respectively) receiving a boost. Implementation of HFxn increased from 4.3% in 2004 to 33.0% in 2014, and the use of a boost declined from 83.3% to 74.6%. HFxn receipt was independently associated with later year of diagnosis, older age, higher income, greater distance from treatment facility, greater facility volume, academic facility type, Western residence, smaller lesions, and nonreceipt of a boost. Factors associated with boost receipt included earlier year of diagnosis, younger age, higher income, community facility type, adverse pathologic features, and nonreceipt of HFxn.

CONCLUSION

Although CFxn with a boost remains the most common external beam radiotherapy strategy for DCIS, implementation of HFxn without a boost appears to be increasing. Practice patterns at present seem to be driven by guidelines for invasive breast cancer and nonclinical factors.