Patterns of Care and Utilization of Radiation for Women With Good-Risk Ductal Carcinoma In Situ: A National Cancer...

Purpose/objective(s) Lumpectomy followed by whole-breast radiation therapy (WBRT) provides a 50% recurrence rate reduction in ductal carcinoma in situ (DCIS) patients when compared to lumpectomy alone. Certain factors increase the risk of recurrence, including higher nuclear grade, large size, age less than 50, and close margins. RTOG 9804 demonstrated a reduction in local failure after WBRT with the use of adjuvant radiation in women with "good-risk disease" (mammographically detected, measuring less than or equal to 2.5 cm, with a predominant nuclear grade of 1 or 2, and a margin of greater than or equal to 1 cm, or a negative re-excision). The purpose of this study is to retrospectively identify the patterns of care in women with low-risk DCIS utilizing the National Cancer Database (NCDB). We hypothesize that with the utilization of hypofractionation, there may be an increase in the delivery of RT for these "good-risk" patients. Materials/methods The National Cancer Database was queried to identify women treated with lumpectomy for <2.5 cm, nuclear grade 1 or 2 DCIS of the breast from 2004 to 2016. Data were collected regarding age, tumor size, endocrine therapy use, ER receptor status, race, insurance type, and distance from the treatment center. The distance was stratified into quartiles consisting of 0-3.9, 4-8, 8.1-15.8, and > 15.8 miles, respectively. Radiation fractionation was collected and categorized as hypofractionation, standard fractionation, or other if fractionation could not be ascertained. Clinical and patient-related factors were compared between patients who received radiation and those who received no radiation. The frequency distributions between categorical variables were compared using the Chi-square test. Multivariable logistic regression was used to identify covariables that impacted the receipt of radiation. Results The eligibility criteria were met by a total of 12,846 patients. Of those, 6,600 (51.4%) received adjuvant WBRT. On multivariable regression, patients whose tumors were ER (OR 1.24, P<0.001) and those who had not received endocrine therapy (OR 2.24, P<0.001) were more likely to receive WBRT. Factors less likely to receive WBRT included increasing age over 50 (age 50-65 OR 0.83, P<0.001; age>65 OR 0.58, P<0.001), and distance of >15.8 miles (OR 0.78, P<0.001). The fractionation technique was categorized as standard or hypofractionated in 52.2% of patients. Of those, the use of hypofractionation increased from 0.4% in 2004 to 8.9% in 2010 and to 53.8% in 2016. Conclusion This NCDB analysis demonstrated that patients who meet the RTOG 9804 criteria for "good-risk" DCIS are less likely to receive RT as time progresses despite an increase in the utilization of hypofractionation techniques. Overall, slightly more than half of these patients receive adjuvant RT.