Underuse of Radiation Therapy After Breast Conservation Surgery in Puerto Rico: A Puerto Rico Central Cancer Registry-Health Insurance Linkage Database Study.

PURPOSE: To identify rates of postoperative radiation therapy (RT) after breast conservation surgery (BCS) in women with stage I or II invasive breast cancer treated in Puerto Rico and to examine the sociodemographic and health services characteristics associated with variations in receipt of RT. METHODS: The Puerto Rico Central Cancer Registry-Health Insurance Linkage Database was used to identify patients diagnosed with invasive breast cancer between 2008 and 2012 in Puerto Rico. Claims codes identified the type of surgery and the use of RT. Logistic regression models were used to examine the independent association between sociodemographic and clinical covariates. RESULTS: Among women who received BCS as their primary definitive treatment, 64% received adjuvant RT. Significant predictors of RT after BCS included enrollment in Medicare (odds ratio [OR], 2.14; 95% CI, 1.46 to 3.13; P ≤ .01) and dual eligibility for Medicare and Medicaid (OR, 1.61; 95% CI, 1.14 to 2.27; P < .01). In addition, it was found that RT was more likely to have been received in certain geographic locations, including the Metro-North (OR, 2.20; 95% CI, 1.48 to 3.28; P < .01), North (OR, 1.78; 95% CI, 1.20 to 2.64; P < .01), West (OR, 4.04; 95% CI, 2.61 to 6.25; P < .01), and Southwest (OR, 2.79; 95% CI, 1.70 to 4.59; P < .01). Furthermore, patients with tumor size > 2.0 cm and ≤ 5.0 cm (OR, 0.61; 95% CI, 0.40 to 0.93; P = .02) and those with tumor size > 5.0 cm (OR, 0.37; 95% CI, 0.15 to 0.92; P = .03) were found to be significantly less likely to receive RT. CONCLUSION: Underuse of RT after BCS was identified in Puerto Rico. Patients enrolled in Medicare and those who were dually eligible for Medicaid and Medicare were more likely to receive RT after BCS compared with patients with Medicaid alone. There were geographic variations in the receipt of RT on the island.