COMPLICATIONS ASSOCIATED WITH NEW RADIOTHERAPY TECHNOLOGY

Purpose: Accelerated partial breast radiotherapy (RT) with balloon brachytherapy is a relatively new RT modality that requires only 5 days of RT following breast-conserving surgery (BCS), rather than standard-of-care whole breast RT that requires 4-7 weeks. However, accelerated RT may be associated with new or differing risks of morbidity, and lacks long-term clinical trial evidence of effectiveness.

Methods: Using 2005-2007 Medicare claims data for a U.S. cohort of 50,504 women ages 66+ undergoing RT after BCS, we compared 1-year complication rates by RT type. We included breast pain, cellulitis, infection, general radiation complications, wound complications, seroma, rib fracture, dermatological burn, fat necrosis, fibrosis, lung injury, telangiectasias, and hospitalizations. We calculated the Charlson comorbidity index and conducted multivariable logistic regression analysis to assess complication rates for any complication and for subtypes, controlling for age and comorbidity. We excluded cases with axillary node dissection and/or chemotherapy indicating more advanced cancer, personal history of cancer, Medicare eligibility due to other than age, or enrollment in an HMO.

Results: Overall, 1,598 (n=3%) of 48,906 women received accelerated brachytherapy. The odds of any complication was significantly higher for women undergoing accelerated brachytherapy (OR=1.6; 95%CI: 1.4-1.9), with 4,554 women overall having at least one complication. Complications were more likely in women as age increased (p<0.02) and in those with more comorbidities (p<0.0001). Infection was 2.1 times more likely (95%CI: 1.7-2.8) in those receiving brachytherapy. Also more likely in the brachytherapy group were seroma (OR=3.6; 95%CI: 2.1-6.4), breast pain (OR=1.7; 95%CI: 1.4-2.1) or wound complication (OR=1.4; 95%CI: 1.0-2.0). Hospitalization, cellulitis, lung injury, telangiectasias, general radiation complications, rib fracture, fat necrosis, fibrosis, and dermatological burns were not different based on RT type (p>0.05).

Conclusions: Accelerated partial breast brachytherapy, with its minimal evidence of long-term effectiveness and during its early adoption period, is associated with higher overall complication rates that will in turn affect patient quality of life and total costs of care. Certain complications were rare or may require more than one year of follow-up to show differences. Patients should be made aware that seroma, infection, breast pain, and wound complications may be more likely following accelerated partial breast RT by balloon brachytherapy compared to whole breast RT. As balloon brachytherapy for breast RT matures over time, complication rates may decrease.