Population‐based study of the effect of preoperative breast MRI on the surgical management of ductal carcinoma in situ

Background Determinants of the use of breast MRI in patients with ductal carcinoma in situ (DCIS) in the Netherlands were studied, and whether using MRI influenced the rates of positive resection margins and mastectomies. Methods All women aged less than 75 years, and diagnosed with DCIS between 2011 and 2015, were identified from the Netherlands Cancer Registry. Multivariable logistic regression analyses were performed, adjusting for incidence year, age, hospital type, DCIS grade and multifocality. Results Breast MRI was performed in 2382 of 10 415 DCIS cases (22·9 per cent). In multivariable analysis, patients aged less than 50 years, those with high‐ or intermediate‐grade DCIS and patients with multifocal disease were significantly more likely to have preoperative MRI. Patients undergoing MRI were more likely to have a mastectomy, either as first surgical treatment or following breast‐conserving surgery (BCS) in the event of positive margins (odds ratio (OR) 2·11, 95 per cent c.i. 1·91 to 2·33). The risk of positive surgical margins after BCS was similar for those with versus without MRI. The secondary mastectomy rate after BCS was higher in patients who had MRI, especially in women aged less than 50 years (OR 1·94, 1·31 to 2·89). All findings were similar for low‐ and intermediate/high‐grade DCIS. Conclusion Adding MRI to conventional breast imaging did not improve surgical outcome in patients diagnosed with primary DCIS. The likelihood of undergoing a mastectomy was twice as high in the MRI group, and no reduction in the risk of margin involvement was observed after BCS. Antecedentes Se estudiaron los determinantes del uso de la resonancia magnética (RM) de mama en pacientes con carcinoma ductal in situ (ductal carcinoma in situ, DCIS) en los Países Bajos y si el uso de la RM influía en las tasas de márgenes de resección positivos y de mastectomías. Métodos Todas las mujeres menores de 76 años de edad y diagnosticadas de DCIS fueron identificadas a partir del Registro de Cáncer de los Países Bajos de 2011‐2015. Se realizaron análisis de regresión logística multivariable, ajustando por año de incidencia, edad, tipo de hospital, grado de DCIS y multifocalidad. Resultados Se realizó una RM de mama en 2.382 de 10.415 (23%) pacientes con DCIS. En el análisis multivariable, en las pacientes de edad