A Multigene Expression Assay to Predict Local Recurrence Risk for Ductal Carcinoma In Situ

Extract

The incidence of ductal carcinoma in situ (DCIS) has seen a dramatic rise in the United States, particularly over the last three decades. Since the use of screening mammography in the 1980s and with improved technology, DCIS now accounts for 14% to 30% of all diagnosed breast cancers ( 1 , 2 ).

An ipsilateral breast event (IBE) remains the most common first failure event in DCIS management. Mastectomy was once the standard treatment for DCIS, with recurrence rates as low as 1.4% ( 3 , 4 ). Breast-conserving surgery (BCS) has now gained widespread acceptance as an alternative approach, based on the results of four randomized clinical studies led by the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-17 trial ( 5–8 ).

Although the use of BCS for DCIS is not a debatable issue, the need for adjuvant radiation therapy (RT) is ( 9 ). There is substantial heterogeneity in the management of DCIS. Patients at low enough risk that they do not require RT after BCS have not been identified reliably in prospective clinical trials ( 10–12 ). However, four, large, prospective, randomized clinical trials have studied the benefit of adding RT after BCS in the treatment of DCIS. The addition of RT after BCS in these trials was shown to reduce the risk of local invasive recurrence and overall recurrence by 50% without a survival benefit ( 13 ). The NSABP B-24 trial ( 14 , 15 ) and the United Kingdom, Australia, New Zealand trial ( 16 ) evaluated both RT and tamoxifen in the treatment of DCIS. Although ipsilateral breast tumor recurrence (IBTR) is reduced by 25% ( 14 , 15 ) with tamoxifen, it is not a substitute for RT after excision of DCIS ( 5 , 14 , 16–20 ).