Shurell E et al. -the association between ipsilateral breast tumor recurrence (IBTR) and the timing of radiotherapy (RT) in women with ductal carcinoma in situ (DCIS) undergoing breast-conserving surgery (BCS) was studied. In the current study it was shown that a delay in RT >12 weeks is associated with a significantly higher risk of IBTR in women undergoing BCS for DCIS.

Methods

• Women with DCIS who were treated with BCS and RT were enrolled.
• The IBTR rates, measured from the time of RT completion, were compared between women who initiated RT ≤8 weeks, >8 to 12 weeks, and >12 weeks after the completion of surgery.

Results

• 1323 women were studied.
• The median follow-up was 6.6 years.
• 126 IBTR events occurred.
• Patients were categorized by RT timing, as follows: 806 patients (61%) with timing of ≤8 weeks; 386 patients (29%) with timing of >8 to 12 weeks; and 131 patients (10%) with timing >12 weeks.
• The 5-and 10-year IBTR rates were 5.8% and 13.0%, respectively, for RT starting ≤8 weeks after surgery; 3.8% and 7.6%, respectively, for RT starting >8 to 12 weeks after surgery; and 8.8% and 23.0%, respectively, for an RT delay >12 weeks after surgery.
• Based on multivariable analysis, menopause (HR, 0.54) and endocrine therapy (HR, 0.45) were protective against IBTR, whereas a delay in RT >12 weeks compared with ≤8 weeks was associated with a higher risk of IBTR (HR, 1.92).
• There was no difference in IBTR noted between RT initiation at ≤8 weeks and initiation at >8 to 12 weeks after BCS.