PURPOSE
The optimal treatment strategy for ductal carcinoma in situ (DCIS) continues to evolve and should consider the consequences of initial treatment on the likelihood, type, and treatment of recurrences.
METHODS
We conducted a retrospective cohort study using two data sources of patients who experienced a recurrence (DCIS or invasive cancer) following breast-conserving surgery (BCS) for index DCIS: patients with an index DCIS diagnosed from 1997 to 2008 at the academic institutions of the National Comprehensive Cancer Network (NCCN; N = 88) and patients with an index DCIS diagnosed from 1990 to 2001 at community-based integrated healthcare delivery sites of the Health Maintenance Organization Cancer Research Network (CRN) (N = 182).
RESULTS
Just under half of local recurrences in both cohorts were invasive cancer. While 40 % of patients in both cohorts underwent mastectomy alone at recurrence, treatment of the remaining patients varied. In the earlier CRN cohort, most other patients underwent repeat BCS (39 %) with only 18 % receiving mastectomy with reconstruction, whereas only 16 % had repeat BCS and 44 % had mastectomy with reconstruction in the NCCN cohort. Compared with patients not treated with radiation, those who received radiation for index DCIS were less likely to undergo repeat BCS (NCCN: 6.6 vs. 37 %, p = 0.001; CRN: 20 vs. 48 %, p = 0.0004) and more likely to experience surgical complications after treatment of recurrence (NCCN: 15 vs. 4 %, p = 0.17; CRN: 40 vs. 25 %, p = 0.09).
CONCLUSION
We found that treatment of recurrences after BCS and subsequent complications may be affected by the use of radiotherapy for the index DCIS. Initial treatment of DCIS may have long-term implications that should be considered.