Purpose: Turkish Radiation Oncology Study Group investigated local recurrence rates and prognostic factors in patients with ductal carcinoma in situ (DCIS) of the breast treated with breast conservative surgery (BCS) followed by radiotherapy (RT) and Eastern Cooperative Oncology Group (ECOG) Study E5194 were compared with the original study.
Patients and Methods: Totally 252 patients were evaluated retrospectively. Prognostic factors that might influence local control (age, nuclear grade, comedo necrosis, surgical margins, tumor size, hormone receptor status) were compared. The eligibility criteria of ECOG 5194 were stratified into two groups as in the original study and were compared for local control.
Results: The median follow-up time was 59 (21-220) months. Local recurrence was observed in 9 patients (3.6%) who had invasive carcinoma (3 patients) and DCIS (6 patients). Ten years local control rates was 91.8%. We found that the risk of ipsilateral breast recurrence was significantly higher in women younger than 50 years old(p=0.016). In addition, a statistically significant trend was found in patients with tumor larger than 1 cm and HER2 positive tumors (p=0.051, p=0.068 respectively). When 12-year results were compared with the ECOG 5194, adjuvant RT produced an absolute difference of 11% in low-intermediate and 20% in high grade in local control.
Conclusion: In our study, the 10-year local control rate was 92% and younger than 50 years old was the most important unfavorable prognostic factor for local recurrence. There was provided 20% absolute local control with adjuvant radiotherapy which eligibility criteria of ECOG 5194 high grade group.