Ipsilateral in-breast tumor relapse after breast conservation therapy: true recurrence versus new primary tumor

Ipsilateral breast tumor relapse (IBTR) occurs in approximately 8-20% of women 10 years after breast conservation therapy (BCT). The aim of this study is to classify ipsilateral breast tumor relapses in patients treated with conservative surgery and radiation therapy as true recurrences or new primary and to show the clinical significance of classification into these two types of recurrences.

Out of 267 patients treated at National Cancer Institute, Cairo University in the period extending from 1993 to 2000, 29 patients have experienced ipsilateral tumor relapse as the first site of recurrence. These relapses were classified as true recurrence if it was located within 3cm of the primary tumor bed and was of the same histologic subtype. All other ipsilateral breast tumor relapses were considered as new primary. The patients were followed-up until January 2005.

After a mean follow-up period of 7.9 +/- 2.6 years following the original diagnosis, the overall ipsilateral breast tumor relapse rate was 9.6% (29/267). Relapses were classified as TR in 21 patients (72.4%) and were considered as a new primary in 8 cases (27.6%). Patients diagnosed with a new primary had a longer mean time to breast relapse (6.09 years for NP Vs 3.09 years for TR, p < 0.001) and were significantly younger than true recurrence patients (38.38 years Vs 47.54 years, p=0.006). Patients with a new primary had a 10- year overall survival of 87.5%; whereas, it was 61.90% for TR cases (p=0.13).

It appears that a significant portion of patients who experience ipsilateral breast tumor relapse following conservative surgery and radiation therapy have new primary tumors as opposed to true recurrences. Patients with a new primary had better survival rates than those with true recurrence. Distinguishing new primary breast carcinoma from local disease recurrence may have importance in therapeutic decisions and chemoprevention strategies.