Classification of ipsilateral breast tumor recurrence after breast-conserving therapy: new primary cancer allows a good prognosis.

PURPOSE: To classify and assess ipsilateral breast tumor recurrences (IBTR) after breast-conserving therapy.
METHODS: Between 1986 and 2001, 2,137 patients who had breast cancer underwent breast-conserving surgery with or without radiotherapy at the Cancer Institute Hospital of the Japanese Foundation for Cancer Research. Of these patients, 83 (3.9%) had an IBTR. We classified the IBTR as a new primary cancer (NP) if the primary tumor had completely negative margins at first operation by detailed pathological examination and if the IBTR had an intraductal component. All other IBTRs were judged true local recurrence (TR).
RESULTS: Of the 83 patients, 42 patients were classified as TR (29 had no radiotherapy) and 41 as NP (40 had no radiotherapy). Mean time to disease recurrence was 37 months for TR (52% were within 2 years) versus 55 months for NP (19% were within 2 years) (p=0.031). Six patients (14%) with TR did not receive re-operation, and 67% received salvage mastectomy and 19% re-lumpectomy. All cases of NP were operable, 78% underwent salvage mastectomy and 22% underwent re-lumpectomy. Distant metastases were observed in 33% of patients with TR and 5% of patients with NP, and cause-specific death occurred in 6 cases with TR and in one with NP. The patients with NP had improved 5-year rates of overall survival (NP 91% vs. TR 76%, P=0.0627) and distant disease-free survival (NP 93% vs. TR 61%, P=0.0028). Patients with NP more often developed contralateral breast cancer (NP 37% vs. TR 12%, P=0.018)
CONCLUSIONS: Patients with NP had better survival rates than those with TR. Distinguishing new primary breast carcinomas from local disease recurrences may have importance in therapeutic decisions and chemoprevention strategies.