Survival Outcomes in Women with Ipsilateral Breast Tumor Relapse: An Analysis of Cohorts Classified Clinically as 'True Recurrence' Versus 'New Primary'.
Authors: Truong P. , Truong P. , McDonald R. , Panet-Raymond V. , Alexander C. , Ryhorchuk A. , Watson P. , Watson P. 
Published: December 2010

Background:Ipsilateral breast tumor relapse (IBTR) can occur in ∼5-20% of women after breast conserving therapy. Two entities of IBTR have been described: "True Recurrence" (TR), suggested to be cases of regrowth of pre-malignant or malignant cells not completely eradicated by surgery or radiation therapy; and "New Primary" (NP), distinct in histology and located away from the index tumor. Whether these two entities have different prognoses is unclear. This study examined a method of IBTR classification using chart review with pre-defined decision rules to assess histology and tumor location and compared survival between two groups classified as either TR or NP.Methods:Between 1989-1999, 6020 women with newly diagnosed invasive breast cancer, pT1-T2, 0-3 positive nodes, M0, treated with breast conserving surgery with clear margins were referred to the BC Cancer Agency. Of these, 289 cases had pathologically-confirmed IBTR, defined as the first recurrence occurring in the ipsilateral breast. Retrospective chart review was performed to abstract clinical data related to the index tumor and the IBTR. A set of decision rules established a priori (figure 1) was applied to classify these cases as either TR or NP.Time to recurrence, distant-relapse free survival (DRFS), and overall survival (OS) were compared between the two cohorts using Kaplan-Meier and log-rank statistics.Results:Of 289 subjects, 131(45%) were classified as TR, 128 (44%) as NP, and 30 (10%) unclassified due to insufficient information. The distributions of age at diagnosis, age at recurrence, index tumor histology, T size, nodal status, grade, lymphovascular invasion, and estrogen receptor status were similar in the two cohorts, (all p &gt;0.05). The mean time to recurrence was shorter in TR compared to NP patients (4.7 years vs. 6.3 years, p=0.001). Surgical treatment of IBTR differed in the two groups, with 76% mastectomy and 21% local excision only in the TR cohort, compared to 81% mastectomy and 16% local excision only in the NP cohort (p&lt;0.001). Systemic therapy at the time of IBTR also differed in the two groups, with hormone therapy alone used more frequently in the TR compared to the NP cohort (42% vs. 38%, p&lt;0.001); and a smaller proportion of the NP cohort receiving both chemotherapy and hormone therapy compared to the TR cohort (8% vs. 15%, p&lt;0.001). In the TR and NP cohorts, 10-year DRFS were 57% vs. 61%, p=0.59; and 10-year OS were 45% vs. 53%, p=0.67.Conclusions:The median time to recurrence is significantly longer in patients with IBTR classified as 'new primary' compared to 'true recurrence'. Non-statistically significant trends for more favorable DRFS and OS were observed for patients with NP compared to TR tumors. The hypothesis that NP and TR tumors are distinct entities with different survival prognoses requires confirmation with pathology review and molecular analyses.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4116.