oops! bc mets after her2+ primary can be her2- in ~25% of cases--seems 2be due2 chemo

[Lani]

rather than herceptin--an argument for trying multi-targeted regimen without chemo??? as prognosis of those who reurred with her2- mets had worse prognosis than those who recurred with her2+ mets


Clinical significance of metastatic-tumor HER2 status in patients with HER2-positive primary breast cancer.


Sub-category:
HER2+

Category:
Breast Cancer - HER2/ER

Meeting:
2011 ASCO Annual Meeting

Abstract No:
545

Citation:
J Clin Oncol 29: 2011 (suppl; abstr 545)


Attend this session at the
ASCO Annual Meeting!
Session: Breast Cancer - HER2/ER

Type: General Poster Session

Time: Monday June 6, 1:00 PM to 5:00 PM

Location: McCormick Place Hall A

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Author(s): N. Niikura, J. Liu, N. Hayashi, E. A. Mittendorf, Y. Gong, S. L. Palla, Y. Tokuda, A. M. Gonzalez-Angulo, G. N. Hortobagyi, N. T. Ueno; University of Texas M. D. Anderson Cancer Center, Houston, TX; Tokai University School of Medicine, Kanagawa, Japan; M. D. Anderson Cancer Center, Houston, TX


Abstract Disclosures


Abstract:

Background: Studies have suggested that trastuzumab may convert HER2-positive (HER+) primary breast tumors to HER2-negative (HER2–). Whether this conversion happens between primary and metastatic lesions is unknown. We tested the hypothesis that trastuzumab increases the number of patients with HER2+ primary tumors and HER2– metastases (HER2 discordance). We assessed the same effect of chemotherapy. We also compared overall survival (OS) durations of patients with HER2 discordance and patients with HER2 concordance (ie, HER2+ primary and metastatic tumors). Methods: We retrospectively identified 182 patients who had been diagnosed with HER2+ (IHC 3+ and/or FISH+) primary breast cancer in 1997–2008 at MD Anderson Cancer Center and had known HER2 status of the metastasis. Median follow-up was 18 (1-90) months. OS rates were determined using the log-rank test and Cox proportional regression models. Results: Of 182 patients with HER2+ primary tumors, 43 (24%) had HER2– metastases (discordance). Of 76 patients who received trastuzumab before their metastasis biopsies, 15 (20%) had HER2 discordance. Similarly, of 106 patients who did not receive trastuzumab before their metastasis biopsies, 28 (26%) had discordance. There was no significant difference in discordance rates based on trastuzumab (P = .296). However, discordance rates differed significantly based on chemotherapy (P = .022); 39 (27%) of 142 patients who received chemotherapy (with or without trastuzumab) before their metastasis biopsies had discordance, compared with 4 (10%) of 40 patients who did not receive chemotherapy. Patients with HER2 discordance had shorter OS than patients with HER2 concordance (hazard ratio = .43; P = .003). A survival difference remained among the 67 patients who received trastuzumab before their metastasis biopsies (hazard ratio = .56; P = .083). Conclusions: One-fourth of primary HER2+ breast cancers converted to HER2–. Our hypothesis was rejected; trastuzumab did not affect discordance rate, although chemotherapy did. Patients with HER2 discordance had poorer prognoses than those with concordance. A prospective study is warranted to determine whether HER2 discordance affects prognosis and treatment.