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DOI: 10.1055/s-0039-1683576
Association between gastrin-releasing peptide receptor expression based on Ga-68-RM2-PET and histopathological tumor regression after neoadjuvant chemotherapy in primary breast cancer
Publication History
Publication Date:
27 March 2019 (online)
Ziel/Aim:
The gastrin-releasing peptide receptor (GRPR) is overexpressed in breast cancer tissue and can be visualized by positron emission tomography (PET) using the GRPR antagonist Ga-68-RM2. This study assessed tumor uptake of RM2 before and after neoadjuvant chemotherapy (NAC) in primary breast cancer with reference to histopathological response.
Methodik/Methods:
Five female patients with biopsy-confirmed primary breast carcinoma (1 bilateral tumor) underwent Ga-68-RM2-PET/CT before and after NAC (6 cycles of TAC (Taxotere, Adriamycin and cyclophosphamide) in 4 patients; 12 cycles of weekly Taxol + Trastuzumab in 1 patient). PET/CT was acquired 1h after injection of 150 – 200 MBq Ga-68-RM2. Time from pre-NAC PET to beginning of NAC was 23 ± 4.9 days, from end of NAC to post-NAC PET 18.7 ± 6.3 days and from post-NAC PET to surgery 9.5 ± 10.8 days. In vivo tumor uptake of Ga-68-RM2 was assessed before and after NAC and then correlated to histopathological response according to Sinn and residual tumor size.
Ergebnisse/Results:
All tumors (6/6) were positive for estrogen (ER) and progesterone receptors (PR), with negative HER2-neu status and showed strongly increased Ga-68-RM2 uptake compared to normal breast tissue (NBT) on pre-NAC PET (SUVMAXpre 13.2 ± 7.3). Ga-68-RM2-uptake was significantly reduced on post-NAC PET in primary tumors (SUVMAXpost 2.4 ± 0.8; p < 0.05) and also in normal breast tissue (SUVMAXpre 1.7 ± 0.5 vs. SUVMAXpost 1.1 ± 0.2; p < 0.05). Pathological response criteria according to Sinn1 showed 4/6 tumors with grade 2 and 2/6 tumors with grade 1 response. Residual tumor size correlated well with SUVMAXpost (R2= 0.77; p < 0.05).
Schlussfolgerungen/Conclusions:
In this preliminary study, residual uptake of Ga-68-RM2 in ER-positive primary breast cancer correlated closely with residual tumor size on histopathological examination after NAC. This suggests that GRPR-PET might serve as a response-predictor of NAC.
Literatur/References:
[1] Sinn et al., Histologic regression of breast cancer after primary (neoadjuvant) chemotherapy, Geburtshilfe und Frauenheilkunde 1994 Oct; 54(10): S. 552 – 8.
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