Angiogenesis versus Metabolic Imaging in Locally Advanced Breast Cancer Patients - A Comparative Study

The comparison of angiogenesis imaging (Ga-68-DOTA-Arginine-Glycine-Aspartic Acid [RGD]) positron emission tomography/computed tomography [PET/CT]) with metabolic imaging (F-18 fluorodeoxyglucose [FDG] PET/CT) in primary staging and response assessment to neoadjuvant chemotherapy (NACT) in locally advanced breast cancer (LABC) patients.

In this prospective study, 85 female patients with LABC were subjected to two PET/CT studies (Ga-68-DOTA-RGD₂ and F-18 FDG) within 1 week of each other. Thirty patients had repeat studies 4 weeks after completing eight cycles of NACT. Response assessment was done by RECIST 1.1 criteria.

Ga-68-DOTA-RGD₂ and F-18 FDG uptake in the primary tumor were seen in all patients. Ipsilateral axillary and internal mammary lymph nodes were detected in 77 (90.5%) versus 80 (94.1%) and 22 (25.8%) versus 27 (31.7%) patients on Ga-68-DOTA-RGD₂ and F-18 FDG scans, respectively. Ipsilateral supra-clavicular lymph nodes and skeletal lesions were noted in 17 (20%) versus 21 (24.7%) patients and 23 (27.0%) versus 24 (28.2%) patients on Ga-68-DOTA-RGD₂ versus F-18 FDG studies, respectively. However, the Ga-68-DOTA-RGD₂ did not show uptake in F-18 FDG avid liver lesions (LLs) in 10 patients, adrenal lesion in one patient, mediastinal lymph nodes in 2 patients, lung nodules, and pleural soft-tissue deposits, each in one patient. In response assessment, 23 and 25 patients had concordance with RECIST1.1 criteria on F-18 FDG and Ga-68-DOTA-RGD₂ scans, respectively. However, there were discordant results in four patients on Ga-68-DOTA-RGD₂ scan and two patients on F-18 FDG scans.

Metabolic imaging is better in primary staging and chemotherapy response assessment than angiogenesis imaging in LABC patients. The latter may miss the metastatic soft-tissue deposits, adrenal, and LLs.