Evaluation of Somatostatin Receptor Expression in PET 68Ga-DOTATOC in Patients Followed for Metastatic Breast Cancer

In women, breast cancer is the 1st largest cancer and accounted for 31% of new cancer cases in women in 2017. With 11,913 deaths in 2015, breast cancer is the 1st largest cancer death in women (19%) and the 3rd largest cancer death (men and women included) after lung and colorectal cancer. At initial diagnosis at any stage, approximately 31% of patients have regional lymph node involvement and 5 to 10% present metastatic involvement from the outset. Progression to a metastatic form occurs in about 20% of cases. The risk of metastatic evolution is variable depending on the histological subtype and is a major prognostic event directly impacting overall survival. DOTATOC-68Ga PET scans allows in vivo evaluation of SST2 somatostatin receptor expression. Its use is widely validated in clinical practice for the assessment of extension of neuroendocrine tumors. It is also being used to evaluate the feasibility of SST2-targeted internal radiotherapy therapy with Lutathera (177Lu-Oxodotreotide) in patients with metastatic small intestine neuroendocrine tumours.

Inclusion criteria

• Age over 18
• Patients with metastatic breast cancer who have completed at least one first line of systemic therapy for metastatic breast cancer
• Patient labeled on the primary lesion ER+HER2- (20)
• Presence of metastatic liver and bone lesions identifiable with 18F-FDG PET-Scan
• Presence of at least 10 identifiable secondary lesions in 18F-FDG PET-Scan
• No therapeutic change between 18F-FDG PET-Scan and 68Ga-DOTATOC PET-Scan.
• Performing the PET scan with 68Ga-DOTATOC within a maximum of 21 days after the 18F-FDG PET-Scan
• Person affiliated to or benefiting from social security
• Person who has given written informed consent

Exclusion criteria

• Patients followed or with history of other active neoplastic pathology (including neuroendocrine tumor)
• Known allergy to 68Ga-DOTATOC or its excipients
• Subject refusing to sign the consent to participate
• Minor subject
• Subject excluded from another study
• Persons referred to Articles L1121-5 to L1121-8 of the Public Health Code (CSP)
• Subject cannot be contacted in case of emergency