Worldwide, breast cancer (BC) is the most frequent type of cancer in women yet, it is associated with relatively lower mortality rates, as it ranks fifth in cancer-related deaths overall, which is attributed to evolution in the treatment of recurrent and metastatic lesions, especially when these lesions were detected early . BC recurrence can occur even 15 years after primary treatment.

life-long routine monitoring is mandatory. Although histopathologic confirmation is the definitive diagnostic method for BC recurrence, it is not always easy to perform as in cases with deeply located or very small-size lesions, or lesion too close to organs or great vessels, making sampling either inaccessible or hazardous. BC recurrence can be assessed using morphological imaging studies or tumor markers. Mammography, ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) are currently the most commonly used morphological imaging methods for detecting breast cancer recurrence. However, both of the two modalities have some restrictions.

Cancer antigen 15-3 (CA 15-3) and carcinoembryonic antigen (CEA) are two tumor markers that are frequently used in the monitoring of BC patients . However, the findings of many studies on these markers in BC follow-up are conflicting.

The introduction of integrated 2-deoxy-2-[18 F] fluoro-D-glucose (18FDG) positron emission tomography (PET) computed tomography (CT), known as PET/CT, has become a helpful tool for this purpose.

PET/CT is the functional imaging tool that can measure increased glucose metabolism in cancer cells by using 18F-FDG. Its ability to identify tumor recurrence before detection of morphologic changes in conventional imaging reflecting its importance in detecting BC recurrence in asymptomatic patients with high tumor markers and negative results of radiological imaging. 18F-FDG PET/CT is frequently used for BC evaluation. However, data on its value in evaluating BC recurrence in patients with elevated tumor markers are limited and unclear

Inclusion Criteria:

• female patient with pathologically proved breast cancer who will be referred to do PET\CT imaging at the nuclear medicine unit, Assiut university hospital due to suspicion of recurrence based on elevated level of tumor marker in the period between October 2021 until the end of the study .

Exclusion Criteria:

• patients with newly diagnosed BC patients with early stages of BC BC patients with normal serum level of tumor markers

female patient with pathologically proved breast cancer who will be referred to do PET\CT imaging at the nuclear medicine unit, Assiut university hospital due to suspicion of recurrence based on elevated level of tumor marker