Generally, scans (like CT scans, PET/CT scans, and bone scans) and blood work (like tumor markers) for breast cancer surveillance are not routinely performed after treatment ends in patients who have no symptoms and have undergone a normal physical exam and mammogram.
The American Society of Clinical Oncology does not recommend the routine use of scans or blood work for patients who do not have symptoms or abnormalities on clinical exam. These tests by themselves are often a poor indicator of breast cancer recurrence. They can be too sensitive (resulting in false positives); they may lead to additional unnecessary tests and biopsies; and they have not been shown to improve outcomes in patients with early stage breast cancer who develop a recurrence.
Currently, the only test recommended routinely is follow-up imaging of the treated breast, along with screening of the unaffected breast at least once a year.