Background: Follow-up tests for patients after diagnosis and primary treatment of breast cancer are routinely performed. However, the usefulness of these follow-up parameters remains unclear. We determined the yield of a variety of blood tests used to detect the presence of overt metastatic disease.
Methods: 4105 patients enrolled in International (Ludwig) Breast Cancer Study Group (IBCSG) randomized clinical trials from 1978 to 1985 were analyzed for abnormal or equivocal findings in six routine blood tests obtained every 3 months for the first two years, every six months for years 3-5 and yearly thereafter. The relationship of test results to the occurrence of overt metastatic disease was evaluated. The relapses were categorized as follows in order to estimate the yield of the different tests for relevant sites of metastases: any breast cancer relapse, bone +/- other; liver +/- other.
Results: Alkaline phosphatase alone was abnormal in a high proportion of patients with either bone metastases, liver metastases, or both. SGOT and gamma-GT were also sensitive for patients with liver metastases. Bilirubin, serum calcium, and serum creatinine were relatively insensitive indicators of relapse. Abnormal test results were reported sometime during a patient's disease-free period for 3% to 6% of patients, depending on the test.
Conclusions: Alkaline phosphatase was the most effective blood test to distinguish patients with relapse from those without relapse. It is inexpensive and its yield is relatively high for predicting liver and bone metastases. The routine use of the other tests analyzed to detect metastases was not justified.