From the Guidelines
CA 15-3 is primarily associated with breast cancer, particularly in monitoring treatment response and detecting recurrence in patients already diagnosed with the disease. The association of CA 15-3 with specific types of cancer is mainly focused on breast cancer, as it is a protein produced by normal breast cells but often elevated in patients with breast cancer, especially when the cancer has metastasized beyond the breast 1.
Key Points
- CA 15-3 is not recommended as a screening test for breast cancer but rather as a tool to monitor treatment response and detect recurrence in patients already diagnosed with breast cancer 1.
- The normal range for CA 15-3 is typically below 30 U/mL, though this can vary slightly between laboratories.
- Elevated levels may indicate disease progression or recurrence, while decreasing levels often suggest effective treatment.
- CA 15-3 levels can also be elevated in other conditions, including benign breast disorders, liver disease, and other cancers such as lung, ovarian, and pancreatic cancer 1.
- Therefore, CA 15-3 results should always be interpreted in conjunction with clinical findings, imaging studies, and other diagnostic tests.
Clinical Use
- Regular monitoring of CA 15-3 levels during and after breast cancer treatment can help clinicians assess treatment efficacy and detect recurrence early 1.
- For monitoring patients with metastatic disease during active therapy, CA 15-3 can be used in conjunction with diagnostic imaging, history, and physical examination.
- However, present data are insufficient to recommend use of CA 15-3 alone for monitoring response to treatment, and caution should be used when interpreting a rising CA 15-3 level during the first 4-6 weeks of a new therapy, since spurious early rises may occur 1.
From the Research
Association of CA 15-3 with Specific Types of Cancer
- CA 15-3 is a tumor marker associated with mammary tumors, and increased levels have been observed in patients with breast cancer 2.
- The CA 15-3 level was above normal in 31% of patients with breast cancer, in 22% of patients with other malignancies, and in 9% of patients with benign diseases 3.
- CA 15-3 was found to be more sensitive than CEA in detecting recurrences of breast cancer, with 73% of patients with recurrences having CA 15-3 concentrations above 25 U/ml 3.
- Serum levels of CA15-3 are potential biomarkers for breast cancer monitoring, and are greatly associated with the tumor stage, increasing as breast tumor stage worsens 4.
- CA 15-3 appears to be a better marker than CEA for breast cancer, especially as a monitoring marker, and is highly useful for the prediction of organ and bone recurrence 5.
Clinical Uses of CA 15-3
- The potential clinical uses of CA 15-3 include monitoring of patients with breast cancer, prognosis, and early detection of recurrence 2.
- CA 15-3 may be used as a prognostic marker in breast cancer, with high preoperative levels indicating a worse outcome 6.
- CA 15-3 is independent of both tumor size and nodal status as a prognostic marker, and its prognostic impact is stronger than that of tumor size and at least as strong as nodal status 6.