What does a low CA-125 level after treatment indicate for a woman with ovarian cancer?

A low CA-125 level after treatment typically suggests that there is no active disease or that the treatment has been effective in reducing tumor burden. CA-125 (cancer antigen 125) is a protein that is often elevated in women with ovarian cancer and can be used as a tumor marker to monitor treatment response or disease progression.

When CA-125 levels decrease significantly post-treatment, it indicates a positive response to therapy, such as surgery or chemotherapy. However, it is important to consider that CA-125 is not always sensitive enough to detect small changes in tumor development, particularly in the presence of non-malignant conditions or in early-stage cancer, which can lead to false reassurance. Therefore, while a low level can be encouraging, it does not entirely rule out the possibility of disease recurrence or the presence of residual tumor, especially if the patient's initial levels were only slightly elevated.

Thus, recognizing that CA-125 may not be sensitive enough to monitor every possible tumor development thoroughly supports the assertion that interpretation of its levels must be done cautiously, considering the patient's overall clinical picture and other diagnostic modalities.