A study designed to evaluate the prognostic role of the tumor marker CA 27.29 measured before chemotherapy has reported some preliminary findings. Several previous trials have found that tumor markers measured upon initial diagnosis of cancer can predict its dissemination and therefore indicate prognosis. While CA 27.29 is frequently used to monitor the effectiveness of treatment in stage IV breast cancer, its role upon initial diagnosis is not clear. The present study represented a translational research project within the SUCCESS trial, which compared two types of chemotherapy and two versus five years of zoledronate (a bisphosphonate) in lymph node-positive and high-risk node-negative patients with breast cancer. CA 27.29 was measured after surgery to remove the tumor but before the beginning of chemotherapy in 2,669 patients. Levels above 31 U/ml were classified as elevated for purposes of the study.
The average level of CA 27.29 before chemotherapy was 19 U/ml (range: 3 to 410). A total of 202 (7.6%) of the participants were found to have elevated CA 27.29 levels. No correlations were found between lymph node status, tumor grade, hormone receptor status, or HER2/neu status and level of CA 27.29. On the other hand, larger tumor size, lobular type, older age, and postmenopausal status each were significantly associated with higher CA 27.29 levels. The authors conclude that the data indicate a close relationship between CA 27.29 and tumor mass persisting several weeks after surgery (which indicates prognostic relevance). However, the data also indicates that women who are older or have lobular breast cancer may have somewhat elevated CA 27.29 levels without also having a poor prognosis. Further follow-up of the SUCCESS trial will clarify the degree of usefulness of CA 27.29 as a prognostic marker, as well as a marker for treatment monitoring in advanced breast cancer.