Expression of the inflammatory protein, cyclooxygenase-2 (COX-2), in benign breast biopsy samples may be associated with an increased risk of a breast cancer diagnosis in the future.

Many breast biopsies uncover non-cancerous but abnormal tissue growth patterns, including atypical hyperplasia. Although women with such a diagnosis are at a higher risk of developing breast cancer in the future, not all of them will do so. Identifying ways to distinguish precancerous lesions from ones that will remain benign is important. One marker that has been associated with cancer development in animal models and some human cancers is COX-2.

Lynn Hartmann, M.D., of the Mayo Clinic in Rochester, Minn., and colleagues tested archival biopsy samples for expression of COX-2 and collected information on subsequent breast cancer diagnoses from medical records and a study questionnaire. The risk of developing breast cancer was compared with that of the general population.

A total of 235 women participated in the study, each of whom had been diagnosed with atypical hyperplasia between 1967 and 1991. After a median follow-up of 15 years, 41 women had developed breast cancer. The risk of a breast cancer diagnosis increased with the intensity of COX-2 expression in the initial biopsy sample. The trend of increasing risk with increasing expression intensity was of borderline statistical significance. For those with the highest level of expression, the risk rose 5.66-fold, from an expected 1.6 cases of breast cancer to nine observed cases.

These data, together with other studies in breast cancer, suggest COX-2 “may be a relevant target for chemoprevention strategies,” the authors wrote in the Journal of the National Cancer Institute.

SOURCE:
Journal of the National Cancer Institute, March 11, 2008