Background: The prognostic value of DNA ploidy has been extensively studied in breast cancer; however, the results remain controversial. Flow cytometry (FCM) studies of DNA ploidy on frozen sections have not yet been performed in a large series of Japanese women with node-negative breast cancer.
Methods: An FCM analysis of DNA ploidy was performed on frozen sections of node-negative breast cancer from 653 Japanese women, with a mean follow-up duration of 46 months.
Results: Three hundred and twenty-four (49.6%) patients showed a diploid tumor, while 329 (50.4%) showed an aneuploid tumor. There was a significant correlation between DNA ploidy and estrogen receptor (ER) status. Patients with an aneuploid tumor had a significantly worse outcome in terms of both disease-free survival (DFS; P = 0.0116) and overall survival (OS: P = 0.0492) than those with a diploid tumor, while the same effect, in terms of DFS, was also seen in ER-positive breast cancer. Multivariate analyses indicated DNA ploidy to be an independent prognostic factor for DFS, while DNA ploidy and tumor size were found to be independent prognostic factors for OS. DNA ploidy was also shown to be an independent prognostic factor for DFS in ER-positive breast cancer.
Conclusion: Our findings demonstrated DNA ploidy, based on FCM, to have an important prognostic value in Japanese women with node-negative breast cancer.