Rare (breast) phyllodes tumors -- 0.5 percent to 1 percent of all breast tumors -- tend to be more prevalent in Hispanic women, U.S. researchers say. Lead study author Dr. Jose M. Pimiento, surgical oncology fellow at Moffitt Cancer Center in Tampa, Fla., said population-based estimates indicate the incidence of malignant phyllodes tumors is 2.1 cases per million women, but the highest frequencies are in Hispanic women. Little is known about phyllodes tumors, which have unpredictable behavior and recurrence rates as high as 40 percent, Pimiento said. \"We found substantial pathologic differences by race, with higher-grade tumors present more often in Hispanic patients,\" Pimiento said in a statement. \"Although we did not determine that these variances could be translated into a survival difference by race, we believe that our findings can improve the understanding of this disease.\" The researchers conducted a retrospective study of breast cancer patients with phyllodes tumors at two hospitals from 1999 to 2010. Of the 124 patients studied, the mean age at diagnosis was age 44; 33 patients required mastectomy; 42 percent were Caucasian; 43 percent were Hispanic; and 12 percent were African-American. \"We found substantial pathologic differences by race, with higher-grade tumors present more often in Hispanic patients,\" Pimiento said. \"Although we did not determine that these variances could be translated into a survival difference by race, we believe that our findings can improve the understanding of this disease.\"