Molecular epidemiologic features of inflammatory breast cancer: a comparison between Egyptian and US patients

Background Inflammatory breast cancer (IBC) is a lethal form of breast cancer with unknown etiology. A higher frequency of IBC and a more aggressive IBC phenotype was reported in Egypt than in the United States. This difference in disease frequency and presentation might be related to molecular epidemiologic factors. Methods We used tumor blocks and demographic, epidemiologic, and clinical data of 48 IBC patients from Egypt and 12 patients from the United States. We counted tumor emboli in tumors before and after immunohistochemical staining with lymphatic vessel endothelial receptor-1 (LYVE-1), and measured the expression of RhoC GTPase protein in the two groups. Results Erythema, edema, and peau d'orange were found in 77% of the Egyptian patients as compared with 29% found in the US patients (P = 0.02). The number of tumor emboli was significantly higher in tumors from Egypt (mean +/- SD, 14.1 +/- 14.0) than in the tumors from the United States (5.0 +/- 4.0, P = 0.01). The number of tumor emboli in LYVE-1 positive vessels was higher in tumors from Egypt (3.5 +/- 2.8) than tumors from the United States (1.6 +/- 0.5, P = 0.15). We detected a high level of RhoC in 87% of the tumors from Egypt and 14% of the tumors from the United States (P = 0.0003). Conclusion Patients from Egypt have a more aggressive form of IBC than those in the United States. Our analysis of IBC patients shows that distinct molecular phenotypes can be found when these two study populations are compared. Future studies should explore the epidemiologic and environmental exposures and the genetic factors that might lead to the different clinical and molecular features of IBC in patients from these two countries.