A study detection of the ROS1 gene fusion by FISH and ROS1 protein expression by IHC methods in patients with ovarian malignant or borderline serous tumors.

OBJECTIVE

ROS1 is an orphan receptor protein tyrosine kinase which is supposed to undergo genetic rearrangement in carcinogenesis. In the current study, we aimed to investigate the frequency and clinicopathologic features associated with ROS1 gene fusion and ROS1 protein expression in patients with ovarian serous carcinoma or serous borderline tumors.

MATERIALS AND METHODS

Tissue samples of 102 patients with high or low grade serous carcinoma and borderline serous tumors were selected randomly from the archives of Department of Gyneco-pathology, and analyzed for ROS1 gene expression. (Fluorescence in situ hybridization (FISH) method was used to assess ROS1 gene rearrangement, while ROS1 protein expression was analyzed using immunohistochemistry.

RESULTS

The study consisted of 94 cases of high-grade serous carcinoma (92.1%), 2 cases of low-grade serous carcinoma (%2) and 6 cases of serous borderline tumor (5.9%). ROS1 gene rearrangement analysis revealed that 4 patients (3.9%) were FISH-positive; whereas the immunohistochemical analysis yielded only 1 patient (0.9%) exhibiting faint positive expression of ROS1 protein. Given the low incidences of ROS1 gene rearrangement and protein expression, their relationships with clinicopathologic parameters could not be statistically analyzed.

CONCLUSION

Although rare, patients with ovarian serous carcinoma or serous borderline tumor may exhibit ROS1 gene rearrangement and ROS1 protein expression. Further large-scale studies are necessary to explore the clinicopathologic significance of ROS1 gene expression in ovarian serous carcinoma.