Abstract:
Objective: To determine the frequency of immunohistochemical expression of ROS1 in invasive ductal carcinoma of the
breast in relation to hormonal receptor status and HER2 expression.
Study Design and Setting: Descriptive cross-sectional study. Department of Histopathology, Armed Forces Institute of
Pathology, Rawalpindi from May 2022 to Dec 2022.
Methodology: This study was conducted on a sample size comprising 137 patients diagnosed with invasive breast carcinoma
(ductal carcinoma) on histopathological biopsy specimen. Immunohistochemistry was performed using ROS1, estrogen
receptor, progesterone receptor and HER2 antibodies on patients’ tissue samples. Results were interpreted by two independent
histopathologists. Finally data was analyzed using SPSS version 25.
Results: The mean age of sample population was 50.85 ± 12.17 years. 131 patients were women and 6 were men. ROS1
was positive in 54 cases. ROS1 shows weak staining in 41 cases and moderate to strong staining in 13 cases. ER and PR
showed no significant statistical correlation with ROS1 expression. HER2 was positive in 37 cases, equivocal in 11 cases
and negative in 89 cases. A significant statistical correlation was seen between ROS1 and HER2 as 23 of HER2 positive
cases showed ROS1 expression (p=<0.001).
Conclusion: Significant number of ROS1 expressing cases in invasive breast carcinoma can be more revealing in the
understanding of pathogenesis of breast carcinoma. In addition, it can also lead to use of certain recent tyrosine kinase
inhibitors for treatment of this most common carcinoma in females.
