Immunohistochemical Expression of Anaplastic Lymphoma Kinase in Invasive Breast Carcinomas- A Retrospective Study

Introduction: Breast carcinoma remains one of the most common causes of mortality among female cancer patients inspite of improvements in treatment modalities. Increased survival rate can be achieved by identification of new targeted therapies. Anaplastic Lymphoma Kinase (ALK) alterations are present in many solid and haematological tumours indicating its role in pathogenesis and treatment. There are studies regarding the expression of ALK in few breast cancers but its importance was not clearly mentioned. Hence, identification of ALK overexpression in breast cancers, particularly in Triple Negative Breast Cancers (TNBC) might play a role in their chemotherapy with the help of ALK inhibitors. Aim: To study the ALK expression in different subtypes of invasive carcinomas of breast. Materials and Methods: This was a retrospective cross-sectional study conducted in the Department of Pathology at Great Eastern Medical School (GEMS) and Hospital, Srikakulam, Andhra Pradesh, India, from January 2022 to July 2022. The data of 60 patients, from January 2021 to December 2021 was retrieved using Hospital Information Management System (HIMS) and the Haematoxylin and Eosin (H&E)-stained slides and formalin fixed paraffin embedded tissue blocks of breast tumour were retrieved and reviewed. Estrogen receptor (ER), Progesterone receptor (PR) and Human Epidermal growth factor Receptor 2 (HER2) immunostains were performed and categorised based on molecular classification as Luminal, Her2 and Triple negative. ALK Staining was performed on all cases and its expression was studied. Statistical Package for Social Sciences (SPSS) software version 2.0 was used for analysis of data. Mean with standard deviation is used for quantitative variables and prevalence, ratio is used for quantitative variables. Chi-square test and Fischer exact test were used for detecting significance. The p-value <0.05 was considered as significant. Results: Out of 60 cases, majority (N=22; 36.66%) of patients were in the age group of 51-60 years. The mean tumour size was 3.2±0.5 cm. The most common histological type was invasive breast carcinoma, No Special Type (N=44; 73.34%). Majority of the tumours showed grade 1 and 2 with 24 (40%) and 25 (41.67%) cases, respectively. A total of 30 cases (50%) of tumours belonged to stage T2. Luminal molecular subtype was the most common 31 (51.67%) cases followed by TNBC, 16 (26.67%) cases and Her2neu 13 (21.67%) cases. Among all the cases, ALK overexpression was seen in 17 (28.33%) cases and among different molecular subtypes, its expression was seen in 5 (8.33%) cases of Luminal type, 3 (5.0%) cases of HER2 type and in 9 (15.0%) cases of TNBC cases. Conclusion: Immunohistochemical analysis showed ALK over expression in a substantial proportion of cases and possibly plays a significant role in aggressive behaviour of breast cancer. ALK inhibitors offer an opportunity to treat aggressive subtypes of breast cancer