Partial PTEN Deletion in Breast Cancer

Breast cancer is the most common carcinoma detected in women, accounting for about one fifth of new cancer cases in females. In Egypt breast cancer is the most common malignancy in women, accounting for 38,8% of cancers in this population, with the estimated number of breast cancer cases nearly 22700 in 2020 and forecasted to be approximately 46000 in 2050. Surgical removal of the cancer represents the standard of care followed by radiation and adjuvant therapy in patients considered to be at particular risk for systemic disease. Estimation of prognosis is of vital importance for tailoring adjuvant therapy in individual breast cancer patients. Conventional pathological parameters such as histological grade, tumor size and presence of lymph node metastasis are not accurate enough to select subsets of patients who are at sufficiently low risk of progression to be spared extensive adjuvant therapy without compromising the prognosis. Much hope is placed on cytogenetic features analysis which might help to improve prediction of patient prognosis. Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique that enables the detection of genetic abnormalities such as gene amplification, deletions, and chromosomal rearrangements. Deletions of chromosome 10q23 including the PTEN (phosphatase and tensin homolog) locus are known to occur in breast cancer patients. The PTEN gene is a phosphatase which metabolises PIP3, the lipid product of PI 3-kinase, directly opposing the activation of the oncogenic PI3K/AKT/mTOR signalling network. Inactivation of PTEN leads to constitutively activated levels of AKT, thus promoting cell growth, proliferation, survival and migration through multiple downstream effectors. PTEN is one of the most frequently deleted genes in various human cancer types. In breast cancer, the frequency of PTEN deletions or reduced expression varies from 4 % to 63 %.