Role of advanced MRI techniques in predicting and evaluating the response of breast cancer to neoadjuvant chemotherapy Essay

Abstract

In Egypt, breast cancer is the most common cancer among women, representing 18.9% of total cancer cases (35.1% in women and 2.2% in men). Neoadjuvant chemotherapy (NAC) followed by surgery was introduced about 2 decades ago to treat patients with locally advanced breast cancer, which represents approximately 20% of all women who receive a diagnosis of breast cancer. NAC gives high clinical response rates (70-98%). The differentiation between responders and non-responders early in the course of treatment protocol helps in reaching this goal, and avoids unnecessary toxicity of ineffective treatments .While on the other hand it permits early detection of resistant tumors to choose alternative and possibly more efficacious treatments, such as other types of chemotherapy or early surgery. Early change in tumor size measured on MR images, particularly after the second cycle of chemotherapy, proved recently to be the best predictor of final response after NAC. However, it takes some time for the tumor to shrink. Substantial research effort has been spent on investigating whether other information provided by MR imaging may serve as earlier response indicators than change in tumor size. Pharmakokinetic assessment in DCE MRI, spectroscopic imaging and diffusion weighted imaging can provide useful information which helps differentiating responders from non-responders to neoadjuvant chemotherapy. In the follow up studies during and after completion of chemotherapy, the most reliable and significant parameters were: The pharmacokinetic parameters (K trans) and (Ve). The spectroscopic metabolite (t Cho) after first and second cycles of chemotherapy, which drops significantly in the responder group,but to date no exact cut-off value is found for choline concentration fall on follow up examinations. The diffusion imaging parameter (ADC) which shows increased values during follow up studies in responder groups. A sensitivity of 79 % and specificity of 80% can be reached by using a cut-off value of 23.8% in percentage ADC increase following 3 cycles of NAC.