Diffusion-weighted magnetic resonance imaging and adc values in assessing treatment response in locally advanced breast cancers receiving neoadjuvant chemotherapy

TURGUT ÇOBAN, L. (2023). Diffusion-Weighted Magnetic Resonance Imaging and ADC Value in Evaluating Treatment Response in Locally Advanced Breast Cancers Receiving Neoadjuvant Chemotherapy Treatment. Van Yüzüncü Yıl University, Faculty of Medicine, Department of Radiology. Master thesis. Van. Objective: Breast cancer is the most common type of cancer among women, and approximately one out of every eight women is diagnosed with breast cancer. Thanks to screening programs in the early diagnosis of breast cancer, the mortality rate due to breast cancer tends to decrease in recent years. Neoadjuvant chemotherapy has become a standard treatment for patients with locally advanced breast cancer. Reducing the stage of the disease and enabling breast-conserving surgery are among the most important benefits of NAC treatment. Magnetic Resonance Imaging has become an indispensable imaging method in the diagnosis and treatment process of breast cancer patients. The DAG sequence is an examination for tissue cellularity, and there are studies showing that DAG shows high sensitivity in the early period in the evaluation of response to neoadjuvant chemotherapy in tumor cells. It recommends inclusion of DWI in the routine breast MRI examination in the evaluation of response to neoadjuvant chemotherapy in locally advanced breast cancers. The aim of this study is to evaluate the neoadjuvant chemotherapy response and to show its correlation with pathological responses by using DAG and ADC values before and after treatment in locally advanced breast cancer. Material and Method: Between May 2019 and December 2022, 78 patients who applied to the breast diseases outpatient clinic of our hospital's general surgery clinic and were evaluated in the tumor council of our hospital in accordance with clinical, radiological and histopathological findings and diagnosed with locally advanced breast cancer and started NAC treatment were included in the study. Before neoadjuvant chemotherapy, a user-dependent ROI was placed in the region corresponding to the most diffusion restriction in the ADC map of the breast mass. The measurements made from the ADC maps obtained on the post-treatment diffusion-weighted images were compared with the pre-treatment measurements and whether they were compatible with the size assessment. The measurements made from the ADC maps obtained on the post-treatment diffusion-weighted images were compared with the pre-treatment measurements and whether they were compatible with the size assessment. During the study, in patients with locally advanced breast cancer who received neoadjuvant chemotherapy, clinical information such as pathological diagnosis, estrogen and progesterone receptor status, HER2 status, Ki-67 proliferation value, tumor grade, treatment responses were obtained, and patient classification was made according to histological, grade and molecular subtypes. Accordingly, treatment responses were determined. Results: The mean lesion MRI ADC values before and after NAC were measured as 0.82±0.12x10-3 and 1.22±0.27x10-3, respectively. It was determined that there was a statistically significant mean increase of 0.40 (95% CI: 0.32; 0.49) in the lesion ADC after NAC compared to before NAC (t=9.720; p<0.001). According to the pathological tumor response, there was no statistically significant difference in pre-NAC lesion MRI ADC values (p>0.05). In the radiological evaluation after NAC of tumors with pathological complete, partial response and no signs of regression, the mean MRI ADC values were 1.48±0.19 x10-3, 1.20±0.21 x10-3 and 1.00±0, respectively. While it was determined that it was 24 x10-3; A statistically significant difference was found in the lesion MRI ADC values after NAC according to the pathological tumor response (F=15.795; p<0.001). There was no statistically significant difference in lesion MRI ADC values before and after NAC according to molecular subgroups (p>0.05). Compared to pre-NAC, the luminal-B group MRI ADC values were 0.39 (0.30;0.48), 0.34 (0.10;0.57) in the HER2-positive group and 0.61(A statistically significant increase of 0.11;1.11 points was detected (p<0.001 and p<0.05). Conclusion: DWI imaging and ADC mapping, which are imaging modalities, are new prognostic parameters in predicting the response of locally advanced breast cancers to NAC and are promising in the future. As the use of DWI in breast diseases becomes widespread, we think that this modality will have avery important place in evaluating the treatment response in LIMT cancers in new studies in the literature. Key words: Magnetic resonance imaging, Diffusion-weighted imaging, Locally advanced breast cancer, Neoadjuvant chemotherapy