Background and Objective: Micro-ribonucleic acids (microRNAs) have introduced a new field in the molecular diagnosis of cancer. However, the role of circulating microRNAs in the plasma/serum of colorectal cancer patients is still unclear. This study was conducted to determine the expression of let-7d microRNA in patients with colorectal cancer.
Methods: This case-control study was conducted on 40 patients with colorectal cancer and 40 healthy people. In this study, 7 mL blood samples were collected from patients with colorectal cancer (both before and after tumor resection) and healthy individuals (only once). The serum samples were isolated and stored at - 80°C until molecular analysis. MicroRNAs were extracted from serum samples, and cDNA was synthesized. Let-7d expression was examined using the RT-qPCR method. Data were analyzed using GraphPad Prism v. 9 software. The receiver operating characteristic (ROC) curve analysis, sensitivity, and specificity were also calculated for the let-7d microRNA data to introduce a diagnostic biomarker between the preoperative patient group and the control group.
Results: In the preoperative samples of the patients, the expression of let-7d microRNA was significantly lower than that of the control group (P˂0.05). The expression of let-7d microRNA significantly increased after tumor resection compared to before. The ROC analysis for let-7d microRNA in the preoperative patient group with the control group showed that the sensitivity was 33.3%, specificity was 92.3%, and the area under the curve (AUC) was 0.622.
Conclusion: Let-7d microRNA could potentially serve as a new noninvasive diagnostic biomarker for the early detection of colorectal cancer. However, further studies are required on this subject.

Background and Objective: Breast cancer is the most common cancer among women, causing the death of many worldwide each year. Given the importance of determining prognosis and the role of biomarkers, this study aimed to determine the expression level Ki-67 biomarker and its relationship with metastasis time and location in breast cancer patients.
Methods: This descriptive-analytical study was conducted on 154 breast cancer women admitted to the Fifth Azar Educational-Therapeutic Center in Gorgan, Iran, during 2009-2019. Upon admission, Ki-67 expression levels in tissue were determined using immunohistochemistry (IHC). Other required information, including demographic characteristics, disease stage, time interval from diagnosis to metastasis, and metastasis location, were identified and evaluated.
Results: Most of the patients (63%) were in the 40-60 age group. Ki-67 levels were determined to be below 15% in 45 patients (29.2%) and above 15% in 109 patients (70.8%). A statistically significant relationship was observed between Ki-67 expression levels and the time interval from diagnosis to metastasis (P<0.05). No statistically significant relationship was found between Ki-67 expression levels and age group, metastasis location, or disease stage.
Conclusion: The results of this study demonstrated that individuals with tissue Ki-67 levels above 15% experienced metastasis within a shorter period of time.