Differences in Clinical, Epidemiological, and Pathological Features of Breast Cancer in the Saudi Population: An Analytical Cross-Sectional Single Institution Study

<b>Background:</b> In Saudi Arabia, breast cancer is the most common malignancy among women, significantly impacting cancer-related morbidity and mortality. The country's unique demographics and rapid socioeconomic development contribute to distinct breast cancer patterns. <b>Objective:</b> To analyze demographic and pathological characteristics of breast cancer with an emphasis on associations between the Ki67 proliferation index, tumor stages, and molecular subtypes. <b>Materials and Methods:</b> An analytical cross-sectional study was conducted on 294 breast cancer patients from 2013 to 2019, recruited from the Comprehensive Cancer Center at King Fahad Medical City, Riyadh, Saudi Arabia. A one-way ANOVA and logistic regression were used to identify risk factors associated with elevated Ki67 levels. Significance was set at a 95% confidence level. <b>Results:</b> The mean age of patients was 51.58. Among them, 67% were overweight/obese, 21.1% were diabetic, and 17% were hypertensive. Approximately 28.9% of all tumors were classified as T3, 46.9% as Grade III, and 40% as Stage IV. Invasive ductal carcinomas (83.9%) were the most common. ER, PR, and HER2 expression were positive in 63.4%, 54.3%, and 34.9% of patients, respectively, with a high Ki67 index in 50.7%. As compared to Grade I cancer, grade II cancer increased the likelihood of elevated Ki67 by 41 times (<i>p</i> = 0.001), Grade III cancer by 7.43 times (<i>p</i> = 0.001), and Stage IV cancer by 2.26 times (<i>p</i> = 0.03). Conversely, invasive lobular carcinomas and other cancer types were significantly less likely to have high Ki67 levels (<i>p</i> < 0.05). <b>Conclusions:</b> Elevated Ki67 appeared to predict higher tumor grades and certain molecular subtypes cancer.