Clinicopathological Characteristics of Breast Cancer in Women Aged 40 Years or Younger in Saudi Arabia: A Single-Center Descriptive Study

Background/Objectives: Breast cancer is the most commonly diagnosed cancer among women in Saudi Arabia, yet evidence on younger women remains limited. This study aimed to characterize the clinicopathological, molecular, and treatment features of women diagnosed at age ≤ 40 years and to explore differences between women aged ≤ 35 and 36–40 years. Methods: We conducted a retrospective study of 135 women aged 22–40 years diagnosed with breast cancer at King Saud University Medical City, Riyadh. Variable-specific available-case denominators were used without imputation. Characteristics were summarized descriptively, and age groups were compared using Pearson’s chi-square or exact tests, as appropriate. Results: A breast mass was the most frequent presentation (79.3%), and invasive ductal carcinoma was the predominant diagnosis (80.7%). Tumors > 2 to ≤5 cm accounted for 48.9% of cases; axillary involvement was documented in 47.4%, distant metastasis in 16.7%, and grade 3 disease in 68.2% of patients with documented grade. Luminal B (31.5%) and triple-negative (29.2%) were the most frequently documented molecular subtypes. No statistically significant differences were detected between the age groups in clinical presentation, tumor-size category, axillary involvement, distant metastasis, histological grade, documented molecular subtype, or treatment characteristics. Conclusions: Symptomatic presentation and potentially unfavorable pathological features were common in this tertiary-center cohort. The absence of statistically significant clinicopathological, molecular, or treatment differences between age groups does not establish clinical equivalence and should be interpreted cautiously given the exploratory design and modest sample size. The findings highlight the need for standardized staging, hereditary-risk assessment, and multicenter longitudinal data to inform care for younger women with breast cancer.