Triple negative breast cancer: Insights from the Mexican population.

Abstract

e13148 Background: Breast cancer (BC) is the leading cause of cancer related deaths among women worldwide, driven by multifactorial influences resulting in gene mutations and malignant cell overgrowth. BC represents 30% of cancers in women with a mortality-to-incidence ratio of 15%.Triple negative breast cancer (TNBC) represents 15% of BC cases, characterized by the absence of progesterone and estrogen receptor expression and lack of HER2 overexpression. It is a biologically and clinically aggressive subtype with a highly proliferative rate, poor prognosis and limited treatment options. Methods: Original, retrospective, and descriptive study approved by the Research and Bioethics Committee ON24-0023. Patients aged ≥18 years diagnosed with TNBC treated at Hospital Universitario Dr. José E. González from 2020 to 2024 were included. Demographic, epidemiologic, histologic, diagnostic and treatment data were obtained from clinical records. Statistical analysis was performed using IBM SPSS (V26), with χ² used to evaluate associations between clinical stage and time from symptom onset to diagnosis. The primary endpoint was to analyze demographic, clinical, and treatment variables. Patients with missing data were excluded; no confounders were identified. Results: A total of 2032 BC patients were evaluated, 405 with TNBC. Data from 180 patients was analyzed. The prevalence was 19.9% in our cohort. Obesity was present in 33.9% of patients. Hypertension and diabetes were reported in 24.7% and 16.7%, respectively. The menarche mean age was 12.42 ± 1.4 years (yr) and 46.18 ± 5.7 for menopause; 87.5% were premenopausal, and 8.5% nulligravid. Family history of BC in first-degree relatives was present in 20%. Median time from symptom onset to diagnosis: 2 months (IQR 1-6). Infiltrative ductal subtype was observed in 83.9%, with a G3 tumor grade in 61.1% and Ki-67 >20% in 41.1%. Genetic testing was performed only in 23 patients; BRCA1 was positive in 7.8% and 2.2% in BRCA2. The mean age at diagnosis was 50.94 ± 12.44 yr. Stages II and III were predominant, with 42.8% and 39.4%, respectively. Distant metastases were present in 13.4%. Neoadjuvant chemotherapy regimens, primarily carboplatin, taxanes, doxorubicin and cyclophosphamide were given to 58%. Modified radical mastectomy was performed in 54.4%, adjuvant chemotherapy and radiotherapy were given to 58.9% and 70.6 %, respectively, with 40 Gy in 15 fractions as the most common radiotherapy regimen. Clinical stage ≥ IIIA was significantly associated with a diagnostic delay of >6 months (p = 0.037). Conclusions: TNBC prevalence in this study exceeded international estimates. Advanced stages at diagnosis were primarily attributed to barriers in healthcare access and education. This, along with highly proliferative tumors compared to hormone-sensitive ones, complicates treatment and prognosis. Larger cohort studies, genetic testing, and follow-up can provide a broader perspective on this problem.