Breast cancer: update

Epidemiology and Magnitude of the Problem

Breast cancer imposes a substantial health burden worldwide. In 2022, approximately 2.3 million new cases and about 665 000 deaths were reported from this cause. (1,2) These figures confirm that it is a priority public health problem. Projections for 2050 indicate that, if current trends persist, both incidence and mortality will increase significantly. (3)

The geographic distribution of the disease is uneven. Incidence is generally higher in more developed countries, whereas relative mortality is higher in regions with fewer resources, lower screening coverage, and limited access to specialized treatments. This disparity highlights that survival depends not only on tumor biology but also on the organization and response capacity of the healthcare system.(1-3)

Risk factors

Risk factors include non-modifiable and modifiable elements. Among the non-modifiable factors, female sex, advanced age, family history of breast cancer, germline mutations in BRCA1 and BRCA2, early menarche, and late menopause are notable. (11,12) For women at high hereditary risk, recent literature supports intensive surveillance strategies and genetic counseling. (5)

Among the modifiable factors, obesity, sedentary lifestyle, alcohol consumption, and certain hormonal exposures are prominent. Adiposity is particularly important in the postmenopausal stage due to its association with increased peripheral estrogen production and chronic inflammatory processes. Therefore, weight reduction, regular physical activity, and moderation of alcohol consumption are included among the recommended preventive measures. (13,14)

Biological bases and biomarkers

Breast cancer exhibits significant biological heterogeneity. The expression of hormonal receptors, HER2, and Ki-67, together with specific genomic alterations, defines distinct clinical subtypes (4,7,12). The most recent recommendations suggest evaluating ER, PR, Ki-67, and HER2 in early disease, as well as BRCA in high-risk patients and other markers such as PIK3CA, ESR1, and PD-L1 in advanced disease, according to subtype (7,8,15,16).

Biomarkers allow estimation of prognosis, selection of therapies, and avoidance of overtreatment. In patients with positive hormone receptors, genomic platforms such as Oncotype DX, MammaPrint, Prosigna, and EndoPredict help determine the appropriateness of adjuvant chemotherapy (7). Furthermore, recent literature highlights the emerging role of circulating biomarkers and circulating tumor DNA tests for monitoring and predicting relapse (9,10). This approach reinforces the transition toward more individualized precision medicine.

Diagnosis and Screening

The diagnosis of breast cancer requires integration of clinical, imaging, and histopathological findings. Mammography remains the primary screening method for average-risk women (17,18). In 2024, the USPSTF recommended biennial mammography for women aged 40 to 74, with insufficient evidence for those over 75 years of age (17), which is because at that age, due to mammary gland atrophy, cancer is not visible on mammography. In its 2026 guideline, the American College of Physicians maintained a stance of shared decision-making for women aged 40 to 49 and recommended biennial mammography for women aged 50 to 74 (19).

Breast ultrasound serves a complementary function, especially in dense breasts or palpable lesions. Magnetic resonance imaging is reserved for high-risk patients, evaluation of local extension, or complex diagnostic scenarios.(4,5) Once the lesion is detected, core needle biopsy confirms the diagnosis and defines key histological and molecular characteristics.(4,7)

Recent evidence also underscores the need to individualize screening. In women with dense breasts, some guidelines favor supplemental tomosynthesis, but they do not recommend routine supplemental MRI or ultrasound in the average-risk population.(17,19) The author considers that this stance seeks to balance benefits, harms, costs, and available resources.

Classification and Prognosis

The classification combines anatomical and biological criteria. The most important subtypes include luminal tumors, HER2-positive, and triple-negative tumors.(4,7,12) Luminal tumors usually have a better prognosis and respond to hormone therapy. HER2-positive tumors show great benefit from anti-HER2 therapies. Triple-negative tumors are more aggressive and have fewer available targeted treatments.(4,20,21)

Prognosis depends on stage, tumor size, nodal status, histological grade, and response to neoadjuvant therapy.(4,12) Pathological complete response after neoadjuvant therapy has great prognostic value, especially in triple-negative and HER2-positive tumors.(20,21) Recent population-based registries show improvements in overall survival, although inequalities between regions persist.(22)

Local treatment

Local treatment includes surgery and radiotherapy. Breast-conserving surgery offers oncologic control equivalent to mastectomy in appropriately selected patients.(4,5) Mastectomy remains a valid option for extensive tumors, multicentric tumors, or in high-risk genetic contexts.(5,11)

Sentinel lymph node biopsy has reduced axillary morbidity by replacing complete dissection in many patients with early-stage disease.(4,5) Radiotherapy complements conservative surgery and also has specific indications after mastectomy when there is a high risk of recurrence. Recent guidelines include more flexible fractionation schemes, with an emphasis on efficiency and safety.(23,24)

Systemic treatment

Systemic treatment is adapted to the molecular subtype and clinical stage. Chemotherapy remains the cornerstone in high-risk tumors, especially in triple-negative and some HER2-positive tumors.(4,8,20) In early-stage disease, neoadjuvant therapy allows tumor size reduction and response evaluation. The 2024 systematic review on adjuvant and neoadjuvant therapy showed benefits in terms of recurrence and mortality, although with relevant toxicity in some regimens.(8)

Hormone therapy is the cornerstone of treatment in hormone receptor-positive tumors. Tamoxifen, aromatase inhibitors, and other endocrine strategies reduce recurrence and improve survival.(4,7,15,16) In HER2-positive cancer, anti-HER2 therapies have substantially changed the prognosis.(4,6)

In triple-negative disease, immunotherapy has gained greater importance. The 2024 meta-analysis on checkpoint inhibitors in the neoadjuvant setting showed improvements in pathological complete response in selected subgroups.(20) Likewise, recent literature on triple-negative confirms that treatment requires more refined selection based on biomarkers and clinical risk.(21)

Advanced and metastatic disease

Metastatic disease requires a focus on symptom control, prolongation of survival, and maintenance of quality of life. In HR+/HER2- cancer, the 2026 Canadian recommendations highlight the use of endocrine therapy, CDK4/6 inhibitors, genomic testing, and risk-based intensification.(15) In HER2-positive advanced disease, therapeutic sequences incorporate new-generation anti-HER2 combinations.(6,16)

In triple-negative tumors, immunotherapy and certain targeted agents expanded options in selected patients. In all cases, early palliative treatment, pain control, nutritional support, and emotional care are essential.(6) The author believes that the comprehensive approach should not be limited to tumor control, but should also address functional and psychological well-being.

Prevention and Public Health

Primary prevention includes actions to reduce modifiable risk factors. Evidence supports physical activity, healthy eating, reducing alcohol, and body weight control.(13,14) The author believes that these measures are useful not only for breast cancer but also for other chronic diseases.

Secondary prevention is based on mammographic screening. Biennial mammography is an effective strategy in selected age groups. However, recent evidence favors an individualized decision based on age, family risk, breast density, and patient preferences.(17,19) The author considers that health education and early consultation for breast changes are fundamental elements to improve timely detection.

Psychosocial dimension

Breast cancer produces significant emotional and social repercussions. Anxiety, depression, fear of recurrence, alteration of body image, and changes in sexuality are frequent consequences of the disease. Surgery, chemotherapy, and radiotherapy can also affect functionality and self-esteem.(6,22)

Comprehensive care requires psychological support, physical rehabilitation, therapeutic education, and active participation of the patient in decision making.(6,22) Recent guidelines also highlight the importance of addressing long-term sequelae such as lymphedema, neuropathy, and treatment-induced menopausal symptoms.(23-26) The author considers that this person-centered approach promotes a better quality of life.