General Notions about Breast Cancer

Abstract

Breast cancer is a multifactorial, non-communicable disease with high global prevalence, responsible for approximately 2.3 million new cases and over 666,000 deaths worldwide in a single year. It is the most commonly diagnosed cancer in women and the second most frequent overall in Brazil, representing over 10% of all diagnoses. Anatomically, the female breast contains 15 to 20 glandular lobes responsible for milk production, lactiferous ducts converging at the nipple, and a surrounding matrix of connective and adipose tissue, typically located between the second and seventh ribs, over the pectoralis major and serratus anterior muscles. This structure varies across individuals, influencing both breast density, which complicates imaging diagnostics in younger women, and the patterns of tumor dissemination. The disease arises from genetic alterations that lead to deregulated cell growth and failure of apoptosis, with a subset of cases linked to inherited mutations in genes such as BRCA1, BRCA2, PALB2, and TP53. Risk factors include hormonal influences like early menarche and late menopause, behavioral aspects such as alcohol consumption, obesity, and sedentary lifestyle, and environmental exposure to ionizing radiation. Women have a breast cancer risk approximately 100 times higher than men, and this risk increases significantly with age, reaching a lifetime probability of about 1 in 8. Clinically, breast cancer usually presents as a painless, immobile lump, often accompanied by changes in skin texture, nipple inversion or discharge, and axillary lymph node enlargement, although most breast lumps—around 90%—are benign. While predominantly a female disease, it also affects men in rare cases. Early detection through screening mammography, especially between the ages of 50 and 69, can increase cure rates up to 95% for tumors smaller than one centimeter. Treatment is based on staging: early stages are managed with conservative surgery and radiotherapy; intermediate stages often require neoadjuvant chemotherapy followed by surgical and local measures; and advanced or metastatic stages demand systemic therapies including chemotherapy, hormone therapy, and molecularly targeted agents like monoclonal antibodies, tailored to tumor biology and receptor status.