Confronting clinical tradition: ipsilateral arm use after breast cancer surgery in Japan.

The long-standing practice of prohibiting ipsilateral arm use for intravenous access, blood draws, or blood pressure monitoring after breast cancer surgery has persisted in many countries and remains common in some Japanese institutions, often based on routine signage and overly simplified education. While historically justified in the era of Halsted's radical mastectomy owing to high postoperative lymphedema rates, today's surgical landscape, with the increasing use of breast-conserving surgery and sentinel lymph node biopsy (SLNB), has seen a marked decline in clinically significant arm swelling. Recent large retrospective studies and society statements (Society for Ambulatory Anesthesia, American Society of Breast Surgeons, and Australian and New Zealand College of Anaesthetists) support risk-based, individualized assessments rather than blanket exclusion. This article examines the cultural, educational, and systemic factors that maintain outdated restrictions and presents a symptom-guided risk stratification framework. Asymptomatic patients 1 year after SLNB or 3 years after axillary lymph node dissection/regional lymph node radiation are at low risk for access-related complications. This article explores the unintended harm of rigid policies, including compromised access, delay in care, and patient distress, and proposes strategies for institution-level policy revision and patient education. Shifting from prohibition to personalization aligns clinical practice with modern evidence, promotes patient autonomy, and prevents the perpetuation of outdated norms.