Biomedical information systems (BIS) encompassing electronic health records, clinical decision support platforms, laboratory information systems, and networked medical devices have transformed modern healthcare delivery while simultaneously introducing significant vulnerabilities to data integrity and cybersecurity. This paper provides a comprehensive review of the principal data integrity failure modes and cybersecurity threats confronting contemporary BIS, and examines their implications for patient safety and healthcare infrastructure. Through a narrative synthesis of peer reviewed literature, regulatory reports, and documented incident analyses, five categories of data integrity failure are identified alongside a parallel taxonomy of cybersecurity threats, including ransomware, phishing, Internet of Medical Things exploitation, and insider threats. Evidence links these failures to measurable adverse patient safety outcomes, including medication errors, diagnostic inaccuracies, and preventable mortality. The economic burden of healthcare data breaches consistently exceeds that of any other industry sector. The findings underscore an urgent need to reconceptualize biomedical information security as a core clinical quality imperative, requiring integrated technical, organizational, and regulatory responses.