Correlation Between the Prognostic Nutritional Index and Breast Cancer in U.S. Adults: NHANES 2001–2018

Background Previous studies have reported that both inflammation and nutrition may affect breast cancer development, but there has been no comprehensive analysis of the influence of the immune nutritional indicator Prognostic Nutritional Index on breast cancer. The Prognostic Nutritional Index (PNI), integrating serum albumin and lymphocyte count, serves as a dual biomarker reflecting systemic nutritional status and antitumor immune competence. Mechanistically, hypoalbuminemia signifies malnutrition and cancer-associated chronic inflammation, while lymphocytopenia indicates impaired immune surveillance facilitating tumor evasion. Clinically validated across gastrointestinal and breast malignancies, low PNI correlates with therapeutic resistance and reduced survival, attributable to compromised tissue repair and antitumor immunity. Despite its cost-effectiveness and calculability from routine blood tests, PNI's potential as an accessible risk stratification tool remains.