Abstract
BACKGROUND: Breast cancer (BC) risk, based on either known risk factors (objective) or self-assessment (subjective), may influence natural killer cell activity (NKCA) directly or through psychological distress. OBJECTIVE: The main objective of this study was to examine the relationships of objective and subjective BC risks with NKCA and a mediating role of psychological distress in a community sample of healthy women. METHODS: In a cross-sectional descriptive study, a convenience sample of 117 healthy women (mean age, 36.5 years) completed questionnaires for BC risk and psychological distress and provided blood for NKCA measurement. RESULTS: Objective and subjective BC risks were positively correlated (P < .001). Regression analyses revealed that objective BC risk had a significant negative relationship with NKCA at the 12.5:1 effector-to-target cell ratio (P = .011), whereas subjective risk was not associated with NKCA at any effector-to-target cell ratio tested. Only subjective risk had a positive association with both BC-specific (P = .002) and general (P < .001) psychological distress. Psychological distress failed to mediate the relationship between subjective risk and NKCA. CONCLUSIONS: Objective BC risk had a limited but significant relationship with NKCA. Subjective risk was highly associated with psychological distress but was not associated with NKCA. IMPLICATIONS FOR PRACTICE: Despite the limited relationships between BC risk and NKCA, the impact of BC risk on other tumor defense mechanisms needs to be further explored. Collective findings in this area will suggest early preventive strategies for monitoring BC risk and maintaining better tumor defense in healthy women.