Nipple Aspirate Fluid (NAF) cytology supports prediction of breast cancer risk using the IBIS model

Introduction Ductal Hyperplasia is part of most breast cancer predictive algorithms including IBIS, conferring a 1.9 – 4.2 fold risk increase for resp. benign- and atypical hyperplasia. However, absent of prior biopsy, information on ductal pathology is usually absent, leading to underestimation of BCa risk. We explored the contribution of ductal pathology information to IBIS' ability to classify women to risk groups.

Methods. IBIS risk factors were recorded from women w/o prior history of BCa during routine annual exams. To assess hyperplasia, NAF was collected with the ForeCYTE Breast Aspirator. Cytology was graded per King. IBIS risk was calculated with and w/o hyperplasia information in the model, and each woman classified to 1 of 3 groups: high (≥8%), medium (> 5≤8%), and low (< 5%) 10-year risk, and analysis stratified by age (< 45 vs. ≥45).

Results. Information on IBIS factors incl. hyperplasia was available for 832 women Age ≥45 and 509 Age < 45. Absent hyperplasia information, IBIS classified 3.7% (19/509) of women Age< 45 and 20.6% (171/832) Age ≥45 as having > 5≤8% 10-year risk; 1.4% (7/509) Age< 45 and 4.2% (35/832) women Age ≥45 were classified to ≥8% 10-year risk. Low risk were 483 women Age < 45 and 626 women Age ≥45. With hyperplasia information added to IBIS, the number classified to ≥8% 10-year risk increased to 13.9% (71/509) for women Age < 45 and 11.2% (93/832) for Age ≥45. 11 women Age < 45 (2.3%) and 15 women Age ≥45 (2.4%) moved from low (< 5%) to medium (> 5≤8%) 10-year risk.

Conclusions. Availability of ductal pathology information aids the IBIS model in identifying more women at increased risk for BCa. Among various factors in BCa predictive algorithms, hyperplasia is the most actionable, as it presents a target for therapeutic intervention.