Investigation of p16 protein expression and its association with histopathologic parameters in breast cancer

We investigated the association between p16 expression and histopathologic parameters including size, neural and vascular invasion, and lymph node involvement in breast cancer. 58 specimens from patients with different grades of breast cancer were included. Hematoxylin and eosin and immunohistochemistry staining for p16 was performed. 5 patients (8.6%) had grade I, 23 (39.7%) had grade II, and 30 (51.7%) had grade III breast cancer. Assessment of the tumor size showed that 5 (8.6%) tumors had a size of ≤2cm, 29 (50%) were between 2-5 cm and 24 (41.4%) had a size of ≥5cm. Moreover, 45 (77.6%) of the included patients had axillary lymph node involvement. Investigation of association between p16 positivity with pathological parameters in three groups with positivity to p16 (1-25%, 26-75%, >75%) showed that there was no association between p16 positivity and other parameters including histologic score (p=0.44), tumor size (p=0.77), neural invasion (p=0.79), perivascular invasion (p=0.98) and the number of involved LNs (p=0.49). From the group including eight patients with >75% p16 positivity, seven (87.5%) were found with neural invasion and two (25%) with perivascular invasion. P16 positivity was not associated with size, neural and vascular invasion, and LN involvement in breast cancer.