The clinicopathological variables for the available (n = 252) and unavailable (n = 260) tumours were compared using χ2 analysis and Fisher’s Exact test, with no significant difference being seen in terms of patient age (p = 0.927), tumour size (p = 0.582), tumour grade (p = 0.271), histological type (p = 0.368), nodal status (p = 0.479), ER status (p = 0.578), PR (p = 0.612), Her2 (p = 0.192) or Ki67 (p = 0.754) expression between available and unavailable samples. This evidence concerns the gene ESR1 and neoplasm.