PTK7 and neoplasm: High expression of PTK7 mRNA was significantly associated with higher NPI group (χ2 = 38.023, d.f. = 2, p < 0.001), ER-negative tumours (χ2 = 203.406, d.f. = 1, p < 0.001), PgR-negative tumours (χ2 = 69.697, d.f. = 1, p < 0.001), and HER2-positive tumours (χ2 = 38.726, d.f. = 1, p < 0.001) (Table 2).