GSTP1 and breast cancer: There was, however, evidence of increasing BC risk with increasing number of GSTP1-Val alleles; the HR for developing BC was 1.36 (95% CI 1.02–1.81, P=0.04) and 2.00 (95% CI 1.18–3.38, P=0.01), respectively, for Ile/Val heterozygotes and Val/Val homozygotes, as compared with that for Ile/Ile homozygotes (see P-values after correction for multiple comparisons in the footnote of Table 1).