For example, a breast cancer study examining SNPs involved in the metabolism of tamoxifen found no association with any single SNP, but when a combined SNP analysis was performed, harbouring two variant alleles in the genes sulfotransferase family cytosolic 1A phenol-preferring member 1 (SULT1A1) and UPD glucuronosyl transferase 2 family polypeptide B15 (UGT2B15) revealed an increased risk of recurrence and reduced survival (235). This evidence concerns the gene SULT1A1 and breast carcinoma.