PIK3CA mutations, phosphatase and tensin homolog, human epidermal growth factor receptor 2, and insulin-like growth factor 1 receptor and adjuvant tamoxifen resistance in postmenopausal breast cancer patients

Table 3 Adjusted hazard ratios and interaction tests between PI3K and/or MAPK molecular alterations and tamoxifen

		Number	adjusted HR^cfor tamoxifen versus control (95% confidence interval)	Adjusted Pvalue for interaction
*PIK3CA*	Wild type	308	0.51 (0.30-0.88)
	Exon 20 mutant ^a	82	0.77 (0.25-2.36)	0.51
	Exon 9 mutant ^a	71	0.82 (0.22-3.04)	0.51
PTEN	Negative	78	0.44 (0.15-1.28)	0.63
PTEN	Positive	348	0.58 (0.34-0.98)	0.63
HER2	Negative	479	0.52 (0.33-0.80)	0.52
HER2	Positive	41	0.85 (0.19-3.95)	0.52
IGF-1R	Low (0–2)	390	0.55 (0.33-0.91)	0.90
IGF-1R	High (3)	38	0.60 (0.20-1.76)	0.90
Any molecular alteration	Absent	206	0.48 (0.22-1.02)	0.36
Any molecular alteration	Present ^b	151	0.76 (0.38-1.53)	0.36

^aFour tumors exhibited both exon 9 and exon 20 mutations. ^b Defined as the presence of either a PIK3CA mutation, negative PTEN status, positive HER 2 status, or high IGF-1R.
^cCovariates included age (≥65 versus <65 years), grade (grade 3 versus grades 1 to 2), tumor size (T3 to T4 versus T1 to T2), HER2 status (positive versus negative), and progesterone receptor status (positive versus negative).

ISSN: 1465-542X