Impact of cytochrome P450 2D6 polymorphisms on decision-making and clinical outcomes in adjuvant hormonal therapy for breast cancer

Table 4 Univariate correlation analyses of clinicopathological parameters and clinical outcome with type of hormonal agent received

	Aromatase inhibitors, n = 56	Tamoxifen, n = 14	P value
CYP2D6 phenotype			0.339
IM	43	9
EM/UM	13	5
Median age in yr	62 (50 to 80)	63 (52 to 86)	0.008
Disease stage			0.795
I	23	7
II	21	4
III	12	3
Ethnicity			0.126
Chinese	50	10
Malay	3	2
Indian	3	1
Others	0	1
Comorbidities			1.000
Yes	45	12
No	11	2
Tumor histology			0.918
IDC	45	11
ILC	6	2
Others	5	1
Tumor grade			0.686
1	15	4
2	27	8
3	14	2
Median tumor size in mm	16.5 (1.2 to 70.0)	19.0 (1.6 to 53.0)	0.747
Lymphovascular invasion			0.526
Yes	17	6
No	39	8
ER intensity			0.509
Low intensity	1	1
Moderate intensity	10	4
High intensity	44	9
Negative	1	0
Proportion of tumor cells staining ER-positive			0.386
1%-10%	3	1
11% to 49%	4	3
50% to 89%	15	2
More than 90%	33	8
PR status			1.000
Positive	49	13
Negative	7	1
PR intensity			0.161
Low intensity	3	3
Moderate intensity	10	4
High intensity	36	6
Negative	7	1
Proportion of tumor cells staining PR-positive			0.318
1%-10%	11	3
11% to 49%	6	4
50% to 89%	21	4
More than 90%	15	2
HER2 status			0.700
Positive	10	3
Negative	46	10
Tumor subtypes			0.754
ER+/HER2-	46	10
ER+/HER2+	9	3
ER-/HER2+	1	0
Type of surgery			0.756
Mastectomy	35	10
Wide local excision	21	4
Treatments received			0.045
Systemic therapy1 and hormonal therapy	12	2
Systemic therapy1, radiation and hormonal therapy	18	0
Radiation and hormonal therapy	12	5
Hormonal therapy alone	14	7
Disease recurrence2			0.260
Yes	3	2
No	53	12
Mortality2			0.344
Yes	1	1
No	55	13
Contralateral breast cancer2			0.551
Yes	2	1
No	54	13

¹Systemic therapy refers to chemotherapy with or without trastuzumab.

²Events occurring within 5 years.

ER: Estrogen receptor; PR: Progesterone receptor; HER2: Human epidermal growth factor receptor-2; IDC: Invasive ductal carcinoma; ILC: Invasive lobular carcinoma; IM: Intermediate metabolizers; EM/UM: Extensive metabolizers/ultra metabolizers; CYP2D6: Cytochrome P450 2D6.