Breast cancer risk factors in relation to molecular subtypes in breast cancer patients from Kenya

Sayed, Shahin; Fan, Shaoqi; Moloo, Zahir; Wasike, Ronald; Bird, Peter; Saleh, Mansoor; Shaikh, Asim Jamal; Figueroa, Jonine D.; Naidoo, Richard; Makokha, Francis W.; Gardner, Kevin; Oigara, Raymond; Njoroge, Faith Wambui; Magangane, Pumza; Mutebi, Miriam; Chauhan, Rajendra; Mwanzi, Sitna; Govender, Dhirendra; Yang, Xiaohong R.

doi:10.1186/s13058-021-01446-3

Breast Cancer Research

Table 4 Associations between breast cancer risk factors and tumor molecular subtypes in Kenyan breast cancer patients (N=821*)

From: Breast cancer risk factors in relation to molecular subtypes in breast cancer patients from Kenya

							Tumor subtypes
	Luminal A n=286		Luminal B n=294		Luminal B vs. Luminal A		HER2-enriched n=88		HER2-enriched vs. Luminal A		Triple negative n=153		Triple negative vs. Luminal A
	N	%	N	%	OR (95% CI)†	P†	N	%	OR (95% CI)†	P†	N	%	OR (95% CI)†	P†
Age at diagnosis/year
< 50	142	50.2	180	61.4	1.00 (Ref)		44	50.0	1.00 (Ref)		77	50.3	1.00 (Ref)
≥ 50	141	49.8	113	38.6	0.87 (0.36, 2.06)	0.74	44	50.0	1.84 (0.57, 5.92)	0.30	76	49.7	0.52 (0.20, 1.40)	0.20
BMI/ kg/m²
Normal (< 25.0)	60	27.3	71	30.5	1.00 (Ref)		29	41.4	1.00 (Ref)		43	32.6	1.00 (Ref)
Overweight (25.0–29.9)	84	38.2	99	42.5	1.09 (0.66, 1.82)	0.73	25	35.7	0.55 (0.28, 1.11)	0.10	49	37.1	0.91 (0.49, 1.68)	0.75
Obese (≥ 30.0)	76	34.5	63	27.0	0.76 (0.43, 1.33)	0.33	16	22.9	0.36 (0.16, 0.81)	0.013	40	30.3	0.89 (0.46, 1.72)	0.73
Trend‡					0.87 (0.66, 1.15)	0.32			0.59 (0.39, 0.88)	0.011			0.94 (0.68, 1.32)	0.73
Premenopausal: BMI^a
Normal (< 25.0)	36	32.4	51	34.7	1.00 (Ref)		16	45.7	1.00 (Ref)		23	38.3	1.00 (Ref)
Overweight (25.0–29.9)	43	38.7	59	40.1	0.98 (0.51, 1.88)	0.95	11	31.4	0.52 (0.19, 1.40)	0.20	16	26.7	0.49 (0.20, 1.21)	0.12
Obese (≥ 30.0)	32	28.8	37	25.2	0.78 (0.37, 1.61)	0.49	8	22.9	0.44 (0.14, 1.35)	0.15	21	35.0	0.84 (0.34, 2.07)	0.71
Trend‡					0.89 (0.62, 1.27)	0.52			0.65 (0.37, 1.1)	0.13			0.91 (0.57, 1.45)	0.69
Postmenopausal: BMI^a
Normal (< 25.0)	24	22.0	20	23.5	1.00 (Ref)		13	37.1	1.00 (Ref)		20	27.8	1.00 (Ref)
Overweight (25.0–29.9)	41	37.6	40	47.1	1.35 (0.57, 3.20)	0.50	14	40.0	0.48 (0.17, 1.40)	0.18	33	45.8	1.70 (0.68, 4.26)	0.25
Obese (≥ 30.0)	44	40.4	25	29.4	1.10 (0.43, 2.82)	0.84	8	22.9	0.24 (0.07, 0.81)	0.022	19	26.4	1.28 (0.48, 3.46)	0.62
Trend‡					1.02 (0.64, 1.64)	0.92			0.47 (0.26, 0.88)	0.018			1.10 (0.68, 1.78)	0.71
Age at menarche/year
≤ 13 (9–13)	69	25.8	71	24.8	1.00 (Ref)		23	26.4	1.00 (Ref)		33	22.9	1.00 (Ref)
14	68	25.4	69	24.1	1.28 (0.73, 2.25)	0.39	26	29.9	1.65 (0.73, 3.74)	0.23	37	25.7	1.43 (0.73, 2.81)	0.30
≥ 15 (15–20)	131	48.9	146	51.1	1.29 (0.79, 2.13)	0.31	38	43.7	1.32 (0.64, 2.73)	0.46	74	51.4	1.43 (0.78, 2.60)	0.24
Trend‡					1.13 (0.88, 1.45)	0.34			1.12 (0.78, 1.59)	0.54			1.18 (0.88, 1.58)	0.28
Age at first pregnancy/year
< 20	72	26.2	58	19.9	1.00 (Ref)		31	35.6	1.00 (Ref)		51	34.0	1.00 (Ref)
20–24	121	44.0	133	45.5	1.51 (0.84, 2.70)	0.17	30	34.5	0.64 (0.29, 1.37)	0.25	69	46.0	0.81 (0.43, 1.51)	0.51
25–29	51	18.5	62	21.2	1.76 (0.85, 3.65)	0.13	16	18.4	0.92 (0.34, 2.51)	0.87	19	12.7	0.67 (0.28, 1.60)	0.37
Nulliparous^b or ≥ 30	31	11.3	39	13.4	1.06 (0.40, 2.82)	0.90	10	11.5	1.18 (0.31, 4.53)	0.81	11	7.3	0.66 (0.20, 2.18)	0.50
Trend‡					1.09 (0.82, 1.45)	0.54			1.02 (0.67, 1.56)	0.93			0.84 (0.59, 1.20)	0.33
Parity
Nulliparous^b	14	4.9	20	6.8	1.09 (0.30, 3.88)	0.90	4	4.5	0.56 (0.07, 4.77)	0.60	3	2.0	0.67 (0.11, 4.12)	0.66
Parous	272	95.1	274	93.2	1.00 (Ref)		84	95.5	1.00 (Ref)		150	98.0	1.00 (Ref)
Number of children
1–2	73	26.8	101	36.9	1.00 (Ref)		19	22.6	1.00 (Ref)		31	20.7	1.00 (Ref)
3–4	113	41.5	101	36.9	0.47 (0.28, 0.79)	0.005	26	31.0	0.85 (0.37, 1.98)	0.71	59	39.3	1.16 (0.59, 2.29)	0.66
≥ 5	86	31.6	72	26.3	0.45 (0.23, 0.87)	0.018	39	46.4	1.71 (0.65, 4.53)	0.28	60	40.0	1.27 (0.56, 2.89)	0.56
Trend‡					0.65 (0.47, 0.90)	0.0099			1.34 (0.82, 2.20)	0.24			1.11 (0.75, 1.66)	0.60
Cumulative breastfeeding duration/month^c
Q1: 1–< 39	64	24.3	88	33.2	1.00 (Ref)		15	18.3	1.00 (Ref)		20	13.9	1.00 (Ref)
Q2: 39–< 62	59	22.4	68	25.7	0.99 (0.54, 1.80)	0.97	22	26.8	2.48 (0.97, 6.33)	0.058	40	27.8	2.98 (1.33, 6.71)	0.008
Q3: 62–< 96	71	27.0	53	20.0	0.66 (0.33, 1.30)	0.23	14	17.1	0.80 (0.27, 2.39)	0.69	40	27.8	1.80 (0.74, 4.38)	0.20
Q4: ≥ 96	69	26.2	56	21.1	0.99 (0.44, 2.20)	0.97	31	37.8	1.30 (0.40, 4.16)	0.66	44	30.6	1.87 (0.69, 5.07)	0.22
Trend‡					0.93 (0.71, 1.20)	0.56			0.97 (0.67, 1.41)	0.88			1.12 (0.82, 1.52)	0.47
Mean breastfeeding duration per child/month
< 12	34	12.9	48	18.1	1.00 (Ref)		11	13.4	1.00 (Ref)		23	16.0	1.00 (Ref)
12– 23	142	54.0	139	52.5	0.65 (0.35, 1.21)	0.18	49	59.8	1.24 (0.47, 3.29)	0.66	71	49.3	0.75 (0.36, 1.59)	0.46
≥ 24	87	33.1	78	29.4	0.64 (0.32, 1.27)	0.20	22	26.8	1.21 (0.42, 3.52)	0.73	50	34.7	1.09 (0.49, 2.43)	0.83
Trend‡					0.84 (0.60, 1.16)	0.28			1.07 (0.66, 1.72)	0.80			1.13 (0.76, 1.66)	0.55
Age at first pregnancy and Number of children
Age 25+ years, 1–3 births	54	20.7	64	23.5	1.00 (Ref)		15	17.9	1.00 (Ref)		20	13.6	1.00 (Ref)
Age < 25 years, 1–3 births	80	30.7	93	34.2	0.93 (0.52, 1.67)	0.81	19	22.6	0.82 (0.31, 2.15)	0.69	47	32.0	1.39 (0.65, 2.97)	0.40
Age 25+ years, 4+ births	15	5.7	18	6.6	0.77 (0.29, 2.05)	0.60	8	9.5	2.10 (0.58, 7.54)	0.26	7	4.8	1.12 (0.29, 4.27)	0.87
Age < 25 years, 4+ births	112	42.9	97	35.7	0.55 (0.29, 1.05)	0.068	42	50.0	1.31 (0.51, 3.39)	0.58	73	49.7	1.38 (0.62, 3.08)	0.43
Trend‡					0.81 (0.66, 0.99)	0.041			1.16 (0.86, 1.56)	0.33			1.07 (0.84, 1.37)	0.58
Number of children and Cumulative breastfeeding duration
Nulliparous or ≤ 3 children and < 62 months	117	42.2	146	51.2	1.00 (Ref)		31	36.0	1.00 (Ref)		51	34.7	1.00 (Ref)
≤ 3 children and ≥ 62 months	30	10.8	25	8.8	0.61 (0.30, 1.22)	0.16	6	7.0	0.41 (0.11, 1.56)	0.19	17	11.6	1.19 (0.53, 2.66)	0.68
≥ 4 children and < 62 months	20	7.2	30	10.5	0.89 (0.38, 2.07)	0.79	10	11.6	2.34 (0.78, 6.99)	0.13	12	8.2	1.31 (0.49, 3.53)	0.59
≥ 4 children and ≥ 62 months	110	39.7	84	29.5	0.52 (0.30, 0.89)	0.02	39	45.3	1.26 (0.57, 2.78)	0.56	67	45.6	0.96 (0.50, 1.84)	0.91
Trend‡					0.81 (0.68, 0.97)	0.02			1.11 (0.85, 1.44)	0.44			0.99 (0.80, 1.22)	0.91
Menopausal status^a
Premenopausal	144	50.3	174	59.4	1.00 (Ref)		44	50.0	1.00 (Ref)		68	44.7	1.00 (Ref)
Postmenopausal	142	49.7	119	40.6	0.69 (0.32, 1.48)	0.33	44	50.0	0.69 (0.22, 2.10)	0.51	84	55.3	1.82 (0.78, 4.28)	0.17
Age at menopause/year
Premenopausal	144	50.3	174	59.4	N/A		44	50.0	N/A		68	44.7	N/A
< 50 years	58	22.5	58	20.9	1.00 (Ref)		28	33.7	1.00 (Ref)		44	32.1	1.00 (Ref)
> 50 years	56	21.7	46	16.6	0.88 (0.45, 1.74)	0.72	11	13.3	0.38 (0.15, 0.997)	0.049	25	18.3	0.66 (0.31, 1.40)	0.28

*Seventeen cases were excluded from analyses because of their missing data for HER2 status. † Point estimates and 95% confidence intervals were from multivariable models, adjusting for the same series of covariates (except where noticed): age at diagnosis, BMI, age at menarche, age at first pregnancy, number of children, mean breastfeeding duration per child, age at menopause, family history of breast cancer in first-degree female relative, occupation, education level, and location of the facility. Estimates of numbers of children, cumulative and mean breastfeeding duration, and combined age at first pregnancy, and number of children were computed among parous women. ‡ Results were from the trend analysis using the categorical risk factor as a trend. ^a Multivariable modeling analysis without adjusting for age at menopause. ^bWomen who reported never pregnant, never gave birth, and had no child were grouped as "Nulliparous" in modeling analyses. ^c Multivariable modeling analysis without adjusting for mean breastfeeding duration per child. BMI, body mass index; CI, confidence interval; HER2, human epidermal growth factor receptor-2; OR, odds ratio; Q, quartile

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