World J Oncol

World Journal of Oncology, ISSN 1920-4531 print, 1920-454X online, Open Access

Article copyright, the authors; Journal compilation copyright, World J Oncol and Elmer Press Inc

Journal website https://www.wjon.org

Original Article

Volume 11, Number 4, August 2020, pages 165-172

Distribution of Breast Cancer Subtypes Among Nigerian Women and Correlation to the Risk Factors and Clinicopathological Characteristics

**Table 1.** Characteristics of Breast Cancer Patients
Characteristics	Frequency (%)
SD: standard deviation.
Age (years)
Mean ± SD	46.1 ± 10.9
Range	18 - 76
Marital status
Living with a partner	196 (78.1)
Not living with a partner	55 (21..9)
Occupation
Unemployed	45 (17.9)
Minimally skilled	93 (37.1)
Skilled and professional	113 (45.0)
Education level
None	14 (5.6)
Primary	14 (5.6)
Secondary	123 (49.0)
Tertiary	100 (39.8)

Table 1. Characteristics of Breast Cancer Patients

Characteristics

Frequency (%)

SD: standard deviation.

Age (years)

Mean ± SD

46.1 ± 10.9

Range

18 - 76

Marital status

Living with a partner

196 (78.1)

Not living with a partner

55 (21..9)

Occupation

Unemployed

45 (17.9)

Minimally skilled

93 (37.1)

Skilled and professional

113 (45.0)

Education level

None

14 (5.6)

Primary

14 (5.6)

Secondary

123 (49.0)

Tertiary

100 (39.8)

**Table 2.** Immunohistochemistry Distribution Among Breast Cancer Patients
Receptor status	Frequency (%)
HER-2: human epidermal growth factor receptor 2.
Estrogen receptor status
Negative	143 (57.0)
Positive	108 (43.0)
Progesterone receptor status
Negative	181 (72.1)
Positive	70 (27.9)
HER-2 receptor status
Equivocal	6 (2.4)
Negative	199 (79.3)
Positive	46 (18.3)
Hormonal receptor status
Negative	141 (56.2)
Positive	110 (43.8)
Triple negativity	119 (47.4)

Table 2. Immunohistochemistry Distribution Among Breast Cancer Patients

Receptor status

Frequency (%)

HER-2: human epidermal growth factor receptor 2.

Estrogen receptor status

Negative

143 (57.0)

Positive

108 (43.0)

Progesterone receptor status

Negative

181 (72.1)

Positive

70 (27.9)

HER-2 receptor status

Equivocal

6 (2.4)

Negative

199 (79.3)

Positive

46 (18.3)

Hormonal receptor status

Negative

141 (56.2)

Positive

110 (43.8)

Triple negativity

119 (47.4)

**Table 3.** Distribution of Clinical Characteristics by Tumor Subtype
Characteristics	Frequency (%)	Hormonal status	HER-2 status	Triple negative
HER-2: human epidermal growth factor receptor 2; SD: standard deviation; BMI: body mass index; ECOG: Eastern Cooperative Oncology Group.
Age at diagnosis
Mean ± SD	45.6 ± 11.0	46.3 ± 10.9	45.0 ± 11.2	0.357	43.6 ± 10.0	46.0 ±11.2	48.7 ± 13.9	0.321	44.9 ± 11.3	0.363
BMI (kg/m²)	28.4 ± 7.1	27.6 ± 5.5	29.0 ± 8.1	0.109	30.0 ± 5.2	28.5 ± 7.6	27.4 ± 5.2	0.854	29.1 ± 8.6	0.111
Comorbidities				0.154				0.271		0.125
Yes	75 (29.9)	38 (34.5)	37 (26.2)		18 (39.1)	55 (27.6)	2 (33.3)		30 (25.2)
No	176 (70.1)	72 (65.5)	104 (73.8)		28 (60.9)	144 (72.4)	4 (66.7)		89 (74.8)
History of breast surgery	105 (41.8)	49 (44.5)	56 (39.7)	0.520	16 (34.8)	85 (42.7)	4 (66.7)	0.016*	48 (40.3)	0.208
Menopausal status				0.832				0.313		0.910
Premenopausal	157 (62.5)	68 (61.8)	89 (63.1)		33 (71.7)	121 (60.8)	3 (50.0)		74 (62.2)
Postmenopausal	94 (37.5)	42 (38.2)	52 (36.9)		13 (28.3)	78 (39.2)	3 (50.0)		45 (37.8)
ECOG score				0.613				0.563		0.388
0	95 (37.8)	45 (40.9)	50 (35.5)		20 (43.5)	72 (36.2)	3 (50.0)		41 (43.2)
1	111 (44.2)	45 (40.9)	66 (46.8)		19 (41.3)	91 (45.7)	1 (16.7)		58 (52.3)
2	45 (17.9)	20 (18.2)	25 (17.7)		7 (15.2)	36 (18.1)	2 (33.3)		20 (44.4)
Tumor site				0.373				0.010*		0.113
Left	114 (45.4)	54 (49.1)	60 (42.6)		26 (56.5)	86 (43.2)	2 (33.3)		49 (41.2)
Right	126 (50.2)	50 (45.5)	76 (53.9)		15 (32.6)	108 (54.3)	3 (50.0)		67 (56.3)
Bilateral	11 (4.4)	6 (5.4)	5 (3.5)		5 (10.9)	5 (2.5)	1 (16.7)		8 (6.1)

Table 3. Distribution of Clinical Characteristics by Tumor Subtype

Characteristics

Frequency (%)

Hormonal status

HER-2 status

Triple negative

Positive (n = 110)

Negative (n = 141)

P-value

Positive (n = 199)

Negative (n = 46)

Equivocal (n = 6)

P-value

n = 119

P-value

HER-2: human epidermal growth factor receptor 2; SD: standard deviation; BMI: body mass index; ECOG: Eastern Cooperative Oncology Group.

Age at diagnosis

Mean ± SD

45.6 ± 11.0

46.3 ± 10.9

45.0 ± 11.2

0.357

43.6 ± 10.0

46.0 ±11.2

48.7 ± 13.9

0.321

44.9 ± 11.3

0.363

BMI (kg/m²)

28.4 ± 7.1

27.6 ± 5.5

29.0 ± 8.1

0.109

30.0 ± 5.2

28.5 ± 7.6

27.4 ± 5.2

0.854

29.1 ± 8.6

0.111

Comorbidities

0.154

0.271

0.125

Yes

75 (29.9)

38 (34.5)

37 (26.2)

18 (39.1)

55 (27.6)

2 (33.3)

30 (25.2)

176 (70.1)

72 (65.5)

104 (73.8)

28 (60.9)

144 (72.4)

4 (66.7)

89 (74.8)

History of breast surgery

105 (41.8)

49 (44.5)

56 (39.7)

0.520

16 (34.8)

85 (42.7)

4 (66.7)

0.016*

48 (40.3)

0.208

Menopausal status

0.832

0.313

0.910

Premenopausal

157 (62.5)

68 (61.8)

89 (63.1)

33 (71.7)

121 (60.8)

3 (50.0)

74 (62.2)

Postmenopausal

94 (37.5)

42 (38.2)

52 (36.9)

13 (28.3)

78 (39.2)

3 (50.0)

45 (37.8)

ECOG score

0.613

0.563

0.388

95 (37.8)

45 (40.9)

50 (35.5)

20 (43.5)

72 (36.2)

3 (50.0)

41 (43.2)

111 (44.2)

45 (40.9)

66 (46.8)

19 (41.3)

91 (45.7)

1 (16.7)

58 (52.3)

45 (17.9)

20 (18.2)

25 (17.7)

7 (15.2)

36 (18.1)

2 (33.3)

20 (44.4)

Tumor site

0.373

0.010*

0.113

Left

114 (45.4)

54 (49.1)

60 (42.6)

26 (56.5)

86 (43.2)

2 (33.3)

49 (41.2)

Right

126 (50.2)

50 (45.5)

76 (53.9)

15 (32.6)

108 (54.3)

3 (50.0)

67 (56.3)

Bilateral

11 (4.4)

6 (5.4)

5 (3.5)

5 (10.9)

5 (2.5)

1 (16.7)

8 (6.1)

**Table 4.** Distribution of Pathologic Characteristics by Tumor Subtype
Characteristics	Frequency (%)	Hormonal status	HER-2 status	Triple negative
^aOthers: medullary, mucinous and papillary carcinoma. HER-2: human epidermal growth factor receptor 2.
Tumor size				0.871				0.454		0.852
1	3 (1.2)	2 (1.8)	1 (0.7)		1 (2.2)	2 (1.0)	0 (0.0)		1 (0.8)
2	26 (10.4)	11 (10.0)	15 (10.6)		1 (2.2)	25 (12.6)	0 (0.0)		14 (11.8)
3	92 (36.7)	41 (37.3)	51 (36.2)		19 (41.3)	71 (35.7)	2 (33.3)		42 (35.3)
4	130 (51.8)	56 (50.9)	74 (52.5)		25 (54.3)	101 (50.7)	4 (66.7)		62 (52.1)
Nodal status				0.731				0.902		0.996
0	27 (10.8)	14 (12.7)	13 (9.2)		3 (6.5)	23 (11.6)	1 (16.7)		13 (10.9)
1	99 (39.4)	45 (40.9)	54 (38.3)		19 (41.3)	77 (38.7)	3 (50.0)		47 (39.5)
2	118 (47.0)	48 (43.6)	70 (49.6)		22 (47.9)	94 (47.2)	2 (33.3)		56 (47.1)
3	7 (2.8)	3 (2.8)	4 (2.9)		2 (4.3)	5 (2.5)	0 (0.0)		3 (2.5)
Tumor metastasis	44 (17.5)	18 (16.4)	26 (18.4)	0.668	11 (23.9)	31 (15.6)	2 (33.3)	0.240	18 (15.1)	0.342
Disease stage				0.793				0.368		0.801
I	2 (0.8)	1 (0.9)	1 (0.7)		1 (2.2)	1 (0.5)	0 (0.0)		1 (0.8)
II	35 (13.9)	18 (16.4)	17 (12.1)		3 (6.5)	32 (16.1)	0 (0.0)		16 (13.4)
III	168 (66.9)	72 (65.4)	96 (68.1)		31 (67.4)	133 (66.8)	4 (66.7)		83 (69.7)
IV	46 (18.3)	19 (17.3)	27 (19.1)		11 (23.9)	33 (16.6)	2 (33.3)		19 (41.3)
Tumor grade				0.224				0.460		0.202
I	40 (15.9)	21 (19.1)	19 (13.5)		4 (8.7)	35 (17.6)	1 (16.7)		17 (14.3)
II	132 (52.6)	60 (54.5)	72 (51.1)		28 (60.9)	102 (51.3)	2 (33.3)		58 (48.7)
III	79 (31.5)	29 (26.4)	50 (35.5)		14 (30.4)	62 (31.2)	3 (50.0)		44 (37.0)
Histology type				0.531				0.317		0.379
Invasive ductal carcinoma	233 (92.8)	100 (90.9)	133 (94.3)		185(93.0)	43 (93.5)	5 (83.3)		113 (95.0)
Invasive lobular carcinoma	8 (3.2)	4 (2.8)	4 (2.8)		5 (2.5)	2 (4.3)	1 (16.7)		2 (1.7)
Others^a	10 (4.0)	6 (6.3)	4 (2.9)		9 (4.5)	1 (2.2)	0 (0.0)		4 (3.3)

Table 4. Distribution of Pathologic Characteristics by Tumor Subtype

Characteristics

Frequency (%)

Hormonal status

HER-2 status

Triple negative

Positive (n = 110)

Negative (n = 141)

P-value

Positive (n = 199)

Negative (n = 46)

Equivocal (n = 6)

P-value

n = 119

P-value

^aOthers: medullary, mucinous and papillary carcinoma. HER-2: human epidermal growth factor receptor 2.

Tumor size

0.871

0.454

0.852

3 (1.2)

2 (1.8)

1 (0.7)

1 (2.2)

2 (1.0)

0 (0.0)

1 (0.8)

26 (10.4)

11 (10.0)

15 (10.6)

1 (2.2)

25 (12.6)

0 (0.0)

14 (11.8)

92 (36.7)

41 (37.3)

51 (36.2)

19 (41.3)

71 (35.7)

2 (33.3)

42 (35.3)

130 (51.8)

56 (50.9)

74 (52.5)

25 (54.3)

101 (50.7)

4 (66.7)

62 (52.1)

Nodal status

0.731

0.902

0.996

27 (10.8)

14 (12.7)

13 (9.2)

3 (6.5)

23 (11.6)

1 (16.7)

13 (10.9)

99 (39.4)

45 (40.9)

54 (38.3)

19 (41.3)

77 (38.7)

3 (50.0)

47 (39.5)

118 (47.0)

48 (43.6)

70 (49.6)

22 (47.9)

94 (47.2)

2 (33.3)

56 (47.1)

7 (2.8)

3 (2.8)

4 (2.9)

2 (4.3)

5 (2.5)

0 (0.0)

3 (2.5)

Tumor metastasis

44 (17.5)

18 (16.4)

26 (18.4)

0.668

11 (23.9)

31 (15.6)

2 (33.3)

0.240

18 (15.1)

0.342

Disease stage

0.793

0.368

0.801

2 (0.8)

1 (0.9)

1 (0.7)

1 (2.2)

1 (0.5)

0 (0.0)

1 (0.8)

35 (13.9)

18 (16.4)

17 (12.1)

3 (6.5)

32 (16.1)

0 (0.0)

16 (13.4)

III

168 (66.9)

72 (65.4)

96 (68.1)

31 (67.4)

133 (66.8)

4 (66.7)

83 (69.7)

46 (18.3)

19 (17.3)

27 (19.1)

11 (23.9)

33 (16.6)

2 (33.3)

19 (41.3)

Tumor grade

0.224

0.460

0.202

40 (15.9)

21 (19.1)

19 (13.5)

4 (8.7)

35 (17.6)

1 (16.7)

17 (14.3)

132 (52.6)

60 (54.5)

72 (51.1)

28 (60.9)

102 (51.3)

2 (33.3)

58 (48.7)

III

79 (31.5)

29 (26.4)

50 (35.5)

14 (30.4)

62 (31.2)

3 (50.0)

44 (37.0)

Histology type

0.531

0.317

0.379

Invasive ductal carcinoma

233 (92.8)

100 (90.9)

133 (94.3)

185(93.0)

43 (93.5)

5 (83.3)

113 (95.0)

Invasive lobular carcinoma

8 (3.2)

4 (2.8)

5 (2.5)

2 (4.3)

1 (16.7)

2 (1.7)

Others^a

10 (4.0)

6 (6.3)

4 (2.9)

9 (4.5)

1 (2.2)

0 (0.0)

4 (3.3)

**Table 5.** Distribution of Risk Factors by Tumor Subtype
Characteristics	Frequency (%)	Hormonal status	HER-2 status	Triple negative
HER-2: human epidermal growth factor receptor 2. *P < 0.05.
Smoking	3 (1.2)	1 (0.9)	2 (1.4)	1.000	0 (0.0)	3 (1.5)	0 (0.0)	1.000	2 (1.7)	0.605
Alcohol intake	36 (14.3)	18 (16.4)	18 (12.8)	< 0.001*	6 (13.0)	30 (15.1)	0 (0.9)	0.785	15 (12.6)	0.477
Oral contraceptive use	36 (14.3)	17 (15.5)	19 (13.5)	0.718	5 (10.9)	29 (14.6)	2 (33.3)	0.274	15 (12.6)	0.456
Family history	29 (11.6)	6 (5.5)	23 (16.3)	0.009*	2 (4.3)	27 (13.6)	0 (0.0)	0.004*	22 (18.5)	0.001
Radiation exposure	1 (0.4)	1 (0.9)	0 (0.0)	0.438	1 (2.2)	0 (0.0)	0 (0.0)	0.207	0 (0.0)	1.000
Physical inactivity	146 (58.2)	49 (44.5)	56 (39.7)	0.442	18 (39.1)	83 (41.7)	4 (66.7)	0.489	49 (41.2)	0.841
Previous benign/malignant breast lump	24 (9.6)	11 (10.0)	13 (9.2)	0.835	2 (4.3)	19 (9.5)	3 (50.0)	0.002*	12 (10.1)	0.789
Did not breastfeed	50 (19.9)	25 (22.7)	25 (17.7)	0.325	10 (21.7)	39 (19.6)	1 (16.7)	0.936	22 (18.5)	0.589
Early menarche	14 (5.6)	7 (6.4)	7 (5.0)	0.632	2 (4.3)	12 (6.0)	0 (0.0)	1.000	6 (5.0)	0.725
Late first pregnancy	72 (28.7)	38 (34.5)	34 (24.1)	0.070	16 (34.8)	55 (27.6)	1 (16.7)	0.505	30 (25.2)	0.248
Overweight/obesity	169 (67.3)	72 (65.5)	97 (68.8)	0.743	33 (71.7)	133 (66.8)	3 (50.0)	0.763	80 (67.2)	0.672
Nulliparity	61 (24.3)	29 (26.4)	32 (22.7)	0.501	12 (26.1)	48 (24.1)	1 (1.6)	0.872	29 (24.4)	0.981

Table 5. Distribution of Risk Factors by Tumor Subtype

Characteristics

Frequency (%)

Hormonal status

HER-2 status

Triple negative

Positive (n = 110)

Negative (n = 141)

P-value

Positive (n = 199)

Negative (n = 46)

Equivocal (n = 6)

P-value

n = 119

P-value

HER-2: human epidermal growth factor receptor 2. *P < 0.05.

Smoking

3 (1.2)

1 (0.9)

2 (1.4)

1.000

0 (0.0)

3 (1.5)

0 (0.0)

1.000

2 (1.7)

0.605

Alcohol intake

36 (14.3)

18 (16.4)

18 (12.8)

< 0.001*

6 (13.0)

30 (15.1)

0 (0.9)

0.785

15 (12.6)

0.477

Oral contraceptive use

36 (14.3)

17 (15.5)

19 (13.5)

0.718

5 (10.9)

29 (14.6)

2 (33.3)

0.274

15 (12.6)

0.456

Family history

29 (11.6)

6 (5.5)

23 (16.3)

0.009*

2 (4.3)

27 (13.6)

0 (0.0)

0.004*

22 (18.5)

0.001

Radiation exposure

1 (0.4)

1 (0.9)

0 (0.0)

0.438

1 (2.2)

0 (0.0)

0.207

0 (0.0)

1.000

Physical inactivity

146 (58.2)

49 (44.5)

56 (39.7)

0.442

18 (39.1)

83 (41.7)

4 (66.7)

0.489

49 (41.2)

0.841

Previous benign/malignant breast lump

24 (9.6)

11 (10.0)

13 (9.2)

0.835

2 (4.3)

19 (9.5)

3 (50.0)

0.002*

12 (10.1)

0.789

Did not breastfeed

50 (19.9)

25 (22.7)

25 (17.7)

0.325

10 (21.7)

39 (19.6)

1 (16.7)

0.936

22 (18.5)

0.589

Early menarche

14 (5.6)

7 (6.4)

7 (5.0)

0.632

2 (4.3)

12 (6.0)

0 (0.0)

1.000

6 (5.0)

0.725

Late first pregnancy

72 (28.7)

38 (34.5)

34 (24.1)

0.070

16 (34.8)

55 (27.6)

1 (16.7)

0.505

30 (25.2)

0.248

Overweight/obesity

169 (67.3)

72 (65.5)

97 (68.8)

0.743

33 (71.7)

133 (66.8)

3 (50.0)

0.763

80 (67.2)

0.672

Nulliparity

61 (24.3)

29 (26.4)

32 (22.7)

0.501

12 (26.1)

48 (24.1)

1 (1.6)

0.872

29 (24.4)

0.981