Decreased survival in patients with carcinoma of axillary tail versus upper outer quadrant breast cancers: a SEER population-based study

Figures & data

Table 1 Baseline characteristics of patients with CATS or UOBC from the SEER database 1990–2012

Characteristics	CATS (n=2,683)	UOBC (n=146,343)	P-value
Year, %			<0.001
1990–1997	15.1	12.3
1998–2005	42.8	39
2006–2012	42.1	48.7
Age (years), %			<0.001
18–45	26.6	18.4
46–55	27.9	28.1
56–65	22.4	26.8
66–79	23.1	26.7
Race, %			<0.001
White	80.3	81.9
Black	13.5	9.7
Others	5.8	8.1
Unknown	0.5	0.4
Marital status, %			0.008
Married	63.9	61.1
Not married	33	35.9
Unknown	3.2	3.1
Laterality, %			0.902
Left	49.8	49.7
Right	50.2	50.3
Histology, %			0.024
IDC	78.9	77.8
ILC	5.1	6.4
Others	16	15.8
Grade, %			<0.001
I	19.4	20.6
II	37.2	41.4
III and UD	43.4	38.1
Stage, %			0.062
I	47.5	46.8
II	37.6	39.5
III	15	13.7
Tumor size, %			<0.001
0–20 mm	68.4	61.6
21–50 mm	28	33
>50 mm	3.6	5.4
LN status, %			<0.001
Negative	60	63.3
Positive	40	36.7
LN examined, %			<0.001
1–3	24	31.6
4–9	23.8	22.6
>9	48.9	42.7
Unknown/no examine	3.4	3.2
LN positive, %			0.001
0	58	61.7
1–3	25.8	24.1
4–9	8.5	7.9
>9	4.4	3.6
Unknown/no examine	3.4	2.8
LNR, %			0.06
≤0.3	81.5	83
>0.3 and ≤0.7	9.4	9.2
>0.7	5.5	4.5
Unknown/no examine	3.6	3.3
HoR, %			<0.001
Negative	26.1	20.8
Positive	73.9	79.2
Surgery, %			<0.001
Lumpectomy	72.9	61.7
Mastectomy	27.1	38.3
Radiation, %			<0.001
Yes	63.6	59
No	1.2	0.9
Unknown	35.2	40.1
Chemotherapy, %			0.006
Yes	51	48.4
No/unknown	49	51.6

Abbreviations: CATS, carcinoma of the axillary tail of Spence; HoR, hormone receptor; IDC, infiltrating duct carcinoma; ILC, infiltrating lobular carcinoma; LN examined, number of examined lymph node; LN positive, number of positive lymph node; LNR, lymph node ratio; LN status, lymph node status; OS, overall survival; SEER, Surveillance, Epidemiology, and End Results; UD, undifferentiated; UOBC, upper outer quadrant breast cancer.

Figure 1 Kaplan–Meier plots of the 10-year BCSS and OS were utilized to compare CATS and UOBC.

Notes: Patients with CATS had a worse survival than the UOBC population for BCSS (competing risks analysis P=0.001) (A). There was no statistical significance in the 10-year OS between CATS and UOBC (78% vs 78.8%, log-rank test P=0.161) (B).

Abbreviations: BCSS, breast cancer-specific survival; CATS, carcinoma of the axillary tail of Spence; OS, overall survival; UOBC, upper outer quadrant breast cancer.

Table 2 Multivariate Cox regression model analysis of the BCSS and OS between CATS and UOBC

Variablesa	BCSS			OS
	HR	95% CI	P-values	HR	95% CI	P-values
Year
1990–1997	Reference			Reference
1998–2005	0.65	0.63–0.68	<0.001	0.77	0.74–0.79	<0.001
2006–2012	0.49	0.47–0.52	<0.001	0.6	0.58–0.62	<0.001
Age (years)
18–45	Reference			Reference
46–55	0.96	0.92–1.01	0.091	0.97	0.93–1.01	0.191
56–65	1.09	1.04–1.15	<0.001	1.3	1.25–1.36	<0.001
66–79	1.50	1.43–1.57	<0.001	2.69	2.59–2.80	<0.001
Race
White	Reference			Reference
Black	1.38	1.32–1.45	<0.001	1.37	1.32–1.42	<0.001
Others	0.88	0.82–0.93	<0.001	0.81	0.77–0.85	<0.001
Marital status
Married	Reference			Reference
Not married	1.15	1.12–1.20	<0.001	1.31	1.28–1.34	<0.001
Location
UOBC	Reference			Reference
CATS	1.20	1.07–1.34	0.001	1.11	1.02–1.22	0.019
Histology
IDC	Reference			Reference
ILC	0.93	0.86–1.01	0.073	0.85	0.80–0.90	<0.001
Others	0.94	0.90–0.99	0.010	0.92	0.89–0.96	<0.001
Grade
I	Reference			Reference
II	2.11	1.94–2.30	<0.001	1.22	1.17–1.28	<0.001
III and UD	3.41	3.13–3.71	<0.001	1.68	1.60–1.76	<0.001
Tumor size
0–20 mm	Reference			Reference
21–50 mm	2.00	1.93–2.08	<0.001	1.66	1.61–1.71	<0.001
>50 mm	3.41	3.22–3.61	<0.001	2.79	2.66–2.92	<0.001
LN status
Negative	Reference			Reference
Positive	2.83	2.72–2.94	<0.001	2.03	1.97–2.09	<0.001
HoR
Negative	Reference			Reference
Positive	0.56	0.54–0.58	<0.001	0.64	0.62–0.66	<0.001
Surgery
Lumpectomy	Reference			Reference
Mastectomy	1.30	1.25–1.35	<0.001	1.25	1.21–1.29	<0.001
Radiation
Yes	Reference			Reference
No	2.16	1.90–2.45	<0.001	1.84	1.66–2.04	<0.001
Chemotherapy
Yes	Reference			Reference
No/unknown	0.95	0.91–0.99	0.014	1.21	1.17–1.25	<0.001

Notes:

a Adjusted by Cox proportional hazards models, including location (UOBC or CATS), year of diagnosis, age, race, marital status, histology, grade, tumor size, LN status, hormone receptor status, surgery type, radiation, and chemotherapy.

Abbreviations: BCSS, breast cancer-specific survival; CATS, carcinoma of the axillary tail of Spence; HoR, hormone receptor; HR, hazard ratio; IDC, infiltrating duct carcinoma; ILC, infiltrating lobular carcinoma; LN status, lymph node status; OS, overall survival; UD, undifferentiated; UOBC, upper outer quadrant breast cancer.

Figure 2 Kaplan–Meier plots of the 10-year BCSS comparing 1:1 matched CATS and UOBC cases.

Notes: The survival analysis of the matched groups showed that CATS presented a worse outcome for the BCSS (10-year BCSS: 85% vs 87.4%, competing risks analysis P=0.019).

Abbreviations: BCSS, breast cancer-specific survival; CATS, carcinoma of the axillary tail of Spence; PSM, propensity score matching; UOBC, upper outer quadrant breast cancer.

Figure 3 Forest plot of the hazard ratios for CATS versus UOBC in the subgroup analysis.

Notes: The forest plots of the HRs in the subgroups were plotted to describe the stratified prognosis value of ATS location of breast cancer. The HRs of CATS versus UOBC were significant in most of the subgroups for BCSS (A) and in almost half of the subgroups for OS (B).

Abbreviations: ATS, axillary tail of Spence; BCSS, breast cancer-specific survival; CATS, carcinoma of the axillary tail of Spence; HoR, hormone receptor; HR, hazard ratio; LN, lymph node; OS, overall survival; UD, undifferentiated; UOBC, upper outer quadrant breast cancer; IDC, infiltrating duct carcinoma; ILC, infiltrating lobular carcinoma.

Table 3 Multivariate logistic regression analysis on LN metastasis

Variables	OR	95% CI	P-values
Year
1990–1997	Reference
1998–2005	0.98	0.95–1.02	0.301
2006–2012	0.83	0.80–0.86	<0.001
Age
18–45	Reference
46–55	0.86	0.84–0.89	<0.001
56–65	0.74	0.72–0.77	<0.001
66–79	0.59	0.57–0.61	<0.001
Race
White	Reference
Black	1.12	1.08–1.16	<0.001
Others	0.88	0.84–0.92	<0.001
Location
UOBC	Reference
CATS	1.26	1.16–1.37	<0.001
Histology
IDC	Reference
ILC	0.92	0.87–0.96	0.001
Others	0.86	0.83–0.89	<0.001
Grade
I	Reference
II	1.84	1.78–1.91	<0.001
III and UD	2.36	2.27–2.45	<0.001
Tumor size
0–20 mm	Reference
21–50 mm	3.20	3.13–3.28	<0.001
>50 mm	8.14	7.71–8.59	<0.001
HoR
Negative	Reference
Positive	1.34	1.30–1.39	<0.001

Abbreviations: BCSS, breast cancer-specific survival; CATS, carcinoma of the axillary tail of Spence; HoR, hormone receptor; IDC, infiltrating duct carcinoma; ILC, infiltrating lobular carcinoma; LN, lymph node; OR, odds ratio; OS, overall survival; UD, undifferentiated; UOBC, upper outer quadrant breast cancer.