Effect of Clinical and Treatment Factors on Survival Outcomes of Triple Negative Breast Cancer Patients

Figures & data

Table 1 Clinical Characteristics of Patients with Triple Negative Breast Cancer Treated with Radiation Therapy

Characteristics	n	%
Number of patients	214	100
Age at diagnosis (year)
Median (range)	60.6 (31–90)
<50	42	19.6
≥50	172	80.4
Laterality
Left side	100	46.7
Right side	114	53.3
T-stage
T1	111	51.9
T2	84	39.2
T3	13	6.1
T4	6	2.8
Nodal status^a
N0	133	62.1
N1	47	22.0
N2	20	9.3
N3	11	5.1
Surgery
Conserved	168	78.5
Mastectomy	46	21.5

Note:^aThree patients were nodal status NX (regional lymph nodes could not be assessed (previously removed)).

Table 2 Effect of Tumor Size on Disease-Free Survival and Overall Survival in Patients with Triple Negative Breast Cancer

Tumor Size	T1 (n=111)	T2 (n=84)	T3, T4 (n=19)	P value
Age at diagnosis (year; mean {SD})	67.6 (10.7)	63.2 (12.7) v T1, p=0.010	64.5 (14.0)	0.038
Radiation technique (n)
IMRT	53/111	39/84	7/19
3DCRT	58/111	45/84	12/19
Fractionation (n)
Conventional	37/109	26/84	7/19
Hypofractionated	72/109	58/84	12/19
	p=0.0001^a	p=0.0001^a	p=0.194^a
Disease-free survival (months; mean {SD})	106.5 (39.88)	107.3 (46.47)	54.78 (46.55)	<0.0001^b
Overall survival (months; mean {SD})	110.2 (39.88)	108.4 (58.01)	66.60 (44.68)	0.0004^b

Notes:^aCompared to conventional fractionation; ^bLogrank test.

Abbreviations: 3D CRT, 3-dimensional conformal radiotherapy; IMRT, intensity modulated radiotherapy.

Figure 1 Disease-free survival (A, C) and overall survival (B, D) for triple negative breast cancer patients. Survival stratified by tumor size are compared in (A and B); survival by nodal status are compared in (C and D).

Table 3 Effect of Nodal Status on Disease-Free Survival and Overall Survival in Patients with Triple Negative Breast Cancer

Nodal Status ^a	N0 (n=133)	N1 (n=47)	N2, N3 (n=31)	P value
Age at diagnosis (year; mean {SD})	66.9 (10.7)	64.1 (14.7)	61.5 (11.8) v N0, p=0.014
Radiation technique (n)
IMRT	63/133	18/47	16/31
3DCRT	70/133)	29/47	15/31
		p=0.0386^b
Fractionation (n)
Conventional	41/130	19/46	20/31
Hypofractionated	89/130	27/46	11/31
	p=0.0001^c		p=0.0413^c
Disease-free survival (months; mean {SD})	109.3 (35.57)	86.1 (39.86)	64.82 (60.80)	<0.0001^d
Overall survival (months; mean {SD})	110.4 (38.14)	92.0 (34.14)	94.12 (53.67)	0.012^d

Notes:^aThree subjects were NX status (regional lymph nodes could not be assessed [previously removed]); ^bCompared to IMRT; ^cCompared to conventional fractionation; ^dLogrank test.

Abbreviations: 3D CRT, 3-dimensional conformal radiotherapy; IMRT, intensity modulated radiotherapy.

Table 4 Effect of Radiation Technique on Disease-Free Survival and Overall Survival in Patients with Triple Negative Breast Cancer

Treatment Type	IMRT (n=99)	3D CRT (n=115)	P value
Age at diagnosis (years; mean {SD})	61.4 (11.5)	59.7 (13.0)	0.316
Proportion receiving 50 Gy to chest/breast	33/99	36/108	1.00
Proportion receiving dose to SCF	33/99	37/110	1.00
Proportion receiving boost	82/99	80/109	0.1319
Disease-free survival (months; mean {SD})	83.9 (35.06)	105.6 (46.71)	0.818^a
Overall survival (months; mean {SD})	90.6 (27.25)	106.7 (46.57)	0.232^a

Note:^aLogrank test.

Abbreviations: 3D CRT, 3-dimensional conformal radiotherapy; IMRT, intensity modulated radiotherapy; SCF, Supraclavicular fossa.

Figure 2 Disease-free survival (A, C) and overall survival (B, D) for triple negative breast cancer patients. 3D CRT and IMRT are compared in (A and B); breast-conserving surgery and mastectomy are compared in (C and D).

Abbreviations: 3D CRT, 3-dimensional conformal radiotherapy; IMRT, intensity modulated radiotherapy.

Table 5 Effect of Conventional versus Hypofractionated Radiation Doses to Chest/Breast on Disease-Free Survival and Overall Survival in Patients with Triple Negative Breast Cancer^a

Chest/Breast Dose (Gy)	Conventional^b (n=71)	Hypofractionated^b (n=141)	P value
Age at diagnosis (year; mean {SD})	56.0 (10.6)	62.7 (12.5)	0.0001
Proportion receiving boost	59/71	104/141	0.1671
Disease-free survival (months; mean {SD})	107.7 (45.04)	84.7 (38.14)	0.678^c
Overall survival (months; mean {SD})	111.5 (42.97)	88.1 (36.25)	0.395 ^c

Notes:^aInformation unavailable for 2 patients (treated offsite); ^bConventional doses totalled 50 Gy; hypofractionated doses, 40 Gy; ^cLogrank test.

Table 6 Mastectomy versus Breast-Conserving Surgery and Disease-Free Survival and Overall Survival in Patients with Triple Negative Breast Cancer

Treatment Type	Mastectomy (n=46)	Breast Conservation (n=168)	P value
Age at diagnosis (year; mean {SD})	59.3 (14.5)	61.0 (11.7)	0.409
Proportion receiving boost	23/46	139/168	<0.0001
T stage
T1	14 (30.4%)	97 (57.7%)	0.001
T2	20 (43.5%)	64 (38.1%)	0.610
T3	8 (17.4%)	5 (3.0%)	0.001
T4	4 (8.7%)	2 (1.5%)	0.020
Nodal status^a	(45)	(166)
N0	11 (24.4%)	123 (74.1%)	<0.0001
N1	17 (37.8%)	29 (17.5%)	0.007
N2	11 (24.4%)	9 (5.4%)	0.0005
N3	6 (13.3%)	5 (3.0%)	0.0135
Disease-free survival (months; mean {SD})	65.2 (47.88)	114.2 (41.8)	<0.0001^b
Overall survival (months; mean {SD})	80.5 (41.16)	115.5 (40.55)	0.0015^b

Notes:^aThree patients were nodal status NX (regional lymph nodes could not be assessed (previously removed)). ^bLogrank test.

Table 7 Effect of Laterality on Disease-Free Survival and Overall Survival in Patients with Triple Negative Breast Cancer

Laterality	Left Side (n=100)	Right Side (n=114)	P value
Age at diagnosis (year; mean {SD})	65.2 (12.4)	65.9 (11.7)	0.6715
Radiation technique (n)
IMRT	42/100	57/114	0.2727
3DCRT	58/100	57/114	0.2727
	(p=0.0336) ^a
Fractionation (n)^b
Conventional	29/99	42/113	0.2457
Hypofractionated	70/99	71/113	0.2457
	(p <0.0001)^c	(p =0.0002)^c
Disease-free survival (months; mean {SD})	100.3 (52.2)	105.0 (39.9)	0.057^d
Overall survival (months; mean {SD})	109.2 (45.3)	106.2 (44.9)	0.383^d

Notes:^aCompared to IMRT for Left sided group; ^bInformation unavailable for 2 patients (treated offsite); ^cCompared to conventional fractionation; ^dLogrank test.

Abbreviations: 3D CRT, 3-dimensional conformal radiotherapy; IMRT, intensity modulated radiotherapy.

Table 8 Multivariate Cox Proportional Hazard Modelling of Clinical and Treatment Factors

Variable	Disease-Free Survival			Overall Survival
	HR	95% CI	P value^a	HR	95% CI	P value^a
Radiation technique
3D CRT	1			1
IMRT	1.025	0.524 to 2.004	0.943	0.670	0.287 to 1.563	0.354
Fractionation
Conventional	1			1
Hypofractionated	1.090	0.527 to 2.257	0.816	1.298	0.544 to 3.096	0.556
Surgery
Conserved	1			1
Mastectomy	2.099	0.927 to 4.753	0.076	2.073	0.781 to 5.499	0.143
Tumor size
T1	1			1
T2	0.984	0.440 to 2.202	0.989	1.058	0.427 to 2.622	0.904
T3, T4	2.988	1.166 to 7.655	0.023	3.384	1.217 to 9.407	0.019
Nodal status
N0	1			1
N1	1.558	0.601 to 4.038	0.362	0.985	0.338 to 2.870	0.978
N2/N3	5.529	2.187 to 13.977	0.0003	1.977	0.670 to 5.834	0.217
Chemotherapy
No	1			1
Yes	0.638	0.234 to 1.737	0.379	0.689	0.249 to 1.907	0.473

Notes:^aP values were adjusted using a multivariate Cox proportional hazard regression model including all factors listed; bold type indicates significance.

Abbreviations: CI, confidence interval; HR, Hazard ratio; IMRT, intensity modulated radiotherapy; 3D CRT, 3-dimensional conformal radiotherapy.