Comparison of long-term results between radiotherapy after breast-conserving surgery and postmastectomy radiotherapy in stage T1-2N1M0 breast cancer

Figures & data

Table 1 Characteristics of 1816 pathologically staged T1-2N1M0 breast cancer with or without postoperative radiotherapy

Characteristics	No-RT (n=1040)		RT (n=776)
N	%	N	%
Age (years)
≤40	201	19.3	203	26.2
>40	839	80.7	573	73.8
Primary tumor site
OQ	730	70.2	558	71.9
IQ/CQ	281	27.0	180	23.2
Unknown	29	2.8	38	4.9
Menopausal status
Premenopausal/perimenopause	570	52.5	515	66.4
Postmenopausal	470	45.2	261	42.7
Type of surgery
Mastectomy	1009	97.0	397	51.2
BCS	31	3.0	379	48.8
Tumor size
≤3 cm	809	77.8	648	83.5
>3 cm	231	22.2	128	16.5
Number of positive axillary LNs
1–2	905	87.0	625	80.5
3	135	13.0	151	19.5
Histological grade
I/II	679	65.3	448	57.7
III	292	28.1	310	39.9
Unknown	69	6.6	18	2.3
LVI status
No	842	81	462	59.5
Yes	198	19	314	40.5
Molecular subtype
Luminal A	249	23.9	191	24.6
Luminal B/Her-2 -	372	35.8	297	38.3
Luminal B/Her-2+	164	15.8	148	19.1
Her-2 enriched	118	11.3	51	6.6
TNBC	137	13.2	89	11.5

Abbreviations: RT, radiotherapy; OQ, outer quadrant; IQ, inner quadrant; CQ, central quadrant; BCS, breast-conserving surgery; LN, lymph node; LVI, lymphovascular invasion; Her-2, human epidermal growth factor receptor-2; TNBC, triple-negative breast cancer.

Table 2 Survival analysis for 1406 T1-2N1M0 breast cancer underwent mastectomy

	n	LRR	P-value	DM	P-value	LRFS	P-value	DMFS	P-value	DFS	P-value	BCSS	P-value
			0.008		0.791		0.012		0.591		0.325		0.084
No- RT	1009	8.9		14.8		85.3		84.5		82.5		91.3
RT	397	4.2		14.8		89.0		85.0		84.2		92.8

Note: P-values were calculated using the unadjusted log-rank test.

Abbreviations: RT, radiotherapy; LRR, locoregional relapse; DM, distant metastasis; LRFS, locoregional relapse-free survival; DMFS, distant metastasis-free survival; DFS, disease-free survival; BCSS, breast cancer-specific survival.

Table 3 Summary of prognostic factor univariate analysis in 1040 pathologically staged T1-2N1M0 breast cancer without postoperative radiotherapy

Factors	n	LRR	P-value	DM	P-value	LRFS	P-value	DMFS	P-value	DFS	P-value	BCSS	P-value
Age (years)			0.005		0.01		0.041		0.047		0.008		0.05
≤40	201	15.5		20.4		79.2		79.6		74.8		89.2
>40	839	7.0		13.6		86.5		85.4		84.2		91.5
Primary tumor site			0.000		0.013		0.141		0.054		0.074		0.269
OQ	730	5.6		11.5		87.7		87.6		85.5		92.2
IQ/CQ	281	13.5		19.3		82.1		80.4		78.8		88.5
Menopausal status			0.568		0.176		0.578		0.876		0.879		0.555
Premenopause/perimenopause	570	9.9		16.5		84.8		83.5		80.9		90.8
Postmenopause	470	7.4		13.1		85.2		85.2		83.8		91.3
Tumor size			0.003		0.000		0.000		0.000		0.000		0.000
≤3 cm	809	7.2		11.9		88.2		87.5		85.5		92.7
>3 cm	231	14.7		25.9		74.0		72.8		70.6		85.1
Number of positive axillary LNs			0.399		0.525		0.361		0.413		0.354		0.884
1–2	905	8.5		14.9		85.3		84.5		82.6		91.1
3	135	10.3		15.6		83.2		82.8		80.3		90.4
Histological grade			0.454		0.109		0.141		0.052		0.119		0.273
I/II	679	7.4		13.3		87.2		86.2		84.5		92.0
III	292	10.6		18.0		81.6		80.9		79.0		89.3
LVI status			0.088		0.000		0.000		0.000		0.000		0.01
No	842	8.3		12.8		86.5		86.6		84.5		91.9
Yes	198	12.6		27.6		76.5		70.5		69.3		86.6
Molecular subtype			0.000		0.009		0.000		0.006		0.001		0.001
Luminal A	249	3.3		90.8		92.4		90.4		89.9		94.6
Luminal B/Her-2 -	372	7.2		87.2		86.7		86.2		84.4		93.7
Luminal B/Her-2+	164	9.6		82.0		84.2		82.0		79.2		90.1
Her-2 enriched	118	18.1		78.0		74.0		78.0		73.4		82.8
TNBC	137	14.8		77.7		76.8		75.4		73.0		84.7

Note: P-values were calculated using the unadjusted log-rank test.

Abbreviations: RT, radiotherapy; OQ, outer quadrant; IQ, inner quadrant; CQ, central quadrant; LN, lymph node; LVI, lymphovascular invasion; Her-2, human epidermal growth factor receptor-2; TNBC, triple-negative breast cancer; LRR, locoregional relapse; DM, distant metastasis; LRFS, locoregional relapse-free survival; DMFS, distant metastasis-free survival; DFS, disease-free survival; BCSS, breast cancer-specific survival.

Table 4 Summary of prognostic factor multivariate analysis in 1040 pathologically staged T1-2N1M0 breast cancer without postoperative radiotherapy

		HR	95% CI	P-value
LRR	Age >40 y	0.529	0.33–0.85	0.009
	IQ/CQ	2.275	1.40–3.25	<0.001
	Molecular subtype			0.001
DM	Age >40 y	0.645	0.46–0.91	0.013
	IQ/CQ	1.505	1.09–2.08	0.013
	Tumor size >3 cm	2.144	1.54–2.98	<0.001
	Lymphovascular invasion	2.033	1.39–2.98	<0.001
	Molecular subtype			0.039
LRFS	Tumor size >3 cm	1.95	1.41–2.70	<0.001
	Molecular subtype			0.001
DMFS	Molecular subtype	1.372	1.00–1.88	0.05
	Tumor size >3 cm	2.081	1.51–2.86	<0.001
	Lymphovascular invasion	2.155	1.50–3.10	<0.001
	Molecular subtype			0.025
DFS	Age >40 y	0.673	0.49–0.93	0.16
	Tumor size >3 cm	1.915	1.41–2.60	<0.001
	Lymphovascular invasion	1.996	1.41–2.83	<0.001
	Molecular subtype			0.011
BCSS	Age >40 y	0.658	0.44–1.00	0.047
	Tumor size >3 cm	2.030	1.38–2.99	<0.001
	Lymphovascular invasion	1.755	1.07–2.88	0.026
	Molecular subtype			0.006

Note: P-values were calculated using an adjusted Cox proportional hazards model with forward conditional method.

Abbreviations: IQ, inner quadrant; CQ, central quadrant; LRR, locoregional relapse; DM, distant metastasis; LRFS, locoregional relapse-free survival; DMFS, distant metastasis-free survival; DFS, disease-free survival; BCSS, breast cancer specific survival.

Figure 1 Kaplan-Meier survival curves for 196 pairs of BCS/mastectomy underwent postoperative radiotherapy. (A) Locoregional relapse. (B) Distant metastasis. (C) Distant metastasis-free survival. (D) Distant metastasis-free survival. (E) Progression-free survival survival. (F) Breast cancer-specific survival. P-values were calculated using an unadjusted log-rank test.

Table S1 Summary of characteristics distribution in BCS or mastectomy underwent postoperative radiotherapy before and after PSM

Characteristics	BCS n=379		Mastectomy n=397		P-value	BCS n=196		Mastectomy n=196		P-value
	N	%	N	%	N	%	N	%
Before PSM					After PSM
Age (years)					0.315					1.000
≤40	93	24.5	110	27.7		47	24.0	47	24.0
>40	286	75.5	287	72.3		149	76.0	149	76.0
Primary tumor site					0.001					1.000
OQ	287	75.7	271	68.3		153	78.1	153	78.1
IQ/CQ	84	22.2	96	24.2		40	20.4	40	20.4
Unknown	8	2.1	30	7.5		3	1.5	3	1.5
Menopausal status					0.057					1.000
Premenopausal/perimenopause	239	63.1	276	69.5		138	70.4	138	70.4
Postmenopausal	140	36.9	121	30.5		58	29.6	58	29.6
Tumor size					0.000					1.000
≤3 cm	348	91.8	300	83.5		243	88.7	243	88.7
>3 cm	31	8.2	97	16.5		31	11.3	31	11.3
Number of positive axillary LNs					0.000					1.000
1–2	328	86.5	297	74.8		170	86.7	170	86.7
3	51	13.5	100	25.2		26	13.3	26	13.3
Histological grade					0.568					1.000
I/II	226	59.6	222	55.9		119	60.7	119	60.7
III	145	38.3	165	41.6		75	38.3	75	38.3
Unknown	8	2.1	10	2.5		2	2.9	2	2.9
Lymphovascular invasion status					0.433					1.000
No	231	60.9	231	58.2		166	60.6	166	60.6
Yes	148	39.1	166	41.8		108	39.4	108	39.4
Molecular subtype					0.000					1.000
Luminal A	118	31.1	73	18.4		52	26.5	52	26.5
Luminal B/Her-2 -	154	40.6	143	36.0		82	41.8	82	41.8
Luminal B/Her-2+	66	17.4	82	20.7		38	19.4	38	19.4
Her-2 enriched	12	3.2	39	9.8		5	2.6	5	2.6
TNBC	29	7.7	60	15.1		19	9.7	19	9.7

Note: P-values were calculated using chi-square test.

Abbreviations: BCS, breast conserving surgery; PSM, propensity score match; OQ, outer quadrant; IQ, inner quadrant; CQ, central quadrant; LN, lymph node; LVI, lymphovascular invasion; Her-2, human epidermal growth factor receptor-2; TNBC, triple-negative breast cancer.

Figure S1 Kaplan-Meier survival curves for 1816 T2N1M0 breast cancer with or without postoperation radiotherapy. (A) Locoregional relapse. (B) Distant metastasis. (C) Distant metastasis-free survival. (D) Distant metastasis-free survival. (E) Progression-free survival survival. (F) Breast cancer-specific survival. P-values were calculated using an unadjusted log-rank test.