Table 3 Cox regression analysis of overall survival for the entire patient cohort.

From: De-escalation of radiation therapy in patients with stage I, node-negative, HER2-positive breast cancer

 

Univariate analysis [HR, 95% CI, p value]

Multivariate analysis [HR, 95% CI, p value]

No RT vs. RT

10.18 (7.36–14.08), p < 0.0001

5.32 (3.68–7.69), p < 0.0001

Age

≥70 yrs vs. <70

3.69 (2.68–5.09), p < 0.0001

2.03 (1.42–2.88), p < 0.0001

Comorbidities

0

Reference

Reference

≥1

2.00 (1.40–2.87), p = 0.0002

1.41 (0.97–2.05), p = 0.0716

Laterality

Right

Reference

N/A

Left

0.93 (0.68–1.28), p = 0.6590

 

Hormone status

ER+ or PR+

Reference

N/A

ER−/PR−

1.01 (0.70–1.46), p = 0.9488

 

Treatment group

HS, received ET

Reference

Reference

HS, no ET

5.55 (3.86–7.97), p < 0.0001

3.33 (2.23–5.00), p < 0.0001

ER−/PR−

1.60 (1.07–2.40), p = 0.0222

1.28 (0.84–1.95), p = 0.2490

Tumor size

≤1 cm

Reference

Reference

>1–2 cm

1.29 (0.92–1.82), p = 0.1418

1.45 (1.01–2.07), p = 0.0438

Tumor grade

Grade 1–2

Reference

Reference

Grade 3

1.25 (0.91–1.73), p = 0.1730

1.33 (0.95–1.87), p = 0.0985

Unknown

0.87 (0.38–2.02), p = 0.7507

1.01 (0.43–2.35), p = 0.9841

Facility type

Other

Reference

Reference

Academic

0.75 (0.53–1.07), p = 0.1077

0.80 (0.56–1.15), p = 0.2363

Unknown

0.21 (0.03–1.48), p = 0.1166

0.22 (0.03–1.62), p = 0.1385

Race/ethnicity

NH-White

Reference

Reference

NH-Black

1.16 (0.72–1.86), p = 0.5368

1.19 (0.73–1.96), p = 0.4849

Hispanic

0.82 (0.36–1.85), p = 0.6290

0.73 (0.32–1.68), p = 0.4578

NH-Other

0.15 (0.02–1.04), p = 0.0547

0.14 (0.02–1.02), p = 0.0526

Unknown

0.97 (0.14–6.96), p = 0.9782

0.87 (0.12–6.26), p = 0.8873

No HSD

<20%

Reference

Reference

≥20%

1.38 (0.994–1.91), p = 0.0546

1.22 (0.80–1.76), p = 0.3858

Unknown

0.78 (0.25–2.45), p = 0.6664

0.59 (0.23–2.40), p = 0.6235

Income status

≥$46,000/yr

Reference

Reference

<$46,000/yr

1.50 (1.08–2.07), p = 0.0149

1.21 (0.82–1.78), p = 0.4444

Unknown

0.87 (0.27–2.76), p = 0.8097

0.90 (0.28–2.88), p = 0.8627

Distance to facility

<8.9 miles

Reference

N/A

≥8.9 miles

0.89 (0.65–1.21), p = 0.4489

 

Chemotherapy

Single-agent

Reference

Reference

Multi-agent

0.61 (0.44–0.85), p = 0.0036

0.72 (0.51–1.01), p = 0.0593

Not specified

0.99 (0.31–3.17), p = 0.9918

1.01 (0.32–3.25), p = 0.9830

  1. Hazards ratio > 1 implies the factor is associated with increased risk of death.
  2. HR hazards ratio, CI confidence interval, RT radiation therapy, HS hormone-sensitive, ET endocrine therapy, NHW non-Hispanic white, NHB non-Hispanic Black, HSD high-school diploma.
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