Table 3 Univariate andmultivariate analysis of overall survival predictors for patients with multiple primary lung cancers

 Age (y)

1.045 (1.033–1.058)

< 0.001

1.042 (1.024–1.060)

< 0.001

 Time interval (months)

0.976 (0.972–0.980)

< 0.001

0.973 (0.967–0.979)

< 0.001

 First tumor size (mm)

1.020 (1.005–1.036)

0.008

1.010 (0.988–1.048)

0.377

 Second tumor size (mm)

1.024 (1.008–1.040)

0.003

1.023 (0.999–1.048)

0.064

 Sex

0.016

0.001

  Female

0.782 (0.641–0.956)

0.634 (0.479–0.838)

  Male

Ref. level

Ref. level

 Number of primary

0.482

  Two

1.126 (0.809–1.568)

  Three or more

Ref. level

 Tumor site relationship

0.035

0.663

  Ipsilateral

1.256 (1.016–1.551)

1.064 (0.805–1.406)

  Bilateral

Ref. level

Ref. level

 Frist histology

0.003

0.233

  AC

0.680 (0.524–0.883)

0.004

0.719 (0.492–1.051)

0.089

  SCC

0.933 (0.696–1.252)

0.645

0.807 (0.523–1.243)

0.330

  Others

Ref. level

Ref. level

 Second histology

0.008

0.332

  AC

0.701 (0.559–0.878)

0.002

0.887 (0.611–1.286)

0.526

  SCC

0.857 (0.646–1.136)

0.282

0.723 (0.464–1.125)

0.150

  Others

Ref. level

Ref. level

 Frist grade

0.048

0.285

  Well and moderately

0.799 (0.639–0.998)

0.847 (0.624–1.149)

  Poorly and undifferentiated

Ref. level

Ref. level

 Second grade

0.004

0.256

  Well and moderately

0.678 (0.522–0.882)

0.835 (0.613–1.139)

  Poorly and undifferentiated

Ref. level

Ref. level

 Frist types of surgery

< 0.001

0.034

  Lobectomy

0.278 (0.216–0.357)

< 0.001

0.570 (0.328–0.992)

0.047

  Sublobectomy

0.478 (0.367–0.623)

< 0.001

0.805 (0.461–1.407)

0.447

  No surgery

Ref. level

Ref. level

 Second types of surgery

0.009

0.004

 Lobectomy

0.707 (0.538–0.929)

0.013

0.454 (0.282–0.731)

0.001

  Sublobectomy

0.749 (0.601–0.934)

0.010

0.549 (0.363–0.829)

0.004

  No surgery

Ref. level

Ref. level