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Table 3 Multivariable cox models for overall and disease-free survival a

From: Adjuvant chemotherapy for stage III colon cancer: relative dose intensity and survival among veterans

 

Overall survival (5 years)b

Disease free survivalc(3 years)

HR (95% CI)

P values

HR (95% CI)

P values

Chemotherapy regimens

    

 5-FU/ LV

Reference

 

Reference

 

 Oxaliplatin plus 5-FU/LV

0.55 (0.34,0.91)

0.02

0.65 (0.41,1.05)

0.08

 Oxaliplatin plus Capecitabine

1.15 (0.42,3.16)

0.79

1.07 (0.42,2.70)

0.89

 Capecitabine Monotherapy

0.80 (0.43,1.50)

0.50

0.91 (0.50,1.64)

0.75

 Mixed/Other

0.89 (0.50,1.59)

0.70

1.20 (0.70,2.05)

0.51

Relative dose intensity

    

 ≤70%

Reference

 

Reference

 

 >70%

NAd

 

0.75 (0.50,1.11)

0.15

 At year 1

0.58 (0.37,0.89)

0.01

  

 At year 2

0.74 (0.47,1.18)

0.21

  

 At year 3

0.86 (0.52,1.44)

0.57

  

 At year 4

0.96 (0.54,1.68)

0.88

  

 At year 5

1.04 (0.56,1.91)

0.90

  

 Unknown or Missing

0.95 (0.51,1.78)

0.88

0.97 (0.53,1.77)

0.91

Age (years)

    

 <55

0.68 (0.30, 1.52)

0.34

1.00 (0.50, 1.97)

0.99

 55-64

Reference

 

Reference

 

 65-74

0.99 (0.61,1.62)

0.96

1.14 (0.72,1.82)

0.57

 75+

2.06 (1.25,3.40)

0.005

1.98 1.21,3.23)

0.006

Male

1.70 (0.39,7.52)

0.48

1.67 (0.39,7.27)

0.49

Race/Ethnicity

    

 White (non-Hispanic)

Reference

 

Reference

 

 Hispanic

0.56 (0.17,1.80)

0.33

0.27 (0.08,0.93)

0.04

 Black (non-Hispanic)

0.75 (0.37,1.50)

0.41

0.76 (0.40,1.44)

0.40

 Other/Missing

1.42 (0.58,3.48)

0.44

1.35 (0.59,3.11)

0.48

Charlson Comorbidity Index (per unit)

1.17 (1.06,1.30)

0.002

1.15 (1.04,1.27)

0.007

Married

0.66 (0.45,0.97)

0.03

0.86 (0.59,1.24)

0.42

Tumor

    

 T1/T2e

Reference

 

Reference

 

 T3

1.62 (0.83,3.14)

0.15

1.63 (0.88,3.02)

0.12

 T4

5.88 (2.69,12.9)

<0.001

5.84 (2.82,12.1)

<0.001

Node

    

 N1

Reference

 

Reference

 

 N2

1.68 (1.12,2.50)

0.01

1.89 (1.30,2.77)

0.001

Lymphovascular invasion

    

 No

Reference

 

Reference

 

 Yes

1.69 (0.90,3.17)

0.10

1.95 (1.10,3.45)

0.02

 Unknown or Missing

1.09 (0.57,2.07)

0.79

1.20 (0.66,2.16)

0.55

Bowel obstruction

    

 No

Reference

 

Reference

 

 Yes

2.32 (1.36,3.95)

0.002

2.12 (1.28,3.51)

0.003

 Unknown or Missing

1.05 (0.57,1.95)

0.88

1.19 (0.67,2.10)

0.56

Days between surgery and start of chemotherapy

    

 ≤30

Reference

 

Reference

 

 31-60

1.44 (0.40,5.22)

0.58

1.14 (0.37,3.49)

0.82

 61-90

1.65 (0.43,6.25)

0.47

1.35 (0.42,4.33)

0.61

 91-120

1.84 (0.46,7.41)

0.39

1.56 (0.46,5.32)

0.47

  1. aVariable selection: Predictor variables that were suggestive of a bivariate association (i.e., P < 0.15) were included in the initial multivariable model, and then the final models included only variables with P < 0.05 in either model. Chemotherapy regimens, RDI, age, sex, ethnicity/race, Charlson Comorbidity Index, days between surgery and start of chemotherapy, and fixed effects for site were forced into both models.
  2. bA hazard ratio (HR) >1 indicates the covariate is associated with an increased risk of death from any cause, and therefore, decreased overall survival.
  3. cA HR > 1 indicates the covariate is associated with an increased risk of colon cancer recurrence or death, and therefore, decreased disease-free survival.
  4. dThe proportional-hazards assumption does not hold for RDI in the overall survival model. The log hazard of RDI > 70% at time 0 is −0.52 (95% CI −0.94, −0.09), and the log hazard for the interaction between time (year) and RDI > 70% is 0.37 (95% CI 0.07, 0.66), P = 0.01, which indicates that the protective effect of RDI > 70% attenuates over time.
  5. eT1 andT2 were collapsed because of small sample size, and both are typically together in the anatomic staging/prognostic groups of stage III colon cancer.