Table 4 Association between acute grade ≥2 cutaneous toxicity and clinical and dosimetric characteristics

From: Intensity-modulated radiation therapy with simultaneous integrated boost for locally advanced breast cancer: a prospective study on toxicity and quality of life

 

N

Acute grade ≥2 cutaneous toxicity

Univariate analysis*

Multivariate analysis**

n

%

p-value

OR (95%CI)

p-value

Age (years)

—

—

—

0.51

NA

 

BMI (kg/m²)

—

—

—

0.003

1.14 (1.05–1.24)

0.003

Bra cup size (n = 113)

   

0.020

ND

 

A-B

53

12

22.6%

   

≥C

60

26

43.3%

   

Smoking

   

0.44

NA

 

No

86

28

32.6%

   

Yes

35

14

40.0%

   

Diabetes (n = 119)

   

0.52

NA

 

No

108

37

34.3%

   

Yes

11

5

45.5%

   

Chemotherapy

   

0.017

0.49 (0.16–1.49)***

0.21

No

28

15

53.6%

   

Yes

93

27

29.0%

   

Aesthetic aspect before RT (n = 66)

   

0.70

NA

 

Moderate

14

6

42.9%

   

Good

33

10

30.3%

   

Excellent

19

7

36.8%

   

Dosimetric parameters

Volume of breast CTV (cc)

—

—

—

0.064

ND

 

Volume of breast PTV (cc)

—

—

—

0.055

ND

 

Volume of subclavian CTV (cc)

—

—

—

0.064

0.98 (0.969–1.001)***

0.051

Volume of subclavian PTV (cc)

—

—

—

0.070

ND

 

Dmean (Gy) for the skin (Gy)

—

—

—

0.045

ND

 

D50% for the skin (Gy)

—

—

—

0.014

ND

 

D95% for the skin (Gy)

—

—

—

0.047

1.11 (1.01–1.22)

0.033

D95% for the susclavian skin (Gy)

—

—

—

0.089

ND

 

D98% for the susclavian skin (Gy)

—

—

—

0.047

1.04 (1.003–1.09)

0.034

V95% of CTV breast (cc)

—

—

—

0.068

1.00 (0.992–1.014)***

0.56

V95% of PTV breast (cc)

—

—

—

0.072

ND

 
  1. CTV: clinical target volume; PTV: planning target volume; RT: radiotherapy; OR: odds ratio; CI: confidence interval.
  2. Dx%: dose (Gy) received by x% of the volume; Vx%: volume (cc) of the breast target volume that received x% of the dose.
  3. *Univariate analysis: Khi-2 test, Student t-test or Wilcoxon test.
  4. **Multivariate analysis: logistic regression.
  5. NA: not applicable because not included in multivariate regression model (p > 0.10 in univariate analysis).
  6. ND (not done): variable not included in multivariate analysis for collinearity reasons (bra cup size, volume of breast CTV and PTV: highly correlated to BMI; subclavian PTV volume: highly correlated to subclavian CTV volume; Dmean and D50% to skin: highly correlated to D95% to skin; D95% to susclavian skin: highly correlated to D98% to susclavian skin; V95% of PTV: highly correlated to V95% of CTV).
  7. ***Variable included in multivariate analysis but removed from the model because of the stepwise procedure.
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