Association between breast cosmesis and two common radiotherapy regimens Open Access

Wang, Yawen (Spring 2019)

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Background: As the adjuvant therapy to lumpectomy, radiation therapy is critical for patients to lower the local recurrence and mortality rate. However, this radiation therapy may worsen breast cosmesis in the long term. There remains a gap in the evidence as to whether the different types of radiation regimens have different effects on breast cancer thickening. This study focuses on 1) the association between time and skin thickness under two types of radiation therapies; and 2) other factors that may affect this association.

Methods: A total of 143 patients were recruited in the study, where 84 patients received conventional fractional radiation and 59 patients underwent hypo-fractional radiation. Five evaluation time points using ultrasound technique were included in this one-year longitudinal study. Descriptive analysis was performed on patients’ characteristics and skin thickness ratio. Linear mixed models were fitted to 1) find the relationship between time and skin thickness for each type of radiation therapy and 2) determine significant factors affect this association.

Results: Axillary lymph node dissection (ALND) was the only clinical factor that was significantly (p = 0.009) different in two treatment groups. Skin thickness ratio increased during the first four evaluation and a drop at the last evaluation in both treatment groups. Smoking status, T stage, N stage, stages, chemotherapy status, ALND and age were significant covariates relating to the skin thickness ratio in the univariate analysis. After the multivariable analysis, the skin thickness ratio was not significantly associated to time (p = 0.1639) and no difference in the pattern between two treatment groups (p = 0.9318) was detected. ALND was the only variable that had a significant (p = 0.0006) association with skin thickness ratio.

Conclusion: We did not find a time-effect or a treatment-effect on the skin thickness ratio. ALND was the only significant factor affecting the skin thickness ratio. Since there was a relatively small sample size and unbalanced data between two treatment groups, further studies may focus on a matched data analysis or larger sample size.

Table of Contents

1     Introduction. 1

2     Method. 3

2.1      Research Design & Data Collection. 3

2.1.1    Sample 3

2.1.2    Radiation Treatment 4

2.1.3    Patient Ultrasound Imaging. 5

2.2      Statistical Analysis Method. 6

2.2.1    Descriptive Statistics 6

2.2.2    Linear Mixed Model 6

3     Results 7

3.1      Patients’ Characteristics 7

3.2      Linear Mixed Models. 8

3.2.1    Univariate Analysis 8

3.2.2    Multivariable Analysis 9

4     Conclusion and Discussion. 9

5     Reference. 11

6     Tables and Figures 13


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