Abstract P1-10-21: Influence of timing of radiation therapy following breast-conserving surgery on 10-year disease-free survival

Autor: John H. Maduro, MC van Maaren, H. Struikmans, R. Bretveld, Kcgm Groothuis-Oudshoorn, Sabine Siesling, Philip Poortmans, Renske K. Veenstra, Jan J. Jobsen, Lja Strobbe
Rok vydání: 2017
Předmět:
Zdroj: Cancer Research. 77:P1-10
ISSN: 1538-7445
0008-5472
Popis: Background In the Netherlands, one of the indicators of quality of care is that radiation therapy (RT) should start within six weeks following breast-conserving surgery (BCS). However, there is still much controversy regarding timing of RT in literature. This study investigated the effect of timing of RT on disease-free survival (DFS) in a Dutch nationwide population-based cohort. Methods All women diagnosed with primary invasive stage I-IIIA breast cancer in 2003, treated with BCS plus RT, of whom the start date of RT was known, were included. Patients who received chemotherapy between surgery and RT were excluded, as this affects delay. Patients were categorised into three groups: 55 days, between surgery and start of RT. The primary outcome was 10-year DFS. Secondary outcomes were 10-year locoregional recurrence-free (LRRFS) and distant metastasis-free survival (DMFS). Multivariable Cox regression was used to correct for confounding. Since adjuvant systemic therapy largely influences DFS, all analyses were stratified for use of adjuvant systemic therapy (chemotherapy and/or endocrine therapy). Results In total, 2,759 patients were included. The median number of days between BCS and RT was 45 (IQR 37-54 days). The hazard ratio (HR) for 10-year DFS was 0.79 (95% CI: 0.65-0.96) for 42-55 days and 0.71 (95% CI: 0.56-0.90) for >55 days, both compared to 55 days compared to 55 days (HR 0.63 (95% CI: 0.42-0.96) compared to 55 days, compared to 10-year DFS, LRRFS and DMFS for different time intervals between BCS and RT, stratified for use of adjuvant systemic therapy Entire cohort (n=2,759)No adjuvant treatment (n=1,761)Adjuvant treatment (n=998)Time intervalHR [95% CI]*HR [95% CI]*HR [95% CI]*10-year DFS55 days0.71 [0.56-0.90]0.77 [0.57-1.03]0.63 [0.42-0.96]10-year LRRFS55 days0.90 [0.59-1.37]0.99 [0.61-1.60]0.67 [0.29-1.57]10-year DMFS55 days0.64 [0.45-0.91]0.73 [0.44-1.22]0.59 [0.36-0.96]* Corrected for all relevant confounders. HRs in bold are statistically significant (p Conclusion and interpretation In conclusion, patients treated with adjuvant systemic therapy following RT showed increasing 10-year DFS and DMFS with longer BCS-RT intervals, which was not the case for patients not receiving adjuvant systemic therapy. Possible explanations for these results have to be explored further. Citation Format: van Maaren MC, Bretveld RW, Jobsen JJ, Veenstra R, Groothuis-Oudshoorn KCGM, Struikmans H, Maduro JH, Strobbe LJA, Poortmans P, Siesling S. Influence of timing of radiation therapy following breast-conserving surgery on 10-year disease-free survival [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-10-21.
Databáze: OpenAIRE
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