The Impact of Post-Mastectomy Chest-Wall Radiation on Overall Survival for Intermediate Risk Breast Cancer Patients: A National Cancer Data Base Analysis Pubblico
Jiang, Chen (Spring 2019)
Published
Abstract
Background:
The recommendation of post-mastectomy radiation therapy (PMRT) to breast cancer women with intermediate-risk disease requires clinical judgment without a single, validated formula. We assessed the impact of PMRT on overall survival (OS) among breast cancer patients considered intermediate risk for local recurrence by querying the National Cancer Data Base (NCDB) 2004-2014.
Methods:
We replicated the SUPREMO phase III clinical trial by including patients with pT1-2N1 (or pT2N0 with either histologic Grade = 3 or presence of lymph vascular invasion) who underwent total mastectomy and did not receive neoadjuvant therapy. PMRT had a total radiation dose 40-70 Gy given within 6 months after surgery. OS was defined as survival duration in months from surgery date. Logistic regression assessed the pattern of PMRT utilization. Cox proportional hazard model was used for the association with OS. Propensity score (PS) overlap weighting was implemented to balance observed baseline characteristics. The effect of PMRT in subgroups was estimated through a multivariable model (MVA) with interactions.
Results:
We obtained 35,244 eligible subjects with a median follow up of 65.5 months. The median age was 57, 82.6% were white, the median tumor size was 2.4 cm, 38.4% had Grade III-IV, 96.2% had a negative surgical margin, and 68.3% received adjuvant chemotherapy. 4841 (13.7%) received PMRT while 30,403 (86.3%) without. Factors associated with a higher probability of PMRT usage include 3 PLN, present of LVI, younger age, and larger tumor size. The 10-year survival rate was 72.1% (PMRT+) vs. 68.7% (PMRT-). According to MVA, the hazard ratio (HR) for PMRT+ vs. PMRT- was 0.82 (95%CI: 0.75-0.89), and it was 0.84 (95%CI: 0.74-0.95) by the PS weighting approach. In the subgroups, compared to PMRT- group, PMRT increased the OS among patients with age > 60 (HR=0.68, 95%CI: 0.60-0.77) and ER positive (HR = 0.75, 95% CI: 0.67-0.84).
Conclusion:
In this large respective study based on NCDB, PMRT provided significant long-term survival benefits among intermediate-risk breast cancer patients, with larger survival benefits noted amongst patients age > 60 and ER positive. Additional guidance for PMRT may require information such as disease-specific survival or recurrence, which is unavailable in NCDB.
Table of Contents
Introduction.............................................................1
Method....................................................................3
Data Source..............................................................3
Sample Selection Criteria..........................................3
Variable Descriptions................................................4
Statistical Analysis....................................................5
Results.....................................................................6
Discussion and Conclusion........................................9
Reference................................................................12
Appendix................................................................26
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