Evaluation of conditional treatment effects of adjuvant treatments on patients with synovial sarcoma using Bayesian subgroup analysis

Sung Wook Seo,Jisoo Kim,Jihye Son,Sungbin Lim

doi:10.1186/s12911-020-01305-9

Abstract

BackgroundThe impact of adjuvant chemotherapy or radiation therapy on the survival of patients with synovial sarcoma (SS), which is a rare soft-tissue sarcoma, remains controversial. Bayesian statistical approaches and propensity score matching can be employed to infer treatment effects using observational data. Thus, this study aimed to identify the individual treatment effects of adjuvant therapies on the overall survival of SS patients and recognize subgroups of patients who can benefit from specific treatments using Bayesian subgroup analyses.MethodsWe analyzed data from patients with SS obtained from the surveillance, epidemiology, and end results (SEER) public database. These data were collected between 1984 and 2014. The treatment effects of chemotherapy and radiation therapy on overall survival were evaluated using propensity score matching. Subgroups that could benefit from radiation therapy or chemotherapy were identified using Bayesian subgroup analyses.ResultsBased on a stratified Kaplan–Meier curve, chemotherapy exhibited a positive average causal effect on survival in patients with SS, whereas radiation therapy did not. The optimal subgroup for chemotherapy includes the following covariates: older than 20 years, male, large tumor (longest diameter > 5 cm), advanced stage (SEER 3), extremity location, and spindle cell type. The optimal subgroup for radiation therapy includes the following covariates: older than 20 years, male, large tumor (longest diameter > 5 cm), early stage (SEER 1), extremity location, and biphasic type.ConclusionIn this study, we identified high-risk patients whose variables include age (age > 20 years), gender, tumor size, tumor location, and poor prognosis without adjuvant treatment. Radiation therapy should be considered in the early stages for high-risk patients with biphasic types. Conversely, chemotherapy should be considered for late-stage high-risk SS patients with spindle cell types.

Highlights

The impact of adjuvant chemotherapy or radiation therapy on the survival of patients with synovial sarcoma (SS), which is a rare soft-tissue sarcoma, remains controversial
The results indicate that chemotherapy is significantly beneficial for survival in all patients (p = 0.0001; Fig. 1b, c)
The baseline characteristics and standardized differences of the matched samples for radiation therapy (RT) are presented in Table 1 and Fig. 2a

Summary

Introduction

The impact of adjuvant chemotherapy or radiation therapy on the survival of patients with synovial sarcoma (SS), which is a rare soft-tissue sarcoma, remains controversial. Bayesian statistical approaches and propensity score matching can be employed to infer treatment effects using observational data. The effects of adjuvant chemotherapy or radiation therapy (RT) on survival in patients with SS remain controversial because definitive evidence from randomized trials is unavailable [3, 5, 6]. Seo et al BMC Med Inform Decis Mak (2020) 20:320 identify based on definitive evidence, because extensive randomized clinical trials (RCTs) are difficult to conduct [5] and subgroup analyses are often inadequately representative due to their small sample sizes. Average treatment effects can be inferred from observational data using propensity score matching (PSM). PSM [7, 8] allows us to compare patients with similar distributions of baseline covariates, thereby minimizing the effects of confounders

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Discussion

Conclusion