Original Study
Sarcopenia Evaluated Using the Skeletal Muscle Index Is a Significant Prognostic Factor for Metastatic Urothelial Carcinoma

https://doi.org/10.1016/j.clgc.2015.07.015Get rights and content

Abstract

Background

The purpose of the study was to evaluate the prognostic value of sarcopenia (muscle loss) in patients with metastatic urothelial carcinoma (UC), in a comparison of several methods of computed tomography (CT)-based evaluation of sarcopenia.

Patients and Methods

We retrospectively reviewed 100 patients with metastatic UC who underwent first-line systemic chemotherapy between 2003 and 2014. Sarcopenia was assessed by the following CT-based methods: skeletal muscle index (SMI), total psoas area (TPA), axial and/or transversal psoas thickness at the level of the third lumbar vertebrae, and axial and/or transversal psoas thickness at the umbilicus level (U-TPT). All parameters were standardized by either height or height squared. Cutoff points were SMI: < 55 cm2/m2 (men), < 39 cm2/m2 (women); others: lowest sex-specific quartiles. Predictive values for cancer-specific survival (CSS) were assessed using the Cox proportional hazards regression model.

Results

Sixty-four patients met the eligibility criterion for analysis: those who underwent CT scans within 30 days before chemotherapy. Of them, 52 (81%) died of UC during the follow-up, with a median survival time of 13 months. Univariate analysis associated decreased SMI, TPA, and U-TPT with poor CSS. Multivariate analysis together with other pretreatment clinicopathologic parameters showed decreased SMI to be an independent predictor of poor CSS.

Conclusion

Evaluation using SMI showed sarcopenia was an independent predictor of poor prognosis for patients with metastatic UC who underwent first-line systemic chemotherapy. Our results might improve stratification of patients and help optimize evaluation of sarcopenia.

Introduction

In 2012, approximately 430,000 patients were diagnosed with urothelial carcinoma (UC) of urinary bladder, resulting in 160,000 deaths worldwide.1 Metastatic UC is known to be intractable, with a median survival of 14 months, even after implementation of contemporary cisplatin-based chemotherapy regimens.2, 3

Although sarcopenia (age-associated loss of skeletal muscle mass4), is reportedly associated with adverse outcomes in many malignancies,5, 6, 7, 8, 9, 10, 11, 12, 13, 14 to our knowledge, no study has been conducted to investigate its prognostic significance in metastatic UC, despite recent reports associating sarcopenia with outcomes of surgery for localized bladder cancer.12, 13, 14

Moreover, evaluation methods for sarcopenia are not entirely standardized. Although a recent European consensus definition of sarcopenia described computed tomography (CT) and magnetic resonance imaging as gold standards for estimating muscle mass in research,15 several possible alternatives exist. We thus compared several evaluation methods for sarcopenia with special regard to its prognostic values in metastatic UC patients.

Section snippets

Patients

Institutional review board approval was obtained for the study. We reviewed 100 patients with metastatic UC who received first-line systemic chemotherapy at our institution between April 2003 and February 2014. This cohort included 83 patients who were analyzed in our previous study on general prognostic markers.16 Because axial CT images obtained within 30 days before the baseline evaluation were reported to accurately represent muscle status and were recommended for analysis of sarcopenia,17

Results

Of 64 patients, 52 (81%) died of UC during the follow-up, with a median survival time of 13 months (IQR, 9-26 months); 51 (80%) were men and 13 (20%) were women (Table 1). Their median age was 68 years (IQR, 63.3-73 years) at the start of first-line chemotherapy. Primary tumor sites were: bladder, 31 patients (48%); upper urinary tract, 28 (44%); and both, 5 (8%). Forty-two (66%) patients had undergone resection of the primary site, and 17 (27%) had received previous adjuvant chemotherapy.

Discussion

To our knowledge, the present study is the first assessment of the prognostic significance of sarcopenia in patients with metastatic UC. It is also the first to discern that, of the several CT-based methods to evaluate sarcopenia, SMI provides an independent predictor for CSS.

The European consensus definition of sarcopenia described CT and magnetic resonance imaging as gold standards for estimating muscle mass in research.15 However, the optimal evaluation method for sarcopenia has yet to be

Conclusion

Sarcopenia evaluated using the SMI was an independent predictor of poor prognosis for patients with metastatic UC who underwent first-line systemic chemotherapy. Our results might improve stratification of patients and help optimize evaluation of sarcopenia.

Disclosure

The authors have stated that they have no conflicts of interest.

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