Skeletal Muscle Mass Reduction Velocity as a Simple Prognostic Indicator for Patients with Metastatic Urothelial Carcinoma Receiving Second-Line Chemotherapy

Document Type: Research Articles

Authors

1 Department of Nephro-urology, Nagoya City University, Graduate School of Medical Sciences, Nagoya, Japan.

2 Department of Urology, Anjo Kosei Hospital, Anjo City, Japan.

3 Department of Pharmacy, Nagoya City University Hospital, Nagoya, Japan.

Abstract

Background: Patients with metastatic urothelial carcinoma (mUC) have an uncertain prognosis. The aim of the
current study was to evaluate the prognostic potential of a skeletal muscle mass reduction index measured by computed
tomography (CT) for mUC patients undergoing second-line gemcitabine and docetaxel (GD) chemotherapy. Methods:
We retrospectively reviewed 44 patients with mUC who received second-line GD chemotherapy between 2006 and
2015 in our hospital. Skeletal muscle area (SMA) at the third lumbar vertebra was measured using CT images obtained
from medical records, and a skeletal muscle index (SMI) was calculated for each patient as: SMI = SMA / height2.
Changes in SMI across timepoints (SMI inclination) were calculated as: SMI inclination = [( SMI/SMI)/duration of
the interval between imaging visits]. Patients were then divided into two groups: a “steep” group (SMI inclination <
-0.01) and a “gentle” group (SMI inclination ≥ -0.01). Kaplan-Meier curves and multivariate Cox proportional hazards
regression models were used to evaluate the relationship between SMI inclination and overall survival (OS). Results:
There were no differences in patient characteristics between the two groups with respect to median age, gender, Eastern
Cooperative Oncology Group Performance Status (ECOG-PS), disease control rate or first-line treatment regimen. OS
from the start of second-line GD therapy group was significantly shorter in the “steep” group relative to the “gentle”
group. The multivariate analysis revealed that “steep” SMI inclination and presence of anemia were strong predictors
of poor prognosis. Conclusion: Higher values of SMI inclination, indicating a faster rate of skeletal muscle mass
reduction, may serve as a useful predictive marker for OS in mUC patients undergoing second-line GD chemotherapy.

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