Extracellular pH and P-31 magnetic resonance spectroscopic variables are related to outcome in canine soft tissue sarcomas treated with thermoradiotherapy.
OBJECTIVE
The objective was to test whether tumor pH and (31)P magnetic resonance spectroscopic end points were related to treatment outcome in pet canine patients with spontaneous soft tissue sarcomas treated with thermoradiotherapy.


METHODS
Forty-two dogs with evaluable (31)P magnetic resonance spectroscopic end points and pH data were included in this study. Tumor variables (grade and volume), extracellular pH (pHe), T(2) relaxation times, intracellular pH, and selected phosphometabolite ratios were examined for correlation with clinical outcome.


RESULTS
From 39 dogs, pHe was a predictor of metastasis-free survival (MFS), with hazard ratio (HR, 0.29; P = 0.005) and overall survival (OS) with (HR, 0.36; P = 0.013). Tumor volume (>19 cm(3)) was related to MFS (HR, 2.14; P = 0.04), time to local failure (HR, 3.4; P = 0.025), and OS (HR, 2.27; P = 0.03). There was no association between T(2) or intracellular pH and clinical outcome. Tumor grade (high versus low/intermediate) and phosphodiester/betaATP ratio were identified as significant predictors for MFS, with (HR, 2.66; P = 0.009) and (HR, 0.75; P = 0.027), respectively, and as predictors of OS with (HR, 2.66; P = 0.009) and (HR, 0.76; P = 0.03), respectively. The phosphodiester/phosphocreatinine ratio predicted time to local failure (HR, 1.24; P = 0.017).


CONCLUSIONS
pHe was predictive of metastasis and OS in canine spontaneous sarcomas. To our knowledge, this is the first time that pHe has been shown to be predictive of clinical outcome. The results suggest that additional studies should be considered evaluating the prognostic significance of this variable. Phospholipid resonances, related to membrane metabolism, were related to clinical outcome, confirming recent results reported in human patients with soft tissue sarcomas treated with thermoradiotherapy.
Lora-Michiels
Michaël
M
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
Yu
Daohai
D
Sanders
Linda
L
Poulson
Jean M
JM
Azuma
Chieko
C
Case
Beth
B
Vujaskovic
Zeljko
Z
Thrall
Donald E
DE
Charles
H Cecil
HC
Dewhirst
Mark W
MW
D000818:Animals; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D004283:Dog Diseases / Q000473:pathology / Q000628:therapy*; D004285:Dogs; D005260:Female; D006863:Hydrogen-Ion Concentration; D006979:Hyperthermia, Induced; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D010759:Phosphorus Isotopes; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D012509:Sarcoma / Q000473:pathology / Q000628:therapy / Q000662:veterinary*; D012983:Soft Tissue Neoplasms / Q000473:pathology / Q000628:therapy / Q000662:veterinary*; D016896:Treatment Outcome
D010759:Phosphorus Isotopes