Impact of 18F-fluorodeoxyglucose positron emission tomography before and after definitive radiation therapy in patients with apparently solitary plasmacytoma.
OBJECTIVE
To evaluate the impact of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) on management of patients with apparently isolated plasmacytoma.


METHODS
Twenty-one patients with apparently solitary plasmacytoma who underwent FDG-PET for staging or restaging were identified from a central PET database. They were either candidates for or had received definitive radiation therapy (RT).


RESULTS
Seventeen patients had initial staging scans for bone (n = 11) or soft tissue (n = 6) plasmacytomas, and 11 had PET scans after RT. Only 1 of 14 known untreated sites of plasmacytoma was not identified on staging PET (lesion sensitivity = 93%). Three plasmacytomas were excised before PET. Staging PET influenced management in 6 of 17 patients (35%) by showing multiple myeloma (n = 1), discouraging RT after complete resection (n = 1), excluding plasmacytoma at a second site (n = 1), by increasing RT fields (n = 2), or by suggesting sarcoidosis (n = 1). Fifteen of 17 patients with initial staging PET scans received definitive RT. Restaging PET scans after RT showed complete metabolic response in 8 of 11 cases and progressive disease in 2. Two patients with either no response or partial metabolic response had late responses. Staging sestamibi and PET scans were concordant in five of six occasions (one sestamibi scan was false negative).


CONCLUSIONS
FDG-PET has value for staging and RT planning in plasmacytoma and potentially could have a role in response-assessment after RT. Slow resolution of FDG uptake posttreatment does not necessarily imply an adverse prognosis.
Kim
Paul J
PJ
Department of Radiation Oncology, California Pacific Medical Center, San Francisco, CA, USA.
Hicks
Rodney J
RJ
Wirth
Andrew
A
Ryan
Gail
G
Seymour
John F
JF
Prince
H Miles
HM
Mac Manus
Michael P
MP
D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D019788:Fluorodeoxyglucose F18; D006801:Humans; D010954:Plasmacytoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18