Outcomes and patterns of failure in solitary plasmacytoma: a multicenter Rare Cancer Network study of 258 patients.
OBJECTIVE
To assess the outcomes and patterns of failure in solitary plasmacytoma (SP).


METHODS
The data from 258 patients with bone (n = 206) or extramedullary (n = 52) SP without evidence of multiple myeloma (MM) were collected. A histopathologic diagnosis was obtained for all patients. Most (n = 214) of the patients received radiotherapy (RT) alone; 34 received chemotherapy and RT, and 8 surgery alone. The median radiation dose was 40 Gy. The median follow-up was 56 months (range 7-245).


RESULTS
The median time to MM development was 21 months (range 2-135), with a 5-year probability of 45%. The 5-year overall survival, disease-free survival, and local control rate was 74%, 50%, and 86%, respectively. On multivariate analyses, the favorable factors were younger age and tumor size <4 cm for survival; younger age, extramedullary localization, and RT for disease-free survival; and small tumor and RT for local control. Bone localization was the only predictor of MM development. No dose-response relationship was found for doses >30 Gy, even for larger tumors.


CONCLUSIONS
Progression to MM remains the main problem. Patients with extramedullary SP had the best outcomes, especially when treated with moderate-dose RT. Chemotherapy and/or novel therapies should be investigated for bone or bulky extramedullary SP.
Ozsahin
Mahmut
M
Department of Radiation Oncology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. mahmut.ozsahin@chuv.ch
Tsang
Richard W
RW
Poortmans
Philip
P
Belkacémi
Yazid
Y
Bolla
Michel
M
Dinçbas
Fazilet Oner
FO
Landmann
Christine
C
Castelain
Bernard
B
Buijsen
Jeroen
J
Curschmann
Jürgen
J
Kadish
Sidney P
SP
Kowalczyk
Anna
A
Anacak
Yavuz
Y
Hammer
Josef
J
Nguyen
Tan D
TD
Studer
Gabriela
G
Cooper
Rachel
R
Sengöz
Meriç
M
Scandolaro
Luciano
L
Zouhair
Abderrahim
A
D000704:Analysis of Variance; D001859:Bone Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000473:pathology; D010954:Plasmacytoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D016896:Treatment Outcome