Extramedullary disease portends poor prognosis in multiple myeloma and is over-represented in high-risk disease even in the era of novel agents.
BACKGROUND
Extramedullary disease is an uncommon manifestation in multiple myeloma and can either accompany newly diagnosed disease or develop with disease progression or relapse. We evaluated the impact of this disease feature on patients' outcome in the context of novel agents.


METHODS
We analyzed clinical and biological features of extramedullary disease in 936 patients with multiple myeloma enrolled in Total Therapy protocols, 240 patients in non-Total Therapy protocols, and 789 non-protocol patients, all of whom had baseline positron emission tomography scans to document extramedullary disease at diagnosis and its subsequent development at the time of disease progression or relapse.


RESULTS
The most common sites for extramedullary disease at diagnosis were skin and soft tissue whereas liver involvement was the striking feature in extramedullary disease at disease relapse or progression. Regardless of therapy, extramedullary disease was associated with shorter progression-free and overall survival, as well as the presence of anemia, thrombocytopenia, elevated serum lactate dehydrogenase, cytogenetic abnormalities, and high-risk features in 70-and 80-gene risk models in univariate analysis. Multivariate analysis with logistic regression revealed that this disease feature was more prevalent in patients with an elevated centrosome index, as determined by gene expression profiling, as well as in myeloma molecular subtypes that are more prone to relapse. These include the MF subtype (also called the "MAF" subtype, associated with over-expression of the MAF gene seen with chromosome translocation 14;16 or 14;20) and the PR subtype (also called the "Proliferation" subtype, associated with overexpression of pro-proliferative genes).


CONCLUSIONS
These data show that extramedullary disease is more prevalent in genomically defined high-risk multiple myeloma and is associated with shorter progression-free survival and overall survival, even in the era of novel agents. All clinical trials included in the analyses were registered with www.clinicaltrials.gov (NCT00083551, NCT00083876, NCT00081939, NCT00572169, NCT00644228,NCT00002548,NCT00734877).
Myeloma Institute for Research and Therapy, University of Arkansas for Medical Sciences, Little Rock, AR 72205-7199, USA. susmani@uams.edu
Saad Z
SZ
Usmani
Christoph
C
Heuck
Alan
A
Mitchell
Jackie
J
Szymonifka
Bijay
B
Nair
Antje
A
Hoering
Yazan
Y
Alsayed
Sarah
S
Waheed
Sajjad
S
Haider
Alejandro
A
Restrepo
Frits
F
Van Rhee
John
J
Crowley
Bart
B
Barlogie
D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000628:therapy; D008297:Male; D009101:Multiple Myeloma / Q000000981:diagnostic imaging / Q000401:mortality / Q000628:therapy; D049268:Positron-Emission Tomography; D011859:Radiography; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000628:therapy; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000628:therapy