Has the Incidence of Extramedullary Disease Changed with the New Therapeutic Approaches? Analysis of a Cohort of 965 Multiple Myeloma (MM) Patients (pts).
Authors: Varettoni Marzia , Corso Alessandro , Pica Gianmatteo , Zappasodi Patrizia , Mangiacavalli Silvia , Pascutto Cristiana , Lazzarino Mario 
Published: October 2019

Abstract
Extramedullary myeloma (EMM) at diagnosis or during the course of the disease is rare and often anecdotal. We reviewed the records of 965 consecutive MM pts diagnosed and followed from 1969 to July 2007 in order to evaluate:
the overall incidence of EMMs and the changes over time clinical presentation, response to treatment and outcome of EMM pts divided into two subgroups according to the time of appearance, at diagnosis or during the course of the disease.
We considered three periods: 1969–1989 (conventional chemotherapy, CCT); 1990–1999 (introduction of high-dose therapy, HDT); 2000–2007, (era of novel agents). The overall incidence of EMM was of 13% (129/965 pts), 87/42 M/F, median age 58 (31–80) years. A prior MGUS was present in 24 pts and a solitary plasmacytoma in 10 (8%). Characteristics at the time of EMM were: 77 pts IgG (60%), 23 IgA (18%), 2 IgM (2%), 16 light chain (12%), 11 not secretory (8%); 29 pts were in stage I, 14 in stage II, 86 in stage III; 30/129 pts (23%) were asymptomatic. More frequently involved sites were: paravertebral (40%), rib cage (32%), pelvis (10%). Multiple localizations were present in 27 pts (21%). A plasmacytic leukemia was observed during the follow-up in 9 pts (7%). The overall median follow-up was 24.4 (2.5–148) months. Seventy-three pts presented EMM at the time of diagnosis with different incidences in the 3 periods: 1969–1989 4.5%, 1990–99 4.3%, 2000–07 12.7%. These pts were treated with HDT in 43 cases (59%) and CCT in 30 (41%). Radiotherapy (RT) was associated in 38 pts (52%). A partial response (PR) was achieved in 49 pts (67%). Progression or relapse were observed in 46 pts (63%) and the median time to progression (TTP) and overall survival (OS) in this subgroup of pts were 17.3 and 21.5 months respectively. The other 56 pts showed an EMM during the course of the disease after a median time of 20 (2–144) months from diagnosis. EMM incidence varied as follows: 1969–1989 2.7%, 1990–99 7.2%, 2000–07 7.4%. Median number of previous lines of therapy was 1 (range: 1–7), including HDT in 22 pts (39%), thalidomide or lenalidomide in 18 (32%), bortezomib in 5 (9%). The median time from HDT to EMM was 17 (2–125) months. Treatment of these pts consisted of CCT in 36 cases (64%), thalidomide in 3 (5%) and bortezomib in 8 (14%). RT was given in 29 cases (52%). Response rate in this subgroup was low, only 30% of pts obtained a PR. The median TTP and OS from the time of appearance of EMM were 4.7 and 6.5 months respectively and the overall survival from the diagnosis was 29.9 months. The two groups of EMM pts were also compared for all the clinical characteristics, response to therapy and outcome. EMM pts at diagnosis showed higher levels of monoclonal component and haemoglobin, and lower bone marrow plasmacytosis with respect to the others. OS from diagnosis was similar in the two groups. In conclusion, our study shows an increased incidence of EMM over time. The more recent increase of EMM at diagnosis might be due to the wider use of more sensitive imaging techniques as CT scan and magnetic resonance, while during the course of the disease after 1990 could be related to the longer survival of pts thanks to the new therapeutic approaches. Anyway, the presence of EMM whether at diagnosis or at progression seems to negatively affect the outcome of pts since the OS is shorter than MM pts without EMM.