Plasmacytoma. Treatment results and conversion to myeloma

Abstract

Forty‐six cases of solitary plasmacytoma were reviewed for response to radiation and progression to multiple myeloma. Cases were classified as solitary plasmacytomas of bone (SPB) (32 cases) or extramedullary plasmacytomas (EP) (14 cases). There was an overall 93% response rate of the tumor to radiation therapy: 62% had a complete response after radiation therapy, whereas 31% had a partial response. Conversion to multiple myeloma was influenced by the type of plasmacytoma; 53% of the patients with SPB converting to myeloma versus 36% of the patients with EP. Time from diagnosis to conversion for patients with SPB showed no evidence of plateau, with conversion continuing to occur even after 17 years. The median survival time for patients after conversion to myeloma was 14.5 months and was not affected by time to conversion. Serum protein level, presence of monoclonal gammopathy, and size of primary lesion were of some prognostic significance in predicting conversion to myeloma. Adjuvant chemotherapy did not affect the incidence of conversion but did appear to delay conversion to myeloma. Seven patients in whom multiple sequential solitary plasmacytomas developed formed a distinct subset, with a median time to a second plasmacytoma of 63 months. In three of these patients, conversion to myeloma occurred subsequently. This study supports the idea of EP having a lower incidence of conversion to myeloma and a different natural history from SPB, with SPB likely to be multiple myeloma in evolution. Cancer 1992; 69:1513‐1517.

Radiotherapy of solitary plasmacytoma

“…Compared to other studies, the median time to progression of 34.3 months we saw in our patients forms the upper end of the reported range of 13 -36 months [1,7,8,9]. Six out of nine patients with progressive disease developed multiple myeloma in the first year after diagnosis.…”

“…For EP, significantly better local control was reported for doses >45 Gy (100% 5-year LCR vs. 55% for <45 Gy) [15]. Considering the low treatment toxicity, doses of 40-50 Gy seem to be a general consensus for SBP [1,12,16] and of 40-60…”

Radiotherapy Alone is Associated with Improved Outcomes Over Surgery in the Management of Solitary Plasmacytoma

“…Reported by Huang et al, in patients with SP of cervical spine, adjunctive RT following excision obviously decreased MM progression (Huang et al, 2010). Another retrospective study showed favorable effects related to melphalan-based chemotherapy in preventing MM development (Mayr et al, 1990), but others didn't report any benefits of chemotherapy (Holland et al, 1992;Katodritou et al, 2014). Unfortunately, our study doesn't have the potency to explore the effectiveness of intensive therapy in patients of high risk owing to the small number of events.…”

Clinical and pathologic findings in 52 consecutively autopsied cases with multiple myeloma

“…Primary extramedullary plasmacytomas are also rare, and they commonly originate in head and neck, especially in the upper aerodigestive tract [4,5]. Extraosseous spread was found in approximately two-thirds of the myeloma patients at autopsy [2,6].…”