We intended to assess the patterns of care and failure in patients with solitary plasmacytoma (SP), treated at our institute from 2011-21. Data pertaining to the management of patients with SP was abstracted by retrospective chart review. Progression free survival (PFS) and overall survival (OS) were defined as the time intervals from the date of diagnosis to the date of progression (local, systemic or both) and death or last follow up, respectively. PFS and OS were analyzed by Kaplan Meier method. Atotal of 72 patients were diagnosed with SP (61-bone plasmacytoma; 11-extramedullary plasmacytoma) in between 2011 and 2021. The median age at diagnosis was 52 years. The male: female ratio was 2.27. The ECOG PS were 0, 1, 2, 3, and 4 in 1, 46, 11, 10, and 3 patients, respectively. The median diameter of the lesion was 6.7 cm (range 2.3-18.4 cm). The median M protein was 0.375 g/dl (range 0.63-5.3 g/dl). On bone marrow examination, 8 and 64 patients had no and minimal marrow involvement, respectively (median bone marrow plasma cells 4%). Radical radiotherapy (RT) was administered in 71 patients, the techniques being 2D-conventional in 35, 3D-conformal in 14, IMRT in 8 and VMAT in 5 patients (details not available in 9). The median RT dose was 45 Gy in 25 fractions over 5 weeks (range 45-50 Gy). In addition, 5(7%) patients underwent surgery prior to RT and 6(8.5%) patients received systemic chemotherapy. After RT, the median quantum of symptom relief was 75% (range 0-100%). The best response to RT was CR, PR, SD and PD in 41(57.7%),18(25.4%),3(4.2%) and 4(5.6%) patients, respectively (response assessment could not be done in 5). Local control with primary RT was achieved in 58(81.7%) patients. No RT related grade 3/4 acute or late toxicity was reported. The median follow up was 48.3 months (range 1.3-141.6 months). A total of 28(39.4%) patients experienced disease progression (systemic in 15, local in 7 and both in 6), out of which 13 could be successfully salvaged with further systemic chemotherapy (mostly bortezomib, lenalidomide/pomalidomide and dexamethasone based) with or without local treatment. On progression to multiple myeloma, 9 patients underwent high dose chemotherapy(melphalan) followed by autologous stem cell transplant. Nine (12.7%) patients died, the causes being COVID-19 infection in 1, surgical complications in 1, PD in 2, second malignancies in 3 and unknown in 2. The actuarial rates of PFS & OS were 58.4% & 92.5% at 3 years and 50.3% & 89.4% at 5 years, respectively. Metachronous second malignancies were noted in 4 patients (B-ALL-1, lung cancer-1, metastatic carcinoma cervix-1, metastatic carcinoma gall bladder-1). In patients with SP, radical RT with a modest dose (45-50 Gy) leads to satisfactory symptom relief, response and local control. Close to 40% patients eventually progress to multiple myeloma, out of which 50% can be successfully salvaged with further systemic chemotherapy. The 5-year OS approaches 90% in this cohort.
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