Second Primary Malignancies Post Autologous Stem-cell Transplant in Multiple Myeloma from India – Knowing the Unknown

To evaluate the incidence, clinical characteristics and outcomes of second primary malignancies (SPM) in Multiple myeloma patients post autologous stem-cell transplant (ASCT). This is a report of myeloma patients from a prospectively maintained database who underwent ASCT between 1st March, 2007 to 31st December, 2022. Baseline characteristics, details of induction, transplant and post-transplant maintenance therapy of these patients were retrieved. Details of treatment received for SPM, and outcomes were also obtained. In total,178 patients underwent 192 ASCTs (14 patients with two ASCTs). Of 178 patients, six patients (3.3%) developed SPM [3-solid (1.6%) and 3-haematological (1.6%)] at a median follow-up post-ASCT of 8.7 years. Median follow-up of entire cohort (<i>n</i> = 178) post-ASCT was 51 months. Median time from diagnosis and transplant to second malignancy was 9.0 years (5.4-13.5 years) and 8.2 years (4.0-12.3 years), respectively. Median duration of lenalidomide exposure from diagnosis to second malignancy in these six patients was 25.8 months (Range: 15-40 months). Amongst our six patients with SPM, three patients (50%) are alive. At a median follow-up of more than 8 years post-ASCT, the incidence of SPM was 3.3% in our cohort. This highlights the need for life-long surveillance for SPM in myeloma patients post-ASCT.