Multiple myeloma is a plasma cell neoplasm that can cause painful bone lesions. The main treatment for these lesions and pain control is radiotherapy, usually in daily fractions. In 2017, a phase III study proved the effectiveness of using a single dose of 8 Gy, but without description of several important oncological outcomes. This is a single-arm prospective cohort study. This study aims to describe these outcomes, including retreatment rate and bone events. Also, as secondary objectives, describe the quality of life and use of analgesic medications in this population.

Inclusion Criteria:

• Biopsy of plasma cell neoplasm with bone lesion treatable with radiotherapy;
• Age between 18 and 85 years old;
• Performance on the ECOG scale less than or equal to 2.
• Not using systemic therapies for 4 weeks OR being on maintenance therapy with the same drug for at least 4 weeks before radiotherapy.

Exclusion Criteria:

• Refusing to sign or inability to understand the consent term;
• Pain less than 2/10 on the numeric pain rating scale;
• Change in systemic treatment scheme, including use of bone metabolism modulation drugs, up to 4 weeks before radiotherapy treatment;
• Technical incapacity for the treatment, including, but not limited to, weight greater than 115Kg, inability to abduct the limb to be treated in appendicular bones, intolerable pain to remain in the treatment position;
• Previous cancer and previous oncological treatments;
• Previous autoimmune diseases, even if controlled;
• Current pregnancy.