41 NCCN Guidelines for Patients ® : Multiple Myeloma, 2019 4 Treatment guide Solitary plasmacytoma Follow-up tests After you finish primary treatment, you should have follow-up tests every 3 to 6 months. People with soft tissue and head and neck plasmacytoma may be followed less often after the first follow-up visit. The follow-up tests are used to check how well treatment worked. An outcome or improvement caused by treatment is called a treatment response . See page 46 to read about the types of treatment responses. Most of the follow-up tests given after treatment are the same as those used to confirm myeloma and assess symptoms. Ongoing, frequent tests to measure M-protein levels are used to check the status of the cancer to make sure treatment is still working. (See Part 2 on page 14 for more details on each test listed in the guide.) If follow-up tests show that the plasmacytoma has come back after primary treatment, local therapy may be an option depending on the location and size of the mass. If the cancer has spread, see Guide 1 on page 16 for recommended testing to assess the severity of multiple myeloma and its symptoms. Next steps If tests show the cancer has spread, the next treatment options depend on the severity of myeloma and its symptoms. For smoldering (asymptomatic) myeloma, see Guide 4 on page 42. For active (symptomatic) myeloma, see Guide 5 on page 43.