Of patients presenting with multiple myeloma, 5% to 15% satisfy criteria for the diagnosis of multiple myeloma but have no or minimal symptoms and do not require chemotherapy (NRC). These patients are classified as having smoldering, asymptomatic stage 1, or indolent multiple myeloma in order of their increasing risk of progression. We avoid chemotherapy, especially with alkylating agents in such patients, and we either closely monitor them or use a nonchemotherapeutic intervention. If significant bone lesions, renal failure, or hypercalcemia occur, chemotherapy or transplant is recommended. Patients with mild anemia or with small or isolated bone lesions who are asymptomatic or minimally symptomatic because of anemia may be monitored and are classified as having indolent multiple myeloma.
Unnecessary treatment with melphalan or cyclophosphamide probably has no benefit in multiple myeloma NRC and can cause significant risk. In long-term follow up, 25% of patients receiving alkylating agents develop myelodysplastic syndrome or acute leukemia. Patients who do not receive chemotherapy must be monitored closely to avoid complications of overt multiple myeloma, including anemia, bone lesions, renal failure, and hypercalcemia. We and others have begun to take a more active approach with the use of nonchemotherapeutic agents in selected patients. We use bisphosphonates in patients with bone lesions or osteoporosis or when there is a progressive rise in M-protein. We use dexamethasone alone in NRC multiple myeloma to reduce tumor burden in selected patients who do not yet have overt multiple myeloma or who are not candidates for chemotherapy. We use bisphosphonates to prevent osteoporosis in such patients. We use erythropoietin to correct anemia, and dexamethasone and erythropoietin together in patients with higher tumor burden (eg, indolent multiple myeloma).
Future progress in treating multiple myeloma NRC depends on better identification of new therapeutic targets that control progression from the stable asymptomatic to the progressive symptomatic phase of multiple myeloma. We need to better understand the biologic target of new agents like thalidomide to design more effective treatment for this early phase of multiple myeloma. Although these approaches may delay chemotherapy, it is not known whether survival is prolonged. Nonchemotherapeutic approaches must be systematically studied in clinical trials in order to be put to better use.