Chemotherapy and survival for patients with multiple myeloma: findings from a large nationwide and population-based cohort.

OBJECTIVE: To assess the patterns of chemotherapy use for patients with multiple myeloma and to determine if chemotherapy is effective in prolonging survival outside the clinical trial settings.
METHODS: We studied a nationwide and population-based retrospective cohort of 4902 patients > or =65 years of age with stage II or III multiple myeloma from 1992 to 1999, identified from the Surveillance, Epidemiology, and End-Results-Medicare data. Multivariate logistic regression was used to estimate the odds ratio of receiving chemotherapy and Cox proportional hazard model was used to estimate the hazard ratio of mortality associated with chemotherapy.
RESULTS: Of 4902 patients with stage II or III multiple myeloma, 52.0% received chemotherapy during the course of the disease. The receipt of chemotherapy decreased significantly with age from 65.7% in the 65- to 69-year age group to 34.3% in those > or =80 years. Blacks (47.6%) were less likely to receive chemotherapy than whites (52.8%). Use of chemotherapy decreased significantly with comorbidity scores and increased over time. Risk of all-cause mortality was significantly reduced in patients who received chemotherapy compared with those who did not (adjusted hazard ratio = 0.65; 95% confidence interval = 0.61-0.69). A similar pattern as observed for myeloma-specific mortality (0.61; 0.56-0.67). Survival benefit increased with increasing cycles of chemotherapy (P < 0.001 for trend) and was significant across different age groups, gender, ethnic groups, and comorbidity scores.
CONCLUSION: Chemotherapy was significantly associated with increased survival in patients with multiple myeloma outside the clinical trial settings. This survival benefit was significant across different groups by age, gender, race, and comorbidity. A substantial number of patients with multiple myeloma did not receive chemotherapy.