The aim of this retrospective single-center study was to determine the characteristics of immunologically different subtypes among 595 evaluable cases with previously untreated MM in northern China.
RESULTS: The major distribution of MM subtypes were
immunoglobulin (Ig)G, 47.9%;
IgA, 23.3%; and light-chain, 21.0%. Nonsecretory,
IgD, and biclonal subtypes were rarely seen, comprising only 7.7%. The male-to-female ratio was 1:7, and the median age was 59 years. In the
IgG subtype, more patients presented with elevated M
protein, fulfilling the major diagnostic criteria determined by Durie, and
infection occurred more frequently; however, the prognosis was favorable. In the
IgA subtype, in which survival was significantly poorer, the extent of
anemia was more severe, and nonhyperdiploid abnormality may be its adverse
indicator. In the light-chain subtype, the mean level of serum
IL-6 was the highest, and more patients presented with advanced renal dysfunction, bone destruction, and
thrombocytopenia. However, more light-chain patients were staged at International Staging System I, partially resulting in the favorable median survival of 51 months (almost equivalent to 50 months with the
IgG subtype). Another rare subtype with unfavorable outcome was
IgD myeloma, in which the median age was 50 years, and the serum
calcium level was significantly decreased. Intriguingly, we also noted that more patients presented
hypocalcemia than
hypercalcemia (37.7% vs. 15.7%) in the current series. Multivariate analysis revealed that independent adverse indicators included age > 50 years, Durie-Salmon stage III, and increased values of
C-reactive protein and beta2-microglobulin.
CONCLUSION: