Patients with solitary osseous plasmacytomas (SOP) differ from those with extramedullary plasmacytomas (EMP) in that they are younger and the proportion of males is smaller. The median survival of the two groups is similar: 86.4 mo for SOP, and 100.8 mo for EMP. Progression-free survival, however, is much better for EMP. Only five EMP patients have progressed following initial radiation therapy: one developed a single bony lesion, two progressed to multiple myeloma, and two developed multiple EMP. Thus, 71% of EMP patients are progression free at 10 yr, and most deaths do not result from plasma cell neoplasia. In contrast, 13 SOP patients have progressed to develop additional osteolytic lesions, so that only 16% of SOP patients are progression free at 10 yr; death resulted from progression to multiple myeloma in most of these patients. In EMP patients the occurrence of involved lymph nodes at the time of diagnosis in seven, and initial relapse in regional nodes in three, suggest that consideration should be given to including regional lymph nodes in the radiation fields used to treat these patients.

Previously untreated patients with myeloma were randomized to initial treatment with melphalan and prednisone (and to cyclophosphamide or carmustine if relapse or progression occurred)(Group A, 125 patients), melphalan, cyclophosphamide, carmustine and prednisone in alternating (Group B, 123 patients) or concurrent (Group C, 116 patients) schedules. The groups were similar with respect to known prognostic factors. Response rates and survival were also similar. We were unable to identify a subgroup of patients who responded or survived better on melphalan-cyclophosphamide-carmustine and prednisone than on melphalan and prednisone. We conclude that the combination of the four drugs is not better than melphalen and prednisone for inducing responses or prolonging the survival of patients with myeloma. Myelomas producing only gamma chains have a poorer prognosis (P greater than 0.001) than IgG, IgA, or kappa myeloma. Acute leukemia has developed in 14 patients. The actuarial risk of developing acute leukemia, has increased rapidly to 17.4 per cent at 50 months.

Although there are some differences, the SPIN Cohort is broadly comparable with other large prevalent SSc cohorts, increasing confidence that insights gained from the SPIN Cohort should be generalizable, although it should be noted that all three cohorts include primarily White participants.

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