P-146: A prospective study of conventional skeletal survey versus Whole-body CT for osteolytic lesions in Multiple Myeloma

Abstract

Background Multiple Myeloma (MM) is a bone marrow cancer with high prevalence of osteolytic disease. Evaluating bone involvement is essential as it is an important criterion for starting treatment. For many years conventional skeletal survey (CSS) has been used but based on retrospective data. The International Myeloma Working Group now recommends using Whole Body CT (WBCT). This study compares CSS to WBCT at baseline and prospectively for up to 4 years for finding progression of bone involvement. Methods 96 MM patients from the cooperating hospitals were followed for up to 4 years. Patients were scanned every year for the first 2 years and every 6 months thereafter or if suspicion of bone disease was raised. Progressive bone disease was defined as new lesions of at least 5 mm or growth of lesions by at least 5 mm. For evaluation paired t-test for numeric analysis of lesions and McNemars exact test for comparison of proportions of paired observations were used. Results 534 investigations (267 pairs) were evaluated. WBCT consistently found more bone lesions per patient 8.2 (CI 6.8;9.6) vs CSS 3.6 (CI 2.7;4.5). The additional lesions found by WBCT were primarily in the axial skeleton while there was no difference in the skull. In the extremities a few more lesions were found on CSS 0.40 (CI 0.2-0.5) vs WBCT 1.80 (CI 1.1;2.4). In total 23.6% (CI 20.6;26.6) of patients had a negative CSS and a positive WBCT (P<0.0001). Over the period a total of 19 cases of progressive bone disease (PBD) was found with 20 new lesions and 3 growing lesions found on WBCT vs 8 cases with 8 new lesions on CSS (P<0.001). The cases not found on CSS were primarily in the spine, sternum, and pelvic region. There were no cases of PBD on CSS not found on WBCT. Of the 19 cases of progressive bone disease, 5 cases were “bone only” progressors with no biochemical signs of progression. Conclusions WBCT consistently outperformed CSS for finding osteolytic lesions. This supports the current recommendation for using WBCT for skeletal evaluations. Significantly more new lesions were found during follow-up by WBCT compared to CSS suggesting that using only CSS is likely to underestimate progression rates. Multiple Myeloma (MM) is a bone marrow cancer with high prevalence of osteolytic disease. Evaluating bone involvement is essential as it is an important criterion for starting treatment. For many years conventional skeletal survey (CSS) has been used but based on retrospective data. The International Myeloma Working Group now recommends using Whole Body CT (WBCT). This study compares CSS to WBCT at baseline and prospectively for up to 4 years for finding progression of bone involvement. 96 MM patients from the cooperating hospitals were followed for up to 4 years. Patients were scanned every year for the first 2 years and every 6 months thereafter or if suspicion of bone disease was raised. Progressive bone disease was defined as new lesions of at least 5 mm or growth of lesions by at least 5 mm. For evaluation paired t-test for numeric analysis of lesions and McNemars exact test for comparison of proportions of paired observations were used. 534 investigations (267 pairs) were evaluated. WBCT consistently found more bone lesions per patient 8.2 (CI 6.8;9.6) vs CSS 3.6 (CI 2.7;4.5). The additional lesions found by WBCT were primarily in the axial skeleton while there was no difference in the skull. In the extremities a few more lesions were found on CSS 0.40 (CI 0.2-0.5) vs WBCT 1.80 (CI 1.1;2.4). In total 23.6% (CI 20.6;26.6) of patients had a negative CSS and a positive WBCT (P<0.0001). Over the period a total of 19 cases of progressive bone disease (PBD) was found with 20 new lesions and 3 growing lesions found on WBCT vs 8 cases with 8 new lesions on CSS (P<0.001). The cases not found on CSS were primarily in the spine, sternum, and pelvic region. There were no cases of PBD on CSS not found on WBCT. Of the 19 cases of progressive bone disease, 5 cases were “bone only” progressors with no biochemical signs of progression. WBCT consistently outperformed CSS for finding osteolytic lesions. This supports the current recommendation for using WBCT for skeletal evaluations. Significantly more new lesions were found during follow-up by WBCT compared to CSS suggesting that using only CSS is likely to underestimate progression rates.