Findings from a German retrospective study indicate that whole-body magnetic resonance imaging can help identify patients with monoclonal gammopathy of undetermined significance who are at increased risk of progressing to symptomatic multiple myeloma.
The whole-body magnetic resonance imaging (MRI) results show that almost one-fourth of the MGUS patients in the study had clearly defined (focal) lesions in their bone marrow. These lesions, or areas of abnormal cells, were solely within the patients’ bone marrows. They were not lesions in the outer (hard) area of the bone — lesions which are often called “lytic lesions.”
The researchers found that the presence and number of focal lesions in the bone marrow were associated with an increased risk of disease progression, as was the level of a patient’s monoclonal protein (M-spike).
The investigators believe that whole-body MRI may be more effective than spinal MRI for detecting bone marrow lesions in patients with MGUS because 19 percent of patients in the study had marrow lesions outside the spinal area. In comparison, only 12 percent of patients had lesions that would have been detected by spinal MRI. (Seven percent of the patients had lesions both outside and within the spinal area.)
Despite their findings, the researchers do not currently recommend that whole-body MRI be carried out as standard practice in MGUS patients, not least because of the procedure’s cost. They also state that there is no evidence yet that MGUS patients with lesions should be treated.
Given that their study was retrospective in nature, the investigators recommend further prognostic studies over longer periods of time. The also state that additional study is needed to determine whether all lesions in the bone marrow eventually lead to bone destruction.
Background
MGUS is a plasma cell disorder characterized by an elevated level of monoclonal (M) protein in the blood. Unlike myeloma patients, however, MGUS patients do not experience any disease-related symptoms, such as elevated calcium levels, kidney damage, anemia, or bone lesions. Typically, MGUS patients do not receive treatment unless their disease worsens.
According to the investigators, multiple myeloma patients typically undergo computed tomography (CT) scans or skeletal surveys for the assessment of their disease. These techniques, however, focus on finding lesions in a patient’s outer (hard) bone, rather than the bone marrow.
Recent research, however, has shown that MRI can be an effective method of identifying lesions in the bone marrow, and the presence of these lesions has important implications in plasma cell disorders.
The number of bone marrow lesions detected by MRI has been linked, for example, to the risk of progression in patients with smoldering myeloma (see related Beacon news), and to overall survival in myeloma patients who have undergone stem cell transplantation (see related Beacon news)
Spinal MRI is commonly recommended for detecting bone marrow lesions in patients with asymptomatic blood disorders, such as MGUS and smoldering myeloma.
However, according to the study authors, spinal MRI misses bone marrow lesions that occur away from the spine and pelvis, which can amount to 50 percent of lesions in myeloma patients.
Thus, the investigators sought to determine the prognostic value of whole-body MRI in patients with MGUS.
Study Design
Researchers from the University Hospital of Heidelberg, the German Cancer Research Center in Heidelberg, and the U.S. National Cancer Institute analyzed the MRI findings of 137 MGUS patients who underwent whole-body MRI at the two German institutions between June 2006 and March 2010.
The median age of the patients was 58 years.
The median follow-up time was five years.
Study Results
Overall, 23 percent of the patients had distinct, or focal, lesions in the bone marrow and 38 percent had scattered, or diffuse, lesions in the marrow.
Most patients only had focal lesions outside the spinal area (19 percent of patients). An additional 7 percent of patients had lesions both in and outside the spinal area, and 5 percent had lesions just in the spinal area.
Based on the findings, the researchers believe whole-body MRI appears to be better than spinal MRI in detecting bone marrow lesions.
The investigators found that 8 percent of the patients experienced disease progression to the point that they required treatment; 3 percent developed bone disease, 3 percent anemia, 1 percent lymphoma, and less than 1 percent each developed severe peripheral neuropathy (pain, tingling, or loss of sensation in the extremities), a rapid increase in M-protein, or a plasma cell tumor.
Specifically, 13 percent of the 32 patients with focal lesions, and 12 percent of the 52 patients with diffuse lesions, progressed to the point of requiring treatment.
Factors that were significantly associated with disease progression included the presence of focal lesions, the number of focal lesions, and a patient’s M-protein level.
Patients who had more than one focal lesion in their bone marrow, or an M-spike greater than 1.5 g/dL, were particularly likely to experience disease progression.
None of the patients with light chain MGUS progressed. In light chain MGUS, the abnormal cells mainly produce the light chain portion of antibodies, rather than full antibodies that include both light and heavy chains.
In total, 4 percent of the study participants died due to causes unrelated to myeloma.
For more information, please refer to the study in the journal Leukemia (abstract).
