The number of bone lesions detected by whole-body magnetic resonance imaging after stem cell transplantation may predict overall survival of multiple myeloma patients, according to the results of a recent German study.

In particular, patients without bone marrow lesions after stem cell transplantation had significantly better two-year overall survival rates (100 percent) than patients with more than 20 bone marrow lesions (57 percent).

“In our study, we found a negative prognostic effect of residual lesions after therapy,” said Dr. Jens Hillengass from the University of Heidelberg in Germany and lead author of the study.

According to the German researchers, assessing the number of bone lesions remaining after stem cell transplantation using magnetic resonance imaging (MRI) may prove useful in deciding if the patient is likely to benefit from further treatment.

“In our experience, [MRI] adds information to the standard criteria because lab results can be negative while MRI still shows tumor activity. In the future, it might be possible to steer treatment according to a combination of lab results and imaging findings,” Dr. Hillengass told The Beacon.

“[We] are very interested in the biological implications of the focal lesions,” added Dr. Hillengass. “Future comparisons of conventional MRI, functional MRI, and Positron Emission Tomography – Computerized Tomography (PET-CT) will show which technique is most suitable to answer these questions.”

MRI is a non-invasive, painless technique that uses powerful magnets and radio waves to generate images of the body’s internal organs. Currently, MRI is considered a very sensitive method to detect bone marrow lesions and bone marrow changes in patients with multiple myeloma.

According to Dr. Hillengass, MRI has certain advantages over other imaging techniques.

“It is important to notice that the previous use of imaging was limited to the detection of bone impairment (X-ray, CT) which is a secondary and also rather late event in myeloma, while the novel imaging techniques are actually able to display the bone marrow which is the place where the malignant cells themselves are located,” explained Dr. Hillengass.

Previous studies have shown that bone marrow lesions detected by MRI can predict progression from smoldering to active myeloma (see related Beacon news).

In this retrospective study, German researchers investigated if bone marrow lesions detected by whole-body MRI before and after stem cell transplantation could be associated with changes in monoclonal (M) protein levels and bone marrow infiltration after stem cell transplantation.

M protein levels and the presence of myeloma cells in the bone marrow, also called bone marrow infiltration, are the two main blood-based parameters physicians use to the assess a patient’s response to treatment.

The researchers also examined whether the presence of bone marrow lesions remaining after treatment can predict survival.

They retrospectively analyzed data from 100 myeloma patients who had received a stem cell transplant between 2004 and 2010 at their institution. Median age of participants was 58 years at the time of the first MRI (at the onset of the therapy, prior to transplantation). All patients underwent one or two rounds of high-dose chemotherapy with melphalan (Alkeran) followed by stem cell transplantation and then a second MRI.  The second MRI was typically done three to six months after stem cell transplantation.

The researchers found that after stem cell transplantation, 23 percent of patients had no bone marrow lesions, 52 percent had 10 or fewer lesions, 14 percent had between 11 and 20 lesions, and 11 percent had more than 20 lesions.

They also found that the number of bone marrow lesions seen in the MRI after stem cell transplantation was associated with overall survival.

All patients without bone marrow lesions at the time of their second MRI were alive two years after the MRI, compared to 91 percent of patients with 10 or fewer lesions, 64 percent of patients with between 11 and 20 lesions, and 57 percent of patients who had more than 20 lesions.

The difference in these survival rates was found to be statistically significant.

In contrast, the researchers did not find a statistically significant relationship between the number of bone marrow lesions detected during a patient's first MRI -- carried out at the start of their treatment for myeloma -- and overall survival.

The two-year survival rate was 89 percent for patients with no lesions at their first MRI,  93 percent for patients with 10 or fewer lesions, 81 percent for patients with 11 to 20 lesions, and 75 percent for patients with more than 20 lesions.

According to the researchers, the study results only showed a weak association between results derived from blood-based parameters and the number of bone marrow lesions detected during MRIs.

The researchers concluded that a combination of monitoring M-protein levels and bone marrow infiltration, along with whole-body MRIs, may provide a better assessment of treatment response.

For more information, please see the study in Haematologica (pdf).