A recent study demonstrates that better treatments are still needed for multiple myeloma patients who develop extramedullary disease.  Specifically, the results show that these patients have poorer progression-free survival and overall survival compared to patients without extramedullary disease.

The results also show that extramedullary disease is more common in patients with high-risk multiple myeloma.

Extramedullary disease occurs when multiple myeloma cells develop in the soft tissues and organs outside of the bone marrow. It can occur in newly diagnosed myeloma, but it is more commonly found when myeloma relapses (see related Beacon news).

It is still unclear how common extramedullary disease is. Previous studies have shown that the rate of extramedullary disease can range from 7 percent to 15 percent in newly diagnosed myeloma and from 6 percent to 20 percent during disease progression or relapse.

Extramedullary disease is typically treated with the same therapies used to treat myeloma in the bone marrow. Results of recent clinical trials have shown that novel agents such as Velcade (bortezomib), Revlimid (lenalidomide), and pomalidomide may improve outcomes in patients with extramedullary disease (see related Beacon news).

In the current study, researchers from the University of Arkansas for Medical Sciences (UAMS) sought to determine the impact extramedullary disease has on the survival of myeloma patients.

They retrospectively analyzed data from 1,965 multiple myeloma patients who had extramedullary disease and were treated at UAMS between the years 2000 and 2010.

About half (48 percent) of the patients were treated with the center’s Total Therapy regimens, 12 percent were treated in clinical trials with non-Total Therapy regimens, and the remaining 40 percent were treated but not as part of a clinical trial.

‘Total Therapy’ is a term coined by UAMS to refer to a family of intensive myeloma treatment regimens regularly used at the center.  The regimens combine multi-drug therapy with multiple stem cell transplants.

The study investigators found that when patients were diagnosed with multiple myeloma, 2.4 percent to 4.5 percent of them had extramedullary disease, which was most commonly found in the skin and soft tissue, lymph nodes, chest wall, and liver.

Five years after stem cell transplantation, 3.4 percent to 7.2 percent of patients, depending on their treatment protocol, had developed extramedullary disease.  At relapse, the liver was the most common location of extramedullary disease.

Patients with high-risk genetic abnormalities were more likely to have extramedullary disease at all stages of myeloma.

At diagnosis, the rate of extramedullary disease was 7 percent in high-risk patients compared to 4 percent in standard-risk patients. Five years post-transplant, these measures were 11 percent and 2 percent, respectively.

Low hemoglobin levels and low platelet counts prior to stem cell transplantation were also associated with a higher risk of extramedullary disease.

Regardless of how patients were treated for their myeloma, the presence of extramedullary disease was associated with shorter progression-free survival and overall survival.

After five years, the progression-free survival rate was 21 percent for patients diagnosed with extramedullary disease at the same time they were diagnosed with myeloma compared to 50 percent for patients without extramedullary disease.

Similarly, the five-year overall survival rate was 31 percent for patients diagnosed with extramedullary disease and myeloma at the same time compared to 59 percent for patients without extramedullary disease.

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