Negative PET Scans after Initial Myeloma Treatment Shows Advantages for Outcomes

In a recent study published in Blood Advances, Mayo Clinic Rochester myeloma researchers found that patients who had a negative PET/CT scan 6 months after their initial therapy for their newly diagnosed myeloma had longer time to next treatment and better overall survival. 

Normally, blood markers like the monoclonal protein or bone marrow biopsies are used to monitor response to therapy, but the addition of a PET/CT scan can add significant value to the post-treatment evaluation, according to the study authors. 

The study included 195 patients with newly diagnosed multiple myeloma seen at the Mayo Clinic between 2004 and 2020. All patients had a PET/CT scan at baseline and then another at 6 months after diagnosis. 

A negative PET/CT result was defined as the disappearance of every area of increased FDG update found at baseline or a decrease in activity to less than the surrounding normal tissue. Patients who had remaining myeloma and new areas of "hot spot" activity or they were considered "positive" if the lesions had not disappeared completely. 

The researchers were looking to determine time to next treatment (TTNT) and overall survival (OS). Their findings included:

• Median follow up was 80.6 months
• Median time to next treatment was 24.6 months
• Median overall survival was 79 months
• The most common therapy used was the triple combination of lenalidomide, bortezomib and dexamethasone (28.7%)
• At the 6-month mark only 25.6% of patients had a negative PET/CT scan
• At the 6-month mark 74.6% of patients had detectable disease and 15.3% of patients had signs of progression

Because myeloma can be different in each patient, the treatment of myeloma requires a multi-dimensional approach for disease assesment at diagnosis and follow up.  The authors conclude: 

“Our study highlights the role of PET/CT in the evaluation of patients with multiple myeloma in the posttreatment setting. We showed that PET/CT can consistently improve the definition of biochemical responses, as defined by the IMWG, especially for patients with skeletal involvement at diagnosis.”