According to a recent Italian study, the results of PET/CT scans conducted at diagnosis, after induction therapy, and after stem cell transplantation may predict survival in multiple myeloma patients.

Specifically, the study authors found that patients with PET/CT scans negative for cancer cells, bone lesions, or other signs of active cancer had longer progression-free and overall survival times than patients with positive PET/CT scans.

“[Our study shows] a clear identification of the prognostic relevance of PET/CT [along with] other more known prognostic factors such as chromosomal abnormalities,” said Dr. Elena Zamagni of the Bologna University School of Medicine in Italy and lead author of the study.

“These factors are predictive for a more aggressive disease which could require more intensive treatments,” she added.

Based on their findings, Dr. Zamagni and her colleagues suggested that disease management could be improved by the incorporation of PET/CT scans into myeloma treatment plans. Moreover, they added that if their results were confirmed in larger clinical trials, the use of PET/CT scans after both induction therapy and stem cell transplantation could contribute to the development of individualized therapies for myeloma patients.

A positron emission tomography (PET) scan is a type of imaging test that detects the level of cell activity throughout the body. Patients undergoing a PET scan typically receive an injection of a radioactive sugar molecule called FDG, which accumulates in cancer cells more than in healthy cells. The PET scan then reveals the activity and locations of cancer cells in different parts of the body based on detected radioactivity levels.

PET scans provide more detailed results when combined with a computerized tomography (CT) scan, an X-ray imaging technique that gives clear images of the human anatomy. A PET scan plus a CT scan is called a PET/CT scan.

In their study, researchers inItalysought to determine whether the results of PET/CT scans could predict survival outcomes of multiple myeloma patients.

The study included 192 newly diagnosed myeloma patients with a median age of 56 years.

All patients received thalidomide ^[1] (Thalomid) plus dexamethasone ^[2] (Decadron) as induction therapy, followed by high-dose melphalan ^[3] (Alkeran) and autologous stem cell transplantation. Of the 192 patients included in the study, 40 percent received one transplant and 60 percent received two back-to-back stem cell transplants. All patients then received 160 mg/month of dexamethasone as maintenance therapy until their disease progressed.

All patients received a PET/CT scan at diagnosis and another after stem cell transplantation. Forty-four percent of patients received an additional PET/CT scan within 10 days of completing induction therapy.

The majority of patients (88 percent) were also screened for chromosomal abnormalities. Forty-three percent of these patients had del(13q), 23 percent had t(4;14), and 15 percent had del(17p) abnormalities, which are all associated with a poor prognosis.

At diagnosis, 24 percent of patients had a negative and 76 percent had a positive PET/CT scan, which the researchers defined by the presence of bone lesions, a high level of myeloma activity (measured by a standard uptake value, or SUV level, above 2.5), or the presence of extramedullary disease (the presence of myeloma cells outside the bone marrow).

After induction therapy, 37 percent of patients had a negative PET/CT scan, and that number increased to 65 percent after stem cell transplantation.

At a median follow-up time of 42 months, 80 percent of patients achieved at least a very good partial response as best response after transplantation, with 52 percent of patients showing a complete response. The median progression-free survival time was 56 months, and the four-year overall survival rate was 88 percent.

The researchers found that patients with negative PET/CT scans at diagnosis had significantly better survival outcomes than patients with positive PET/CT scans.

Specifically, patients who had fewer than three lesions had a higher progression-free survival rate after four years than patients who had more than three lesions (69 percent versus 50 percent). Patients who had lower myeloma activity also had higher progression-free (66 percent versus 42 percent) and overall survival (92 percent versus 76 percent) rates after four years than patients with high myeloma activity. Similarly, progression-free survival (63 percent versus 22 percent) and overall survival (92 percent versus 76 percent) rates were higher after four years for patients without extramedullary disease than those with the disease.

After induction therapy, patients whose PET/CT scans showed low myeloma activity also had higher progression-free survival (69 percent versus 44 percent) and overall survival (88 percent versus 75 percent) rates after four years than patients who had higher myeloma activity after induction therapy.

Moreover, patients who had negative PET/CT scans three months after receiving autologous stem cell transplantation had higher progression-free survival (47 percent versus 32 percent) and overall survival (79 percent versus 66 percent) rates than patients who had negative PET/CT scans three months after the transplant.

The chromosomal abnormalities t(4;14), and del(17p) were also associated with shorter progression-free survival in myeloma patients.

Dr. Zamagni acknowledged, however, that while the results of this study may not have immediate practice-changing implications, they could lead to better individualized therapies in the future.

“It is not yet time to tailor treatment based on the PET/CT data, as there is not by now a real tailored treatment based on chromosomal abnormalities. But in the future, [we may expect] prospective protocols based on these prognostic factors,” Dr. Zamagni told The Myeloma Beacon.

For more information, please see the article in the journal Blood ^[4] (abstract).