A preliminary study has shown that a technique called multiparameter flow cytometry (MFC) can effectively detect cancerous cells that remain in the body after myeloma treatment. The technique could be valuable for predicting the risk of myeloma progression or relapse.

The MFC method can accurately and quickly count the number of cancerous cells in a sample of blood or bone marrow. The sample is first treated with fluorescent antibodies that attach to cancerous cells, which a laser then detects and counts. MFC can identify one cancerous cell among 10,000 normal cells.

The continued presence of cancerous cells in patients during or after treatment is called minimal residual disease (MRD). Assessing for MRD is considered standard care for many blood cancers, but it is still being explored in multiple myeloma ^[1]. The study used statistics to show that MRD status is the most important predictor of prognosis for myeloma patients.

Traditionally, the polymerase chain reaction (PCR) method is used to evaluate MRD in myeloma patients. PCR is used to multiply small amounts of DNA, so that even traces of cancerous DNA can be detected. Though the method is highly sensitive, its applications are limited and the procedure is time-consuming.

The study of MFC suggests that it could be used to better predict outcomes in myeloma patients. In fact, MFC is more likely than PCR to successfully identify residual cancer cells. MFC labels the physical changes in these cells, which can be detected in 90 percent of myeloma patients. PCR labels DNA changes, which can be detected in only 75 percent of myeloma patients.

The study was conducted in 295 patients who were treated with chemotherapy and stem cell transplantation. MFC analyses were performed 100 days after the transplantation. Results indicate that survival without tumor progression and overall survival were longer in patients who showed no evidence of cancerous cells. Patients with evidence of remaining cancerous cells demonstrated shorter survival.

With further development, MFC holds promise as a useful technique for identifying patients at varying risks of progression.

For more information, please see the full article in the November 15 issue of Blood ^[2].