Update: The results published in the Journal of the National Cancer Institute article have been called into question in a letter to the Editor ^[1]. Based on results of the meta-analysis, researchers concluded that single and tandem stem cell transplantations produced comparable overall survival and event-free survival rates. The meta-analysis included a study published by the Abdelkefi research group that demonstrated a “dramatic benefit” of single transplantation over tandem. However, this study has been retracted because it contains “biologically implausible findings.” As a result, the summary results and conclusions published in the meta-analysis are no longer valid. Excluding this study from the meta-analysis showed a significantly better event-free survival for tandem transplantation.

Recent studies comparing single and tandem (double) stem cell transplantations ^[2] have suggested that both treatments produce the same overall response and survival rates. A single autologous stem cell transplantation is a process in which physicians collect a patient’s stem cells prior to chemotherapy and return these same cells to the individual following treatment. A double autologous stem cell transplantation simply means that this process is completed twice within a six month period. 

Because the stem cells come from the individual during an autologous stem cell transplant, the patient’s immune system does not recognize them as foreign. Patients therefore have a lower risk of infection and rejection of the transplant during recovery.

High-dose chemotherapy combined with autologous stem cell transplantation is frequently effective in improving response rates and increasing survival, as compared with chemotherapy alone. The stem cells replace the non-cancerous cells and tissue destroyed during chemotherapy.

Single autologous stem cell transplantation is currently the preferred treatment for transplant candidates with multiple myeloma, with complete remission rates reported to be between 25 percent and 35 percent.

The success of this treatment has led to a more intense approach using double autologous stem cell transplantation. This treatment requires patients to undergo two autologous stem cell transplantations within six months.

Despite high hopes that double autologous stem cell transplantation would improve therapeutic outcomes, recent studies have reported that it does not produce a higher overall response rate or survival rate when compared to single autologous stem cell transplantation. Although response rates slightly improved with the tandem treatment, there was also a statistically significant increase in transplant-associated deaths.

For more information, see the full article in the Journal of the National Cancer Institute ^[3].