Formal discussant Ola Landgren, MD, PhD, Chief of the Multiple Myeloma Section at NCI, had some additional comments about the 2011 ASCO presentations on second primary malignancies in lenalidomide-treated patients.¹ He said that the reporting of second primaries has several limitations that patients and doctors need to be aware of. For example, these randomized studies were designed to evaluate responses and survival rates between the study arms. Thus, the sample sizes are too small to allow a careful characterization of the risk—and underlying mechanisms—of second primary malignancies. An alternative strategy to increase the sample size could be to pool several clinical studies and then do a retrospective collection of second primary malignancies. However, analysis-based retrospective data will inherently underestimate their true incidence.

On a general note, when interpreting data on second primary malignancies, and when comparing results from different studies, one has to be cautious. For example, differences in study design, including follow-up time, sample size, controls, and quality of data, will always influence the results. Also, variations in survival differences between study arms play a role.

Most likely, several factors play a role in the development of second primary malignancies, including host-related, treatment-related, myeloma-related, and behavioral factors. An important future research focus should be to determine the relative roles of each of these factors to elucidate the mechanisms involved, as well as to characterize the molecular features of patients who develop second malignancies following myeloma. ■

Disclosure: Dr. Landgren reported no potential conflicts of interest.

Reference

1. Landgren O: Secondary malignancies following multiple myeloma. 2011 ASCO Annual Meeting. Presented June 8, 2011.