Long term follow-up needed for breast cancer patients
May 11, 2011
The effect of adjuvant treatments for breast cancer may vary over time, and this must be considered in the length of follow-up and the choice of statistical models used in analysis of breast cancer clinical trials. According to an article published in the Journal of Clinical Oncology, there is evidence from numerous studies that adjuvant therapy exerts time-dependent effects. However, the underlying assumption of most study designs is that the effect of an experimental treatment in comparison with that of a standard treatment is proportional (constant) over time. In other words, "if an experimental treatment reduces the risk of recurrence by 25% at 3 years, then it is assumed to have the same proportional benefit throughout all other time points" writes lead author Dr. Ismail Jatoi of the University of Texas Health Science Center.
Jatoi and colleagues point out that the biologic mechanisms responsible for early and late breast cancer events differ, and therefore it is logical that the effect of the same treatment may not be constant throughout the course of the disease. According to the authors, "Elucidation of the time-dependent effects of adjuvant therapy will become increasingly important in the years ahead as the number of long-term breast cancer survivors continues to increase."