Cancer. It’s been called “The Big C,” but the more we study it, the more it resembles hundreds of little c’s, each with its own unique molecular makeup. The differentiation exists both among patients with cancers in the same site (the various sub-types of breast cancer, for example) as well as within a single patient. This latter phenomenon is referred to as “intra-patient tumor heterogeneity,” and it has profound implications for the future of cancer treatment, including the viability of so-called “targeted therapies” receiving so much attention and hope.
Many cancer tumors tend to be chaotic mixes of different cell types, some more aggressive – and therefore more dangerous – than others. Chemotherapy and the emerging category of more specific “targeted therapeutics” work by acting on a known characteristic of a particular cancer cell type, like accelerated replication rates or a specific genetic mutation. But in a complex tumor, not all cells will exhibit that specific characteristic, or at least not do so at the same time. Also, it is possible for cancer cells to adapt and become resistant to a particular therapy, in a partially analogous way in which evolution works on a macroscopic scale.
A recent opinion piece published online in the journal The Scientist points out that intra-patient heterogeneity can also involve treatment-relevant difference between the primary tumor and metastases, as well as among metastases. Written by Stanford Cancer Institute Director Beverly Mitchell, MD; David Rubenson, associate director for administration and strategic planning; and Daniel S. Kapp, MD, professor emeritus of radiation oncology at Stanford, the article discusses these matters in detail and lays out many of the significant scientific and clinical questions surrounding the potential for treating cancers with targeted therapies. This fall, the Stanford Cancer Institute will convene an international symposium to discuss these questions and a range of related issues.
Information on the symposium, titled “Intra-patient Tumor Heterogeneity: Implications for Targeted Therapy,” will soon be available on the Stanford Cancer Institute website.