Interpatient variability in response to anticancer drugs is associated with different clinical outcomes, which is partially owing to the individual differences among patients. Many investigators have hoped that tumor heterogeneity would help to reveal the underlying mechanism of interpatient variability in response to anticancer therapy. Numerous studies have demonstrated the presence of intratumor heterogeneity and the heterogeneity in primary tumors and corresponding metastases in a wide range of tumors at different levels and have indicated that the heterogeneity might make sense as a potential determinant of anticancer therapy response. This article discusses tumor heterogeneity, focusing on the heterogeneity in primary tumors and corresponding metastases as well as the effect on anticancer therapy response. Furthermore, an idea of tumor-site-based personalized cancer therapy for patients with metastatic malignancies was hypothesized, and a strategy using a patient-derived tumor tissue xenograft model to realize this idea is also proposed in this article.
Keywords: cancer; genetic heterogeneity; personalized therapy; tumor heterogeneity.