Identifying and Characterizing the Index Lesion

Prostate cancer’s heterogeneity, often multifocal, has traditionally discouraged the use of tissue-sparing treatments. Advances in screening now identify early-stage cases, enabling a potential increased use of focal therapy (FT). This chapter explores multifocality implications and the pivotal role of the index lesion. It investigates how new imaging techniques have changed the selections of patients eligible for FT and how the dual nature debate—monoclonal vs. polyclonal prostatic cancer—has influenced the development of FT for localized prostate cancer.