(A) The orientation of the extracellular matrix (ECM) and fibroblasts in the vicinity of a tumor (pale blue) has an influence on the development of the tumor. A capsule-like orientation will limit the escape of cancer cells from the tumor (1), whereas a perpendicular orientation will encourage escape and the invasion of nearby tissue (2). The orientation of the ECM and the fibroblasts can be quantified by image processing. (B) Experiments in which cancer cells are implanted into an animal have to be stopped when the primary tumor reaches a certain size to prevent unnecessary suffering (1). This can limit the data that can be collected on other aspects of cancer, such as metastasis. An alternative approach is to monitor each animal individually and to resection a tumor when it reaches a certain size (2): this allows for longer studies, including the collection of Kaplan-Meier survival curves similar to those collected during clinical trials.