Mathematical biologists deal with spherical cows, that is, we look for patterns in nature. That means abstracting some details so that we can concentrate our attention on the key features that are relevant to our question.
That is why, as a mathematical modeller working on prostate cancer I was always interested in breast cancer. The first is one of the most common cancers in men whereas the latter is one of the most common in women (although men can also have breast cancer). Both are cancers that initiate in the epithelial cells that form the glands that characterize prostate and breast. Both are usually quite treatable and most patients survive. When things take a wrong turn, both prostate and breast cancer usually metastasise to the bone. Surely there are substantial differences between the two cancers but there are also enough similarities that I was not too surprised with recent findings showing that genes that are usually mutated in breast cancer are found to be mutated in prostate cancer too (a fifth of prostate cancer patients have mutations in BRCA1 and 2). The study has been labeled the Rosetta stone of prostate cancer. One of the take-home messages is that 90% of metastatic tumours are dominated by cells with mutations for which we have treatment. This is a rather optimistic point of view though, as we know that these metastases are heterogeneous and that thus, emergence is likely to emerge.