In Oncology last week:
An interesting article from Larry Marks - which gets at a question often heard in the clinic: "How long have I had this?" Marks uses a variation on Collins Law (well described in the paper) to estimate how long a tumor may have existed from the development of the first clonogen to the time of detection based on local recurrence rates after a curative resection, and finds that some tumors may have existed for many years prior to detection (3-6 years for the sites studied).
Now obviously there are huge assumptions: first that growth rates are similar before and after a curative surgery, and it excludes tumors which may have been treated more aggressively, and recurred distantly. Therefore, one can really only apply this to low grade cancers that are likely to fail locally only. Nonetheless, it's an interesting thought experiment.
Link (requires free membership to login)
How Long Have I Had My Cancer, Doctor? - Cancer Network