Modeling disease progression in recurrent colorectal cancer. Among the subset of individuals who will experience recurrence, cancerous tissue is considered to be present but undetectable until time Di. At time, Si, the patient will develop clinical symptoms of recurrence which will bring them to seek medical attention and will lead to diagnosis of recurrence if not previously detected. At time Ui, the recurrent cancer will become “unresectable”: no longer amenable to curative treatment. Ui may be greater-than (Scenario 1) or less-than (Scenario 2) Si. In a scenario of no follow-up for detection of asymptomatic recurrence, the only patients for whom curative treatment of recurrence would be possible are those with Si < Ui (Scenario 1) since symptoms would have brought them to seek medical attention at a point where curative re-treatment could occur. Continuous, heterogeneous values of Di, Si, and Ui are assigned to each patient who will recur based on the disease progression submodel as described in the text.