Figure 1

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 D_i. At time, S_i, 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 U_i, the recurrent cancer will become “unresectable”: no longer amenable to curative treatment. U_i may be greater-than (Scenario 1) or less-than (Scenario 2) S_i. 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 S_i < U_i (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 D_i, S_i, and U_i are assigned to each patient who will recur based on the disease progression submodel as described in the text.