## Problem 241 — rank:11

**Title:** Cancer avoidance in high-risk and extremely aged populations

**Added binding assumptions (LaTeX):**

```latex
Define the time origin and condition the likelihood on delayed entry into the elderly cohort, with the appropriate prior cancer-free and survival history. Within one fixed cohort cumulative incidence is nondecreasing in age; comparisons across selected survivor groups are different contrasts. Reduced diagnosis probability can reflect competing death or missed lesions. A protective interpretation needs a well-defined target population and exposure intervention, not selection on extreme age itself.
```

**Direct edits:** 0. **Fresh external checks:** None; supplied sources retained as provenance.