Local (blue) and distant (green) premalignant fields give rise to second field tumors and second primary tumors (both red), respectively. In scenario A, there is only one premalignant field (the local field) present at time of cancer initiation (middle panel), and the recurrence occurs inside the local field. In scenario B, two unrelated precancerous fields are present at time of initiation (middle panel), and the recurrence may occur as a second primary tumor in the distant field.