Effect of Lag Time Bias on Subsequent Survival in Stage IV Self-Referred Cancer Patients

Abstract

Gott's Copernican principle states that the longer something has been in existence, the longer it should continue to exist, as long as it is being measured at a random moment. Can this be applied to stage 4 self-referred cancer patients to estimate subsequent survival? The records of 293 consecutive stage IV cancer patients were retrospectively analyzed who consulted at a single cancer center during the year 2003. The large majority was self-referred. The majority had already received treatment at other cancer centers. For each patient, the Lag time was calculated, from date of diagnosis until the date of consultation, and Remaining Survival was calculated, from the date of consultation until the date of death or last contact. Patients had a lag time of 0–299 months until consultation, with a median of 13 months. They had a subsequent Remaining Survival of median 12 months. Grouping by Lag time of <12, 12–24, and >24 months, patients had remaining survival times of 11, 7.5, and 16.5 months (p = 0.015). For the group as a whole, median Remaining Survival was similar to median Lag time. Stage IV cancer patients who were diagnosed more than 24 months before consultation lived longer than those who had a shorter lag period.