Estimates of the lead time in screening for bladder cancer

Area of Science:

• Urology
• Oncology
• Biostatistics

Background:

• Early treatment of bladder cancer (BC) may show survival benefits.
• Lead-time bias (LT) is a potential confounding factor, representing the time between early detection and symptom onset.
• Quantifying LT is essential to accurately assess screening efficacy.

Purpose of the Study:

• To estimate the lead-time (LT) of bladder cancer (BC).
• To evaluate the impact of LT on the perceived survival benefit of early BC detection.
• To determine the uncertainty surrounding the net gain of BC screening.

Main Methods:

• Calculated LT by dividing the prevalence of pre-symptomatic BC by the incidence of symptomatic BC.
• Utilized data from published screening studies for pre-symptomatic BC prevalence.
• Employed national registry data for symptomatic BC incidence, matched by age, gender, and year.

Main Results:

• LT estimates varied based on screening method: 3.3–12.1 years for microhematuria screening and 1.8–5.3 years for urine cytology/cell marker screening.
• These LT estimates align with findings from previous retrospective and prospective cohort studies.
• The calculated LT may explain the observed survival advantage associated with early BC treatment.

Conclusions:

• The lead-time bias in bladder cancer screening is significant and method-dependent.
• Observed survival benefits from early bladder cancer detection may be largely attributable to lead-time bias.
• The actual benefit of bladder cancer screening requires confirmation through controlled randomized trials.