Time from (clinical or certainty) diagnosis to treatment onset in cancer patients: the choice of diagnostic date strongly influences differences in therapeutic delay by tumor site and stage.

Objectives: To analyze whether differences between the interval from suspicion or clinical diagnosis to treatment onset (IClinDT) and the interval from certainty diagnosis to treatment onset (ICertDT) varied by tumor site, stage, and mode of hospital admission. Study Design and Setting: From our hospital cancer registry, we selected all 8,814 patients with breast, colorectal, lung, prostate, or cervical cancer diagnosed between 1992 and 2006. We compared IClinDT and ICertDT with density plots and logistic regression. Results: IClinDT was up to three times higher than ICertDT. There were very large differences among stages and within each stage in IClinDT and ICertDT. Tumor stage significantly influenced the difference between the two intervals in three of the five locations (breast, lung, and prostate cancer); as stage worsened, the difference between IClinDT and ICertDT became smaller. In all tumor sites, the difference was larger in scheduled than in emergency admissions. Overall, therapeutic delays--even when measured by ICertDT--were disturbingly common for important subgroups of patients. Conclusion: The difference between IClinDT and ICertDT varied highly by tumor site, stage, and mode of hospital admission. More standardized definitions and procedures to calculate time intervals between cancer diagnosis and treatment onset are needed. [ABSTRACT FROM AUTHOR]