Understanding Cancer Treatment Delay and Survival

Background: The diagnosis to treatment interval (DTI) is important for patient disease management and survival among patients with cancer. Guidance for conducting studies examining the association between the DTI and overall survival (OS) is needed to address potential bias, improve methodological rigor, and ensure readily comparable results. Evidence describing the association between the cervical cancer DTI and OS is scarce. Methods: This thesis sought to advance the understanding of the epidemiologic methods needed to conduct DTI-OS studies and apply these findings to two cervical cancer cohorts with differing treatment modalities, methodologic considerations, and health system contexts. Objective 1 employed a three-round modified Delphi design to establish consensus-based guidance for conducting studies investigating the association of the DTI and OS. Objective 2 applied the consensus-based recommendations to a cohort of Ontario incident cervical cancer cases receiving curative surgery. Objective 3 applied the consensus recommendations to a cohort of incident cervical cancer cases in Botswana who were treated with curative radiotherapy. Multivariable Cox proportional hazards regression was used to evaluate the independent association between the DTI and OS in both objectives. Results: Twenty-four consensus-based recommendations with accompanying elaborations were generated. Topics included variable definition and measurement, cohort creation, confounder control, important biases to manage, analytic techniques, and balanced interpretation of results. In the Ontario cohort receiving curative surgery, the hazard ratio estimates of OS were elevated for the shortest (2-6 weeks) and longest (22-26 weeks) DTIs in comparison to the 10–14-week referent and the DTI was not significantly associated with OS. A similar pattern of risk was seen in the Botswana cervical cancer cohort receiving curative radiotherapy, where those with the shortest and longest waits had the poorest survival, however, the DTI was significantly associated with OS in this cohort. Conclusions: We provide recommendations to help improve methodological rigor when studying the association between the DTI and OS. We observed similar U-shaped patterns of risk in our Ontario and Botswana cohorts where those with the shortest and longest waits had the poorest survival suggesting an important influence of the wait time paradox.

Department dc:contributor.department

Public Health Sciences

Year dc:date.issued

2026

Author dc:creator

• Jalink, Matthew

Advisors dc:contributor.supervisor

• King, Will
• Hanna, Timothy

• Cancer Epidemiology
• Treatment Delay
• Cervical Cancer
• Health Systems Research
• Global Health
• Delphi Study

Statement dc:rights

• Attribution 4.0 International

Licence dc:rights.uri

• https://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1974/36167

OAI identifier oai:identifier

oai:queensu.scholaris.ca:1974/36167