Background:
World Health Organization (WHO) has recognized patient navigation support as an integral part of comprehensive cancer care to address multifactorial barriers faced by patients in accessing cancer care services. However, evidence remains limited on how patient voices can be systematically integrated into the navigation model.

Objective:
To explore patient-reported barriers and challenges in accessing cancer care services and to develop an evaluation framework for the community-based lay navigators using a Theory of Change (ToC) approach in Puducherry, India.

Methods:
A Theory of Change framework was developed to explain how the inputs and activities of a community lay navigator model were expected to bring about change. It outlined the immediate, short-term and intermediate outcomes across the cancer care continuum. The ToC was formulated by patient experiences and refined through feedback from existing navigation systems, including a hospital-based navigation programme (KEVAT) and a community-based tribal navigation initiative.
To operationalise the Theory of Change and enable systematic monitoring during implementation, a set of monitoring indicators was developed. These indicators were aligned with navigator roles, formative findings, and the implementation science frameworks guiding the study. Key inputs identified are trained community and hospital-based navigators, engagement with primary health centres and regional cancer centres, navigation tools and tracking system.

Results:
Patient voices revealed multi-level barriers at individual, community, and health-system levels. Patients commonly reported limited understanding of diagnostic and treatment pathways, inadequate counselling at early points of care, financial and logistical constraints, missed or delayed appointments, and fragmented referral and back-referral processes. Emotional distress, fear, and uncertainty further compounded delays in care-seeking and treatment initiation.
The Theory of Change analysis, derived from formative findings and the health system context, highlighted that patients and caregivers require early, consistent, and reliable guidance to navigate complex cancer care pathways. It demonstrated that informal navigation currently provided by caregivers, community health workers, and hospital staff can be strengthened through clearer role definition, targeted training, and improved coordination. It further indicated that integrating navigation functions within existing health system workflows is more feasible and sustainable than creating parallel systems. Enhanced coordination between community-based services and tertiary care facilities was identified as a key mechanism for improving continuity of care and patient experience without increasing workforce burden. Strengthening informational, emotional, and logistical support emerged as critical to improving patient-reported outcomes and overall care experiences during cancer treatment.

Conclusion:
Integrating patient voices within a Theory of Change framework offers a robust approach to evaluating and strengthening cancer care navigation programmes. This ICMR study demonstrates how ToC can link patient-reported experiences to measurable outcomes, supporting the development of monitoring indicators and offering evidence to strengthen community lay navigator models in resource-constrained settings.

Theory of Change findings for the community-based lay navigation model