Effect of an Interdisciplinary Shared Decision-Making Intervention on Decisional Conflict in Advanced Cancer Patients Receiving Third-Line Therapy

Decisional Conflict in Patients With Advanced Cancer in a Shared Decision-Making Model: A Randomized Clinical Trial

The study aims to evaluate whether an interdisciplinary intervention based on a shared decision-making model can reduce decisional conflict in patients with metastatic solid tumors (lung, breast, colorectal, prostate, or ovarian cancer) who are indicated for third-line systemic treatment. Participants are randomized to receive either standard oncology consultation or an additional interdisciplinary consultation involving oncology, palliative care, and psychology. The intervention emphasizes providing information and support for treatment decisions.

• Problem Statement: In Colombia, advanced cancer is common and treatment options become increasingly complex by the third line of therapy, often lacking standardized guidelines. This complexity, along with uncertainty about prognosis and treatment benefits, can lead to significant decisional conflict for patients.
• Objective: To determine whether a structured interdisciplinary intervention using shared decision-making reduces decisional conflict compared to standard care.
• Population: Adults (≥18 years) with metastatic lung, breast, colon, ovary, or prostate cancer at Hospital San Ignacio, eligible for third-line systemic therapy.
• Intervention: The intervention group receives an additional consultation involving a medical oncologist, palliative care physician, and psychologist. The session follows six steps: inviting the patient to participate, describing options, detailing benefits and risks, clarifying patient goals, facilitating decision deliberation, and outlining next steps-all based on the shared decision-making model.
• Control Group: Receives standard oncology consultation only.
• Randomization: Assignment is done randomly and independently.
• Outcomes:
• Primary: Decisional conflict measured by the Decisional Conflict Scale.
• Secondary: Patient satisfaction, decision regret, perceptions of shared decision-making, symptom burden, and levels of neuroticism, all assessed with validated instruments.
• Sample Size: 62 participants (31 per group) are planned, allowing for potential losses.
• Follow-up: Patients are assessed immediately after intervention/consultation and again at three months.
• Analysis: Data will be analyzed by intention-to-treat, using quantitative scales, and adjusting for confounding factors. Subgroup analyses by demographic and clinical characteristics are planned.

Overall, the study is designed to inform best practices on supporting advanced cancer patients in complex treatment decisions, exploring the effects of an interdisciplinary, patient-centered intervention on decisional conflict and related outcomes.

Inclusion Criteria:

• Age ≥18 years
• Diagnosed with metastatic lung, breast, colon, ovary, or prostate cancer
• Have completed two prior lines of systemic therapy
• Indication for third-line systemic therapy (chemotherapy, immunotherapy, or hormone therapy)
• Under follow-up at Hospital San Ignacio
• Capacity to provide informed consent
• Exclusion Criteria: