Introduction: A substantial corpus of literature has sought to describe the information-seeking behaviour of patients with cancer. Yet, available evidence comes mainly from cross-sectional studies, which provide 'snapshots' of patients' information needs and information-seeking styles at a single time point. Only a few longitudinal studies currently exist; however, these are quantitative in nature and, despite successfully documenting changes in patients' information needs throughout the clinical course of cancer, they have failed to provide an evidence-based interpretation of the causes and consequences of change. The goal of this study is threefold: First, we wish to provide a holistic understanding of how cancer information-seeking behaviour may evolve across different stages of the patient journey. Second, we will seek to elucidate the contextual and intervening conditions that may affect possible changes in information seeking. Third, we will attempt to identify what the consequences of these changes are, while heightening their implications for clinical practice and policy. Methods and analysis: We will carry out a longitudinal qualitative study, based on face-to-face, in-depth interviews with approximately 25 individuals diagnosed with cancer. Patients will be recruited from 2 oncology hospitals located in Ticino, Switzerland, and will be interviewed at 3 different time points: (1) within 2 weeks after receiving the cancer diagnosis; (2) within 2 weeks after their initial treatment; and (3) 6 months after their initial treatment. All interviews will be recorded and transcribed verbatim. A grounded theory approach will be used for the analysis of the data. Ethics and dissemination: The study protocol has been approved by the Ethics Committee of Canton Ticino (CE 2813). Participation in the study will be voluntary, and confidentiality and anonymity ensured. Prior to study participation, patients will be asked to provide signed informed consent. Findings will be disseminated in international peer-reviewed journals and presented in relevant conferences.