Polymedication in palliative oncology care is a real public health problem. This phenomenon has been shown to increase the risk of iatrogenesis, reduce patients' quality of life and increase healthcare costs. For many years, health policies have been developed in geriatrics to reduce polymedication through deprescription tools.

Recently, palliative care initiatives have been introduced, but without having studied the potential specificities of this population (younger, with a different care dynamic and life trajectory). It is important to better understand this population's perceptions of deprescribing in order to adapt tools/actions to make these approaches more efficient.

The primary aim of this study is to investigate patients' perceptions of deprescribing in palliative cancer care, and the secondary aim is to investigate factors that may influence patients' attitudes and beliefs about deprescribing. At the same time, we will study the psychometric properties of the rPATD (Revised Patients' Attitudes Towards Deprescribing) in this population (a standardized questionnaire validated in geriatric medicine to assess patients' perceptions of deprescription).An ancillary study will be carried out to investigate the link between patients' health literacy and their perception of deprescribing (health literacy is defined as the ability to acquire, understand and use information in ways that promote and maintain good health).

To meet our objectives, we will conduct a 3-year national, prospective, observational, multicenter study with an exploratory sequential mixed design. The study will comprise an initial qualitative phase. Semi-directed individual interviews using a descriptive approach will be carried out (around 25 patients, over an 8-month period). Following analysis of the qualitative data, we will then carry out a quantitative study to determine the distribution of the different profiles within this population and the factors influencing the perception of deprescription. The self-administered questionnaires, rPATD and BMQ (medication beliefs questionnaire), potentially supplemented by other items following analysis of the qualitative data, will be administered to 300 patients (over a 12-month period).The ancillary study will be carried out during this second phase, using a validated self-questionnaire to assess patients' level of literacy.

Thanks to the different results, we will improve our knowledge of the perception of deprescription in palliative oncology care, in order to develop approaches adapted to the specificities of our population to reduce polymedication and thus improve the quality of life of our patients and reduce the risks of iatrogenia.

Inclusion Criteria:

• Patient over 18 years of age
• Locally advanced or metastatic solid cancer (i.e., palliative care as defined by the World Health Organization)
• Life expectancy estimated by the physician at inclusion of less than 1 year (use of surprise question to help clinician estimate life expectancy)
• Hospitalized or in consultation
• With at least one PIMs (identified using STOPPfrail 2)
• Patient not having expressed opposition to participating in the study after receiving information from the physician.

For qualitative study patients :

- Patients who have signed an authorization for the recording of their voice during the semi-structured interview for the purpose of written transcription.

Exclusion Criteria:

• Minor
• Major under guardianship, protected person
• Patient unable to speak or write French
• Patient with impaired judgment, cognitive or sensory impairment that prevents him/her from receiving informed information, answering questionnaires or participating in a study interview.

We'll be looking at major patients with "solid" cancer in a palliative situation (locally advanced or metastatic cancer, thus requiring palliative care as defined by the World Health Organization), who have at least one PIMs, followed up on an inpatient or outpatient basis, with a life expectancy estimated at less than 1 year by the doctor caring for the patient.

To identify whether a patient has at least one PIMs, we will use the STOPPFrail 2 tool . This is a tool developed in geriatrics, validated for a population with an estimated life expectancy of less than 1 year, and which is not specific to oncology. Life expectancy of less than one year will be estimated by the question surprised by the doctor caring for the patient ("Would you be surprised if your patient died within a year?") .

We will carry out a multicenter study in oncology and/or palliative care departments of hospitals located in western France.