PURPOSE: The objective is to explore changes over time in the information and participation preferences of newly diagnosed stage IIIb/IV non-small-cell lung cancer patients. METHODS: Patients were recruited by physicians in 13 hospitals and interviewed every 2 months until the fourth and every 4 months until the sixth interview. RESULTS: Sixty-seven patients were interviewed three times. Over a period of 4 months from diagnosis, half of patients changed their information preferences for palliative care and end-of-life decisions with a possible or certain life-shortening effect (ELDs, e.g., non-treatment decisions) in both directions, from not wanting to wanting the information, but also--and as much--from wanting to no longer wanting it. The latter were more likely to be in a better physical condition. Preferences for participation in medical decision making also changed: 50% to 78%, depending on the type of decision (general, treatment, transfer or ELD), changed their preference towards wanting more or less participation. Pain seemed to be a trigger for patients wanting more involvement, which contrasts with studies suggesting that patients who are more ill tend to give up more control. CONCLUSIONS: Doctors should regularly ask their advanced lung cancer patients how much information and participation they want because preferences do change in unexpected ways