Is having palliative treatment the same as terminal illness for travel insurance.

My husband has oesophageal cancer with liver metastases and has had palliative chemo and now on maintenance targeted therapy. the last scan showed improvement to the liver lesions and a small shrinkage of the tumour.  He doesn't want to know his prognosis. So when applying for travel insurance do I say he is terminally ill or not - and when they ask if prognosis is more or less than 6 months we don't know so what do I answer? Has anyone got any advice on this please?