That seems expensive but I assume also takes into account his age and any other medical conditions, the expense can't all be down to the prostate cancer. The GHI card will cover emergency treatment but nothing else - you would have to pay up front for any drugs, ambulance fees, inpatient costs, etc. The risk in going without travel insurance is that you have no cover for flight cancellations, travel problems, having to cancel beforehand due to ill health, and so on. Have you asked for a quote to exclude the prostate cancer?