A social scientist, Dr Lunt is leading a multidisciplinary team studying the cost of medical tourism for Britain's National Health Service.
An independent health study grant had made the 18-month study possible, Dr Lunt told those assembled to hear his talk.
Estimates of those travellers combining tourism with a medical procedure were "hazy", and ranged widely from 60,000 up to five million patients a year, Dr Lunt said.
Higher estimates were likely to be from enthusiastic trade publications promoting medical tourism as a business.
The term medical tourism was itself fraught, with some preferring "medical outsourcing", "biotech pilgrims" or "medical refugees", depending on the patient's reasons.
Cost was only one factor; medical tourists were also drawn to countries with lax legislation in riskier areas of medicine. Spain, for instance, specialised in fertility treatments unavailable or illegal in other countries.
Dr Lunt said his team was avoiding studying "sensational" procedures like organ transplants, which tended to get much media attention. Instead, it was focused on the more mundane dental, orthopaedic, fertility and cosmetic treatments.
While medical tourism potentially relieved the NHS's health burden, there were potential costs if surgery went wrong, or if people returned home with infections.
Immigrants often combined visits to their homeland with surgery, and this was particularly common for British-Indian citizens, Dr Lunt said.
Anecdotally, there was evidence the same occurred with New Zealand South Korean immigrants, seeking surgery during visits home, he said.
After the meeting, he told the Otago Daily Times flight times to New Zealand meant it was never likely to be a major medical tourism destination.
