The drug industry is spending $72 million a year "educating" doctors, with one company splashing $750,000 on a weekend conference.
A new database of pharmaceutical company-funded events created by Sydney University researchers shows 42 companies shelled out $286 million on 117,000 events for doctors and nurses over a four-year period. The average cost of an event was $2500.
"This suggests an epidemic of drug company influence that is extremely unhealthy and extremely worrying," said Dr Ray Moynihan, an over-diagnosis expert at Bond University.
Swiss giant Roche organised the most expensive event each year, spending an average $750,000 on the two-day event (plus welcome dinner), the "Annual Haematology & Oncology Targeted (HOTT) symposium" for about 300 doctors.
The data shows about half the money covered meals, five-star accommodation, airfares and transfers. How the rest was spent (apart from speaking fees and general event costs) is a mystery.
Dr Quinn Grundy, one of the researchers, said the sheer scale of generosity was worrying because it could lead to doctors prescribing more expensive medicines.
"In the industry, the doctor is the middleman, so in order to access and market to them, these companies are sponsoring events, with some of the money I suspect coming from their marketing budgets," she said.
The data of events between October 2011 and September 2015, shows cancer specialists, who deal with expensive drugs, were frequently targeted and participated in nearly 23,000 events.
It's understood Roche invited select cancer and haemotology specialists and advanced trainees to register for its symposium, held either at Hilton Sydney or Grand Hyatt Melbourne.
Dr Moynihan said Roche wouldn't be spending $750,000 on a single event if the investment didn't translate into increased sales.
"The danger here is that cancer drugs have very high price tags but sometimes have very small benefits and in the context of this debate and growing healthcare costs, why are our cancer specialists getting their education from drug companies?" he asked.
The data, collected by industry peak body Medicines Australia, also shows more than 90 per cent of events included food and beverages.
The researchers said the industry's decision to stop reporting on how much companies spend on food and beverages was a big concern.
"A large extent of industry-sponsored activities will likely disappear from public view," said Dr Grundy.
She said studies showed the provision of a $20 meal was associated with an increase in the prescribing of costly, promoted drugs.
"With Roche, there's a big spend on a large number of people, but I'm also shocked by the fact there are 600 events a week, where sandwiches and sushi are served, which can still influence decision-making," she said.
The data reveals Roche paid about $110 a head for the welcome dinner ahead of each HOTT symposium.
A Roche spokesman said HOTT facilitated the "exchange of knowledge" to "maximise the potential for positive patient outcomes and the quality use of medicines".
He said Roche held HOTT in 2016 and 2017, attracting 270 and 172 delegates respectively. This year it spent $461,000.
Haematology Society of Australia & New Zealand and Medical Oncology Group of Australia said they weren't involved in HOTT and declined to provide further comments.
Milton Catelin, chief executive of Medicines Australia, said the events were educational and any hospitality was "incidental" and no more than what was seen as appropriate.
"The assertion that provision of food is enough to influence the prescribing practices of a highly educated medical professional is both incorrect and unfairly disparaging," he said.