A public awareness campaign about opening access to NHS patient data will be rethought but individual letters might still not be sent to all patients, an NHS England director said today.
Tim Kelsey said the data-sharing would definitely go ahead and was vital to ensure diseases including cancer could be tackled.
But he told the BBC Radio 4 Today programme the extended marketing effort would not necessarily include individual notifications posted to people.
NHS England postponed the launch of the data-sharing programme yesterday, citing a need to build understanding of the benefits of using the information.
Mr Kelsey, director for patients and information, said: " We will be turning to our colleagues in the marketing industry and the professional bodies and really thinking through how best we can target messages.
"I don't know (if we will write to people individually). We need to look at it and, actually, the advice we received from colleagues in other sectors is, oddly ... that doesn't necessarily work."
Mr Kelsey insisted the "important" scheme must go ahead as part of creating a 21st century health service.
He warned: "At the moment we have some of the worst cancer survival rates in Europe, the only way we can improve those is if we understand how to treat people better. This is fundamental to the future of the health service."
Mr Kelsey said understanding people's concerns about the scheme was vital, and moved to ease concerns by insisting laws already in place stopped private firms from using the data in any way that did not benefit patients.
"Fundamentally, this is about public confidence ... the actual facts are it is unlawful to sell this data for insurance purposes. That message has just got lost," Mr Kelsey told the programme.
"There are many private companies who work in the NHS who would go through the appropriate accreditation process and could have access to the data.
"It is unlawful (to use the data for insurance), it is a criminal offence."