Discussions are under way about how the two hospitals – which form the University Hospitals of Northamptonshire group – could work together in the future.
A survey drawn up says that centres of excellence will be created, adding that one service being considered is breast surgery.
An email to staff, seen by the Northants Telegraph, mentioned a ‘senate suggestion of services moving to NGH’.
One KGH worker, who did not want to be named, said: "It’s another attack on women and on those with less income.”
The hospital group breast survey asks people whether they would have difficulty travelling to their neighbouring hospital.
It asks whether people would rather have appointments such as their pre-operative assessment at their local hospital or the hospital where their surgery will be performed.
When contacted for comment the Rothwell Road hospital could not rule out aspects moving to Northampton in the future.
Medical director Rabia Imtiaz said: “We are committed to providing the very best services for our patients wherever they may live in the county and we are exploring ways of doing this.
“We are looking at how best to improve breast services in the future and it is important for us to have a free exchange of ideas during our early discussions on these matters but we hope this will not lead to speculation that could cause undue concern in our local community.
“At such an early stage of discussions, we have not decided where breast services will be based in the future and we would engage with staff and patients in more detail, if and when proposals are developed.”
The KGH worker who raised concerns with this newspaper said moving services elsewhere made no sense.
They said that KGH’s breast clinic is well-renowned for its friendly and supportive service, adding that changes would have a huge impact on those in north Northamptonshire.
They said: "To ask people to travel even further afield, to an unfamiliar hospital at increased cost at a time when affording anything is getting harder...is a recipe for disaster and will again hit women harder.”