Construction work on the radiotherapy centre at Altnagelvin hospital is due to be completed in the coming months with the facility to be handed over in the summer.
The commencement of cancer services is expected sometime this autumn.
Management of the centre will not give an exact date for opening and say the weather is the biggest factor which will decide when the centre will open.
When it is operating it will cater for patients from as far south as Fermanagh to the north Antrim coast and from west Donegal to Tyrone in a catchment of over half a million people.
A total staff of 215 whole time equivalents will cover disciplines that include, oncology, medical physics, pharmacy, ward nurses, medical imaging, allied health professionals and administration.