Health officials say they are making progress but have yet to speak to 28 women at the heart of a breast-screening investigation in Otago and Southland.
The Health Ministry launched the inquiry last Thursday after a radiologist suggested that diagnoses of the women's breast cancer might have been delayed.
The ministry's chief medical officer, Don Mackie, says they first need to understand the women's current health status and what effect any delay may have had on it.
He says they are also looking at how many should have received a clear-cut early recall.
Dr Mackie says it's still early days but he believes it will come down to the system itself, rather than fault by an individual.
In the meantime, he says, mammogram-reading generally has been boosted, with routine second readings now being done outside the region rather than inside it, which he says should reassure women.