Sir Colin Meads' family says it remains unclear what stage his pancreatic cancer is at and he needs to undergo more tests.
The legendary lock, who turned 80 in June, was diagnosed with the disease on Tuesday after six months of ill-health.
Last month Sir Colin was admitted to Waikato Hospital over concerns with a kidney illness.
Sir Colin said the diagnosis has been "tough" on his family.
"It's bloody hard for Verna, the kids and grandkids."
Sir Colin's son, Glynn, says his father needs to go back for further tests at Waikato Hospital.
The Herald was earlier told by a family member that Sir Colin's cancer was terminal, however Glynn has since confirmed his father's cancer is not terminal.
Glynn said Sir Colin had a tough time in Waikato Hospital and had to be put on a diet as his kidney wasn't functioning properly - not flushing and instead was making him retain water.
The news about his father was a big shock and the family expected a tough road ahead. However, they were now hoping to get on and deal with the news privately.
"We're taking some time to sort of deal with it, really. We just want to be left alone to deal with it."
Sir Colin's sister-in-law Beryl Meads told the Herald she expected him to put up a big fight, she said.
Given he was so well-known, he was also popular in the hospital ward but he had been too tired to handle all the visitors.
"He was in the hospital and had his name on the door and other patients were coming in to meet him.
"He was very tired and I'm saying 'he's not there for a holiday' and they finally took his name off the door. Then they put 'Mr M'. Well, nobody was fooled by that."
She has been fielding calls from wellwishers, including his former teammates, from all around the world, she says.
She said whatever happened, the outcome was not good.
"Logic says somethings thing you can't change, but with this, there's no getting away from what's happening now."
Sir Colin today paid tribute to the medical staff in his hometown and at Waikato Hospital for their exemplary care.
"The care and help I've had from the doctors and nurses at Te Kuiti Medical Centre and hospital have been wonderful, and we as a family, appreciate it.
"We are very lucky indeed to have such a great facility in our town.
"I was in Waikato Hospital too for a few weeks and everyone up there was the same - they couldn't do enough for me."
Sir Colin said he's been inundated with get-well messages from New Zealand and overseas and thanked everyone for their concern.
"Thanks to all the people from all over the world for the cards and well wishes, but especially to our great friends locally - their support has been immense.
"But for now, it's about me fighting this, and we want to get on with what we are facing privately, as a family."
Prime Minister John Key today called for the nation to support Meads in his battle with pancreatic cancer.
He hailed Sir Colin as the "most iconic New Zealander I can think of".
"He is a great man and I think the nation loves him dearly.
"The big challenge now is us as a nation giving him both the space he and his family needs but also encouragement and support as he battles cancer.
"This is a guy that's proved he's made of very strong stuff when on the rugby pitch and I think he'll prove that as he does his best to battle pancreatic cancer."
All Blacks coach Steve Hansen offered his best wishes to Colin and his family.
"It's sad, isn't it. He is a legend of our game and a man who has performed heroically for not only the All Blacks but also his province.
"Time is catching up and unfortunately he's got cancer, so we wish him and his family all the best in dealing with that in this tough time."
New Zealand Rugby chief executive Steve Tew also offered Meads the support of everyone involved in rugby.
"Sir Colin remains a true legend of the game and it is with great sadness we hear of the seriousness of his condition. Our thoughts, like so many others in New Zealand and around the rugby world are with him, his wife Verna and his family as he works through the next steps in his treatment.
"We knew Sir Colin had been ill for some time, however, the latest update on his condition is concerning to us all but we remain hopeful that Sir Colin's strength and determination will help him through."
Former All Black captain Ian Kirkpatrick today said Sir Colin would likely draw on the same fighting spirit that saw him carve out a stellar career on the field.
"He would be in the same frame of mind. He'll fight this one as best he can."
He said his thoughts were with his wife Lady Verna, and his family.
"You don't like seeing your mates get something like this. It's very concerning and I really feel for his family in this difficult time. It won't be easy for them. "
Friend and rugby manager Phil Kingsley Jones, who had organised speaking tours to the United Kingdom with Sir Colin in recent years, was upset to hear about the latest health battle.
"I'm so sad. As I grew up he was one of my heroes and he's still my biggest hero," he said, as the shock of the dreadful news sank in.
He described his friend as a superstar who could still draw a large crowd even halfway across the world.
"Everywhere we went he was well received. He would be walking down the street in Crickhowell in South Wales and people couldn't believe they were seeing Sir Colin Meads. We would go into a local pub for a drink and word would quickly get out that Sir Colin was there and it wouldn't take long before it was chock-a-block."
He said Sir Colin was always the last to leave venues shaking hands and talking with people who couldn't get enough of the rugby great.
"He really loved people and had time for everyone."
His thoughts went to Lady Verna at this difficult time who supported her husband going on overseas in recent years even when her own health was failing.
Former All Black Josh Kronfeld said he was devastated by the news about a man who did not shy away from being one of the most recognised players of the 20th century.
Kronfeld said "tree" had a special gift of being able to interact with everybody.
"It's the way he is with people. He's so affable. It doesn't matter who that person is, or where they come from or what their backgrounds are, whether it's rugby, sport or cultural or social, he is able to talk to them and offer them a comment or question or insight and I think people like that are really special. They have that ability to bring a smile to everyone around them because they just connect."
He said Sir Colin was an inspiration on and off the field and the time and effort he put into all aspects of his life made him the great "tree".
In his hometown of Te Kuiti, Waitomo Mayor Brian Hanna said Sir Colin wasn't the type to back away from even this kind of challenge.
Hanna said it would be wrong to underestimate the legendary All Black great's strength and he was sure to face the battle head-on with the full support of the community.
Among those wishing every comfort was IHC New Zealand who described Sir Colin as an important voice for people with intellectual disabilities in rural communities.
"While Colin is best known for rugby to us he is one of a small number of distinguished IHC New Zealand Life Members recognised for their significant support for people with intellectual disabilities," said IHC chief executive Ralph Jones.
"Colin and Verna have always worked as a team in their dedication to IHC's cause and accordingly have made a huge difference to the lives of so many people with intellectual disabilities and their families."
The couple's support included purchasing and donating land for the use of people with intellectual disabilities and supporting the Calf and Rural Fundraising Scheme.
• A disease in which malignant cancer cells form in the tissues of the pancreas
• Smoking and health history can affect the risk of developing pancreatic cancer
• Possible signs include jaundice, pain, and weight loss
Why is it difficult to detect and diagnose early?
• There aren't any noticeable signs or symptoms in the early stages
• The signs of pancreatic cancer are like the signs of many other illnesses
• The pancreas is hidden behind other organs such as the stomach, small intestine, liver, gallbladder, spleen, and bile ducts
What affects the chances of recovery?
• The size of the tumour
• Whether the cancer has spread outside the pancreas to nearby tissues, lymph nodes or other places in the body
• The patient's general health
• Whether the cancer has just been diagnosed or has come back
What are the treatment options?
• Pancreatic cancer can be controlled only if it is found before it has spread, when it can be removed by surgery
• If the cancer has spread, palliative treatment can improve the patient's quality of life by controlling the symptoms
What is the pancreas?
• It is a gland about 15cm long that is shaped like a thin pear lying on its side
• It lies behind the stomach and in front of the spine
• It produces juices that help break down food, and hormones, such as insulin and glucagon, that help control blood sugar level
• The digestive juices are produced by exocrine pancreas cells, where about 95 per cent of pancreatic cancers begin
What are the possible risk factors?
• Long-standing diabetes
• Chronic pancreatitis
• Certain hereditary conditions
(Sources: familydoctor.co.nz and hpbsurgery.co.nz)