Little boy's heartbreaking message as he loses leg to incurable cancer

When Chandler Tran arrived home from holiday care at Easter this year with a pea-sized lump on his knee and a limp, his parents thought he'd probably suffered a bump in the playground.

But Chandler, eight, told them he hadn't had any accidents - which left his parents Cong, 42, and Trang, 41, worried.

After an X-ray at their local hospital the next day, he was sent to Westmead Children's Hospital.

READ MORE: Nurse thought she was having an asthma attack, the reality was worse

A week later, the family was given devastating news.

Little Chandler had osteosarcoma, also known as bone cancer.

It's a rare cancer which usually grows on the longer bones in the body, such as in the legs, and affects only a few dozen children a year.

While the family, from Fairfield East in Sydney's west, was initially hopeful the cancer could be treated, a worse update was to follow.

Chandler also had multiple tumours in his lungs, doctors told them.

Chandler's dad, Cong Tran, said they explained to the little boy about his illness and treatment.

"He's a very smart kid. We talked to him like we would have an adult," Tran told nine.com.au.

"His exact words were, 'I'm going to kick it in the nuts.'"

Chandler spent the next few months in hospital having chemotherapy and lost his hair.

Poignant note after upsetting decision

Meanwhile, Chandler's leg was becoming so painful because of the tumour that he was unable to stand up and doctors started looking at drastic options.

His parents were given the distressing news that they wanted to amputate the leg just above the knee.

It wouldn't cure him of cancer, but it would mean he wasn't in pain.

"We were really heartbroken," Tran said.

"It was gruesome to think about, but you take the emotion away."

Before the upsetting surgery, Chandler's dad helped him with an emotional request.

"He said: 'Can you take a photo of my leg on my tablet?'" Tran said.

"He drew a little love heart over his leg and wrote a little message.

"He wrote: 'Dear leg, I'll miss you so much when you're gone, love Chandler.'

"He was sad about the prospect of losing his leg, but he was like, 'If that's what I need to do to not have pain, then that's okay.'

"For us seeing him coping so well, that really helped us."

Chandler will get a prosthetic leg once he is properly healed.

READ MORE: Why this cancer survivor became a doctor

No further treatment planned

Days after getting over that operation, the family was given more terrible news.

The tumours in Chandler's lungs have grown and there's nothing more doctors can do to save his life.

He's on pain medication and also has portable oxygen tanks.

Doctors simply can't tell his parents how much time he has left.

"They said any treatment would just be palliative, to try and slow the cancer down," Tran said.

"We won't be able to save him."

Chandler is now home with his parents, who are keen to give him time with his six-year-old brother Carson.

He's spending his days enjoying his favourite hobby - playing with LEGO.

The family recently pulled off a special treat for him by getting his idol, LEGO artist Tiago Catarino, who lives in Portugal, to call him for a video chat.

His father said the special call made Chandler "very happy".

The IT infrastructure engineer, wanted to raise awareness about his son's illness.

He said whenever he said his son has cancer, people expected it to be the most common childhood cancer, leukemia.

A fundraiser for the family has raised almost $75,000.

READ MORE: Nurse urges people not to ignore symptoms after shock diagnosis

Osteosarcoma symptoms

There are more than 30 different types of primary bone cancer, according to the Cancer Council

Also called bone sarcoma, the most common types include osteosarcoma, which starts in cells that grow bone tissue, chondrosarcoma, which starts in cells that grow cartilage, and Ewing's sarcoma, which affects cells in bone or soft tissue.

Osteosarcoma symptoms include a swelling or lump on a bone, with or without pain.

Denise Caruso, the CEO of the Australia and New Zealand Sarcoma Association, said sarcomas are unbelievably rare.

READ MORE: Push to get 'nuclear warhead' prostate cancer drug funded

"A GP may see one sarcoma in their entire career," she told 9news.com.au.

She said there are only 25 to 30 osteosarcoma cases in under-15s annually in Australia.

The survival rate is around 50 per cent, she said.

Because the numbers are so small, researchers have to battle alongside more common cancers for funding.

"Because our patients don't often survive, it's hard to get momentum," she said.

She said if parents are worried about symptoms in their children, they should push to have scans done.

Do you have a story? Contact journalist Sarah Swain: sswain@nine.com.au