Identical twin sisters face ultimate heartbreak after one is diagnosed with terminal cancer

But now identical twins Kath and Emily Blunt face being torn apart by a rare bone cancer which has left Emily with only months to live.

Doctors who have been treating her have told her the disease has spread so much that it has become incurable.

Inseparable: Identical twin sisters Kath (left) and Emily Blunt, pictured here on Facebook. Emily has a rare form of bone cancer.

Yet the 20-year-old is refusing to let her condition dent her spirit.

Yesterday the keen football and hockey player told how she is seeking solace in the fact that her twin will live on.

For her part, Kath spoke of her fears at being left alone for the first time without her 'other half'.

Devastating: Doctors have given Emily (left) just months to live

Emily was in her first year at Exeter University last spring, where she was studying sociology, when she developed a pain and swelling in her right shoulder and upper arm.

At first doctors thought she had trapped a nerve playing hockey, but the pain became 'unbearable'.

By the time she was diagnosed she could not even brush her own hair.

She was sent for an X-ray which revealed she had an eight-and-a-half-inch tumour in her right arm. She was diagnosed with osteosarcoma, a form of primary bone cancer, last August.

Further investigations revealed the cancer had spread to her lungs and ribcage.

After ten months of chemotherapy at the Queen Elizabeth Hospital in Birmingham, doctors recently broke the news the illness is terminal.

Doctors have told Emily, who is taking painkillers and steroids, they do not believe she will be well enough to go on a planned family holiday in September.

Emily, of Longlevens, Gloucester, said of her relationship with her sister: 'We have strong personalities but we are very close.

'We have the same taste and a few times when we have gone shopping separately we have come back with exactly the same items.

'We also have sympathy pains  -  when I had a biopsy on my arm it was swollen and when Kath came to see me she had a red rash and swelling in the same area on her arm. My family give me the inspiration to stay strong because we are all so close.

'It is a great comfort to me to know Kath will carry on because she is part of me.'

Brave: Emily says she is comforted by the thought she will live on through her sister

Kath, a sports studies student at the University of Hertfordshire in Hatfield, said she cannot imagine life without the 'shadow' which she has grown up with.

'I just feel so guilty,' she said. 'We have always fought each other's battles  -  but this is one fight I cannot win for her.

'It leaves me thinking, "Why did it happen to her and not me instead?"

'We did everything together, university was the first time we were separated. I was always the cheeky one whereas Emily was the one who took her studies seriously.

'I can't imagine not arguing with, talking to or being with Emily. Part of me will be cut in two.'

She added: 'Emily has been so brave. She will not allow anyone to be sad around her.

'It's hard, but I'm throwing everything into fundraising to try to stop this happening to another family.'

The girls' family - parents Joceline, 48, and Ian, 49, an aircraft technical supervisor, and non-identical twin brothers Philip and Daniel, 23 - now want to raise awareness of osteosarcoma.

They will hold a fun run to raise money for bone cancer research on June 29 in Gloucester.

Mrs Blunt, a former theatre nurse who gave up work to care for her daughter a year ago, said: 'Kids are not being diagnosed  -  the doctors need to know more about it.

'We don't want other people to go through what we have been through.'

According to Cancer Research UK, there are only around 500 cases of primary bone cancer  -  where the cancer starts in the bone  -  each year.

Of these, osteosarcoma is the most common, accounting for around 150 cases.

Its cause is unknown, but localised osteosarcomas have a five-year survival rate of about 55 per cent, with many cured.

But where the cancer has spread, fewer than 10 per cent of patients live beyond five years.