Marian Fields had an aggressive and very rare form of skin cancer, which left her with large, open wounds around her backbone following multiple operations and radiation treatments.
She was beginning to lose all hope of recovery after plastic surgeons in the US refused to take on her case because of the size of the wound.
But her identical twin sister Mary Jane provided the solution.
"There was never a moment of hesitation when the option to donate skin and tissue was a possibility," Mary Jane said.
"I had what she needed. We are two bodies with one soul. She is my other self."
Dr Jesse Selber, a plastic surgeon from the MD Anderson Cancer Centre at the University of Texas, who had previously performed the first skull-scalp transplant, said the surgery was "incredibly challenging and complex".
His team of five plastic surgeons removed skin, tissue and blood vessels from Mary Jane's abdomen and transplanted it to Marian's back, connecting eight different arteries and veins under a microscope during surgery.
The hole in Marian's back was 21.5in by 8.5in (55cm x 22 cm), making it one of the largest tissue transplantations on record.
By donating skin to her sister, Mary Jane - in effect - got a giant tummy tuck.
Having an identical twin made the transplantation process more likely to succeed for Marian because no suppression of her immune system was required - but there were still huge risks.
Surgeons said they were concerned about the donated skin being rejected and the possibility of the cancer recurring.
Although the tumour in Marian's back was very aggressive, it was not a type that spreads to other parts of the body so receiving her sister's skin and tissue was a perfect fix.
Dr Selber said: "Marian's wound was impossibly large - without her genetically identical sister, we would not have had enough tissue to reconstruct it."
The surgery took 14 hours and involved "extensive resection through skin, muscle and bone", followed by "hours of meticulous microvascular work".
This involved re-connecting countless veins and arteries.
The surgery was meticulously planned beforehand - and it paid off, according to Dr Selber.
"It went quite beautifully," he said.
Before the transplant surgery, Marian was in horrible pain. She couldn't lie on her back or sit up in a chair properly.
One month on from the surgery, the twins have been discharged, the stitches have been removed and they have returned home.
Marian says: "I'm looking forward to getting back to work, driving, running and sitting comfortably.
"I've never been sick before 2012 and am ready to get back to life."

The bomber detonated explosives at a checkpoint near Camp Chapman, formerly used by the CIA, in eastern Khost province on Sunday.
Camp Chapman was the site of one of the worst attacks on the agency in 2009 when a bomber killed seven officials.
No US or coalition soldiers were killed in this latest attack.
The base now houses both Afghan and foreign troops, including US soldiers.
Youqib Khan, the deputy police chief in Khost province, told the Associated Press news agency that Sunday's blast hit a checkpoint manned by members of an Afghan unit that guards Camp Chapman.
Officials said those killed were civilians in cars waiting to clear the checkpoint at the time of the blast.
No group has said it carried out the blast as yet, although the Taliban has often targeted troops and launched a fresh offensive in late April.
Khost borders Pakistan and is one of Afghanistan's most volatile provinces.

The government has put aside 10bn roubles ($272m; Â£164m) to pay owners of cars that are at least six-years old an incentive to buy a new vehicle.
Car owners will be eligible for a discount of at least 40,000 roubles.
The government expects the scheme, which will run to the end of the year, to subsidise the sale of more than 170,000 vehicles.
The scheme could "seriously stimulate sales," said Prime Minister Dmitry Medvedev, according to local news agencies.
Car sales fell by almost a quarter in July compared with a year earlier, following a sharp fall in the previous month.
Russia, along with many other countries including the US, the UK, Germany and France, first introduced a car scrappage scheme during the global economic downturn.
The 66-year-old Fields twins, from Missouri, have lived together all their lives - now they are even closer after sharing their skin.
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A suicide car bomb has killed at least 17 people, mostly women and children, near a military base in Afghanistan, officials say.
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Russia has said it will introduce a new scrappage scheme to try to boost flagging car sales.