DAVID Cook had no clue his "pulled" muscle could be a sign of a deadly cancer.
"I never expected when I first experienced back pain that this was the cause, it was the furthest thing from my mind," the dad-of-four said.
In May, after struggling with lower black pain, David, who works as a lawyer in New York, contacted a physiotherapist.
He said: "Over a period of about a month-and-a-half, I was stretching and what not but there was no relief.
"I thought it was age or a pulled muscle."
After his symptoms failed to improve the 66-year-old was referred to a spinal specialist.
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They found David had unknowingly broken his back 40 years ago, most likely during one of his adventurous skiing holidays.
"I played a lot of sports as a kid and skied a lot so it could've been from a number of spectacular ski crashes," he explained.
The medic said the break had healed on its own and that his pain was likely caused by something else.
Further tests revealed a baseball-sized tumour suspected to be growing in David's kidney for the last ten years, which turned out to be cancerous.
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"I was prepared to be told I had six months," David said.
"Me and my wife have this goal to see every continent and all the national parks, and my greatest anguish would be not being able to do that.
"We still want to do that. I was anguished at the thought of my wife being alone. She was very supportive."
The diagnosis came as a shock to David.
"I'm in good shape, I never smoke or drink. I live a very healthy lifestyle so I thought, why me? I was doing all the right things," he said.
The dad underwent an operation where the cancerous tumour was removed and his kidney was luckily saved.
David was told the pain was caused by both the tumour and a condition known as cardiac amyloidosis - a rare disease that develops when abnormally folded proteins called amyloid fibrils build up in the heart muscle, impairing its function.
David said: "The back pain helped save my life.
"I really thought it was just a pulled muscle.
"The doctor actually told me that the back pain had saved my life.
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"Without that pain, the tumour would've just kept growing and it would've been a very different conversation.
"I feel great and very grateful and lucky."
The ‘silent’ symptom of killer kidney cancer that strikes at night – and 6 other signs you must never ignore
THERE are often no obvious symptoms of kidney cancer, so it can be pretty tricky to spot.
But experts say there are some signs of the killer disease you can be on the lookout for.
The most common is blood in the urine, known as haematuria, according to Cancer Research UK (CRUK).
It won't necessarily be there all the time, but you should always see your GP if it's ever-present.
One of the more unusual indicators is "very heavy" sweating.
The bizarre symptom, which often strikes at night, can also occur alongside a high temperature or fever.
While most people who experience this won't have kidney cancer, it is important to get yourself checked out.
Other symptoms worth keeping an eye on include:
- A lump or swelling in your back, under your ribs, or in your neck
- Pain between your ribs and waist that does not go away
- Loss of appetite
- Losing weight without trying to
- Feeling tired or having no energy
The kidneys are two small organs on either side of your spine, just below your ribs.
Cancer of the kidney, also called renal cancer, happens when abnormal cells start to divide and grow in an uncontrolled way.
It is most common in people over 60, and is more frequently diagnosed in men than women.
Smoking and being overweight or obese increase your risk of developing it.
Around 13,300 kidney cancers are diagnosed in the UK each year, CRUK says.
There are about 4,700 deaths annually - or 13 every day.
It is the seventh most common cancer in the UK.
How it is treated depends on what type of kidney cancer you have, where it is and how big it is, if it has spread, and your general health.
Surgery, cryotherapy, radiofrequency ablation, targeted medicines, radiotherapy and chemotherapy are all options.