An achy back was the only sign of my deadly kidney cancer that's rising in young people

When Rob Houliston first felt a twinge of pain in his back, he quickly dismissed it as one of the many injuries sustained during his 33 years playing rugby. 

Even when the pain continued - and worsened - over the next few months, the West Sussex-based father-of-four pushed it to the back of his mind.  

'I just thought "of course I have backache, I play rugby",' says Rob, who works as a security-systems installer.

But over the next three months, Rob's health became dramatically worse. He began feeling sick after eating and quickly lost three and a half stone, forcing him to retire from rugby. 

Then, in a freak incident, he was hit between the legs by a dog, sending him to hospital with a swollen testicle. 

During an ultrasound of the area, doctors noticed a hard, swollen vein behind the enlarged testicle. 

Known medically as a varicocele, newly hard veins or swellings behind the testicles can be linked to kidney issues, as the vein that drains blood from the left testicle empties directly into the left kidney vein. 

When a kidney tumour or blood clot blocks or presses on the renal vein, it can back up blood flow and cause a sudden varicocele to form in the scrotum. 

Pictured with his son, Rob Houliston says the first sign of his deadly kidney cancer was a back ache

Concerned, doctors sent Rob for further tests, which devastatingly revealed a large tumour on his kidney. 

Rob was diagnosed with renal cell carcinoma - the most common form of kidney cancer - and told he had an average life expectancy of just four years.

'Four years is not long, but I'm not going to give up,' he says. 

'It is what it is. There's nothing I can do but crack on, be positive, and fight it.

'There's no point moping around and worrying about it; you just have to live life as best you can and take whatever comes to you.'

Kidney cancer now ranks as the UK's sixth most common cancer, with almost 14,000 Britons diagnosed every year, and 4,700 deaths, amounting to about 13 deaths per day.

Recent studies show a sharp, unexpected rise in early-onset cases among adults under 50s in particular.

A study published in the British Journal of Cancer Reports, which examined four decades of data, found a 157 per cent increase in kidney cancer incidence in men under 50. 

Women under 50 had a 133 per cent increase in cases, meanwhile. 

Experts have linked the phenomenon to the rising prevalence of obesity, high blood pressure and smoking - all known risk factors for renal cell carcinoma. 

But doctors are still baffled by the increase in cases of the disease in fit, otherwise healthy young men like Rob. 

One of the biggest challenges with kidney cancer is that early-stage disease (stages one and two) is almost entirely symptom-free.

As a result, there are often no warning signs to indicate cancer is present unless investigations are carried out for an unrelated reason.

'When I was hit by the dog, I went down like a sack of potatoes; we all laughed,' says Rob.

'My left testicle went massive, honestly like a tennis ball. I was struggling to sit down, but I just thought 'it'll get better'.'

After his diagnosis, doctors found Rob's tumour had been pressing on his stomach, which explained his nausea and lack of appetite.

Rob and his family, including children - Isabel 14, Lucie 12, Ivy eight, and Jakob, three, have raised £17,500 on a GoFundMe for a once-in-a-lifetime trip to Disneyland

He had his kidney and the tumour removed in July but has been told that the cancer cannot be treated by chemotherapy or radiotherapy.

Instead, Rob is set to start immunotherapy - a treatment that uses the body's own immune system to find and fight cancer cells - on September 29, at Brighton hospital.

'There have been cases where people in their 80s have survived ten years with this - I'm strong and quite young, so there's no reason I can't do better than that,' he says.

'I think there are cases where immunotherapy has shrunk tumours like this, and they've disappeared. There are always new treatments coming up as well.'

Rob and his family, including children - Isabel 14, Lucie 12, Ivy eight, and Jakob, three, have raised £17,500 on a GoFundMe for a once-in-a-lifetime trip to Disneyland.

Rob says: 'I'm just blown away by people's incredible kindness and generosity.

'We couldn't believe it, we reached the £8,000 target in six hours and raised £17,000 in 24.'

His goals now are to get back to work in October and back on the Rugby pitch in two years when he's allowed to do contact sports again.

He says: 'Don't give up, set yourself goals and take little steps.

'I'd love to hear from anyone else with this illness who is doing really well, and to hear about new possible treatments to try.'