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Cancer rates in the UK have been steadily increasing over the last few decades, largely because people are living longer. Now, 1 in 2 of us born after 1960 will be diagnosed with cancer in our lifetime.

That’s the picture for all cancers combined. But look a little closer at the numbers for individual cancers and a more complicated picture emerges.

This is the case for kidney cancer.

In the UK, around 5,500 people were diagnosed with kidney cancer each year in the mid-1990s, but this has now more than doubled, hitting about 11,900 a year.

In part, this increase in cases reflects changes in the overall population over time. But worryingly, our projections of what future numbers may look like position kidney cancer rates as among the fastest growing.

There isn’t a clear answer to why this is the case, but some theories are starting to appear.

Kidney cancer usually comes in 1 of 2 forms: transitional cell carcinoma and renal cell carcinoma.

And when we look at the number of people diagnosed with each of these types over time the story becomes more interesting.

In England, cases of transitional cell carcinoma have stayed relatively stable over the last decade.

But the number of people diagnosed with renal cell carcinoma has risen. It now accounts for just over 8 in 10 kidney cancers.

There’s no clear answer why this pattern has emerged. But renal cell carcinoma is linked to smoking and obesity, offering a couple of avenues for further investigation.

So while understanding all the factors behind this surge isn’t an easy task, it may be that in some cases our lifestyle is catching up with us.

Setting the scene

It’s important to remember that not all cases of cancer are preventable.

As with most cancers, part of the rise in kidney cancer rates is down to an ageing population who are at a higher risk of developing the disease because genetic mistakes build up in cells over time, which can lead to cancer.

But some cases could be prevented.

There’s no doubt that smoking has left an indelible mark on world health. But according to our stats smoking can’t entirely explain the rising rates of kidney cancer because of other factors at play.

More and more, public health campaigns have highlighted the rising problem of obesity. And the UK Government’s childhood obesity plan, released last summer, outlined the epidemic that we are facing as a nation.

The International Agency for Research on Cancer (IARC) first reported the link between obesity and kidney cancer 15 years ago. And research since then has helped establish a stronger connection between the two.

So perhaps obesity offers a possible explanation for rising kidney cancer rates?

Almost 2 in 3 people in England are now overweight or obese, a record high.

So the rise in kidney cancer does reflect the surge we are seeing in obesity.

But to explain this link, we first need to try and understand what excess body fat might be doing to the kidneys.

Fuelling kidney cancer – what’s fat got to do with it?

Although we’re certain that obesity causes 13 types of cancer, research has yet to unravel the exact mechanisms at play.

This is what IARC’s Dr Mattias Johansson, and other researchers around the world, are determined to crack. And although his research is at an early stage he has some interesting ideas.

“Unpublished data from our group suggest that high levels of insulin in the body due to excess weight may be one of the drivers of kidney cancer,” he says.

Insulin is a hormone that helps break down carbohydrates and fats, and the kidneys help process this hormone in the body.

Excess weight can lead to cells becoming resistant to insulin, which can cause levels of the hormone to rise and cells to divide more rapidly.

Researchers think that an increase in insulin has an effect on another molecule too, called insulin-like growth factor-1 (IGF-1).

Some studies have shown that IGF-1 encourages kidney cell growth in the lab and in mice, potentially telling cells to divide, and in some cases, leading to cancer.

“Another interesting hypothesis is that sex hormones may play a role in kidney cancer, but there are still few studies on the topic,” says Johansson. Changes in sex hormones, such as oestrogen, have been linked with obesity, and studies suggest that they may influence risk of womb cancer.

In womb and breast cancer the theory is that having excess fat changes the levels of these hormones in your body. Fat cells can become the chief source of oestrogen in women after the menopause, leading to higher levels of this hormone that can tell cells to multiply faster, increasing the risk of cancer.

Although the exact mechanisms linking obesity to kidney cancer are still to be confirmed, researchers are also looking at large population studies to try and identify who could be more at risk, and by how much.

Risky Business

Similar to smoking, where damage to cells builds up over time and increases the risk of cancer, damage from carrying excess weight accumulates over a person’s lifetime. And the more excess weight people carry, the greater their risk.

It’s clear that people who have a higher BMI have a higher risk of developing kidney cancer. This has been demonstrated in numerous studies

–  Dr Mattias Johansson, IARC

One study looking at men found that in relation to kidney cancer risk, fat might start to have an impact on health from an early age. Being overweight in late adolescence was associated with an increased risk of kidney cancer later in life.

Overall, whether or not weight in childhood or as a teenager is directly linked to cancer risk isn’t yet clear.

Some studies on kidney cancer have looked at how the amount of weight gained can effect cancer risk. The more weight gained, the higher the risk.

“It’s clear that people who have a higher BMI have a higher risk of developing kidney cancer. This has been demonstrated in numerous studies,” says Johansson.

“Someone who is obese has up to twice the risk compared to those who are healthy weight, making it one of the most important risk factors of kidney cancer.”

But even this can’t fully explain the rising rates.

If you look, you will find it

Part of the reason we’re seeing more kidney cancers being diagnosed is due to developments in detecting the disease through advances in research and technology. But that could be a double-edged sword.

Finding aggressive cancers earlier, when they’re easier to treat, is good news. And Professor Tim Eisen, a kidney cancer expert at the Cancer Research UK Cambridge Centre, explains why.

Improved and more frequent use of imaging technology means that we increasingly detect tumours much earlier than we used to do

– Professor Tim Eisen, Cancer Research UK

Like a lot of cancers, kidney cancer “usually starts as a slow growing mass. It enlarges over several years and, as it grows, becomes more aggressive and more likely to spread to other parts of the body.

“Improved and more frequent use of imaging technology means that we increasingly detect tumours much earlier than we used to do.”

Doctors often remove these tumours through surgery, or if the tumour is small and the patient has other medical problems, they may suggest keeping an eye on things.

Kidney cancer can also sometimes be found during routine tests for other diseases, before cancer symptoms appear. But it’s not always clear if these cancers need treatment.

This is called overdiagnosis, and its potential role in the rising rates of kidney cancer also remains unclear.

Overdiagnosis is something we’re learning more about as more cancers are diagnosed earlier.

It means finding a cancer that wouldn’t have caused any problems during the person’s lifetime. In other words, if left untreated, it wouldn’t have led to the person’s death. This can happen with some tumours because they are slow-growing and unlikely to become a major health issue.

So while early stage diagnosis of some tumours could be life-saving, in other cases, patients might receive unnecessary treatment for their slow-growing cancer.

What’s clear is that we need more research to tell apart cancers that need treatment from the ones that don’t.

So how can we reduce our risk?

Although not all kidney cancers are preventable, many could be.

Stopping smoking and keeping a healthy weight could spare thousands a life changing diagnosis.

That’s why we’ve developed the Ten Top Tips with Weight Concern to help people lose weight and keep it off.

These include simple ways to eat and drink more healthily and be more active, like choosing sugar-free drinks, watching portion sizes, and trying to hit 10,000 steps a day.

While there are lots of ways you can make your life healthier right now, we know this can be easier said than done. This is why both the food industry and the Government have a large role to play to make the healthy choice the easy choice.

That’s why government needs to continue funding Stop Smoking Services and keep momentum behind their planned tax on sugary drinks.

It’s clear that the trend in kidney cancer cases is one to watch. The number of cases has risen steeply in the last few decades, a trend that’s set to continue if we don’t all take action.

Stephanie McClellan is a senior science press officer at Cancer Research UK

Comments

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Anna July 18, 2017

Nice information, Thanks for sharing.

Rosemary Wylie June 12, 2017

Interesting information. My brother at 70 developed kidney cancer has had surgery and started chemo. He was 18stone now 14. Been told they can halt but not cure him. Two new drugs coming. Would appreciate info for that. I have contributed to cancer research for 18 years monthly.

david palmer May 9, 2017

A well documented and informative piece of work.It brought the message home to me.
Thank you to all the researchers.

Pat Collins May 6, 2017

Informative and well written

Stuart Brown May 6, 2017

I became so scared I nearly died, of fright.

Alex May 5, 2017

or a plant based diet :)

derek May 5, 2017

having had kidney cancer and removal in 2010. i have found that if i have a C.T. scan with iodine the next few days i am feeling bad. for about 2 days. i have now realised that it is the iodine that reduces my last kidney to weak state. beware….

Fraser Sanderson May 5, 2017

This was a very interesting and helpful article. It highlighted the – surprising – increase in incidences of kidney cancer and the possible causes.

Kim Golson May 4, 2017

Why not start advising the lchf or kerogen ic diet. If we didn’t eat carbs we wouldn’t produce excess insulin and the cancer wouldn’t have sugars to feast on

Andrew May 4, 2017

May be pure coincidence, but several people commenting refer to working as joiners or woodworkers. My Dad was a joiner and also had kidney cancer.
P.S. Thanks for the great work

Lisa May 4, 2017

My father had kidney cancer and was an apprentice joiner he died in 2012 after having secondary cancers 10 years after his first diagnosis

Hayley Jane May 4, 2017

If it wasn’t for you guys at cancer Research and the fun raisers where would we be today.!!!!! Keep up the good work☺

Roy Tarbox May 4, 2017

I had transitional cell carcinoma of the renal pelvis in 2012 and had my kidney removed , then later that year it was found in my Bladder which I had tumour removed with diathermy and a cyotoxic bladder wash . then this year I have just had another tumour removed from my Urethra (turbt ) . I have never been over weight and always been fit , I have never smoked, as said above. mind I think that it was referring to Renal cell Carcinoma. I have never filled a survey in either which may help understanding for future cases . My surgeon did ask however if I had ever been in the print industry the answer was no , I was a wood Machinist for about 26 years.

Karen May 4, 2017

My mam died of renal cell carcinoma (kidney cancer in 2002) never smoked wasn’t over weight a healthy eater never drank alcohol & died at 45yrs old after only 5mths from diagnosis .. so these figures aren’t entirely factual

Lin May 4, 2017

Cancer research do a great job of looking at and helping to find ways of curing this terrible ailment.Well done to you all

Barbara May 4, 2017

A vital organisation, without which the statistics of this dreadful disease would be very high.
We are all at risk of cancer and are really fortunate to have such a caring team of researchers in this field. Thank you.

Eileen Livingstone May 4, 2017

I had a nephrectomy two years ago because of early detection of kidney cancer. I have never smoked and have a healthy BMI so I suppose I don’t fit into the normal category of causes but I am Eternally grateful that it was found early and removed with no need for further treatment. Keep up the good work with your research and treatment.

Gladys Edmonds May 4, 2017

Thank you for the information you give us so that we might avoid cancer. Thank you for all the work Cancer Research does.

Joyce Roll May 4, 2017

Thank God for those of us have the courage to become researchers. Their remuneration is often less than if they had not taken on this role. We would all be the poorer if it were not for researchers. I send a very big Thank You.