My uncle Ray found out he had kidney cancer because of a bad back. He had gone for a CT scan after months of nagging pain near his spine, fully expecting to be told about a disc, and the radiologist's report mentioned, almost in passing, a 3.5 cm mass on the upper pole of his left kidney. The back turned out to be arthritis. The mass turned out to be a renal cell carcinoma. He had no blood in his urine, no lump, no weight loss. He was sixty one, a smoker for forty of those years, twenty kilograms heavier than he had been at forty, and on two tablets for blood pressure. Every single one of those was a risk factor, and nobody, including Ray, had ever connected them to his kidneys.
He is fine now, six years on, with one and a half kidneys and a walking habit he would never have predicted. But his story is the reason I wanted to write this properly. Kidney cancer is one of the ten most common cancers in both the UK and the US, its rate has roughly doubled since the 1970s, and more than half of the cases are found the way Ray's was: by accident. That makes knowing the kidney cancer symptoms, the causes and the things you can actually change more valuable than for almost any other cancer. Here is what the evidence says, with the studies.
How common is kidney cancer, and who gets it
Around 82,000 Americans and 14,000 people in the UK are diagnosed with kidney cancer each year. It is about twice as common in men as in women, and the average age at diagnosis is 64. About nine in ten kidney cancers in adults are renal cell carcinomas (RCC), of which the clear cell type makes up roughly 75 percent. Lifetime risk is about 1 in 46 for men and 1 in 80 for women in the US (American Cancer Society, Key Statistics for Kidney Cancer).
Two things about those numbers matter for prevention. First, incidence has been climbing for fifty years, and while better scanning explains some of it, the rise in obesity and high blood pressure explains a good deal of the rest. Second, Cancer Research UK estimates that around 4 in 10 kidney cancer cases in the UK are preventable, chiefly through weight, smoking and blood pressure (Cancer Research UK, Kidney Cancer Risk Factors). That is a higher preventable fraction than for many cancers people worry about far more.
Kidney cancer symptoms: what to look for, and why most people have none
Textbooks used to teach the classic triad: blood in the urine, pain in the flank, and a palpable mass. Today fewer than 10 percent of people present with all three, and more than half are diagnosed incidentally on a scan done for another reason, as Ray was. That is good news, because incidental tumours tend to be smaller and earlier. But it means the symptoms below deserve attention precisely because they suggest a tumour that has grown large enough to announce itself.
- Blood in the urine (haematuria). The most common symptom. It may be visible pink, red or cola coloured urine, or found only on a dipstick test. It often comes and goes, which leads people to ignore it. Any visible blood in urine should be investigated, and in the UK, visible haematuria at age 45 or over triggers an urgent two week referral (NICE NG12).
- Persistent pain in the side or lower back, usually on one side, not related to movement or injury.
- A lump or swelling in the side or abdomen.
- Unexplained weight loss, loss of appetite, tiredness that does not improve with rest, or fevers and night sweats without an infection.
- Anaemia, or the opposite, a high red cell count, on a routine blood test.
- New high blood pressure that is hard to control, or high calcium on blood tests.
- In men, a newly appeared varicocele (enlarged veins in the scrotum), especially on the left side that does not shrink lying down.
None of these is specific to kidney cancer, and most people with them will have something else. But blood in the urine, in particular, is a symptom nobody should wait on.
What causes kidney cancer: the risk factors ranked
Smoking
A meta-analysis of 24 studies found current smokers had about a 50 percent higher risk of renal cell carcinoma than never smokers, with a clear dose response: heavy smokers roughly doubled their risk. Crucially, the risk fell steadily after quitting, dropping by 15 to 30 percent within ten years (Hunt et al., International Journal of Cancer, 2005). Smoking is linked to around 13 percent of UK kidney cancers. The mechanism is thought to involve tobacco carcinogens filtered and concentrated by the kidney, plus chronic low oxygen in kidney tissue.
Excess body weight
This is now the single largest modifiable cause in most Western countries, responsible for roughly a quarter of cases in the UK. In the largest meta-analysis of body weight and cancer, each 5 point rise in BMI raised kidney cancer risk by 24 percent in men and 34 percent in women, one of the strongest links found for any cancer site (Renehan et al., Lancet, 2008). The likely mechanisms are chronic inflammation, high insulin and insulin like growth factor, altered sex hormones and low oxygen in fat laden kidney tissue.
If you do not know your number, our BMI calculator takes half a minute and shows the lower cut offs that apply to people of South Asian, Chinese, Black African and Black Caribbean heritage, where metabolic risk begins around a BMI of 23. For kidney cancer specifically, waist size seems to matter as much as BMI, so a waist more than half your height is worth treating as a signal in its own right.
High blood pressure
Hypertension raises kidney cancer risk by about 60 to 70 percent independently of weight, and the higher the pressure, the higher the risk (Hidayat et al., Journal of Hypertension, 2017). For years there was debate about whether blood pressure tablets themselves were to blame; the weight of evidence now points to the raised pressure, not the treatment, so controlling it is protective on both counts.
Chronic kidney disease and dialysis
People on long term dialysis develop acquired cystic kidney disease, and their risk of kidney cancer is several times that of the general population. Anyone with advanced kidney disease should be aware of this and discuss surveillance with their nephrologist.
Family history and inherited syndromes
Having a first degree relative with kidney cancer roughly doubles your risk. About 3 to 5 percent of kidney cancers are due to inherited conditions such as von Hippel-Lindau disease, hereditary papillary RCC, Birt-Hogg-Dubé syndrome and hereditary leiomyomatosis. These tend to cause tumours young, often in both kidneys. If kidney cancer was diagnosed in a relative before 46, or in more than one relative, ask about genetic counselling.
Other factors
Occupational exposure to trichloroethylene (a degreasing solvent), long term use of high dose painkillers containing phenacetin (now withdrawn), and possibly heavy regular use of some other painkillers add modest risk. Diabetes adds a small independent risk beyond its link with weight. Being tall raises risk slightly, presumably because taller people have more kidney cells.
How to lower your kidney cancer risk: what the evidence supports
1. Stop smoking, at any age
The single most effective step for a smoker. The risk starts falling within years and keeps falling. Ray quit the week he was diagnosed, at 61, which his surgeon said would also improve his healing and lower the risk of a second primary tumour. Free NHS stop smoking services and combination nicotine replacement roughly triple quit rates compared with willpower alone.
2. Bring weight down slowly and keep it there
Because the BMI relationship is a straight line, every point counts and you do not have to reach an ideal weight to benefit. Aim for 0.5 to 1 kg a week through a Mediterranean style diet with less refined starch and sugar, and more vegetables, pulses, fish and olive oil. Weight loss also lowers blood pressure, which addresses two risk factors at once. Studies of bariatric surgery suggest large sustained weight loss lowers kidney cancer incidence, which supports the idea that the risk is reversible.
3. Treat blood pressure to target
Aim for under 140/90, or under 130/80 if you have diabetes or kidney disease, using whichever medicines your doctor recommends. Salt reduction to under 6 grams a day, regular exercise and less alcohol all help. Home monitoring is cheap and catches the "white coat" and "masked" patterns that clinic readings miss.
4. Move most days
A meta-analysis of 19 studies found the most physically active people had about a 12 percent lower risk of kidney cancer than the least active, with the effect holding after adjusting for weight (Behrens and Leitzmann, British Journal of Cancer, 2013). Activity improves insulin sensitivity, lowers blood pressure and reduces inflammation, all of which sit on the causal pathway. The target is 150 minutes of moderate activity a week; brisk walking counts. For a routine, see our kidney cancer diet and exercise guide.
5. Eat more vegetables and fruit, less processed meat
A pooled analysis of 13 cohort studies covering 1,478 kidney cancer cases found the highest fruit and vegetable intake was associated with about a 30 percent lower risk compared with the lowest, with the strongest signal for vegetables (Lee et al., Cancer Epidemiology, Biomarkers and Prevention, 2009). Cruciferous vegetables such as broccoli, cabbage and cauliflower show a consistent protective association in meta-analysis. Higher intakes of well done and processed red meat have been linked with higher risk, possibly through the heterocyclic amines formed in high heat cooking.
6. Keep alcohol modest, and do not start for your kidneys
Curiously, light to moderate drinking, around one drink a day, is associated with a 10 to 15 percent lower kidney cancer risk in pooled analyses (Bellocco et al., Annals of Oncology, 2012). Nobody should take that as a reason to drink, since alcohol raises the risk of seven other cancers. The honest reading is that moderate drinking does not raise kidney cancer risk, while heavy drinking harms the kidneys, blood pressure and everything else.
7. Know your workplace exposures and your family history
If you have worked with degreasing solvents, dry cleaning chemicals or in metal industries, mention it to your GP. If two relatives have had kidney cancer, or one was under 46, ask about genetic assessment. People with known inherited syndromes have regular scans precisely because early tumours are so treatable.
Is there a screening test for kidney cancer?
Not yet for the general population. Urine dipstick tests miss most early tumours, and ultrasound screening of everyone would find many harmless cysts for every cancer. The UK Yorkshire Kidney Screening Trial is testing whether adding an abdominal scan to lung cancer screening CT in smokers is worthwhile, and early results suggest it finds significant numbers of early kidney cancers in that high risk group. Until then, the practical advice is: investigate blood in the urine promptly, and if you already have a scan for another reason, make sure someone reviews the kidneys on it.
A one page kidney cancer prevention plan
| Priority | Action | Approximate risk change |
|---|---|---|
| 1 | Stop smoking | Risk falls 15 to 30 percent within 10 years of quitting |
| 2 | Lose weight at 0.5 to 1 kg a week if BMI is over 25 (23 for some ethnic groups) | Each 5 BMI points is worth 24 to 34 percent |
| 3 | Get blood pressure under 140/90, ideally lower | Hypertension adds 60 to 70 percent |
| 4 | 150 minutes of moderate activity a week | About 12 percent lower, independent of weight |
| 5 | Five plus portions of vegetables and fruit a day, cruciferous most days | Up to 30 percent lower at highest intakes |
| 6 | Limit processed meat and charred red meat | Modest reduction |
| 7 | Never ignore blood in the urine | Earlier stage at diagnosis, far higher cure rate |
What Ray would tell you
He would say he was lucky, and he was: a back scan found a tumour that had not yet done any harm. He would also say that luck is not a plan. He had every modifiable risk factor on this list and had never once heard the words "kidney cancer" from a doctor before it happened. He has one and a half kidneys now, a resting blood pressure his GP describes as boring, and he walks five miles most mornings with a man from his street who had the same operation last year. If you take one thing from his story, let it be this: the things that prevent kidney cancer are the same things that protect your heart, your blood sugar and your remaining kidney. There is no version of the future in which starting them is a mistake.
If you or someone you love has just been diagnosed, the next question is usually whether it can be cured. Our guide Is kidney cancer curable? Survival rates by stage and treatment answers it honestly.
Read next
- Is kidney cancer curable? Survival rates by stage and what treatment involves
- Kidney cancer diet and exercise: foods to eat and avoid after kidney removal
- BMI calculator with Asian and Black thresholds
- How to prevent kidney stones: what the evidence shows
Frequently asked questions
What are the first signs of kidney cancer?
Usually there are none, which is why most cases are found on scans done for other reasons. When symptoms do appear, blood in the urine is the most common, followed by persistent one sided flank pain, tiredness, unexplained weight loss and a lump in the side.
Can kidney cancer be prevented?
Around 4 in 10 cases are estimated to be preventable. Not smoking, keeping a healthy weight, controlling blood pressure, staying active and eating plenty of vegetables are the measures with the strongest evidence.
Does kidney cancer run in families?
A first degree relative with kidney cancer roughly doubles your risk. About 3 to 5 percent of cases are caused by inherited syndromes such as von Hippel-Lindau disease, which tend to cause tumours at a younger age and in both kidneys.
Does drinking a lot of water prevent kidney cancer?
There is no good evidence that extra water lowers kidney cancer risk, although a couple of studies suggest higher fluid intake is not harmful. Water is important for preventing kidney stones, which is a different condition.
This article is for general information and does not replace advice from your own doctor. Blood in the urine, persistent flank pain or unexplained weight loss should always be assessed by a clinician.
