Kidney stones don’t directly cause cancer, but having them is linked to a meaningfully higher risk of developing cancers in the urinary tract. A recent meta-analysis of 13 studies found that people with a history of kidney stones have approximately twice the risk of developing kidney cancer compared to people without stones (pooled risk ratio of 2.36). The connection isn’t random chance: chronic irritation and inflammation from stones appear to drive cellular changes over time that can, in rare cases, become malignant.
How Strong Is the Link?
Multiple large population studies have measured this association, and the numbers are consistent enough to take seriously. A nationwide study using Taiwan’s health insurance database tracked over 43,500 patients with urinary stones and found they had roughly four times the expected rate of kidney cancer and more than three times the expected rate of bladder cancer. A Swedish registry study following more than 61,000 patients hospitalized for stones over 25 years found a 2.5 times higher rate of cancers in the renal pelvis and ureter, and a 1.4 times higher rate of bladder cancer.
An analysis of over 13,000 individuals from the U.S. National Health and Nutrition Examination Survey found that kidney stones were significantly associated with renal cell carcinoma, the most common type of kidney cancer. However, when researchers adjusted for factors like age, sex, and ethnicity, much of that elevated risk shrank. In the fully adjusted model, the association was borderline, suggesting that some of the raw risk is explained by shared factors (like obesity, diabetes, and diet) rather than stones alone.
This is an important nuance. Kidney stones and certain cancers share overlapping risk factors. That makes it difficult to say with certainty that stones themselves are the direct cause versus a marker of an environment in the body that also promotes cancer. Still, the biological mechanisms linking stones to cancer are plausible enough that researchers treat the connection as more than coincidental.
How Stones Could Lead to Cancer
The proposed pathway centers on chronic irritation. A kidney stone sitting in the renal pelvis or ureter constantly rubs against the lining tissue. Over months or years, this mechanical irritation triggers ongoing inflammation, recurrent infections, and repeated cycles of tissue damage and repair. Each repair cycle involves cell division, and the more cells divide, the greater the chance of a DNA copying error that could eventually become cancerous.
This process is especially well documented with staghorn calculi, which are large, branching stones that fill much of the kidney’s internal space. These stones can sit in place for years, causing persistent infection and inflammation. Over time, the normal lining cells of the kidney’s collecting system undergo a transformation called metaplasia, where they change into a different cell type. That altered tissue can then progress to a rare but aggressive form of cancer called squamous cell carcinoma of the renal pelvis. In reported cases of this cancer type, kidney stones were present 87% to 100% of the time.
Which Cancers Are Involved?
The cancers most consistently linked to kidney stones are:
- Renal cell carcinoma: The most common kidney cancer overall. The meta-analysis estimates about double the risk in stone formers.
- Transitional cell carcinoma: Cancer of the lining tissue in the renal pelvis, ureter, or bladder. This is the cancer type most strongly associated with stones in several studies, with one showing nearly four times the odds compared to people without stones.
- Squamous cell carcinoma of the renal pelvis: Very rare (under 1% of all urinary tract cancers), but strongly tied to long-standing stones. It accounts for roughly 0.5% to 8% of malignant kidney tumors.
- Bladder cancer: The Swedish registry data showed a modest but statistically significant increase in bladder cancer risk among stone patients, with about 90% of those cases being transitional cell carcinoma.
Does Risk Differ Between Men and Women?
The data on sex differences is surprisingly mixed. The Swedish and Taiwanese registry studies both found a stronger association between stones and urinary tract cancers in women. One Taiwanese study reported that women with stones had 3.6 times the odds of kidney cancer, while men had about 2.9 times the odds. Yet a separate meta-analysis of controlled studies found the opposite: a significant stone-to-cancer link only in men.
These contradictory findings likely reflect differences in study design, population characteristics, and which confounding factors were accounted for. The takeaway is that the association exists for both sexes, and neither group should assume they’re unaffected.
When Blood in Urine Needs a Closer Look
One practical concern is that kidney stones and urinary tract cancers share a key symptom: blood in the urine. It’s easy to assume that blood is coming from a known stone, but this assumption can delay cancer detection. About 11.6% of patients with recurrent visible blood in their urine will turn out to have a malignancy even after initial tests come back negative.
Imaging with CT scans can identify both stones and early-stage tumors, small masses, and other abnormalities. For anyone over 40 with microscopic blood in the urine, imaging is standard. If the bleeding is visible to the naked eye, a direct look inside the bladder with a scope is typically added. For older patients, both contrast-enhanced CT and cystoscopy are recommended. If you have recurring episodes of blood in your urine and a history of stones, don’t assume the stones are always the explanation, particularly if the pattern changes or the bleeding persists after a stone has passed.
Putting the Risk in Perspective
A doubled risk sounds alarming, but context matters. Kidney cancer is relatively uncommon to begin with, affecting roughly 15 to 20 people per 100,000 annually in the United States. Doubling a small number still gives you a small number. The vast majority of people who form kidney stones will never develop cancer as a result.
The risk is most relevant for people with chronic, untreated stones, particularly large staghorn stones that stay in the kidney for years and cause repeated infections. For someone who passes a calcium stone and takes steps to prevent recurrence (staying hydrated, adjusting diet), the cancer risk is not something that should keep you up at night. Where it does matter is in long-term follow-up: if you’re a recurrent stone former, staying on top of imaging and not dismissing new symptoms as “just another stone” is the most practical thing you can do.