Impact of vitamin D and obesity on bladder cancer; Risk and survival

The project examines whether obesity and vitamin D levels affect the risk of developing bladder cancer.
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Bladder cancer is a common cancer among Norwegian men, occurring 3-4 times more frequently than among women. Smoking and occupational exposure are established risk factors. Over the past decades, both smoking and occupational exposure have decreased in Norway, yet the incidence of bladder cancer continues to rise. Other lifestyle-related factors may also influence the risk of developing this disease.

High body mass index (BMI), low physical activity, metabolic disorders such as high blood pressure, are associated with the risk of various cancers and may also have relevance to bladder cancer. Additionally, previous studies suggest that low levels of vitamin D may increase the risk of this disease.


In this project, we investigate whether there are associations between different lifestyle-associated factors and the risk of developing bladder cancer, using data and serum samples from the Janus Serum Bank and the Cancer Registry. The project examines:

  1. Associations between BMI, physical activity, blood pressure, triglycerides, and cholesterol and the risk of bladder cancer.
  2. Whether serum levels of vitamin D influence the risk of bladder cancer.


The results indicate an association between elevated blood pressure and increased risk of bladder cancer, but no associations for BMI, physical activity, triglycerides, or cholesterol. Generally, the observed associations between lifestyle and bladder cancer were strongest among men and non-smokers. This suggests that smoking may mask some of the associations among smokers. Future studies of associations between lifestyle-associated factors and the risk of bladder cancer should be conducted among non-smokers to ensure better confounding control.

In this project, we found that high levels of vitamin D were associated with reduced risk of bladder cancer, indicating that low levels of vitamin D may be a risk factor. However, we found no association for vitamin D-binding protein.

Furthermore, we found that having insufficient vitamin D levels prior to diagnosis predicted increased mortality from bladder cancer. The results were most pronounced for patients without muscle-invasive disease, which may indicate an important role of vitamin D in the early stages of the disease.


Gislefoss RE, Stenehjem JS, Hektoen HH, Andreassen BK, Langseth H, Axcrona K, Weiderpass E, Mondul A, Robsahm TE. Vitamin D, obesity and leptin in relation to bladder cancer incidence and survival: prospective protocol study. BMJ Open. 2018 Mar 30;8(3):e019309. doi: 10.1136/bmjopen-2017-019309. PMID: 29602840; PMCID: PMC5884376.


Hektoen HH, Robsahm TE, Andreassen BK, Stenehjem JS, Axcrona K, Mondul A, Gislefoss RE. Lifestyle associated factors and risk of urinary bladder cancer: A prospective cohort study from Norway. Cancer Med. 2020 Jun;9(12):4420-4432. doi: 10.1002/cam4.3060. Epub 2020 Apr 21. PMID: 32319230; PMCID: PMC7300409.


Hektoen HH, Robsahm TE, Stenehjem JS, Axcrona K, Babigumira R, Mondul AM, Gislefoss RE, Andreassen BK. Vitamin D and Vitamin D-binding protein and risk of bladder cancer: A nested case-control study in the Norwegian Janus Serum Bank Cohort. Cancer Med. 2021 Jun;10(12):4107-4116. doi: 10.1002/cam4.3960. Epub 2021 Jun 3. PMID: 34080787; PMCID: PMC8209600.


Hektoen HH, Gislefoss RE, Stenehjem JS, Langseth H, Axcrona K, Mondul AM, Robsahm TE, Andreassen BK. Prediagnostic Serum 25-Hydroxyvitamin D and Mortality Among Bladder Cancer Patients in the Janus Serum Bank Cohort. Clin Epidemiol. 2021 Sep 14;13:801-811. doi: 10.2147/CLEP.S319620. PMID: 34548821; PMCID: PMC8449552.