Serum calcium and cancer risk

A new study led by Dr Fergus Hamilton, from the Centre for Academic Primary Care at the University of Bristol and published in the British Journal of Cancer, has shown that high levels of calcium in the blood is a risk factor for cancer developing within one year, especially in men. 

It has long been known that high calcium levels in the blood are quite common in people with cancer, particularly late stage cancer. This is because in late stage cancer the cancer has spread to bone or the cancer secretes substances that cause calcium regulation within the body to be faulty.

In this study the researchers looked instead at people without a diagnosis of cancer but who has high blood calcium levels. They found these subjects by looking at computerised records of 54.000 patients from UK GP databases. They then identified people with or without elevated blood calcium levels who went on to develop cancer within one year.

The normal level of calcium in the blood is between 2.1 and 2.5 millimoles per litre (mmol/L). The researchers found that in men, a small increase outside this range (2.6 - 2.8 mmol/L) increased the risk of cancer being diagnosed within one year by 11.5%. Above 2.8 mmol/L, the risk rose to 28%. In women however, the increase in risk was much smaller. A slight elevation in calcium increased cancer risk by 4.1% and an elevation above 2.8 mmol/L increased the risk by 8.7%.

This difference between men and women was thought to be due to the fact that another cause of high calcium, hyperparathyroidism due to elevated levels of parathyroid hormone, is much more common in women.

Because serum calcium is very easily and cheaply measured this raises the potential for it to be used as a cancer screening test in men. However Dr Safia Danovi, from Cancer Research UK, said about these new findings: "Diagnosing cancer earlier is one of the key ways to improve the chances of survival. This research suggests that measuring calcium levels in the blood could help doctors decide whether to send a patient for further tests, but we don't know whether it could lead to earlier diagnosis or improved survival."

"These are early days and any new technique must be thoroughly trialled to make sure it's reliable, effective and accurate before it can be used with patients."

"In the meantime, it's important for people to be aware of what's normal for them and visit their GP if they notice any unusual or persistent changes."


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