How reliable are blood tests for prostate cancer? Ask the GP Dr Martin Scurr

Concerned about my frequent visits to the loo, a GP gave me a PSA blood test. This was normal for my age of 73 (1.4) but an examination found a small, hard lump and an MRI scan diagnosed prostate cancer. How reliable are PSA tests?

David Fisher, Nottinghamshire.

Prostate cancer is the most common cancer in men — one in eight will be diagnosed with it. There have been calls for men to be screened for the disease from middle age, primarily using the prostate specific antigen (PSA) blood test, which you had.

PSA is a protein made by the prostate, the walnut-sized gland located below the bladder, and the amount shed into the blood can give doctors an idea of how healthy it is. However, this test is far from perfect as PSA levels can be raised by a range of factors, including exercise, sexual activity, an enlarged prostate, constipation and infection — as well as cancer.

As you discovered, it’s also possible to have a false negative result — where the test suggests there is no cancer, when there is. This is why physical examination is vital.

In your case, the cancer was detected because you’d had urinary tract symptoms that your doctor quite rightly wanted to investigate further.

However, a DRE (digital rectal examination) can only detect tumours in the front and back of the prostate — and 25 per cent of tumours occur elsewhere in the gland.

As far as screening goes, the most reliable option is magnetic resonance imaging (MRI), because it allows you to see into the gland. But one issue is its limited availability on the NHS.

Separately, researchers are looking at tests to detect DNA fragments of cancer in the bloodstream. My advice if you have symptoms or are 50 or over and decide you want to have your PSA levels tested, see your GP.

There have been calls for men to be screened for the disease from middle age, primarily using the prostate specific antigen (PSA) blood test. [File image] 

The best policy is that only those at higher risk are screened: this includes men with a first-degree relative (i.e. a father or brother) who’s been diagnosed with prostate cancer under the age of 65, and black men (who, for ill-understood reasons, are at higher risk).

I hope that your cancer is confined to the prostate, as is the case for at least 78 per cent of patients at the time of diagnosis.

If this is the case, the likely treatment is an operation to remove the gland. I wish you a speedy and smooth recovery.

Is a daily calcium supplement a good idea following a diagnosis of osteopenia?

Liz Landau, South London.

This is a good question as there is much confusion about the term osteopenia (as opposed to osteoporosis), and even more about whether calcium supplements are advisable.

Osteopenia refers to the loss of bone mineral — mainly calcium — that we must all expect as years pass. It is a normal part of the ageing process, caused by the body reabsorbing calcium rather than it staying in bones where it keeps them strong.

There is much confusion about the term osteopenia (as opposed to osteoporosis), and even more about whether calcium supplements are advisable, writes Dr Martin Scurr 

It is not a medical diagnosis as such but rather a warning sign that your bone density is falling. This can progress to osteoporosis, where bone mineral density becomes lower than expected for someone of your age, increasing the risk of fractures.

Risk factors include being female (due to the drop in oestrogen during menopause)as well as age, body size, family history and medications such as glucocorticoids. A diet deficient in calcium and vitamin D is another factor.

A daily calcium supplement can help, particularly if it’s taken alongside a vitamin D supplement as this promotes the absorption of calcium. The suggestion is 1,000 mg of calcium and 600 IU of vitamin D.

There is strong evidence these supplements lower bone turnover by a fifth — a powerful mechanism to limit progress from osteopenia towards osteoporosis.

However, studies have shown taking calcium supplements long term may increase the risk of heart disease in some people. Therefore it is a decision to be taken after a consultation with your GP.

Eating a diet rich in calcium-containing foods — milk, cheese and green leafy veg — does not have this negative effect, so should be a priority for you in the meantime.

In my view … Patients should be prioritised over pay

Each time I go grocery shopping I find myself querying if I’ve read the prices correctly. They seem to rise weekly.

The cost of living is more expensive than it was; there can be no doubt about that. So on the one hand I understand why junior doctors would like to increase their wages — the basis of their ongoing industrial action.

A doctor starting their foundation training will be on around £29,384 — not particularly well paid. However, unlike other jobs the chances of progression and a pay rise are guaranteed. [File image] 

A doctor starting their foundation training will be on around £29,384 — not particularly well paid. However, unlike other jobs the chances of progression and a pay rise are guaranteed. While I accept that their pay has not risen in line with inflation, I have concerns that people who train as doctors are prepared to launch day after day of strikes, which so far have led to 196,000 cancelled appointments for patients.

Recommended reading for anyone aspiring to be a doctor has always been the work of William Osler, who became a professor of medicine at the University of Oxford. One of his mottos was ‘Do the kind thing and do it first’. Indeed.

Write  to Dr Scurr 

Write to Dr Scurr at Good Health, Daily Mail, 9 Derry Street, London W8 5HY or email: drmartin@dailymail.co.uk — include contact details. Dr Scurr cannot enter into personal correspondence. Replies should be taken in a general context. Consult your own GP with any health worries.