Screening for prostate cancer, the third most common cancer here among males, has undergone a change in thinking. Doctors are likely to recommend it mainly for those who are at higher risk instead of every male of a certain age, as used to be the case.

This is because the prostate specific antigen (PSA) test is prone to false positives, so about two-thirds of men who have raised levels of the protein in their blood actually do not have cancer, said Dr Ravindran Kanesvaran of the National Cancer Centre Singapore.

They end up undergoing unnecessary biopsies, which have their own risk, just to rule out cancer.

What is more, most men with prostate cancer will not die of it, as it tends to be slow-growing in many cases, said Dr Kanesvaran.

But once diagnosed, men might end up having unnecessary treatments such as surgery or radiation therapy, he said. Screening is best done on men who meet certain criteria, such as those between 50 and 75 years old, with a life expectancy of more than 10 years, and a strong family history of prostate cancer - first-degree relatives who were diagnosed before they turned 65.

The prostate gland, about the shape and size of a walnut, secretes fluids that help in reproduction.

In the 1980s, the rate of metastatic prostate cancer was 72.4 per cent, said Dr Sim Hong Gee, who is a senior consultant urologist of the Ravenna Urology Clinic at Gleneagles Medical Centre. Because of screening, most patients are now diagnosed at Stage 1 or 2, he said.

Incidence and survival rates

It is the third most common cancer suffered by men and causes the sixth most cancer deaths in them. Between 2010 and 2014, 739 men died from the cancer. The incidence of prostate cancer has increased due to better tests, along with a rise in survival rates.

Source: Singapore Cancer Registry

According to the National Registry of Diseases Office, only three in 10 prostate cancer patients were diagnosed at Stage 4. At the National University Health System, one- quarter are diagnosed at Stage 4.

In comparison, about 5 per cent of men in the United States are diagnosed at Stage 4, simply because they screen more, said Dr Lincoln Tan, consultant at the division of surgical oncology (urology), National University Cancer Institute, Singapore (NCIS). But, he added: "In the US, there is a lot of unnecessary treatment going on, it is just overdone."

A test with better accuracy may put the screening dilemma to rest. The NCIS is working on a new blood test for screening called the Prostate Health Index. From a study of 150 men, its accuracy appears to be three times higher than that of the PSA test, said Dr Tan. But it is more expensive - about $120 out of pocket, compared to $30 for the PSA test.

EATING RIGHT

On the treatment front, with prostate cancer being so slow-growing, the NCIS has embarked on an active surveillance programme, in which prostate cancer patients are observed instead of treated right away. They have a PSA test every six months, and a biopsy every one to three years."The key benefit of being on this programme is that patients avoid the toxicity of treatments," said Dr Tan.

Nevertheless, some patients request immediate treatment rather than monitoring. The latest treatments include using radiation seeds implanted directly onto the prostate gland to target cancer cells more directly, and robotic surgery, which is highly precise, to remove the tumour. There is also hormonal therapy to reduce testosterone levels.

As for prevention, a diet rich in certain nutrients is advised."Males may want to include more lycopene in their diet, which is present in tomatoes. Also, cruciferous vegetables and green tea may help. But how far it prevents the cancer, we aren't really sure," said Dr Sim.

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