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Australian Cancer Society report disapproves of screening men for prostate cancer

NORMAN SWAN: The Australian Cancer Society has released a report which strongly recommends against screening men for prostate cancer. There's been a big push for prostate cancer screening for various reasons. One is that it's a common tumour in elderly men although, as you'll hear, it's not such a common cause of death. Another reason is that there is a test called the Prostate-Specific Antigen, or PSA, which when elevated, can sometimes indicate the presence of a tumour. And then there's the gender bias issue. If women can have mammograms for breast cancer, why can't blokes have the PSA test for their prostates? Like most things, it's a lot more complicated.

All of us, including many doctors, confuse diagnostic testing with screening. Screening is a process of doing cheap, simple, accurate tests on healthy people in the hope of discovering a nominated disease which has effective curative treatment if it's caught early enough. But as Dr Jeanette Ward, who was the report's principal author, says, the PSA test just doesn't qualify at the moment.

JEANETTE WARD: There are some important public health, scientific rules that must be followed in actually looking at the effectiveness of a potential screening program. The first is whether the odds of dying from the disease are altered by participating in the screening program. We had well-designed scientific, population-based studies which showed that mammographic screening will reduce the chances of dying from breast cancer by up to a third in older women. We have no such studies as yet available which show that by having a PSA test a man can change his chances of dying from prostate disease.

Four major trials are under way in Europe and in North America to look at that very issue, and that's an important first criterion that must be met.

The second criterion for establishing the effectiveness or value of a screening program is about the performance characteristics of the test itself.

NORMAN SWAN: Meaning how accurate it is?

JEANETTE WARD: The false-positive rate, the false-negative rate - how it performs in the community where indeed the prevalence of the particular condition of interest is likely to be low, and that is a bit of a paradox really. Whilst we know that prostate cancer is relatively common, clinically significant prostate cancer is quite uncommon.

NORMAN SWAN: Meaning prostate cancer that's somebody's going to die of?

JEANETTE WARD: One in 23 men might get prostate cancer through the course of their lifetime, but only one in 70 would die from that. A PSA test that comes up positive is more likely to be a false-positive result than, in fact, a true-positive result.

NORMAN SWAN: And isn't it the case that even if it's positive, the cancer that's found may actually not be a cancer that goes on to kill somebody, and therefore, even if you treat that person, you may be treating unnecessarily.

JEANETTE WARD: And the ethics of that were a major concern to the Australian Cancer Society. It would be quite an injustice to inflict the complications of surgery, the indignity of incontinence, the inconvenience of all of the other complications of surgery if, in fact, that prostate cancer would have laid dormant, not have affected the man's quality of life and he was highly likely to have died of something else.

NORMAN SWAN: Do we know how to predict those cancers that are going to dormant?

JEANETTE WARD: No, we don't, and that's an exciting research agenda. Looking at how to fine-tune PSA testing to ensure that only those clinically significant cases are detected is an important part of meeting that second criterion.

NORMAN SWAN: We've had a lot of press, recently, about Pap smears and missing cervical cancer. How many cancers are missed with the PSA testing?

JEANETTE WARD: The false-negative rate from the PSA test could be as high as 50 per cent.

NORMAN SWAN: Does that mean one in two cancers are missed?

JEANETTE WARD: In other words, if there are 10 men with the disease, five of them will get an abnormal PSA test but five will not get an abnormal test, so they will, in fact, be falsely reassured about whether they have cancer or not.

NORMAN SWAN: And of 10 men with a positive test, how many are going to have cancer, whether it be dormant or active?

JEANETTE WARD: The false-positive rate is likely to be high. If three men have a positive test result, two out of three will not have cancer, and will in fact have been identified incorrectly as potentially having cancer through the screening test.

NORMAN SWAN: One of the reasons that Pap smear campaigns and mammography campaigns have gone ahead is that there are operations which are known to be curative for cervical cancer and breast cancer, and that is one of the criteria for a screening campaign. Do we have curative operations for prostate cancer?

JEANETTE WARD: Treatment of prostate cancer, again, is problematic. In the urological community, there is as yet no consensus about the best treatment for prostate cancer at particular stages. In some studies, watchful waiting has been shown to be just as effective as radical prostatectomy or as radiation therapy. Those choices are significantly different in terms of the side effects and complications that men would suffer.

NORMAN SWAN: So even if you find a cancer, you don't know what the treatment is that's going to cure it?

JEANETTE WARD: Whilst I'm not a clinician, when one looks at the research studies published in the literature, there's a high degree of selectivity and certainly not enough in the way of randomised control trials of various surgical interventions.

NORMAN SWAN: Dr Jeanette Ward of the Australian Cancer Society.

A prostate cancer screening program, by the way, will probably cost around $122 million per year.