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The Norrkoping prostate cancer screening trial — with 20-year follow-up

Posted Apr 01 2011 12:00am 1 Comment


A new report just published as an open access, full-text article at BMJ.com is going to further confuse the issue of whether mass, population-based screening for prostate cancer is or isn’t a good idea.

The report by Sandblom and his colleagues provides data from a study of all 9,026 men in the Swedish city of Norrkoping who were between the ages of 50 and 69 in 1987.

Of these 9,026 men, 1,494 were initially screened for prostate cancer with a DRE exam only in 1987 and again in 1990. In 1993, they also received a PSA test as well as the DRE (with 4.0 ng/ml as the lower ”cut-off” value for a positive PSA result, which we now know to be invalid). And then in 1996 only the men who were still 69 years of age or less received a PSA and a DRE. The remaining 7,532 men did not undergo screening and therefore served as a comparison group.

Now it will immediately be evident that there are problems with this study because some men may only have ever received one PSA test and no one will ever have received more than  two PSA tests within the structure of the clinical trial. On the other hand, this study is the first to ever provide prospective information on a population of patients who were followed for 20 years.

Data on diagnosis, tumor stage, grade, and treatment were obtained from the Swedish South East Region Prostate Cancer Register, and patients were carefully monitored for prostate cancer-specific mortality through 31 December 2008.

Here are the key data reported by Sandblom et al.:

  • Attendance at screenings between 1987 and 1996 was generally good:
  • 85 cases of prostate cancer were diagnosed in the screened group (85/1,494 or 5.7 percent).
  • 292 cases of prostate cancer were diagnosed in the control group (292/7,532 or 3.9 percent).
  • The percentage of men with localized tumours (T1-2, N0/Nx, M0) was significantly higher in the screened group (56.5 percent) than in the control group (26.7 percent, P<0.001).
  • The rates of non-localized tumors were 37/1,494 (2.5 percent) in the screened group and 213/7,532 (2.8 percent) in the control group, which was not a statistically significant difference.
  • The risk ratio for death from prostate cancer in the screened group was 1.16.
  • In a Cox proportional hazard analysis comparing prostate cancer-specific survival in the control group with that in the screened group, the hazard ratio for death from prostate cancer was 1.23.
  • After adjustment for age at start of the study, the hazard ratio was 1.58.

The authors conclude that, “After 20 years of follow-up the rate of death from prostate cancer did not differ significantly between men in the screening group and those in the control group.”

Dr. Sandblom has been quoted as stating that, “In the light of our findings, I would say that the benefit from screening is not sufficient to support mass screening,” bit he continued as follows: “However, the study was initiated more than 20 years ago, when PSA was not available and the treatment of localized prostate cancer was not as effective as it is today. I would thus not categorically advise against PSA testing based on an individual decision from a man who feels concern about prostate cancer.”

Where does this new study seem to leave us? Probably right where we started: PSA testing should be an individual decision between each man and his doctor, based on a careful assessment of the individual patient’s known risk factors. This does not mean that every patient needs to be able to “justify” PSA testing because he has specific risk factors. Rather, it means that there are better reasons to recommend PSA testing for some men than for others.

It is (frankly) unclear whether any trial currently ongoing will be able to give us a concrete set of data about the value of screening for prostate cancer using the PSA and DRE with a 20-year follow-up. The PLCO trial and the ERSCP were both horribly flawed trials in different ways, and we know of no other large, ongoing trial. The “best” large study to date from a methodologic point of view – has been the Göteborg trial. This trial did show a prostate cancer-specific survival benefit in a previously unscreened population (but no overall survival benefit).

Comments (1)
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Cancer screening has been proposed in the past for early detection of cancer and to prevent it earlier, such as this is the prostate cancer screening. However, a long term study has just been released asserting that cancer of the prostate tests do not prevent fatalities. This is far from the first study to suggest it. Screenings are good for catching cancer of the prostate early, however more than two decades of data revealed that individuals who didn't get regular screenings and people who didn't got cancer of the prostate at the same rate. This might help you decide what method is best for you before you take out for medical expenses.
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