Gothenburg PSA Study Shows Impact of Screening Cessation

Kate Johnson

March 24, 2016

MUNICH — Results are now out to 18 years from the famous Gothenburg prostate cancer screening trial, which showed that routine prostate-specific antigen (PSA) testing reduced deaths from prostate cancer. The latest long-term data coming out of this study are now showing what appears to be a shrinking mortality benefit, but a closer look at the numbers suggests the opposite, the senior investigator revealed here at to the European Association of Urology 2016 Congress.

As previously reported by Medscape Medical News, initial results of this study showed a 44% reduction in cancer mortality in men who were invited to regular screening, compared with control subjects who were not (Lancet Oncol. 2010;11:725-732).

"Now, with longer follow-up, the risk ratio for mortality has actually decreased from 44% to 35%," reported Jonas Hugosson, MD, from the University of Gothenburg in Sweden.

But, rather than suggesting a waning benefit of screening, the reduced survival rate is most likely the effect of screening cessation in the study's oldest subjects, according to Dr Hugosson, although he did not show specific numbers for this age group.

 
It seems that the protective effect from screening lasts for somewhere between 10 and 15 years.
 

"We see a large benefit in men who are younger than 60, where we have about a 50% mortality reduction, but we have a lowered effect in the oldest group of men, probably because they're catching up [to the control group]...in those 10 years after they stop screening," he said.

"We thought we could stop the screening at age 70 because we would have a screening effect for about 20 years, but that does not seem to be the case. It seems that the protective effect from screening lasts for somewhere between 10 and 15 years. After that, the mortality in the screening arm is catching up with the control arm," Dr Hugosson reported.

Table. Prostate Cancer Rate Ratio for the Screened Group Compared With the Control Group

Age Group Incidence Rate Ratio Mortality Rate Ratio
50–54 years 1.77 0.50
55–59 years 1.37 0.47
60–65 years 1.39 0.85
All 1.51 0.65

 

The Gothenburg study involved men 50 to 64 years at baseline; 9950 men were randomized to an organized 2-year PSA screening program, and 9949, who were not invited to formal screening but could have been screened on their own, served as the control group.

The screening was offered to the upper age limit of 69 years.

Men in the screening group who had PSA levels of at least 2.5 ng/mL were offered further investigation, including a biopsy.

The 18-year follow-up data show improved detection in the screened group. The overall prostate cancer incidence was 9.7 per 1000 person-years in the screened group and 6.5 per 1000 person-years in the control group (hazard ratio [HR], 4.5).

As expected, prostate cancer mortality was also lower in the screened group than in the control group (0.51 vs 0.79 per 1000 person-years; HR, 0.65), said Dr Hugosson.

Subgroup analyses of the data also showed that men with less education derived more benefit from screening than those with more education, he added.

Although prostate cancer mortality was lower in the screened group than in the control group, the benefit was more pronounced in those with lower education levels (rate ratio [RR], 0.49) than in those with medium–high education levels (RR, 0.76).

"In general, men with higher education have much more access to PSA testing, compared with less-educated men. But if you have a formal screening program, you diminish these differences; they have the same access to testing," said Dr Hugosson. He added that "organized screening has the potential to diminish socioeconomic inequalities in prostate cancer mortality."

Asked by Medscape Medical News to comment on the findings, Deepansh Dalela, MD, from the Henry Ford Hospital in Detroit, said that the Gothenburg study clearly shows that PSA screening is associated with decreased prostate cancer mortality.

On the flipside, Dr Dalela recently showed that cutting back on screening results is increasing cases of advanced disease, as reported by Medscape Medical News.

But too much screening should also be avoided, he said.

"Our results also show that decreasing PSA screening did have a beneficial impact by reducing the likelihood of a diagnosis of low-risk prostate cancer in older men, which most urologists agree is fairly indolent and does not require treatment," he noted.

Dr Dalela also noted that the Gothenburg screening parameters, which are stricter than they have traditionally been in the United States, likely pick up more low-risk disease. He pointed out that "the threshold for performing a prostate biopsy in the Gothenburg study was 2.5 ng/mL, and the common threshold for biopsy in the United States is 4.0 ng/mL."

Dr Hugosson and Dr Dalela have disclosed no relevant financial relationships.

European Association of Urology (EAU) 2016 Congress: Abstract 87. Presented March 12, 2016.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.

processing....