Primary source: The New England Journal of Medicine

Source reference:

Tjan-Heijnen V, et al “Micrometastases or isolated tumor cells and the outcome of breast cancer” N Engl J Med 2009; 7: 653-63.

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Even low doses of radiotherapy that are regarded as safe may contribute to progressive cognitive decline in patients with low-grade glioma brain tumours, according to an Article published Online first and in the September edition of The Lancet Neurology.

Low-grade glioma (LGG) brain tumours are the most common type of brain cancer. Early or delayed radiotherapy is the most common treatment, but many questions remain about the best treatment strategy. Radiotherapy can cause damage to the brain over time and because the average survival time for patients with LGG is 10 years, these patients are at considerable risk of acquiring late or delayed radiation injuries.

In a previous study, the authors found that at an average of 6 years after diagnosis high-level radiation treatment as well as the tumour itself were associated with cognitive impairment. However, the effects of local radiotherapy on cognitive function in long-term survivors of LGG are not known.

In this study, Linda Douw from VU University Medical Center, Amsterdam, Netherlands and colleagues report the long-term radiological and cognitive abnormalities in survivors of LGG from the original study.

65 patients who had stable disease since the first assessment (of whom around half had received radiotherapy) had a follow-up cognitive assessment at an average of 12 years after treatment. Attention, executive functioning, verbal memory, working memory, psychomotor functioning, and information processing speed were calculated to detect differences between patients who were given radiotherapy and those who were not.

In total, 27% of patients who did not have radiotherapy had cognitive disability compared with more than half (53%) of those who had been given radiotherapy.

Overall, patients given radiotherapy had lower ability at attentional functioning, executive functioning, and information processing speed than patients not given radiotherapy. Findings also showed that patients who did not have radiotherapy showed stable radiological and cognitive status.

The authors say that: “By contrast with the results of our earlier study, the current results indicate that radiotherapy is associated with long-term cognitive deterioration, regardless of fraction dose…[and indicate that] all surviving patients who had radiotherapy are at risk of developing attentional problems”, not just those who were given a high-level dose.

They conclude by saying that treating patients who have LGG with radiotherapy should be considered carefully and suggest that deferring treatment might be the treatment strategy that is most beneficial to cognitive status and quality of life.

In an accompanying Reflection and Reaction comment, Paul Brown and Jane Cerhan from the Mayo Clinic in Rochester, USA, point out that there have been substantial improvements in radiotherapeutic techniques since the 1970s when the treatment period in the study started, and caution that it is therefore not possible to make firm generalisations about the risks of modern radiotherapy from these results.

They go on to call for more trials to assess the effects of modern radiotherapy techniques on cognitive function in patients with LGG.

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Source
The Lancet Neurology

• Explain that 92% of European women overestimated the mortality reduction from breast cancer screening by at least an order of magnitude, or reported they didn’t know the reduction, while 89% of men overestimated the mortality reduction from prostate cancer screening in a similar fashion.
• Note that the study was not designed to assess whether or not overestimation resulted in more participation in screening.

European men and women overestimate the benefits of breast and prostate cancer screening, researchers have found.

A total of 92% of women overestimated or didn’t know the mortality reduction from mammography screening while 89% of men did the same for prostate-specific antigen (PSA) testing, according to Gerd Gigerenzer, PhD, of the Max Planck Institute for Human Development in Berlin.

“Information about the benefits of mammography and PSA screening has not reached the general public in nine European countries, including the age tested by screening programs,” the researchers reported online in the Journal of the National Cancer Institute.

The absolute risk reduction in mortality associated with screening for breast cancer is on the order of one in 1,000, the researchers said.

There’s a similar risk reduction for men with PSA testing — though it can be much smaller, with estimates ranging between zero and one in 1,000.

In fact, after reviewing the evidence, the U.S. Preventive Services Task Force said it’s unclear whether increased detection of prostate cancer from screening would reduce morbidity and mortality.

So, to assess perceptions of cancer-specific mortality reduction associated with the screening methods, the researchers conducted interviews with 10,228 patients in Europe between September and December 2006.

They found that only 1.5% of women chose the correct estimate for reduction in mortality due to breast cancer screening.

Four times as many women answered that the benefit was zero, while 92.1% overestimated the benefit by at least one order of magnitude or said they didn’t know.

The greatest overestimation occurred in France, the Netherlands, and the U.K. — countries that have high participation rates in mammography screening, the researchers said.

In their survey, researchers also found that 89.3% of men either overestimated mortality reduction from prostate cancer screening or reported they didn’t know.

The greatest overestimation occurred in France, followed by Austria, the Netherlands, Spain, and the U.K.

The researchers also found that men and women ages 50 to 69 — the targets of screening programs — weren’t better informed about the benefits of mammography and PSA screening than the rest of the population.

Frequently consulting a physician and reading informational pamphlets tended to increase overestimation of the benefit, rather than reduce it, the researchers said.

They noted that previous studies have shown physicians, too, lack knowledge about the benefits of screening, and some have conflicts of interest that support the “possibility that these professionals contribute to overestimation.”

Knowing the benefit of a treatment is necessary for rational decision-making, the researchers said. However, currently available information sources are “not designed to communicate benefits clearly. As a consequence, preconditions for informed decisions about participation in screening are largely nonexistent in Europe.”

The study did not attempt to assess whether overestimation was associated with more screening. The study also may be limited because the results may not be generalizable to populations outside of Europe.

In an accompanying editorial, Steve Woloshin, MD, of Dartmouth, and Lisa Schwartz, MD, of the VA Outcomes Group in White River Junction, Vt., said the method for assessing perception of risk was biased towards overestimation. That should not, however, diminish the study’s findings, they said.

“Whether people overestimate the benefit of screening — or have no idea — the problem is the same,” they wrote. “Without an accurate sense of how well screening works, people cannot begin to make informed decisions. We need to move from selling screening to helping people realize that screening is a genuine choice.”