Friday April 9 2010
PSA tests need confirmation using tissue samples
Men could potentially be distressed by prostate cancer screening, according to BBC News. The website said that even if a tissue sample shows no signs of cancer, men can experience increased levels of distress and doctors should warn men about how testing may affect their mood.
The research behind this news tracked men’s mood and anxiety from an initial blood test until three months after a tissue sample confirmed that they did not have cancer. The results showed that a small proportion of men had clinically significant levels of distress throughout testing and even after a clear result.
The type of prostate screening in this study, which tests for raised levels of a protein called PSA (prostate-specific antigen), is not routinely carried out in the UK as it is not always a reliable indicator of possible cancer. PSA levels can vary between individuals and can be raised by other non-cancerous conditions, principally benign enlargement of the prostate, inflammation or infection. The findings of this study highlight the need for all men who have their PSA level tested to be fully informed about the possible causes of a raised PSA (that it doesn’t necessarily mean cancer), the implications of having the test and the options available when investigating the causes of raised PSA.
Where did the story come from?
This study was carried out by Dr RC Macefield and colleagues at the Universities of Bristol and Nottingham. The study was funded by the National Institute for Health Research and Cancer Research UK, and was published in the peer-reviewed British Journal of Cancer.
BBC News accurately reported the findings of this paper, importantly highlighting that the test is not routinely offered in the UK but that some men above the age of 45 can request one.
What kind of research was this?
Men can be screened for prostate cancer by measuring their levels of a protein called prostate-specific antigen (PSA). If men are positive for PSA (i.e. it is above a certain level), they may go on to have tissue removed from their prostate during a biopsy. However, it is estimated that 75% of biopsies will be negative for cancer. The researchers wanted to assess how going through the testing procedure and having a negative result may affect men psychologically.
This was a cohort study that followed men going through the prostate testing procedure, measuring their mood and levels of distress from their initial test until 12 weeks after their subsequent negative biopsy result.
What did the research involve?
The men included in the study were British and aged between 50 and 69 years old. They were enrolled in the Prostate testing for cancer and Treatment (ProtecT) study, which was a randomised controlled trial of treatment for localised prostate cancer. The men from across the UK had been invited to attend PSA testing with their GP.
Men who had a raised PSA level were offered a biopsy, and 330 men who had a negative biopsy result were selected for this psychological study.
Mood and psychological distress were assessed using questionnaires when the men had their first PSA test, when they attended their biopsy appointment, within a few days of receiving a negative biopsy result, and around 12 weeks after a negative biopsy result.
Their mood was assessed using the Profile of Mood States short form test (POMS-SF), which contains a 37-adjective checklist where individuals rate how well the adjectives describe their mood. By grouping the adjective scores, the researchers could make subscale scores for:
The individuals’ level of distress was measured using the Impact of Events Scale (IES). This was used to assess the frequency of intrusive thoughts and avoidance of issues relating to the test at the time of the questionnaire or while waiting for results. A score of over 19 on this scale indicated high psychological distress.
What were the basic results?
Overall rates of psychological distress and negative mood were relatively low at all time points, and 80-95% of individuals reported levels below the clinical threshold at each stage. However, 19.4% of men reported high levels of tension-anxiety at the time of attending the biopsy and 8.9% once they had received a negative biopsy result. The proportion of men with clinical distress was higher at the time of the biopsy (19.3%) than at the earlier PSA test (0.8%).
The proportion who felt clinical levels of distress when they received negative results decreased by a small amount to 16.9%, and 12.9% still felt distress at 12 weeks. The researchers found that 23 men had undergone a second biopsy while waiting for their 12-week follow-up questionnaire. Out of the total number of men from the complete cohort who had high distress at the 12-week follow-up assessment, 18% (4 out of 22) had undergone a further biopsy.
The researchers had complete data for 195 men and were able to assess how levels of distress changed over the testing period, while waiting for results and after receiving the results. The IES distress score increased around the time of the biopsy by an average of 9.47 points compared to at the time of the PSA test. The participants had an increased score at both the time of the negative biopsy result and 12 weeks later (increase of 2.42 points) compared to the score at the time of the PSA test.
How did the researchers interpret the results?
The researchers say that “most men coped well with the testing process, although a minority experienced elevated distress at the time of biopsy and after a negative result”. They propose that “men should be informed of the risk of distress relating to diagnostic uncertainty before they consent to PSA testing”.
This study highlighted that a small proportion of men may experience high levels of distress throughout testing for prostate cancer and that this distress can persist even if the result of the test is negative.
Prostate PSA screening is not routinely carried out in the UK, due in part to some of the issues demonstrated in this study. Levels of PSA are not always a reliable indicator of possible cancer. These levels can vary between individuals and can be raised by other non-cancerous conditions, principally benign enlargement of the prostate, inflammation or infection.
The findings of this study highlight the need for all men who have their PSA level tested to be fully informed about the implications of having the test and the possible causes of a raised PSA level (i.e. that it does not necessarily mean cancer). The options pursued after testing will also vary depending on the individual and their PSA level. The PSA level may simply be monitored or other diagnostic tests may be required, such as an ultrasound scan or needle biopsy of the prostate.
This was a relatively small study which relied on patients to self-report their feelings of distress. As such, further studies using more-detailed psychological assessments may be needed to determine how the screening processes may affect mood. Establishing the psychological effects of screening may also help inform programmes of psychological support or counselling, if necessary.