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A trial looking at dutasteride as a possible prostate cancer treatment (MAPPED)
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This trial looked at whether dutasteride can shrink prostate cancer in men whose doctors are closely monitoring their cancer (active surveillance).
More about this trial
Some men have slow growing prostate cancer that may never need treatment. They see their doctor regularly for blood tests, rectal examinations and biopsies. They have treatment aimed at curing their cancer (radical treatment) if there are signs that it has started to grow. This approach is called active surveillance. It means men can avoid side effects of treatments they don’t need.
In this trial, the research team looked at a drug called dutasteride (Avodart). It is already used for men with an enlarged prostate who have problems passing urine. We know from research that men with an increased risk of prostate cancer who take dutasteride for 4 years, are less likely to have a biopsy that shows cancer.
The research team hoped dutasteride would help control early stage prostate cancer, or maybe even shrink the cancer. This may mean that men could stay on active surveillance and avoid radical treatment for longer.
In this trial, men had either dutasteride or a dummy drug (placebo). They also had a series of scans, including a powerful type of MRI scan. This type of scan can measure the volume of cancer in the prostate.
The aim of the trial was to see if dutasteride can reduce the volume of prostate cancer seen on MRI scans.
Summary of results
This trial showed that dutasteride can help reduce the volume of prostate cancer in men having active surveillance.
The trial recruited 40 men with low or intermediate risk prostate cancer. This means their cancer is unlikely to grow for some years. So they could have active surveillance, and didn’t need radical treatment aimed at curing their prostate cancer at this stage.
The people taking part were put into 1 of 2 groups at random, and:
- 20 men took dutasteride tablets every day for 6 months
- 20 men took dummy (placebo) tablets every day for 6 months
Neither the men taking part nor their doctors knew who was taking which tablets. This is called a double blind trial.
Everyone taking part had scans before they started treatment, at 3 months and at 6 months. The research team compared the size of the prostate cancer for each man, before and after treatment. They measured the volume of the prostate cancer in millilitres (ml).
The results showed that the average size of the prostate cancer had:
- decreased from 0.55ml to 0.38ml in the dutasteride group
- increased from 0.65ml to 0.76ml in the placebo group
In the dutasteride group, the prostate cancer had:
- got smaller in 15 out of 20 men
- stayed the same in 5 out of 20 men
- not grown in any of the men
In the placebo group, the prostate cancer had:
- got smaller in 2 out of 20 men
- stayed the same in 13 out of 20 men
- grown in 5 out of 20 men
The men taking part had a combination of 3 types of MRI scan. This is called a multi parametric MRI (mpMRI) scan. The scans look at the blood supply and the number and type of cells, as well as the shape and size of the cancer.
Doctors compared the same area of cancer on the different scan results, to see how accurate they were.
The results showed that the area of cancer was more difficult to see on the results of one of the MRI scans in men taking dutasteride, but not in men taking the placebo. This scan is called diffusion weighted imaging, or DWI, and looks at the number of cancer cells and healthy cells.
The research team suggest that the doctors who read DWI scans should be told if men are taking dutasteride. This would mean they could make allowances for the cancer being harder to see.
The team also looked at the blood level of prostate specific antigen (PSA) in the men who took part. They found that it:
- went down in all 20 men in the dutasteride group
- went down in 2 out of 20 men, and up in the other 18 men in the placebo group
No men taking part in this trial had any serious side effects. Some men had a decrease in erectile function. This affected 5 out of 20 men (25%) in the dutasteride group, and 3 out of 19 men (16%) in the placebo group (one man didn’t return the questionnaire).
The trial team concluded that dutasteride reduced the size of prostate cancer in men who were suitable for active surveillance. They also suggest that the scans they used in this trial could be used to assess other treatments for this group of men.
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (
How to join a clinical trial
Professor Mark Emberton
Clinical Imaging Centre
NIHR Clinical Research Network: Cancer
University College London (UCL)
University College London Hospitals NHS Foundation Trust