A trial comparing the outcomes of types of surgery for prostate cancer (CHRONOS B)

Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Prostate cancer




Phase 2/3

This trial is comparing targeted treatments on their own or in combination with other treatments for prostate cancer.     
There are 2 parts to the CHRONOS trial. This is the summary of CHRONOS B. You can read about CHRONOS A

More about this trial

There are treatments that target only the cancer in the prostate. These are:

These are called focal therapies. Some research shows that focal therapies might control the cancer just as well as treatments that treat the whole prostate gland. And that the side effects aren’t as bad. 

Researchers think that combining focal therapy with another type of treatment for prostate cancer might work just as well. 

Another treatment for prostate cancer is hormone therapy. In this trial you have a hormone therapy for a while before having a focal therapy. 

The aims of CHRONOS B are to find out:

  • if people are willing to agree to take part in a randomised clinical trial Open a glossary item comparing focal therapy only with hormone therapy followed by focal therapy
  • if the combination of hormone therapy and focal therapy is as good as focal therapy only for controlling prostate cancer   
  • what people think about the treatments
  • more about the side effects of each type of therapy
  • how each therapy affects quality of life Open a glossary item 

Who can enter

The following bullet points list the entry conditions for this trial. Talk to your doctor or the trial team if you are unsure about any of these. They will be able to advise you. 

Who can take part
You may be able to join this trial if all of the following apply. You:

  • have adenocarcinoma prostate cancer 
  • have a prostate specific antigen Open a glossary item (PSA) of 20ng/ml or less 
  • have a Gleason score Open a glossary item of 7 or 6 
  • have had an MRI scan Open a glossary item before having tissue samples (biopsies Open a glossary item) done to diagnose your prostate cancer. If you couldn’t have an MRI scan you must have transperineal mapping biopsy 
  • are at least 18 years old

Who can’t take part

You cannot join this trial if you have already had treatment for prostate cancer. 

Please note if you are already taking finasteride or dutasteride to take part in the trial you must stop taking them for 6 months before being put into a treatment group.  

Trial design

This is a phase 2/3 trial. In total the researchers need 1,320 men to join. 

There are 2 stages to CHRONOS B. 

In the 1st stage the team need 60 people to join. This is a pilot study to find out whether people are willing to join the trial and be put into treatment groups. 

In this part when you see your doctor to talk about the trial a member of the research team will ask to record the appointment on audio tape.  

The research team member might also ask to interview you. The team will arrange the interview for a time and place that is convenient to you.

You don’t have to agree to your appointment being taped or to the interview if you don’t want to. You can still take part in the trial. 

The 2nd stage of CHRONOS B will open if stage 1 is successful. 

Those who do join part 1 continue into part 2. 

In the 2nd stage of CHRONOS B the team need a further 1,260 men to join. 

This is a randomised trial. You are put into a treatment group. Neither you nor your doctor can choose which group you go into. There are 3 groups:

  • focal therapy only
  • finasteride then focal therapy
  • bicalutamide then focal therapy  

There are 2 types of focal therapy:

Your doctor will talk to you about which is the best one for you. 

HIFU uses high frequency sound waves to target the cancer cells. The waves create heat that destroys the cancer cells. 

To have treatment your doctor puts an ultrasound probe into your back passage (rectum). This probe gives out high intensity ultrasound energy that can destroy the cancer cells in your prostate. The high intensity ultrasound energy travels through the back passage to the prostate. 

You have HIFU as a day case. It takes about 1 to 3 hours. You have a general anaesthetic Open a glossary item so you’re asleep when you have treatment. Before you start treatment your doctor puts a tube (urinary catheter) into your bladder through the hole in your penis. This might stay in for up to a week to drain urine from your bladder. A nurse will show you how to care for the catheter if you do go home with it. 

Cryotherapy uses extreme cold to destroy cancer cells. The doctor puts thin needles into your prostate. The needles go in through the area between your anus and testicles (perineum). They then pass a special gas down the needles into your prostate. 

You have cryotherapy as a day case. It takes 1 to 3 hours. You have either anaesthetic into the fluid around your spinal cord Open a glossary item (spinal anaesthetic) or a general anaesthetic.

Before they start the cryotherapy treatment your doctor puts a tube (warming catheter) through the hole in your penis into your bladder. This helps protect the tube where urine passes (urethra) from possible damage.   

You might need to have another treatment of HIFU or cryotherapy. This will be a year after the first treatment if an MRI scan shows that cancer might still be in the prostate. 

Finasteride is a hormone therapy. It is a treatment for men with enlarged non cancerous prostate glands to help with leakage of urine and other urine problems.

Finasteride is a tablet. You take it once a day for 3 months before your focal therapy. 

Bicalutamide is a hormone therapy. It is a treatment for prostate cancer in people who aren’t fit enough to have surgery or radiotherapy. Some people have it in combination with radiotherapy. 

Bicalutamide is a tablet. You take it once a day for 3 months before your focal therapy. 

Quality of life questionnaire
You fill in a questionnaire:

  • before starting treatment
  • during treatment 
  • for up to 5 years after treatment

The questions ask about:

  • any side effects 
  • your daily activities
  • general heath

You can choose to fill the questionnaire in:

  • when you see your doctor 
  • by telephone – a member of the research team will call you
  • by email – to a secure NHS account

Extra samples for research
You give extra blood and urine samples before and during treatment. 

You have prostate tissue samples (biopsies) taken as a part of your routine care. Your doctor takes these when you are diagnosed and at times during your treatment. The research team want a small piece of these biopsies. 

Researchers want to use these samples to help improve the diagnosis and the treatment of prostate cancer. 

Imaging scan information
As a part of the trial you have scans of your prostate to see how treatment is working. The research team want to store these scans and use them to see if there is a better way to identify prostate cancer. 

You don’t have to agree to this. You can still take part in the trial. 

Health information
The team want to know what happens to your health after the trial has finished. They do this by looking at your health records held by the NHS. 

You don’t have to agree to this. You can still take part in the trial. 

Hospital visits

You see the doctor for some tests before taking part. These tests include:

  • physical examination
  • blood test
  • urine test
  • PSA blood test
  • MRI scan if you are in the focal therapy group and haven’t already had an MRI scan using a contrast dye Open a glossary item

You see the doctor after treatment at:

  • 3 months
  • 1 year and then
  • every 6 months for 5 years

You have the same tests as before. 

You have an MRI scan at 1 year and tissue samples (biopsies) taken. You might have another treatment of focal therapy if the scan shows areas that might be cancer.  

Please note
If the pilot study (stage 1 of the trial) is not successful then the larger trial won’t go ahead. In this case people in the pilot study are followed up by the team for at least  3 months. After this you have routine follow up which your doctor will tell you how often that is. 

Side effects

The trial team monitor you during treatment and afterwards. Contact your advice line or tell your doctor or nurse if any side effects are bad or not getting better. 
Side effects during and immediately after HIFU or cryotherapy can include:

  • discomfort from the tube (catheter)
  • urine infection that can cause stinging or poor flow – can last for up to 8 weeks
  • infection of the testicles
  • discomfort of the back passage
  • problems getting an erection which is temporary commonly lasting for a few weeks
  • not been able to pass urine which is temporary but might need a tube (catheter) put in to help pass the urine

The common side effects 6 months after HIFU or cryotherapy can include:

  • leakage of urine (incontinence) when doing exertion for example physical work
  • problems getting an erection
  • no semen or reduced amount of semen produced by your testicles 
  • narrowing to the tube (urethra) that carries urine from your bladder through your penis to outside your body

We have information about:

The common side effects of bicalutamide can include:

  • tiredness
  • a decrease in the desire for sex (sex drive)
  • weight gain
  • swelling of breast tissue and tenderness

We have information about bicalutamide and its side effects.

Side effects of finasteride can include:

  • tiredness
  • a decrease in the desire for sex (sex drive)

Your doctor or a member of the trial team will talk to you about the side effects of all the treatments in this trial before you agree to take part. 

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Hashim Ahmed

Supported by

Imperial College London
Prostate Cancer UK
Imperial Clinical Trials Unit (ICTU)

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Last reviewed:

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