Regular blood tests for prostate cancer patients could significantly improve their chances of long-term survival, new research suggests.
Having blood tests before and during chemotherapy could help doctors detect whether or not their patient is resistant or developing resistance to docetaxel – a commonly-used drug.
This could allow them to switch the patient to other drugs to treat their cancer, without the need for painful biopsies.
Men with prostate cancer that has started to spread to other parts of the body are often treated with docetaxel, a chemotherapy that can significantly improve survival.
Having blood tests before and during chemotherapy could help doctors detect whether or not their patient is resistant or developing resistance to docetaxel – a commonly-used drug
As part of the new study researchers at Barts Cancer Institute at Queen Mary University of London looked at markers of cancer in the blood known as circulating tumour cells (CTCs).
CTCs are cancer cells that have entered the bloodstream from either the original cancer site or from tumours around the body where the cancer has spread.
The scientists took blood samples from 56 patients with advanced prostate cancer who were being treated at St Bartholomew’s Hospital in London.
The samples were taken over six to eight months and covered the time before the patients started docetaxel treatment, after their first dose of chemotherapy, before their fifth dose and once they had finished all doses.
Specifically, they looked for patterns in the data from men who had responded to the treatment and those who did not, and whose cancer further advanced and at what speed.
Results revealed among men who had more than six CTCs detected per 7.5ml of blood before their second chemotherapy dose, their disease was more likely to recur or progress within three months and they were more likely to die within 18 months.
On the other hand, men who had fewer than six CTCs per 7.5ml of blood were likely to survive for 17 months without their cancer progressing and had an overall survival time of three years.
High numbers of CTCs towards the end of treatment also indicated that men were more likely to see a rapid spread of their cancer and an earlier death.
Caitlin Davies, who led the study, said: ‘Using these patterns, we can apply them to future patients with the goal to predict whether they will respond to therapy and pre-emptively decide on the best course of action that will have maximal benefit.
‘For instance, an increase in CTC numbers may indicate a lack of response to treatment.
‘Furthermore, by monitoring the appearance of potentially drug-resistant CTCs, we can change treatment tactics early on and in a patient-personalised and timely manner.’
Tissue biopsies are currently used to indicate how aggressive prostate cancer might be, and how likely it is to spread to other parts of the body. However these can be painful, and results can take up to 10 days.
However testing for CTCs in blood samples, also known as a liquid biopsy, is painless and easily repeatable, with results within two to three days.
The scientists are now looking at how a clinical trial in patients could help them validate their findings, which were presented at the National Cancer Research Institute festival.
Hashim Ahmed, chair of the NCRI prostate group and professor of urology at Imperial College London, said: ‘These are promising results and have the potential to change clinical practice, if they are confirmed by further research.
‘Assessing the responsiveness of an individual patient’s tumour to docetaxel treatment by means of blood tests will enable clinicians to personalise cancer treatment more easily and effectively, without the patient having to undergo invasive procedures such as tissue biopsies.
‘It could also help to avoid patients undergoing unpleasant systemic treatments that are going to be unsuccessful.’
WHAT IS PROSTATE CANCER?
How many people does it kill?
More than 11,800 men a year – or one every 45 minutes – are killed by the disease in Britain, compared with about 11,400 women dying of breast cancer.
It means prostate cancer is behind only lung and bowel in terms of how many people it kills in Britain.
In the US, the disease kills 26,000 men each year.
Despite this, it receives less than half the research funding of breast cancer and treatments for the disease are trailing at least a decade behind.
How quickly does it develop?
Prostate cancer usually develops slowly, so there may be no signs someone has it for many years, according to the NHS.
If the cancer is at an early stage and not causing symptoms, a policy of ‘watchful waiting’ or ‘active surveillance’ may be adopted.
Some patients can be cured if the disease is treated in the early stages.
But if it diagnosed at a later stage, when it has spread, then it becomes terminal and treatment revolves around relieving symptoms.
Thousands of men are put off seeking a diagnosis because of the known side effects from treatment, including erectile dysfunction.
Tests and treatment
Tests for prostate cancer are haphazard, with accurate tools only just beginning to emerge.
There is no national prostate screening programme as for years the tests have been too inaccurate.
Doctors struggle to distinguish between aggressive and less serious tumours, making it hard to decide on treatment.
Men over 50 are eligible for a ‘PSA’ blood test which gives doctors a rough idea of whether a patient is at risk.
But it is unreliable. Patients who get a positive result are usually given a biopsy which is also not foolproof.
Scientists are unsure as to what causes prostate cancer, but age, obesity and a lack of exercise are known risks.
Anyone with any concerns can speak to Prostate Cancer UK’s specialist nurses on 0800 074 8383 or visit prostatecanceruk.org