This piece explains why a new at‑home DNA risk tool has entered UK debate. BARCODE 1, published in the New England Journal of Medicine, assessed an at‑home spit sample that builds a polygenic risk score (PRS) to flag men at higher risk of prostate cancer. It is a genetic risk calculator rather than a simple yes/no diagnostic.
The process involves posting a small spit sample for DNA analysis. Results estimate future risk and help select who might need earlier screening.
Accuracy here means how well the PRS finds a high‑risk group in whom follow‑up screening uncovers cancers — not a replacement for MRI or biopsy. The headline figures show added value compared with PSA blood measurement for some men.
The article is an evidence‑led explainer that separates results from hype. Readers will learn how the PRS is built, what the trial shows, how PSA compares, and what NHS plans such as the TRANSFORM trial may mean for future screening.
Key Takeaways
- BARCODE 1 used an at‑home spit route to produce a polygenic risk score.
- The tool estimates genetic risk and does not diagnose disease directly.
- Results suggest it may improve selection for further screening alongside PSA.
- The evidence is preliminary; NHS evaluation continues via TRANSFORM.
- Improved risk tools aim to identify men who should be investigated sooner.
Why the saliva ‘spit test’ is making headlines in the UK
A UK research collaboration has put a home-collected DNA risk measure in the spotlight. Researchers at the Institute of Cancer Research, London, and the Royal Marsden NHS Foundation Trust reported BARCODE 1 results showing a polygenic risk score derived from a postal sample can better identify some men at higher future risk than the PSA blood check.
What the Institute of Cancer Research and Royal Marsden NHS teams announced
The teams said the approach can be done at home and still produce useful genetic risk information. This drew media attention because it could help target clinic resources and reduce unnecessary appointments.
Why screening needs tools beyond the PSA test
PSA remains part of GP pathways: risk assessment, GP testing and onward referral for imaging and biopsy. But PSA has limits — many raised results are false positives and some cancers occur despite a normal PSA reading.
That combination of false alarms and missed cases explains why the new tool is seen as a potential addition rather than a direct replacement. For patients and GPs, a better risk-based strategy could mean fewer unnecessary scans and earlier diagnosis of those at higher baseline risk.
- Practical point: the new approach aims to refine who should be invited for further screening.
- Policy note: there is no national screening programme in the UK, so targeted tools are of active interest.
What the BARCODE 1 study tested and who took part
BARCODE 1 used a mailed home kit so participants could provide a small spit sample, making DNA collection simple and scalable.
At-home sample collection and DNA extraction
Men returned the kits by post. Labs extracted DNA and ran genetic analysis to produce a combined risk score.
The men included
The study analysed material from 6,142 European-heritage men aged 55–69, recruited through GP surgeries. This age group was chosen because risk rises and screening impact is greater.
How polygenic risk scores are built
A polygenic risk score (PRS) adds together the tiny effects of many inherited changes. BARCODE 1 used 130 genetic variants linked prostate cancer, based on datasets of hundreds of thousands of men.
Key point: the PRS estimates genetic risk and the trial then checked whether targeting high-risk men raised cancer detection on follow-up. A limitation is that the research focused on men of European ancestry, so broader validation is needed.
| Item | Value | Notes |
|---|---|---|
| Participants | 6,142 men | Age 55–69; recruited via GP surgeries |
| Sample type | Spit (mailed) | Home collection enabled scale |
| Variants used | 130 | Derived from large genetic studies |
| Score purpose | Estimate genetic risk | Used to target high-risk men for follow-up |
Saliva test for prostate cancer accuracy: what the results show
BARCODE 1 used a risk-first pathway that moved only the men at highest genetic risk into imaging and biopsy. This approach measured how well inherited scores flag people who actually have disease on clinical follow-up.
High-risk identification and invitations
The study invited the top 10% by polygenic scores to undergo MRI and biopsy. By concentrating resources on a small group, the trial tested whether genetic selection can better identify men highest risk than broad screening.
Detection after MRI and biopsy
After targeted MRI and biopsy, around 40% of those invited were diagnosed — 187 men in the reports. That is a high detection yield compared with typical population screening.
How many cancers PSA could miss
A striking finding was the number with a normal PSA level. Sources report roughly 63.1% (118/187) in one analysis and 77.8% (147/187) in another had PSA below 3.0 µg/L.
This suggests PSA alone can miss a large share of tumours in men with high genetic risk, supporting the idea that a genetic risk filter helps identify men who need further assessment.
Aggressive disease detection
Importantly, PRS-identified cancers included a higher proportion of clinically significant or aggressive cancers (55.1%) versus 35.5% in a recent PSA-based study. The score therefore picked up more serious disease, not only low-grade lesions.
Important nuance: the genetic score does not diagnose aggressive cancers by itself; it prioritises who should receive definitive tests such as an MRI scan and biopsy.
How it compares with the PSA blood test
Clinicians compare the familiar PSA blood check with a genetic risk score to see which better guides follow-up care.
False positives and overdiagnosis
PSA can give false alarms. Around three out of four raised results do not indicate a dangerous condition. That leads to many men being offered an MRI scan and sometimes an invasive biopsy.
Overdiagnosis is also a concern. PSA can detect slow-growing tumours that may never cause symptoms, creating pressure to treat when monitoring might suffice.
PSA thresholds and what “raised” means
In UK reports a common reference level is 3.0 µg/L. Above that, clinicians often discuss onward imaging or referral.
That threshold influences who enters further screening and who remains under routine care.
Where the PRS approach adds value
The polygenic route acts as a stratification tool. BARCODE 1 suggests it may flag men higher risk who a PSA check alone might miss.
“Using inherited-risk information can focus scarce NHS resources on those most likely to benefit.”
| Measure | Typical outcome | Practical impact |
|---|---|---|
| PSA blood check | Many false positives (≈75%) | More MRI scans and biopsies |
| PRS genetic score | Targets men higher risk | May reduce unnecessary scans |
| Combined approach | Higher yield of clinically significant disease | Smarter screening and resource use |
More accurate than an MRI scan for some high genetic-risk men
In men flagged as high genetic risk, BARCODE 1 found that MRI did not spot a large share of biopsy-confirmed disease. This surprising result shows imaging has limits when used in a targeted pathway.
Biopsy-confirmed cancers that MRI did not detect
Key statistic: roughly two-thirds of biopsy-proven prostate cancer cases in the high-risk group were not seen on MRI—reported as 66.8% (125 men) and 63.6% (119 men) in different analyses.
What “MRI missed” means: the scan showed no suspicious lesion, yet biopsy found cancer. MRI therefore cannot be treated as a definitive rule-out in these men.
- The finding emphasises that genetic selection and imaging serve different roles.
- A combined pathway can direct who needs further assessment even after a negative mri scan.
- Relying on MRI alone in high-risk men could leave many cancers undetected.
| Measure | Result | Implication |
|---|---|---|
| High-risk group | Top decile by genetic score | Targeted imaging and biopsy |
| Missed by MRI | ≈64–67% of biopsy cases | Scan not definitive |
| Practical point | Combined approach | PRS helps decide who should have biopsy despite a negative mri |
Who the test may help most and what it means for risk-based screening
New genetic tools seek to distinguish which men need earlier investigation from those who can be safely monitored. The aim is to concentrate NHS resources on men most likely to develop clinically important disease.
Targeting age, ethnicity and inherited risk
Discussion in the UK centres on age (mid‑50s onward), ethnic background and inherited genetic risk. These factors combine to help identify men who may benefit from more frequent checks or earlier imaging.
Extending to diverse ancestry groups
BARCODE 1 focused on men of European heritage. The Institute of Cancer Research has since developed PRODICT® to perform better in Asian and African ancestry groups. This work matters because Black men are about twice as likely to be diagnosed with prostate cancer.
Related studies shaping evidence
PROFILE and other projects are examining risk markers in Black men and those with a family history. Ongoing cancer research will help refine which men higher risk need targeted follow-up.
What a national programme could look like
A future UK screening pathway might start with a simple risk assessment that includes genetics, then offer tailored screening intervals and focused use of MRI and biopsy. These studies are guiding that direction, but routine access to a spit test is not yet standard NHS practice.
What happens next: TRANSFORM trial, NHS impact and timelines
The £42m TRANSFORM trial will compare inherited-risk screening directly with current NHS approaches. It is funded and instigated by Prostate Cancer UK and partly led by the Institute of Cancer Research team. The trial will run head-to-head, assessing genetic risk via a mailed kit, PSA blood checking and MRI pathways.
How the trial will compare approaches
The design tests which route, or combination, best finds clinically important disease and reduces unnecessary procedures. TRANSFORM will measure detection rates, false positives and downstream resource needs.
Potential benefits and projected NHS impact
Researchers estimate the programme could identify up to 12,350 people earlier and save the NHS around £500m a year. These are projections, not guaranteed outcomes, but they frame why the trial is decisive.
Expert views, practical steps and timelines
Prostate Cancer UK stresses that the PSA blood check remains the best available, accessible option via GPs today. If TRANSFORM shows clear gains, national rollout would need peer review, guideline updates and expanded MRI and biopsy capacity.
“TRANSFORM is designed to establish the most accurate and cost-effective screening pathway for the NHS.”
| Aspect | TRANSFORM aim | Projected figure |
|---|---|---|
| Earlier identification | Find clinically significant disease sooner | Up to 12,350 people |
| Estimated savings | Reduce unnecessary procedures and costs | ≈£500m per year |
| Policy step | Evidence to inform NHS roll-out | Depends on results, review and planning |
Conclusion
The trial indicates inherited-risk screening may sharpen who receives further assessment. In short, the BARCODE 1 approach looks promising as a risk tool, not a standalone diagnosis.
The study showed a high detection yield — about 40% in the top genetic-risk group — and many tumours occurred at normal PSA levels. MRI also missed a notable share of biopsy-confirmed cases, underlining limits of imaging alone.
If larger trials confirm benefit, screening could shift to fewer unnecessary investigations and earlier, focused diagnosis for men at higher risk. For now, PSA remains the routine NHS test and postal saliva kits are still under evaluation by the Institute Cancer Research and partners.
Men with concerns should discuss personal risk and next steps with their GP.
