Prostate cancer referrals have halved since the beginning of lockdown as thousands of men put off seeing their GP.
In total 27,000 fewer men have been referred to a specialist with suspected cases compared to the same period last year, according to analysis of official NHS data by Prostate Cancer UK.
Urgent GP referrals for prostate cancer have now plunged to their lowest level in ten years due to the devastating impact of Covid-19.
Experts say the delays mean around 3,500 men with advanced prostate cancer have not yet been diagnosed, putting their lives at risk.
Early diagnosis dramatically raises survival chances, but it is now feared that coronavirus could undo years of progress in treatment and diagnosis of the deadly condition.
Prostate cancer became the UK's most commonly detected cancer earlier this year, following a surge in men getting tested.
The Daily Mail has spent 20 years campaigning to raise awareness of prostate cancer, to prevent thousands of men dying needlessly after being too slow to report symptoms out of embarrassment or fear.
Urgent GP referrals for prostate cancer have plunged to their lowest level in ten years (stock image)
Latest figures showing there are around 57,000 new prostate cancer cases and 12,000 deaths each year in the UK.
But the number of men referred to see a specialist after going to their GP with symptoms plummeted by 49.5 per cent during lockdown.
Prostate Cancer UK said 27,000 fewer patients than would be expected were referred to see a specialist over the three-month period from April to June, including around 3,500 with high-risk cancer.
Angela Culhane, Chief Executive of the charity, said: 'Detecting prostate cancer earlier helps save lives, but Covid-19 has made it harder for men to visit their doctor this year - especially if they don't feel unwell or have no symptoms. As a result, we estimate there could be 3,500 men in England with a higher-risk prostate cancer which has not yet been diagnosed.
'If we don't act now, we could face a future where thousands of men are diagnosed too late, when the cancer has advanced to a stage that cannot be cured.
'Most men with early prostate cancer don't have any symptoms, so it's important not to wait until you notice something's wrong.'
Prostate cancer often has no symptoms, but some men experience changes including pain during urination.
The charity is calling for men to check their risk of prostate cancer using a 30-second online test.
Those who are over 50, black or have a family history of prostate cancer are more at risk and are urged to discuss the pros and cons of a 'PSA' blood test with their GP.
If this suggests they are at risk, patients will be referred to hospital for further diagnostic tests which can include an MRI scan or a biopsy. They should be seen by a consultant within two weeks.
Ms Culhane added: 'Some areas have been hit especially hard by the pandemic, and it's critical that men feel safe calling their GP. Most GP surgeries offer phone and video consultations, and men need to be reassured that the hospitals their GP may refer them to will be safe and not put them at undue risk from Covid-19.'
The NHS data show that referrals