Just under half of men in the UK admit they would put off going to the doctor if they developed warning signs of cancer, a survey has found.
The majority of testicular cancer patients are cured
The Cancer Research UK survey found only 52% would immediately go to the GP if they found blood in their stool - a common sign of bowel cancer.
Younger men cited embarrassment as the reason for the delay, while older men were worried about what might be found.
Other experts called for better monitoring of prostate cancer risk.
The Institute of Cancer Research said the current PSA (prostate specific antigen) test does not differentiate between which cancers are slow growing and which are aggressive.
It said thousands could be spared unnecessary surgery if men with slightly raised PSA levels should be monitored in case there are further increases which do need surgery.
Experts warn cancer now kills more men in the UK than any other condition.
Around 27,000 men are diagnosed with prostate cancer annually, leading to around 9,900 deaths. Bowel cancer affects 19,000 UK men each year.
Testicular cancer is relatively rare but is the most common cancer in men aged 15 to 44.
Each year, there are around 2,000 new cases in the UK. However, the cancer responds particularly well to treatment if caught early, and more than nine out of 10 patients are cured.
The NOP survey of 1,888 adults found many men said they "didn't have time" to get their symptoms checked.
A third of men said there had been at least one occasion where female partners had convinced them to make a doctor's appointment when they did not really want to.
Cancer Research UK's Man Alive campaign is aiming to promote greater awareness of the symptoms of cancers that affect men, including lung, bowel, prostate and testicular cancer.
The charity runs a cancer information helpline. It says most calls are from women, despite the fact that cancer affects similar numbers of men and women.
Julia Frater, one of the charity's senior cancer information nurses, said: "Our experience reflects the fact that men are reluctant to seek help if they have a problem with their health.
"We know that girlfriends and wives are often instrumental in encouraging their partners to get medical advice, even going as far as making appointments for them."
Dr Lesley Walker, director of cancer Information at Cancer Research UK, said data showed women under 45 were twice as likely to visit their GP over a given period than men of the same age.
She added: "It is understandable that many men are reluctant to visit their doctor.
"They are often less acquainted with GP surgeries than women.
"I would encourage all men to be aware what's normal for them and to see their GP if they are experiencing any health problems.
"Usually, symptoms turn out not to be caused by cancer. However, an early cancer diagnosis ensures all treatment options are available which can help to improve the outcome."
Jola Gore-Booth, chief executive of Colon Cancer Concern, said: "This survey shows that embarrassment and fear are still key factors in preventing men from acting upon their symptoms and that much still needs to be done to change this disturbing trend."