Around one in every four teenagers with cancer went to see their doctor at least four times before they were referred to a specialist, a charity has said.
And around the same proportion never received a referral from their GP, according to a survey by the Teenage Cancer Trust.
Many of the 356 young people polled said it took a long time for them to be diagnosed - another 13% of those questioned said they were only given an appointment with a cancer specialist after visiting their GP three times, although around one in five said they were referred after just one visit.
The annual conference, billed as Find Your Sense Of Tumour, discusses issues faced by young people with cancer.
The Trust's Mike Richards said: "I get to hear what the key priorities are for teenagers and young people with cancer and this spurs me on to make sure that all services in this country are brought up to the best level."