Study leader Tim Eden of the University of Manchester in England said the time between the first symptoms and a diagnosis for 115 patients with bone tumors ranged from four weeks to 184 weeks, with an average time of 15.2 weeks.

A second study looked at 95 patients with a variety of tumors and found that the symptom interval -- the time from first symptom to diagnosis -- ranged from two weeks to 192 weeks, with an average of 9.5 weeks.

A third study, by Sam Smith -- a nurse consultant in the Teenage Cancer Trust Unit at the Christie Hospital in Manchester -- found that out of 207 young people with cancer who took part in an interactive survey, four out of five sought medical help very quickly and 7 percent delayed for a matter of months.

"When we compare these data with studies of children with cancer, teenagers and young adults do face greater delays in diagnosis," Eden said in a statement.

The findings were presented at the Teenage Cancer Trust's Fifth International Conference on Teenage and Young Adult Cancer Medicine.