(AAP) -- Young people with a sibling who has cancer are more prone to depression and psychological distress, a new Australian study has found.

CanTeen, the Australian organisation for young people with cancer, found those aged 12 to 24 were not supported by the health care system.

Adolescents aged 12 to 17 were particularly distressed, clinically and psychologically, and two-thirds of participants needed to talk and spend time with other young people who had been through similar experiences.

A disproportionately high number of young adults aged 18 to 24 had depression levels in the at-risk clinical range and needed professional help, the study found.

Affected households found family dynamics changed.

Study author and CanTeen National Research and Evaluation Manager Dr Pandora Patterson said the siblings felt like bystanders as their parents' attention went to the patient.

"Along with the stress they are already feeling about their brother or sister being ill, this is all placing extra pressure on them, especially as two thirds report feeling guilty about talking of how they were coping," Dr Patterson said.

The study interviewed 71 siblings of cancer sufferers, including 20-year-old Catherine who said she wants "To learn how to continue to have fun, to grow and develop without feeling guilty, there were times when I never thought I would smile again."

CanTeen has also released a booklet "Now What? Dealing with your brother or sister's cancer" and website www.nowwhat.org.au

It aims to help young people with practical advice.

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