Andrew was 14 when he vanished on September 14, 2007.
He left his home at Balby at about 8.30am, withdrawing £200 from his bank account, and boarded a GNER train bound for London King's Cross
CCTV showed Andrew, who was wearing a Slipknot t-shirt and carrying a shoulder bag on the day of his disappearance, arriving at the station at 11.20am.
He hasn't been seen since.
Andrew was wearing glasses, and had brown, collar-length hair when he disappeared.
Detective Chief Inspector Joanne Bates said the force had conducted exhaustive inquiries to try and locate him.
“Andrew’s family, friends and school have all been spoken to on numerous occasions and Andrew’s DNA and fingerprints circulated, as well as his dental and health records, to appropriate agencies and organisations in a bid to trace his whereabouts," she said.
“We have looked into the lens manufacturers for Andrew’s optician’s prescription to try to identify anyone requesting similar prescriptions, and inquiries have been made with the passport office and National Insurance records for any applications for documents.
"A behavioural investigative analyst has also been consulted as part of the investigation in an attempt to shed light on Andrew’s reasons for leaving home, and to discover any new possibilities of people or places he may have gone to.
DCI Bates said Andrew knew many parts of London.
“Andrew had a familiarity with London tourist attractions including Westminster Palace, the London Eye, Leicester Square, Trafalgar Square, Tottenham Court Road, Covent Garden, the subway under the river, Greenwich - the park and village - south Kensington, and the Cutty Sark," she said.
"All possible lines of inquiry have been investigated in relation to these areas."
She urged anyone with information to come forward.
“I would ask anyone, maybe new friends, neighbours or work mates, who believes they know a 24-year-old man that could be Andrew, but aren’t aware of his past beyond the last few years to please make come forward," DCI Bates said.
"In addition, any professionals, including doctors, dentists or hospital staff who may have treated a 24-year-old man who has no records going back beyond the last 10 years, you could hold information that proves vital to locating Andrew.
"I would ask you to please make contact with police."
She appealed to Andrew himself to come forward.
“And to Andrew, a personal appeal, please contact us, completely confidentially, and let us know you are safe and well and we can reassure your family you have come to no harm," DCI Bates said.
Anyone with information is asked to call South Yorkshire Police on 101, quoting incident number 161 of September 13, 2017.