Gary Clifford Hughes, 47, is undergoing radiotherapy for throat cancer while on remand in Long Bay jail, the court heard.

Hughes pleaded guilty to six counts of supplying drugs and single counts of supplying drugs on an ongoing basis, possessing a pistol and dealing with the proceeds of crime.

He will face Newcastle District Court next week.

Strike Force Galvin was established in January last year to investigate the supply of heroin and the drug ice by Hughes's team of dealers, a statement of facts said.

After five months of intercepting the syndicate's telephone services plus conducting a series of undercover operations and surveillance, Hughes, his de facto partner Krisann Caines and several others were arrested in May last year.

Hughes had a home in Scenic Drive, Caves Beach, and another in Elizabeth Street, Sydney.

Police found a loaded .45 calibre pistol in a holster under the mattress Hughes slept on in the Elizabeth Street house as well as more than $20,000 cash in a safe and a dresser drawer and $1710 in Hughes's wallet.

Hughes supplied at least 130 grams of heroin and 111 grams of ice while under investigation, the statement said.

He used Caines to carry drugs from Sydney to the Newcastle where the drugs were distributed to several street-level dealers.

Hughes also had at least 10 personal customers.

An undercover police officer and a registered police source conducted five heroin deals with one of Hughes's dealers in April and May last year, each worth $5000 or $6000.

On each occasion the dealer went to Hughes or Hughes's home to get the drugs.

Caines, 30, from Cronulla, and several other members of the syndicate are awaiting sentence in the District Court.