NRL star Jon Mannah's tragic battle with cancer has been linked to the use of peptides.
The Cronulla Sharks prop was just 23 when he died from Hodgkin's Lymphoma in January.
Now, an independent report into the Sharks' supplements program has referred to an "identified causal link" between peptides CJC-1295 and GHRP-6 and Mannah's cancer relapse in late 2011, the Daily Telegraph reports.
The report, compiled by Australian Sports Anti-Doping Authority (ASADA) former deputy chair Tricia Kavanagh, said that a number of Cronulla players were "administered" with the performance-enhancing drugs in early 2011.
Peptides are often legitimately used by athletes as protein supplements to aid recovery, but the CJC-1295 and GHRP-6 strands are types of human growth hormones and are therefore banned by the World Anti-Doping Agency.
Kavanagh's 60-plus page report, obtained by the Daily Telegraph, said: "Based on the chronology it appears Mannah was administered with substances including CJC-1295 and GHRP-6 during the period from March to May in 2011.
"A brief review of available published medical literature suggests an identified causal link between the use of substances such as CJC-1295 and GHRP-6 and the acceleration of the condition of disease Hodgkin's lymphoma.
"Without knowing anything further about Mannah's exact medical history and without seeking expert opinion from an appropriately qualified oncologist it is difficult to take this issue further."
One of the Sharks' previous directors was so concerned about these comments about Mannah, according to the Telegraph, that he sought advice of independent oncologists for further medical guidance.
The newspaper did not say how those oncologists responded, but it did quote a leading sports physician and inaugural chairman of the National Drugs in Sport Committee, Peter Larkins, who said any attempt to treat a previous cancer sufferer with growth hormones was "an absolutely indefensible thing to do".
"Cancers [are] uncontrolled multiplication of the body's cells," Dr Larkins was quoted as saying.
"If I had any player or any patient that had any history of any cancer process, the last thing I would even contemplate giving them is anything that increased cell growth."
He added that taking peptides was even more risky because the supplements are untested and could have dangerous side effects.
The Sharks has reportedly handed Kavanagh's report over to the ASADA and the NRL.
The ASADA is currently investigating some NRL and AFL clubs over the use of performance-enhancing drugs.
Stephen Dank, a sports scientist recruited by the Sharks at the beginning of the 2011 season, reportedly did not respond to the Telegraph's questions about whether he or any of his staff ever administered peptides to Mannah.
Mr Dank has previously claimed he has never given banned drugs to NRL players and has started legal action against news outlets for $10 million in damages over their reporting of the issue.
Trent Elkin, the former Sharks head trainer who recruited Mr Danks, has also said he has "never condoned the use of performance-enhancing drugs and I have not ever knowingly worked with anyone who did."