Pat Smullen has revealed that he will be unable to ride his Champions Race for Cancer Trials Ireland next month as he is to undergo chemotherapy following a health setback.

The nine-time Irish champion jockey was diagnosed with pancreatic cancer in March of last year and has been undergoing treatment since, and admitted his decision to retire earlier this year was a "simple one".

The 42-year-old was to ride on day two of Longines Irish Champions Weekend on Sunday 15 September and says he is "bitterly disappointed" to confirm his absence.

"On advice from my medical team I am unable to ride in the Champions Race for Cancer Trials Ireland," he said.

"I am bitterly disappointed not to be able to take part in this very special race – I was really looking forward to riding against such a brilliant group of champions, especially at The Curragh.

"I've spoken to Horse Racing Ireland who are helping me with the fundraising activity over Longines Irish Champions Weekend and I am more determined than ever that the fundraising activity goes ahead as pancreatic cancer needs more awareness now than ever before."

The Pat Smullen Champions Race for Cancer Trials Ireland will take place at The Curragh with nine champions - AP McCoy, Ruby Walsh, Charlie Swan, Johnny Murtagh, Richard Hughes, Paul Carberry, Joseph O'Brien, Kieren Fallon and Ted Durcan all making a return to the saddle.

There will also be a number of other fundraising activities happening over the weekend for Cancer Trials Ireland – the leading cancer research trials organisation.

Cancer Trials Ireland has two pancreatic trials ready to start - one is a trial of a new drug and another in radiotherapy, and all proceeds raised over Longines Irish Champions Weekend will ensure that they start as soon as possible.