Hove MP Mike Weatherley will not stand for re-election next year.
The Hove MP has announced in the past few minutes that he will not be standing for re-election in May 2015.
In a letter to Prime Minister David Cameron written by the MP and seen by The Argus, the 57-yeard-old said he had taken the decision after "profound consideration".
He wrote: "It goes without saying that my years representing the wonderful people of Hove and Portslade have been one of the most fulfilling periods of my life which I will look back on with very fond memories.
"I have made so many friends over the years including so many of my loyal supporters both in and out of Brighton & Hove Conservatives. I cannot thank them enough.
"Ultimately, beating cancer two years ago has led me to review what I want for the future.
"It has been the toughest decision of my life but I do feel that now is the time to move on."
Mr Weatherley also offered to continue in some capacity as the PM's adviser on intellectual property rights.
Linda Freedman, chairwoman of Brighton and Hove Conservatives, said: “We all incredibly sad that Mike won’t be restanding.
"He has been a seriously effective representative for Hove and Portslade over the past four years.
"Nothing stands still in politics though so our discussions as to what happens next are already far advanced.
"We’ll be making an announcement on this point shortly.”