Liberal Senator Jim Molan has been diagnosed with an "aggressive" form of cancer and is taking leave from parliamentary duties while he receives treatment.
Senator Molan released a statement on Monday afternoon confirming he would step aside as he undergoes further testing.
"Last week I was diagnosed with an aggressive form of a cancer," he said in the statement.
"I will be taking leave from the Senate for further testing to confirm the prognosis, and to commence treatment."
The former Australian Army Major General - who is 70-years-old - said the news had come as a "shock" and has asked for privacy.
"Although I am personally stepping back for a while, my office will remain open and fully operational," he said.
"Whilst this news has come as a shock, I have many reasons to be positive. I am receiving the best possible care from my clinicians, and have the love, support and prayers of my family.
"I have never been afraid to fight the battles that need fighting, and this is no exception. I thank you for your support, and we ask for privacy at this time."
Prime Minister Scott Morrison posted a tweet on Tuesday morning sending his wishes to Senator Molan and his family.
Senator Molan was first elected in 2017 after Nationals Senator Fiona Nash was ruled ineligible under section 44 of the constitution for being a dual national.
Two years later, he was moved to the unwinnable fourth position on the Coalition's Senate ticket before the election.
However, he returned to the Senate in 2019 to fill the vacancy left by Arthur Sinodinos' departure, who took on the role of Australia's Ambassador to the United States.
Senator Molan has previously served as chief-of-operations during Australia's 2003 deployment in Iraq.
He later went on to become a special envoy for Operation Sovereign Borders under Former Prime Minister Tony Abbott.
