Reason Party Leader and Victorian upper house MP Fiona Patten has been diagnosed with cancer and will undergo surgery in coming weeks to remove one of her kidneys.
In a statement, Ms Patten said her prognosis was good.
"The belief is that the disease has not spread and that I should make a quick and full recovery," she said.
"So many of us are touched by cancer these days – as patients, friends, relatives, carers, and health and medical staff. I have wonderful support medically and personally and realise how lucky I am in this respect."
Ms Patten acknowledged that the timing of her diagnosis was "unfortunate", with the Victorian state election coming up in November.
She said she plans to continue campaigning for the election.
"The surgery will interrupt my election campaign a little and no doubt I will be campaigning for some of that time from a hospital bed," she said.
Ms Patten was first elected in the Northern Metropolitan Region in 2014.
She has pushed for social reforms including voluntary assisted dying laws, the decriminalisation of sex work, and safe access zones to abortion clinics.
Ms Patten said many people who are diagnosed with cancer can't afford private health insurance or the best medical care.
"Many people stay silent upon a cancer diagnosis and are fearful of telling people because they will be judged or pitied. I want people to be able to talk about their health, be that physical or mental," she said.
"I hope that by being public and transparent it might help others do the same."
