The 45-year-old Labor MP, who won the south-east suburban Melbourne seat of Dunkley at the May 18 election, has vowed her "fighting spirit" will get her through.

Sworn in as a new MP just 15 days ago, she received the "unexpected news" last week that her cancer had returned.

"While this has come as a shock, my doctor advises me that my condition is treatable and that he expects me to do well with treatment, which I will start in the coming weeks," Ms Murphy told The Sydney Morning Herald and The Age.

"I have terrific support from family, friends and colleagues, and a strong fighting spirit."

It was her first cancer fight which gave the former barrister the courage to stand for Parliament at the last two elections.

Ms Murphy has spoken openly in the past about how her initial diagnosis had prompted her to enter politics after a previous career as a justice policy advisor to Labor minister and now Federal Court judge Duncan Kerr.

She was first diagnosed with cancerous tumour in her breast in 2011 while acting as a junior counsel in a murder trial.

Ms Murphy and her husband, public sector consultant Rod Glover, moved to Mt Eliza to be closer to family, before a short stint in the United States where she completed her recovery following surgery and intense chemotherapy.

"It sounds like a cliche but at the end of that we wanted to make sure we did something with our lives," she said in 2015.

She campaigned on health funding at the 2016 and 2019 federal elections, having credited Australia's health system with saving her life.

"I had excellent treatment and, having passed the five-year mark since my diagnosis, we were confident that I was in the clear," she said on Wednesday.

Ms Murphy's victory against Liberal MP Chris Crewther in May was the first time Labor had won the seat - which takes in Frankston, Carrum Downs, Langwarrin and Seaford - in 23 years.

She secured a personal swing of 2.4 per cent in her primary vote on top of a boundary redistribution which had moved Dunkley, a notional Labor seat with a wafer-thin margin of 1.3 per cent.

She has vowed to her community to continue to work hard "at home and in the Parliament" while undergoing treatment.

Close colleagues have rallied around the MP in the past days and say she is determined to deliver her first speech, a long-standing convention in which newly elected parliamentarians outline their principles, beliefs and background, next Wednesday.

Prior to her election win Ms Murphy had spent two years as chief-of-staff to veteran Labor frontbencher Brendan O'Connor, whose wife Jodi Dack died breast cancer almost 12 months ago.

Liberal senator Arthur Sinodinos gave an emotional address to Parliament in February having spent more than 18 months fighting stage four non-Hodgkin lymphoma, declaring "cancer really sucks".

"Discovering that you've got it, accepting that you've got it, feeling sick, or, ironically, perhaps even worse - not feeling sick yet feeling totally bewildered; having your life, your family, your work upended; pushing through the multiple rounds of treatment, coping with the side effects of the treatment," he told the Senate.

"Every cancer is different, and everybody's experience of it is so very different. No matter how much we think we can control things, our bodies have a will of their own, and that can play out in triumphant and tragic ways.

"You just can't pick it sometimes."