Getaway host Catriona Rowntree beloved older sister, Lucinda has been diagnosed with Stage 4 cancer.
The devastating diagnosis was made public by the 52-year-old television presenter in April 2023.
In November, Catriona revealed her sister was "in the process" of beginning chemotherapy.
"She was on a trial from the US. We had great hopes and unfortunately that hasn't worked," she told 9Entertainment. "It's not 'no', it's just a 'not yet'."
In June, Lucinda commenced a trial treatment from the US, to which Catriona confessed to the publication she was "responding well."
"I think her doctors are feeling relieved to know that something is moving in the right direction regardless of the treatment that she's on."
In a previous Instagram post, Catriona visited Lucinda in Daylesford and said she was "doing well".
The Getaway host first revealed her sister's cancer diagnosis in a bittersweet post shared on Facebook.
According to Catriona, the cancer is ''apparently incurable'' and has forced Lucinda to quit her job as a schoolteacher in the Upper North Shore suburb of West Pymble in Sydney.
''A bit of a personal post for me, today is my big sister Lucinda's birthday, Lucinda is a true gem. Unlike me, growing up, Lucinda never caused my parents an ounce of worry,'' the post began.
''We recently found out that Lucinda has Stage 4 Cancer, which is apparently incurable. I'm trying so hard to choose my words carefully here, other than to say a lot of tears have been shed - but Lucinda is fighting and positive. We all are,'' Catriona wrote.
''She started chemo (sheer hell) and immunotherapy (our bright light) at Royal North Shore Hospital. Lucina is now unable to work as she commits to the fight of her life,'' the post continued.
''Her girlfriends have created a GoFundMe page to ease the household stress and I've asked her permission to share this with you,'' she added.
According to the GoFundMe, Lucinda is a ''much loved'' member of her local community.
''Her laughter lights up the room and we are keen to lighten the load and help with weekly bills to keep her comfortable in her home during this time,'' the description read.
''We want to show Lucinda, we love her, and we are all with her.''
Despite the terminal prognosis, Lucinda is set to join a ''new medical trial'' that may be able to assist in the recovery of other cancer sufferers in the future.
The post concluded with a powerful message from the heart.
"Trust me when I say to live your life to the absolute max,'' Catriona wrote.
''None of us knows what each moment holds for us and please say a little prayer for Lucinda tonight. Thankyou.''