Karl Stefanovic’s ex-wife Cassandra Thorburn reveals the hidden warning behind her ca:ncer battle — and the moment everything changed
For months, Cassandra Thorburn had no reason to believe anything was seriously wrong.
There was no obvious lump. No alarming finding in her breast. Just occasional discomfort around her armpit that, at the time, seemed easy to explain away.
She was fit, exercising regularly and taking Muay Thai classes. So when the area became sore, she assumed it was simply part of an intense workout routine.
But a routine screening would eventually reveal something she never expected.
Cassandra, 55, was diagnosed with stage three occult breast cancer, a rare form of the disease in which cancer is found in surrounding tissue or lymph nodes but the primary tumour in the breast cannot be identified.
And her experience has left her with a message she hopes other women will hear.
“How can you be told you’ve got breast cancer without a lump?”
Cassandra has revealed that she never felt a lump herself — and neither did doctors during her routine screening.
In February, she attended a mammogram after receiving a reminder to have the screening done.
The scan did not reveal an obvious tumour inside her breast.
Instead, doctors noticed a “grey area” near her underarm, which eventually led to the discovery of the cancer.
The diagnosis was understandably difficult to comprehend.
“How can you be told you’ve got breast cancer without a lump?”
Cassandra said she initially struggled to understand how cancer could be present when there was nothing she could feel.
There was, she later realised, no obvious physical warning that she could have identified herself.
The pain she thought was simply from exercise
Looking back, Cassandra now remembers experiencing some discomfort around her armpit before her diagnosis.
But at the time, it didn’t seem unusual.
She was participating in Muay Thai and considered herself to be in good physical shape.
“Do I have a sore underarm?”
It was the kind of symptom that could easily be attributed to exercise — particularly when there was no lump or other obvious sign.
That is why Cassandra believes her routine mammogram proved so important.
Without it, she fears her cancer might not have been discovered until much later.
A rare form of breast cancer
Occult breast cancer is uncommon.
Unlike more typical breast cancers, where a primary tumour can be detected in the breast, occult breast cancer can initially present through cancer found in nearby lymph nodes or tissue without an identifiable breast tumour.
It accounts for only a small proportion of breast cancer cases.
For Cassandra, the diagnosis meant confronting an illness that had been difficult to detect — even though she had been keeping up with routine screening.
The treatment changed everything
Following her diagnosis, Cassandra underwent an intensive course of treatment that included chemotherapy, surgery and radiation therapy.
She has since revealed that she is now cancer-free, although she still has radiation treatment to complete.
The experience has also changed the way she thinks about what it means to live through cancer.
Earlier this year, Cassandra shared a video after shaving her head, explaining that deciding when to lose her hair and when to tell people about her diagnosis were among the few aspects of treatment she could control.
She said she had no desire to hide what was happening from her adult children or from herself.
“I’m not interested in hiding, and that’s because I’m not alone.”
“There’s no ‘why me?’”
Despite the shock of having her world changed so quickly, Cassandra has tried to approach the experience with determination rather than self-pity.
She acknowledged that her diagnosis had turned her life upside down within days.
But her focus, she said, was on stopping the disease in its tracks.
“There’s no ‘why me?’ There’s no ‘poor me’ here.”
Instead, she has chosen to speak publicly about her experience, recognising that many women have travelled the same difficult road before her.
Why her story matters
Cassandra’s experience is a reminder that breast cancer does not always announce itself in an obvious way.
In her case, there was no lump to discover, and her initial mammogram did not show a conventional breast tumour.
The only symptom she can now look back on was discomfort around her underarm — something she had initially attributed to exercise.
Most importantly, she credits the routine screening invitation with helping uncover the disease.
Her story is not about encouraging women to panic over every ache or pain. It is about taking recommended screening seriously and speaking with a doctor about symptoms that persist or seem unusual.
A life beyond the diagnosis
Cassandra was previously married to television presenter Karl Stefanovic for 21 years. The couple separated in 2016 and share three children: Jackson, Ava and River.
Since stepping away from much of her earlier television career to raise her family, Cassandra has largely lived away from the centre of the spotlight.
Her decision to speak openly about cancer has now brought her back into public view — this time for a very different reason.
She is not presenting herself as someone who has all the answers.
Instead, she is sharing what happened to her in the hope that another woman might recognise the importance of listening to her body and keeping up with screening.
And after everything she has been through, Cassandra’s outlook remains remarkably clear:
her world may have changed in a matter of days, but she is determined not to let the diagnosis define what comes next.