An intense feeling of foreboding would seize Ian Cant every three months.
The former detective lives an incremental existence punctuated by quarter-yearly PET scans and immunotherapy infusions. Would the scans confirm the treatment was working? Or would his cancer push back?
"I would get really anxious and depressed as we got closer to the scan," Mr Cant said.
"I could get angry and selfish ??? I'd shy away from the kids and my partner," the father of three young children said.
In March 2016, Mr Cant was diagnosed with metastatic melanoma. He had a tumour the size of a tennis ball on the top of his left lung. Subsequent scans found 20-30 more tumours in his lungs, an eye-ball sized tumour on his cerebellum, two tumours in his abdomen and melanoma throughout his lymph nodes.
His doctor said he couldn't afford to wait to enrol in a trial of the monoclonal drug pembrolizumab (Keytruda).
The inherent unknowns of immunotherapy treatments, coupled with the grave stakes of being diagnosed with incurable cancer, meant Mr Cant was suspended in a state of uncertainty, like many patients on immunotherapy drug trials.
"It was a very trepidatious time ... Nobody knew what to expect. Not the doctors, no one," Mr Cant said.
Mr Cant remembers a week during treatment when he barely got out of bed. He moped around the house, isolating himself from his partner and three children.
He remembers sitting across the kitchen table from his 12-year-old daughter, Demi.
"She asked me: 'Are you scared of dying dad?'
"I said, 'Yep.' I couldn't say anything else ??? She cried. All the kids cried. We were all doing it really tough.
"When you have cancer, anyone who loves you and cares for you has it as well," Mr Cant said.
His first scan came back clear. The treatment had turbocharged his immune system to attack the cancer cells.
"I always challenge the doctors to answer my question: 'Am I cured?'
"I get dead silence. You can hear a pin drop after I ask that question."
Mr Cant said he was coming "from a very low base" when he was diagnosed with melanoma. The strain of a 19??-year-long career investigating a litany of traumatic cases involving multiple murder-suicides, child deaths and sexual assaults had manifested in PTSD.
"But this whole process would be hard for any cancer patient," he said.
Struggling with deep-seated uncertainty was a common companion for patients on immunotherapy, suggested a Sydney-based study, presented at the Clinical Oncology Society of Australia's (COSA) annual scientific meeting last week.
Study co-author and psycho-oncologist Haryana Dhillon said our understanding of immunotherapy had evolved incredibly quickly that no one expected the speed of change nor the staggering results.
Between 15 and 40 per cent of patients in immunotherapy trials respond "amazingly well" to the treatments.
"We haven't seen results on this scale before [so] we didn't know how long we were going to have really sick people living longer on these sort of treatments," she said.
The small study of 24 patients found many struggled with unpredictabilities surrounding treatment decisions, their disease trajectory, fluctuating life expectancy and the effect these uncertainties had on their relationships.
"There was a considerable amount of ambiguity for these patients," said Dr Dhillon, a research fellow in cancer survivorship at the University of Sydney and chairwoman of the Survivorship Group for COSA.
"They would describe a cycle of increasing anticipatory anxiety around their scans, a feeling that they just didn't know. Something might change dramatically one way or the other based on the scan."
Patients with young children or caring for elderly adults had no assurances about how much time they had with their loved ones.
Patients who believed their death was imminent could now imagine their lives stretching for at least a few more months.
Those who had come to terms with their supposedly imminent death, had quit their jobs, were living off their superannuation or had made provisions for their loved ones were now faced with myriad decisions and no assurances.
Some patients found having autonomy over their treatment decisions helped ease their anxieties. Others controlled how much information they would share with their families.
Some began to think of their cancer as a chronic disease to be managed rather than cured, and learnt to find certainty in the constance of uncertainty.
"We need get better at incorporating patient experience early on in the development of immunotherapy drugs to support them through the process," Dr Dhillon said.
"It's really important that they not feel like they are doing this by themselves."
It has been about six months since Mr Cant's last immunotherapy round, though he still needs regular scans.
"I learnt to push the anxiety stuff to the back of my mind because I've got my family to think about," he said.
"I have too many kids to raise and so many things to do. I can't go anywhere yet," he said.