He'd had diarrhea, constipation, abdominal pain and bleeding, on and off for six months - but only saw his GP as his mother Jo begged him to.
After his diagnosis, he underwent gruelling treatment to remove the tumour, including chemotherapy, radiotherapy and surgery.
And while he admits there was nothing wrong with his actual health care, he was stuck by the way he was treated as a hospital patient.
Especially when, after his surgery, his expected few days stay became four weeks due to serious complications.
"I got world class medicine but the humanity part was often missing," he told nine.com.au.
"It was really disempowering.
"Not only was I sick and in a lot of pain, I was often confused and not really clear when the doctors were coming, what was happening with my treatment, when I was getting out.
"And when a doctor did come they'd often have a whole team with them that I didn't know, and ask me really intimate questions really quickly.
"Even if you had questions, you don't feel brave enough to ask them."
He was also in a shared ward in the Melbourne hospital, where he was decades younger than other patients.
"I spent a lot of time next to one man who on a nightly basis would beg the doctors to die. I started getting anxiety that I was going to end up like that," he said.
"Nobody checked in with me of this stuff. They were focused on the technical stuff."
At one point he said a hospital manager even threatened to give him a feeding tube if he didn't start eating, when he simply couldn't.
Once Bravery recovered, after 18 months of treatment, he returned to his job.
After training as a zoologist, he was running a science communications business.
But he wasn't happy, and despite changing jobs again, had a feeling he knew what he wanted to do.
He Google-searched 'how to become a doctor'.
And aged 32, he went to medical school in Sydney, with the aim of becoming an oncologist.
He wasn't from a typical medical school background, being the first in his family to go to university, and the second to finish high school.
He was born to a young mother and his father wasn't around, and at times Bravery lived in a caravan in south-east Queensland's Logan area.
He explained why he was so drawn to medicine as a profession.
"A lot of people would run from it and never wanna go back," he said.
"I wanted to go back for two reasons. I wanted to give back. I was so grateful for having my life saved. I got world class medicine - and I didn't pay a cent.
"And the second reason was, these things I noticed, sometimes how people spoke to me, sometimes when I didn't feel strong enough to ask questions, or didn't understand, I thought maybe I could go back and make it a bit better for other patients and doctors.
"It's a bare bones keep people alive system, and that's good it does that.
"But what people remember is the grumpy nurse, the doctor who didn't listen to them."
He found medical school tough.
He encountered bullying, a surprising absence of specific training on cancer and a lack of encouragement on treating patients with compassion.
And after graduating in 2018 his first job as an intern was in a hospital in Western Sydney.
But it wasn't what he'd hoped for either.
There were 12-hour days, a high workload, a lack of respect from senior doctors and he felt like patients were treated as numbers rather than people.
He said he saw an elderly man die without his wife there even though she was in the same hospital - because she was bedridden and there were no porters to take her to his side.
He also witnessed a man with terminal cancer, who had broken his arm, wait a week for surgery as he wasn't classed as a priority.
"It was disappointing. The way doctors approached patients, and the way doctors approached doctors, seemed to have a lot of problems," he said.
"I went to medical school to try and make things better for patients and discovered I wasn't going to do that unless I also made things better for doctors.
"I had tried to hold on to who I was, the kindness, the compassion, but it's really hard to implement in practice because you're slammed."
However, he stuck with it, and has now found a specialty where he hopes to make a difference - psychiatry.
Bravery is working in a Sydney hospital and says he has no regrets about his dramatic life change.
Now aged 40, he also has a son, Evren, with wife Sana, who he'd only just met when he was diagnosed.
He was born after IVF - Bravery had frozen his sperm as his cancer treatment had left him infertile.
He also has no evidence of cancer, but still goes for checks.
Bravery said he's still determined to make a difference for other patients, even if, as a junior doctor, he's starting small.
"I'm able to do my little bit, every patient interaction I'm trying to remember I'm having a conversation that might change that person's life," he said.
"But I bring this really interesting mix, having being sick, and going to med school.
"I still see myself as a patient wearing a stethoscope."
Bravery has written a book called The Patient Doctor about his experience, which is out now. Find more details about bowel cancer here.
A history of Aussie medical innovation
