Doctors thought my back pain was creaky joints... it was actually a golf ball-sized tumor in my colon

It might sound odd, but Mark Swanson had been looking forward to his operation for months.

The minor surgery, scheduled for June 2020, would finally repair a common injury in his backside that had been causing a 'nagging' pain for the last 18 months which, at times, would flare up and prevent him from sleeping. 

The issue wasn't life threatening, but it caused enough of a problem day-to-day that it affected his daily tasks. 

He certainly never expected to wake up to a cancer diagnosis.

Mark Swanson originally went in for a surgery to repair an anal fissure

Doctors found a 2.2-inch tumor in his rectum and he was diagnosed with stage three colon cancer

Far from fixing a minor wound, the procedure resulted in his doctors discovering a two inch tumor in his rectum; it was colon cancer. 

Mr Swanson first visited doctors in December 2018 for persistent pain he was experiencing in the lower left area of his back.

He was diagnosed with a sacroiliac joint issue — or improper movement of the joints in the lower spine. 

Doctors determined this diagnosis after a hands-on examination and X-ray, he said.

He was put on over-the-counter pain medications. But when the pain didn't subside, they prescribed him stronger drugs.

This still didn't work, so doctors ordered a radiofrequency ablation in January 2020 — A procedure to kill the nerves around his lower back in order to eliminate the pain. 

This would later turn out to be a procedure he did not need.

After the ablation, Mr Swanson said the pain returned, which led to him being sent to a neurologist — who found nothing.

His primary care physician then referred him to a colorectal surgeon, as they tried to rule out possible causes of the issue.

Mr Swanson said cancer spots were seen in his lungs and he had to undergo further treatment

This surgeon diagnosed him with an anal fissure after 'sticking his finger up my butt' and scheduled him for surgery, the US airforce worker said.

The operation was meant to fix the anal fissure — a small benign tear in the anus that affects one in 10 adults — but when doctors began the surgery they didn't find a tear.

On June 30, 2020, Mr Swanson went in for his scheduled surgery to suture the fissure back together. 

But when he woke up, doctors told him they couldn't carry out the procedure because they found out he didn't have an anal fissure at all, but the then 35-year-old had a 2.2-inch tumor in his rectum that appeared to be growing through the wall of his intestine. 

After undergoing additional testing, Mr Swanson's cancer was determined to be stage three colon cancer the following month — a diagnosis with a 65 percent survival rate.

Mr Swanson, who lives in Ohio, told DailyMail.com he broke down and cried when the doctor told him.

He said: 'I felt like my life was over. The doctor just came in, told me I had cancer, and left. It felt cold, clinical, like it was another day at the office for him — but for me it was life changing.'

He was prescribed 10 rounds of chemo and 35 rounds of radiation therapy to shrink the tumor.

But his cancer wasn't responding to treatment, so he had to have his anus, rectum and the lower part of his colon cut out as doctors attempted to eliminate the cancer. This was carried out in May 2021.

This led to him being fitted with a colostomy bag — or bag on the side of his body into which waste from the intestines empties — which Mr Swanson described as 'life-ending' and causing him to fall into 'severely depressed'.

After visiting several doctors, he was eventually told he could use a method called colostomy irrigation — which involves flushing the intestines every day with water to clear out waste instead of allowing them to slowly empty into a bag. 

He was declared in remission in 2021, but earlier this year, scans revealed two lumps in his lungs and doctors told him the cancer had returned.

He has now gone through another five rounds of radiation to shrink them and is waiting for the results of a scan to find out if the spots have shrunk.

He was offered chemotherapy but told there was only a 50/50 chance of it being successful, so he declined the treatment.

Mr Swanson told this website: 'Every day, I am second guessing that decision.

'Did I make the right call? What will happen now? There are just so many unknowns.'

Data from JAMA Surgery showed colon cancer is expected to rise by 90 percent in people ages 20 to 34 by the year 2030

Mr Swanson is currently waiting for the results of a scan following his radiation therapy for the cancer in his lungs 

He added that he often wonders if, had the cancer been detected when he first visited doctors in December 2018 to complain of pain in his back, his situation could have been avoided.

He said: 'Would it have progressed to stage three? Would I be in the position I am now in fighting lung cancer and terrified it will show up in other places?

'So much was done wrong when coming to my diagnosis and I hope others would be able to learn from my experience and watch out for all the signs and know doctors are not the know-it-alls they pretend to be.

He added: 'I am also gay, and to be told I had to have a colostomy bag, that felt life-ending to me — like I would be judged like no other.'

The colostomy fitting is permanent for Mr Swanson, who will now need to flush his intestines every morning for the rest of his life.

Mr Swanson is just one of millions of young people receiving shocking cancer diagnoses, including Princess Kate, who revealed she had cancer last month which was found during abdominal surgery.

Early-onset cancer — diagnoses before 50 years old — has been on the rise across the world and in the US, where it has increased by about one to two percent every year.

For people under 40 years old in the US, cancer cases have surged 35 percent over the last four decades.

The crisis has been perplexing experts as they race to find an answer to the epidemic. 

Colon cancer is among the diseases spiking the most in young people, with cases rising 50 percent over the last two decades. It is set to become the most common cancer in the age group within the next four decades.

Because of the rise, the US Preventive Services Task Force (USPSTF) has changed the screening age from 50 years old to 45 years old.

But some patients argue this doesn't go far enough to address the issue, saying the the age should be dropped even lower so health insurers will cover colonoscopies - the gold standard of screening - for more young adults.

Doctors had carried out a CT scan in June 2019, Mr Swanson said, but reported his 'colon was normal.'

Mr Swanson said his medical team never recommended a colonoscopy before his surgery for an anal fissure and believes this was because of insurance issues.

A 2020 survey from Colorectal Cancer Alliance found many patients with colorectal cancer symptoms were initially misdiagnosed or dismissed

'They've [USPSTF] dropped the age from 50 to 45 years, but that's just ridiculous when you have this early onset epidemic in men in their 20s and 30s,' he said.

Despite the troubles, Mr Swanson said he entered into a relationship shortly after he was told he was in remission from cancer.

The pair are close, having known each other from when they were growing up in Oklahoma, and Mr Swanson says they now see each other about once a month.

They are both hopeful for the future.