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Despite being preventable and treatable, colon cancer is the second leading cause of death by cancer in Canadian men and the third leading cause of death by cancer in Canadian women.

Lack of awareness is one of the main drivers of these needless deaths.

Dr. Ian Bookman, gastroenterologist at St. Joseph’s Health Centre, wants to change this.

In 2012, he started the Bum Run, an annual multi-city 5 km race that aims to increase awareness about colon cancer, increase screenings, decrease stigma, raise funds and save lives.

For Cancer Awareness Month and ahead of the Toronto Bum Run this Sun., Apr. 28, we sat down with Dr. Bookman to discuss what you need to know about colon cancer.

What are some of the symptoms of colon cancer?

Common symptoms for colon cancer include rectal bleeding, change in bowel habits, abdominal discomfort, unintentional weight loss and fevers.

Most colon cancers, however, don’t cause symptoms until they’ve already grown to the point where they may no longer be resectable.

So, we really like to focus on the fact that colon cancer is one of the slower-growing, predictable cancers that can be controlled by participating in a screening program.

We know that the risk of colon cancer increases with age. But recently, we’ve been seeing more young people being diagnosed. Why is this happening?

That is the million-dollar question. The answer is we do not know.

There were previous suspicions that maybe we were finding more cancer because of more scoping. But when statisticians controlled for this factor, it didn’t seem to be playing as much a role as we thought.

We think it’s happening too rapidly for it to be genetic factors. Therefore, we suspect that it is more environmentally related.

So, diet, inactivity, obesity, more processed foods, less fruits and vegetables and less fibre seem to potentially be playing a role.

What can people do to avoid colon cancer?

The number one thing is to participate in a screening program.

We believe that if everyone participated in the screening programs, 95 per cent of colon cancer deaths could be prevented.

The other factors are lifestyle-related. Things that increase your risk are obesity, a sedentary lifestyle, less fibre, more red meat, less fruits and vegetables. Exercising and a healthy diet decrease your chances.

Also, be sure to see your physician regularly for your annual physical and discuss with them any symptoms that you are having.

What is the Bum Run all about?

Back in 2012, CIBC Run for the Cure was getting record turnouts, raising awareness for breast cancer. It did a wonderful job of changing the norm, making it regular to talk about getting breast screenings and mammograms; you were looked at as unusual if you never went to get a breast screening or mammogram.

Participants in the 2023 Bum Run turn a corner near Queen's Park.
Bum Run 2023. Photo courtesy of Bum Run Facebook page.

But we were having the opposite problem with colon cancer. We saw only 30 per cent participation rates in colon cancer screening programs.

So, I started the Bum Run to create a funny title to make it easier to talk about colon cancer screening and prevention.

It’s a 5-km walk/run to raise awareness about colon cancer.

We wanted it to be a very visible event, so we close down the streets every year in Toronto around Queen’s Park.

Funds that are raised go to colon cancer-related charities, including the St. Joseph’s Health Centre Foundation and the GI Unit.

Why is the Bum Run so important to you?

I was diagnosing at least one or two cases of colon cancer a month that could have been easily prevented. And I felt that I needed to do something more upstream.

Even if you yourself are not personally affected by colon cancer, chances are someone in your network has been affected by it. So, I encourage people to join in and support the Bum Run. I think together, we can conquer the stigmas that we still face in society, and it will save lives.

We’ve now grown the Bum Run to four cities plus a virtual race, and the hope is that we’ll have this happening in every city so that colon cancer screening becomes such a regular thing. We hope that one day, we won’t need to raise awareness anymore.

Bum Run participants pose in front of a larger-than-life colon.
Bum Run 2023. Photo courtesy of Bum Run Facebook page.

Learn more about the Bum Run at

Learn more about Oncology and Endoscopy at Unity Health Toronto.

As told to Kaitlin Jingco. This interview has been edited and condensed.