Know your cancer: do you have right or left sided colorectal cancer?

The colon is roughly an ‘n’ shaped organ with rising, transverse and descending structures. The descending bit is the part closest to your bottom while the ascending bit is the part that your small intestine joins onto – the bit furthest inside your body. The transverse colon is the bit that joins these two. (The middle bit of the ‘n’.)

So why is this important?

Where your cancer is located will determine a lot of things. Although it may appear that the colon is just one big long tube, it isn’t as simple as that. The two parts of your colon have different origins when you developed as an embryo and joined together as you developed. This means that the causes, symptoms, outcomes, prognosis and treatment of your cancer will be different according to its location.

So one question you should definitely ask your medical team is: where is your cancer located? Quite apart from anything else, it helps you have sensible conversations with your doctor. Here’s some doctor speak decoded for you with an indication of the sidedness of the tumour:

  • the cecum – is on the right hand side and comes before the ascending colon. The appendix is connected to this, as is the small intestine (the ileum). A cancer here is right sided
  • ascending colon – the bit that comes after the cecum and before the right hepatic flexure (a right sided tumour)
  • right hepatic flexure – the bend at the top of the ascending colon, nearest to the liver (it’s a right sided tumour)
  • transverse colon – the middle bit of the colon that goes across your body. Cancers here are rarer and can be hard to ascribe to either left or right sides
  • left splenic flexure – the bend at the top of the descending colon, nearest to the spleen (a left sided tumour)
  • descending colon – the bit after the left splenic flexure which joins onto the sigmoid colon (a left sided tumour)
  • sigmoid colon – the last part of the descending colon (a left sided tumour)
  • the rectum – the last part of the colorectal structure, and the bit nearest to your bottom or anus. A cancer here is left sided, but is best seen as a specialised form of left-sided cancer.

Before the colon (large intestine or large bowel) is the small intestine (small bowel), which joins to your stomach. The colon and small intestine are often referred to as ‘your guts’ and are the lower part of your gastrointestinal track.

It’s often easier to understand what’s going on if you see it rather than hear these words. Study a diagram of the colon so that you understand what it looks like. Be clear what structures come before it, and where it’s near. Get your doctor or nurse to draw a picture of your colon and then show you where your cancer is located. Armed with this knowledge you can then start to educate yourself on what this means.

It can be very helpful from an emotional and psychological point of view to be able to pinpoint where your tumour is, rather than it being vaguely somewhere in your tummy. It helped me start talking about it when I could point at my right hand side and say: I have a tumour there, near my liver.  It wasn’t all of me that was faulty, just that bit. It made me feel more in control to be able to do that and it definitely helped me to talk to my surgeon and nurses and make better decisions.


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