I am suffering from rectal cancer. How do I know treatment worked?

Hi @ksanji and welcome to Mayo Connect. Usually follow up testing and scans determine how effective the treatment was. Do you have anything scheduled? How long will your current treatment continue?

I'm sure they'll do a pett scan which will show any signs of cancer

Very likely they will do some kind of imaging, like CT scan, PET scan or MRI to see if the tumour has shrunk due to the chemo.

This is a good question, I would also like an answer. It is a question I’ve repeatedly asked both the oncologist and radio therapist. Neither have given me a definitive answer.
Also there appears to be no evidence that they will kill the cancer.
Could the cancer stay stable if I don’t have treatment?
What evidence does exist, is that both treatments do damage to good cells and healthy tissue. So why am I having treatment?
A Pet scan will show if the cancer has shrunk.
If the treatment for cancer has been successful, to what costs? Scleroderma tomorrow? Recurring ulcerations on skin,in the mouth?
I still have so many questions it bout answers

I’m sorry for your troubles with the treatments and getting the answers you deserve, I know that I would be very frustrated in your situation. I feel that you’re struggling with the situation because you need more answers about what the treatments have done and now the insecurity is there making you doubt yourself. I would continue to go after the doctors and try to get some more information so that you will know if everything you’re going through is working out well, I know that everything will work out for you when you’re given more information, please stay strong and focus on getting better so you can get back to living your best life.

@tomrennie The scan date is in about three weeks. They say there's no point in doing a CT scan or MRI before that. They say they'll consider surgery after that.

@ksanji OK. Typically, the first follow up scanning is done about three months after treatment started. Is that timeline similar in your case? Do you know specifically what type of rectal cancer you have?

@ksanji
If the option for surgery is there,then you are lucky.
Mine was 3B
After my 28 day chemo and RT ,the PET showed only a shrinkage in tumour size after 10 weeks.I had my surgery.All this was in 2017.
I am still in remission.I am sure you will be lucky too.Make sure you have a healthy life style and keep fingers crossed.
I will send all my lucky stars your way and HE will stand by you

I had type 2 and after treatment when the did a mri and petscan tumor was gone now I have after effects with no control with bowels movements. 🫢 I am cancer free they say but still do the mri and scan every 4 months

@helhilton
Why every 4 months,when you are cancer free?
I had only MRI and contrast CT every year.Thanks to Covid season I escaped them in 2020 and 21.
On completing five years I had a colonoscopy .
Now in remission I am advised a colonoscopy once in three years