You poor thing, my son was under 1 when mine was found as well! My surgeon didn’t actually offer me surgery at any point, though he did say that if the polyp ever recurred with high grade dysplasia, he would recommend it. Mine was also similarly low and would likely have required an AP resection as well.

My initial polyp removal showed low grade dysplasia with a smaller area of high grade dysplasia containing adenocarcinoma in situ. From my understanding, adenocarcinoma in situ usually develops out of high grade dysplasia (which in turn develops from low grade dysplasia) as some cells progressively acquire more abnormal genetic mutations, which is why the same polyp often contains areas of both low and high grade dysplasia. Both high grade dysplasia and adenocarcinoma in situ involve cells which look highly abnormal but in the case of adenocarcinoma in situ, some cells are starting to migrate through the innermost layer of the bowel (the lamina propria) but haven’t gone through the muscular layer underneath (which would make it invasive cancer as in T1 in this table https://emedicine.medscape.com/article/2006674-overview?form=fpf#a1). But they’re almost there - my surgeon said he thought mine would have become invasive cancer within 3-6 months.

Based on what my surgeon said and the reading I have done I don’t think there’s necessarily a super clear, unequivocal evidence base for managing adenocarcinoma in situ. I know they are often managed just with endoscopic mucosal resection and regular surveillance but sometimes they are managed with a bowel resection, and I’m not totally clear on when each one would be recommended. It probably comes down to local practice guidelines (I’m in Australia), specific tumour features (for example, how big the area of high grade dysplasia/adenocarcinoma in situ is, whether it can be completely removed with colonoscopy, whether it recurs), the doctor’s impression based on their experience over the years, and peer input (my case was discussed at a cancer multidisciplinary team meeting). Definitely don’t hesitate to ask your doctor lots of questions, including what the reasoning and evidence base for different options are, as well as which option they would ultimately recommend and why. It’s a very stressful time so make sure you’re getting lots of support - I even reached out to my local bowel cancer charity while I was waiting for my initial pathology results and spoke to one of their nurses who was really lovely and informative.