I was diagnosed with cancer in my sophomore and junior year, therefore, I have included that in the additional information section of the Common App. However, recently, I found out that my counselor has forgotten to add my medical issue resulting in a downward trend on the transcript. Although my counselor is sending a separate email to each college with the updated letter of rec, I just had a question if colleges do not think seriously about the medical issues. Please let me know!
I think it is fine if you mentioned it and your GC sends the email. Regarding colleges, they most fundamentally want to know for sure that you can do the work in college. So if you had high grades before & after, and good test scores, some colleges may take it into account. But be sure you have some colleges that match your actual stats, too.