I am 18 with long line of cancer in my family, had a colonoscopy today and six polyps were found. the biggest was 15mm, is it most likely cancer?

Please: don't guess - the pathology report will tell. Take care.

Unlikely: It is unlikely that it is cancer, but ask your primary are provider if genetic testing is appropriate. Familial polyposis is a condition where preventative colon resection is sometimes contemplated. Better to get all the info now, so you can make more informed decisions. Wait for the report, and don't worry - it won't change anything. Hope this helps!