How common does anal leakage indicate anal cancer?

Hemorrhoids: Many issues can cause anal canal irritation resulting in leakage. Anal cancer is very rare in a 22 year old. The most common condition is hemorrhoid flare up followed by other inflammatory process such as perianal dermatitis, abscess/fistula, proctitis, etc - if you belong to the normal risk population. If you are immunocompromised, have a family history of ibd, or std+/- anal sex see a doc now.

See below: Anal leakage at your age could be due to excess fat in stools, or a non-cancerous lesion in the anal canal.