This is not cancer but rather abnormal squamous cells which might develop into cancer.You will need treatment because the abnormal cells are less likely to get better on their own. They might develop into anal cancer, but the risk of them changing to a cancer is very small. Your doctor will discuss the best treatment option for you. Treatments might include:

laser to destroy the cells (laser ablation)
surgery
skin creams such as imiquimod or 5FU.

Talk to your doctor or oncologist about the specific treatment but chances are it won't be that serious but uncomfortable while the healing post surgery occurs