There are different types of anal cancer. Knowing the type you have helps your doctor plan your individual treatment.

Squamous cell carcinoma

Nearly all anal canal cancers (9 out of 10 or 90%) develop in the squamous cells lining the anal canal and anal margin.

There are two main types of squamous cell carcinoma:

• Keratinising tumours.
• Non-keratinising tumours, which develop in the transitional zone. They are sometimes called basaloid carcinomas.

Adenocarcinoma

Some anal canal cancers develop in the glandular cells that make mucus. These are called adenocarcinomas. They are rare – less than 5 in 100 (5%) of all anal cancers are adenocarcinomas. They behave like rectal cancers, and they are treated in the same way as them.

Basal cell carcinoma

This is a type of skin cancer that develops in the area around the anus. It is usually treated in the same way as other basal cell skin cancers.

Melanoma

This is a skin cancer that develops from cells called melanocytes, which give our skin its colour. Anal melanoma is rare – less than 1 in 100 anal cancers (1%) are this type. They are usually treated in the same way as other skin melanomas.

Small cell cancer

This type of cancer usually affects the lung, but it can be found in other parts of the body. Rarely, it can develop in the anus. It is treated in the same way as other small cell cancers.