The aim of this study is to improve the understanding for the tumour biology in relation to treatment response in patients with anal cancer by examining:

• The tumour microenvironment
• The localisation of and cellular interactions between the tumour and immune cells
• The gene and protein expression by cells present in the tumour and surrounding tissue.

All adult patients with anal cancer presenting within the Sahlgrenska University Hospital catchment area or treated at any time at Sahlgrenska University Hospital are eligible and will be asked to participate. The patients that are newly diagnosed or that have a suspected recurrence will be offered to enter the study with biopsies as well as blood samples during the diagnostic examination that is performed under anaesthesia. Biopsies will then be taken during follow-up exams if applicable. Biopsies will also be taken during surgery if that is scheduled and in cases where surgery is not necessary biopsies will be taken if the patient undergoes examinations under anaesthesia after treatment cessation.

If it is not possible to take biopsies prior treatment blood samples will still be drawn.

Inclusion Criteria:

• Newly diagnosed or recurrent anal cancer

Exclusion Criteria:

• No diagnosis of anal cancer, contraindication to biopsies and blood samples

Patients referred to Sahlgrenska University Hospital with anal cancer