A classification of how a PATIENT DIAGNOSIS relating to cancer was identified.

National Codes:

Non-microscopic
0 - Death Certificate	The only information available is from a death certificate
1 - Clinical	Diagnosis made before death but without the benefit of any of the following (2-7)
2 - Clinical Investigation	Includes all diagnostic techniques (e.g. X-rays, endoscopy, imaging, ultrasound, exploratory surgery and autopsy) without a tissue diagnosis
3 - Specific tumour markers	Includes biochemical and/or immunological markers which are specific for a tumour site
Microscopic
5 - Cytology	Examination of cells whether from a primary or secondary site, including fluids aspirated using endoscopes or needles. Also including microscopic examination of peripheral blood films and trephine bone marrow aspirates
6 - Histology of a mestastases	Histological examination of tissues from a metastasis, including autopsy specimens
7 - Histology of a primary tumour	Histological examination of tissue from the primary tumour, however obtained, including all cutting and bone marrow biopsies. Also includes autopsy specimens of a primary tumour
9 - Unknown	No information on how the diagnosis has been made (e.g. PAS or HISS record only)

References:
National Cancer Data Set Version 1.3_ISB October 2002 

This attribute is also known by these names:

Context	Alias
plural	BASIS OF DIAGNOSES