Person with cancer—most valid basis of diagnosis of a cancer, code N

Guide for use:

The most valid basis of diagnosis may be the initial histological examination of the primary site, or it may be the post-mortem examination (sometimes corrected even at this point when histological results become available). In a cancer registry setting, this metadata item should be revised if later information allows its upgrading.

When considering the most valid basis of diagnosis, the minimum requirement of a cancer registry is differentiation between neoplasms that are verified microscopically and those that are not. To exclude the latter group means losing valuable information; the feasibility of making a morphological (histological) diagnosis is dependent upon a variety of factors, such as the health and age of the patient, accessibility of the tumour, availability of medical services, and the beliefs and decisions of the patient.

A biopsy of the primary tumour should be distinguished from a biopsy of a metastasis, for example, at laparotomy; a biopsy of cancer of the head of the pancreas versus a biopsy of a metastasis in the mesentery. However, when insufficient information is available, Code 8 should be used for any histological diagnosis. Cytological and histological diagnoses should be distinguished.

Morphological confirmation of the clinical diagnosis of malignancy depends on the successful removal of a piece of tissue that is cancerous. Especially when using endoscopic procedures (bronchoscopy, gastroscopy, laparoscopy, etc.), the clinician may miss the tumour with the biopsy forceps. These cases must be registered on the basis of endoscopic diagnosis and not excluded through lack of a morphological diagnosis.

Care must be taken in the interpretation and subsequent coding of autopsy findings, which may vary as follows:

a) the post-mortem report includes the post-mortem histological diagnosis (in which case, one of the histology codes should be recorded instead);

b) the autopsy is macroscopic only, histological investigations having been carried out only during life (in which case, one of the histology codes should be recorded instead);

c) the autopsy findings are not supported by any histological diagnosis.

Origin:

International Agency for Research on Cancer

Comments:
Knowledge of the basis of the diagnosis underlying a cancer code is one of the most important elements in assessing the reliability of cancer statistics.