Oncology is a huge area of medicine. Almost every speciality will involve some aspect of oncological care. There are loads of niche terms in oncology, which can be hard to keep track of. Two concepts you should really try to understand are ‘grading’ and ‘staging’.
The grade of a cancer describes how much resemblance the cancer cell has to the original cell type. A cell that does not resemble the original cell type is said to be ‘poorly differentiated’ and is typically associated with more aggressive behaviour and worse outcome. A cell that does resemble the original cell type is said to be ‘well differentiated’ and generally associated with a better outcome.
The stage of a cancer is critical to determine treatments, but can be very complex and important mainly for clinicians involved in treating patients with cancer. Stage also provides prognostic information.
The stage of a cancer describes the extent of cancer spread, which is based on tumour size, presence of lymph node involvement and distant spread.
We call these factors ‘TNM’ (tumour, nodes, metastasis).
Tumour (T): size of tumour (usually in cm)
Nodes (N): number and location of lymph nodes involved
Metastasis (M): presence/absence of spread to a distant site
Within the TNM system, there are a few additional notations to be aware of. Tumour size is usually grouped into categories (for example, T1 = 0-2 cm, T2 = 2-5 cm). The number following ‘N’ usually refers to the number of lymph nodes involved. If tumour size, lymph nodes or distant spread cannot be assessed, the term ‘X’ is typically used (e.g. T2N1MX).
Finally, the complex TNM system may be simplified into stages. For example, the Duke’s classification in colorectal cancer categories it into four stages A-D. Each stage corresponds to specific TNM staging.