The staging and grading of kidney cancer

The staging and grading of kidney cancer

The stage of a cancer is a term used to describe its size and whether it has spread beyond its original site. Knowing the extent of the cancer and the grade (see below) helps the doctors to decide on the most appropriate treatment.

Generally, kidney cancer is divided into four stages, from small and localised (stage one) to spread into surrounding structures (stages two or three) or other parts of the body (stage four). If the cancer has spread to distant parts of the body this is known as secondary cancer (or metastatic cancer).

A commonly used staging system for cancer of the kidney is described below:

• Stage 1 The tumour is found only within the kidney and is less than 7cm in size. It has not spread to nearby tissues, lymph nodes or other organs.
• Stage 2 The tumour is larger than 7cm in size, but has not spread beyond the outer layer (capsule) of the kidney.
• Stage 3 The tumour has begun to spread outside the kidney. It may have spread into the main blood vessels that are close to the kidney (the renal vein or the inferior vena cava); the lymph nodes around the kidney; or into the fat that surrounds the kidney. The adrenal gland, which is on top of the kidney, may also be affected.
• Stage 4 The tumour has spread either to nearby organs, such as the bowel or to parts of the body further away from the kidney, such as the lungs or the brains.

Grading refers to the appearance of the cancer cells under the microscope. The grade gives an idea of how quickly the cancer may develop. Grading systems usually use three grades: grade 1 (low-grade), grade 2 (moderate-grade) and grade 3 (high-grade). Low-grade means that the cancer cells look very like the normal cells of the kidney. They are usually slow-growing and are less likely to spread. In high-grade tumours the cells look very abnormal. They are likely to grow more quickly and are more likely to spread.