Grading of Kidney Cancer
The grade of a cancer cell is an assessment of its appearance compared to that of a normal, healthy cell. Grading is done on a scale of 1 to 4: Grade 1 RCC cells differ little from normal kidney cells, typically spread slowly, and have a good prognosis for treatment. Grade 4 RCC cells look extremely different and indicate an aggressive cancer with poor prognosis.
Staging of Kidney Cancer
Although grading and the identification of cancer cell types help determine a patient's prognosis, most doctors believe that the cancer's stage is a better indicator of a patient's survivability.
Staging allows a physician to gauge the size and location of tumors by using information gathered from imaging studies such as CT scans and MRIs, and from pathology tests and physical examinations.
Staging factors that influence a patient's prognosis are:
- Spread to tissues surrounding the kidney
- Spread to contiguous organs
- Spread to nearby lymph nodes (the small, bean-shaped structures found throughout the body that produce and store infection-fighting cells)
- Distant metastasis
There are two staging systems for RCC, Robson and TNM.
The Robson system classifies tumors as stages.
|Stage I||The tumor is confined to the kidney and does not involve the capsule of tissue that surrounds the kidney|
|Stage II||The tumor extends through the capsule of the kidney|
|Stage III||The tumor involves lymph node(s) or extends into the renal vein (the main blood vessel that carries blood from the kidney) or inferior vena cava (the large vein that drains blood back to the heart)|
|Stage IV||The tumor has invaded organs adjacent to the kidney (e.g., pancreas or bowel) or shows evidence of distant spread to organs such as the lungs|
The TNM (tumor-node-metastasis) system uses stages generally similar to those of the Robson system. This staging system is becoming more widely accepted because it provides a more detailed description of the tumor(s).
The TNM system stages RCC tumors at four intervals:
|Stage I||Small tumors (less than 1 inch) without evidence of local invasion; no lymph node involvement and absence of distant disease|
|Stage II||Tumors larger than 1 inch without evidence of local invasion; no lymph node involvement and absence of distant disease|
|Stage III||Tumors of any size that involve one lymph node (less than 1 inch); tumors that invade the adrenal gland or surrounding renal tissues; tumors that invade the renal vein or the inferior vena cava|
|Stage IV||A mixed group including tumors that invade adjacent structures; any tumor that has evidence of distant spread; any tumor in which more than one lymph node is involved|
The TNM system also uses alphanumeric subcategories to define areas and degrees of invasion. These are as follows:
Primary tumor (T); all sizes measured in greatest dimension:
|TX||Primary tumor cannot be assessed.|
|T0||No evidence of primary tumor.|
|T1||Tumor 7 centimeters (cm) or less, limited to the kidney.|
|T2||Tumor more than 7 cm, limited to the kidney.|
|T3||Tumor extends into major veins or invades the adrenal gland or surrounding tissue, but not beyond the Gerota's fascia (the fibrous tissue surrounding the kidney that separates it from adjacent musculature).|
|T3a - Tumor invades the adrenal gland or surrounding tissue, but not beyond the Gerota's fascia.|
|T3b - Tumor grossly extends into the renal vein or veins (the main blood vessels that carry blood from the kidney) or the vena cava (the large vein that drains blood back to the heart).|
|T4||Tumor invades beyond the Gerota's fascia.|
Regional lymph nodes (N):
|NX||Regional lymph nodes cannot be assessed.|
|N0||No regional node metastasis.|
|N1 -||Metastasis in a single regional lymph node.|
|N2||Metastasis in more than one regional lymph node.|
Distant metastasis (M):
|MX||Presence of metastasis cannot be assessed.|
|M0||No distant metastasis present.|
|M1||Distant metastasis present.|