Staging and grading of cancer
The standardized processes and guidelines for assessing the severity of cancer after diagnosis. A cancer’s stage and grade help determine the most effective treatment options. Though each type of cancer has its own specific staging and grading protocol, general methodologies apply to nearly all types of cancer, except LEUKEMIA.
Cancer Staging
The stage of a cancer identifies how contained or widespread the cancer is. The traditional method of staging assigns a number to the level of the cancer’s severity based on the tumor’s location, penetration into lymph nodes, and spread to adjacent or distant tissues. The higher the number, the more extensive the cancer. A stage 0 cancer is small and completely contained, often in situ (confined to the cells in which the cancer started). A stage 4 cancer is widespread with multiple tumors distant from the primary tumor (site where the cancer first started). Staging criteria vary somewhat among the different types of cancer.
| GENERAL CANCER STAGING: TRADITIONAL METHOD | |
|---|---|
| Stage | Extent of Cancer |
| Stage 0 | in situ; tumor confined to the cells of its origin |
| Stage 1 | tumor remains localized though has spread beyond the cells of its origin |
| Stage 2 | tumor has spread to adjacent tissues or lymph nodes |
| Stage 3 | tumor has spread to adjacent tissues and lymph nodes or is locally recurrent |
| Stage 4 | multiple tumors distant from the primary tumor; cancer is recurrent |
Another method of tumor staging is the TNM system in which T represents the tumor size, N represents the involvement of local and regional lymph nodes, and M represents METASTASIS to distant sites. The TNM system is internationally standardized and provides more detail about the cancer’s characteristics than the traditional, or stage grouping, method. It also allows for more precise characterization of the cancer. As is the case with traditional staging, criteria vary somewhat among the different types of cancer.
| GENERAL CANCER STAGING: TNM METHOD | |
|---|---|
| Stage | Extent of Cancer |
| Tumor (T) | |
| T0 | no evidence of cancer |
| Tis | in situ; tumor confined to cells of origin |
| T1 | localized tumor less than 3 centimeters (cm) in size |
| T2 | tumor is larger than 3 cm or has invaded adjacent tissues |
| T3 | tumor is larger than 3 cm and has invaded adjacent tissues |
| T4 | large tumor has invaded adjacent tissues or is inoperable |
| Lymph Nodes (N) | |
| N0 | no cancer in regional lymph nodes |
| N1 | cancer in local lymph nodes |
| N2 | cancer in regional lymph nodes |
| N3 | cancer in lymph nodes beyond the region of the primary tumor |
| Metastasis (M) | |
| M0 | cancer remains local or regional (no METASTASIS) |
| M1 | cancer has spread to distant sites (metastasis) |
Cancer Grading
The grade of a cancer identifies the characteristics of its cells and their growth patterns. Grade is relevant only for cancers that can have varying aggressiveness, such as sarcomas and some types of brain cancer. The pathologist determines the tumor’s grade from tissue samples and assigns a numeric value that indicates the tumor’s aggressiveness and likelihood for metastasis. As with cancer staging, the criteria differ among the types of cancer, though in general a higher grade value indicates a more extensive or serious cancer. Some tumors have a mix of different cancer cells, in which case the pathologist usually assigns the higher grade to the tumor overall.
| GENERAL TUMOR GRADING | ||
|---|---|---|
| Grade Cancer | Cell Characteristics | Cancer Aggressiveness |
| G1 | good differentiation, nearly normal cells | low |
| G2 | moderate differentiation, somewhat abnormal cells | intermediate |
| G3 | poor differentiation, abnormal cells | high |
| G4 | no differentiation, unstructured cells | very high |
Stage, Grade, and Outlook
Oncologists use cancer staging and grading as the general framework for making treatment decisions and assessing prognosis (expected outcome). Though many types of cancer are treatable, controllable, or curable with today’s range of treatment options, the individual variation in cancer diagnosis is significant. Each person who has cancer has a unique response based on numerous and sometimes intangible factors. Staging, grading, and other diagnostic parameters represent only a best attempt to characterize a cancer so as to structure an optimal treatment approach; they do not define the outcome.
See also CANCER TREATMENT OPTIONS AND DECISIONS; DIAGNOSING CANCER; LYMPH NODE; TUMOR MARKERS.
