Grading and Staging

Tumors are also classified as Grade I through Grade IV. The more aggressive and dangerous the tumor is, the higher the grade.

The most commonly used system of grading is as per the guidelines of the American Joint Commission on Cancer. As per their standards, the following are the grading categories.

· GX Grade cannot be assessed

· G1 Well differentiated (Low grade)

· G2 Moderately differentiated (Intermediate grade)

· G3 Poorly differentiated (High grade)

· G4 Undifferentiated (High grade)

Note! Grading systems are also different for each type of cancer.

Staging is another way to describe a tumor. Staging is used to communicate whether a tumor has spread. Staging for central nervous system tumors is typically inferred based upon CT scans and MRI images or by examining the cerebrospinal fluid.

Contemporary practice is to assign a number from I-IV to a tumour, with I being an isolated tumour and IV being a cancer which has spread to the limit of what the assessment measures. The stage generally takes into account the size of a tumor, how deeply it has penetrated within the wall of a hollow organ (intestine, urinary bladder), whether it has invaded adjacent organs, how many regional lymph nodes it has metastasized to (if any), and whether it has spread to distant organs.

Tumour staging can be divided into:

¤ a clinical stage

¤ a pathologic stage

In the TNM (Tumor, Node, Metastasis) system, clinical stage and pathologic stage are denoted by a small "c" or "p" before the stage (e.g., cT3N1M0 or pT2N0).

The TNM Classification of Malignant Tumours (TNM) is a cancer staging system that describes the extent of a person's cancer.

T - describes the size of the original (primary) tumor and whether it has invaded nearby tissue,

N - describes nearby (regional) lymph nodes that are involved,

M - describes distant metastasis (spread of cancer from one part of the body to another).

Note! This staging system is used for most forms of cancer, except brain tumors and hematological malignancies.

Clinical stage is based on all of the available information obtained before a surgery to remove the tumor. Thus, it may include information about the tumor obtained by physical examination, radiologic examination, and endoscopy.

Pathologic stage adds additional information gained by examination of the tumor microscopically by a pathologist.

Because they use different criteria, clinical stage and pathologic stage often differ.

Pathologic staging is usually considered the "better" or "truer" stage because it allows direct examination of the tumor and its spread, contrasted with clinical staging which is limited by the fact that the information is obtained by making indirect observations of a tumor which is still in the body.

However, clinical staging and pathologic staging should complement each other. Not every tumor is treated surgically, therefore pathologic staging is not always available. Also, sometimes surgery is preceded by other treatments such as chemotherapy and radiation therapy which shrink the tumor, so the pathologic stage may underestimate the true stage.

Overall Stage Grouping is also referred to as Roman Numeral Staging. This system uses numerals I, II, III, and IV (plus the 0) to describe the progression of cancer.

v Stage 0: carcinoma in situ.

v Stage I: cancers are localized to one part of the body. Stage I cancer can be surgically removed if small enough.

v Stage II: cancers are locally advanced. Stage II cancer can be treated by chemo, radiation, or surgery.

v Stage III: cancers are also locally advanced. Whether a cancer is designated as Stage II or Stage III can depend on the specific type of cancer; for example, in Hodgkin's Disease, Stage II indicates affected lymph nodes on only one side of the diaphragm, whereas Stage III indicates affected lymph nodes above and below the diaphragm. The specific criteria for Stages II and III therefore differ according to diagnosis. Stage III can be treated by chemo, radiation, or surgery.

v Stage IV: cancers have often metastasized, or spread to other organs or throughout the body. Stage IV cancer can be treated by chemo, radiation, surgery.

Note! Staging systems are specific for each type of cancer (e.g., breast cancer and lung cancer). Some cancers, however, do not have a staging system.

Correct staging is critical because treatment (particularly the need for pre-operative therapy and/or for adjuvant treatment, the extent of surgery) is generally based on this parameter. Thus, incorrect staging would lead to improper treatment.

Classified by their histologic origin, tumors derived from epithelial tissues are called carcinomas; from epithelial and glandular tissues, adenocarcinomas; from connective, muscle, and bone tissues, sarcomas; from glial cells, gliomas; from pigmented cells, melanomas; and from plasma cells, myelomas. Cancer cells derived from erythrocytes are known as erythroleukemia; from lymphocytes, leukemia; and from lymphatic tissue, lymphoma.

Traditionally, descriptive data on cancers occurring in people of all ages combined have been presented with the diagnoses categorized according to the International Classification of Diseases (ICD), in which cancers other than leukemias, lymphomas, Kaposi's sarcoma, cutaneous melanoma, and mesothelioma are classified purely on the basis of primary site. The malignant solid tumors of children are histologically very diverse and a substantial proportion consists of characteristic entities that are rarely seen in adults. Therefore, it is appropriate to group childhood cancers in a way which more fully takes morphology into account, and standard classifications have been devised with the categories defined according to the codes for topography and morphology in the International Classification of Diseases for Oncology (ICD-O). The current scheme is the International Classification of Childhood Cancer, Third Edition (ICCC-3), based on the third edition of ICD-O. ICCC-3 contains 12 main diagnostic groups:

International Classification of Childhood Cancer, Third Edition (ICCC-3)
1.	Leukemias, myeloproliferative diseases, and myelodysplastic diseases
2.	Lymphomas and reticuloendothelial neoplasms
3.	The central nervous system (CNS) and miscellaneous intracranial and intraspinal neoplasms
4.	Neuroblastoma and other peripheral nervous cell tumors
5.	Retinoblastoma
6.	Renal tumors
7.	Hepatic tumors
8.	Malignant bone tumors
9.	Soft tissue and other extraosseous sarcomas
10.	Germ cell tumors, trophoblastic tumors, and neoplasms of gonads
11.	Other malignant epithelial neoplasms and malignant melanomas
12.	Other and unspecified malignant neoplasms

All of the groups except retinoblastoma are split into subgroups, and the most heterogeneous subgroups are in turn split into divisions. Most groups contain only malignant neoplasms, but groups #3 and #10 also include nonmalignant intracranial and intraspinal tumors since they are usually recorded by cancer registries.

Successive classifications have been designed to have as much continuity as possible with their predecessors, while recognizing advances in understanding of tumor pathology and biology. Although the nomenclature of many groups and subgroups has changed since the previous version of the classification, their contents are largely the same.

Дата добавления: 2014-10-15