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Grades and Stages of Bone Cancer

Grades and Stages of Bone Cancer

Executive Summary

The staging system of bone cancer depends upon the size of the tumor, its metastasis and its time of occurrence. The TNM staging system is used as a staging approach for bone sarcoma. The five stages of bile duct cancer are determined: stage 0, stage I, stage II, stage III, and stage IV. T category includes skeleton, trunk, skull and facial bones, spine, and pelvis. The grading system in cancer determines the similarity of the cancer cells with the healthy cells. The low-grade tumor and high-grade tumor are the two grouping systems in grading. The grading system ranges from GX, G1, G2, and G3. The different stages of bone sarcoma include stage 0, stage I (IA, IB), stage II (IIA, IIB), stage III, and stage IV (IVA, IVB). Recurrent bone sarcoma is observed among the patients even after completing their treatment.

Staging of Bone Cancer

Staging determines where the tumor is located, whether it has spread or not, and how it grows. While assessing Stages of Bone Cancer, many factors are taken into account.

Doctors use diagnostic tests to discover cancer's stage, so staging may not be complete until all tests are finished.

TNM staging system

The TNM system is the tool doctors use to describe the stage of Bladder cancer ?1?.

  • T is for tumor - How large the tumor is and where is its location
  • N is for nodes - Has cancer spread to lymph nodes, and if so, where and how many?
  • M is for metastasis - Whether cancer has metastasized to other body parts distant from the bladder.

In most primary bone sarcomas, there are five stages: stage 0 (zero) and stages I through IV (1 through 4).

Also Read:Symptoms based on Cancer types

T categories

  • Skeleton, trunk, skull and facial bones
  • TX - Primary tumor can not be evaluated.
  • T0 - There is no evidence for tumors.
  • T1 - The tumor is about 8 cm or smaller
  • T2 - The tumor is greater than 8 cm.
  • T3 - There is more than one different tumor on the primary site.
  • Spine
  • TX - Primary tumor can not be evaluated.
  • T0 - There is no evidence for tumors.
  • T1- The tumor is found only on one part of the vertebrae or on vertebrae that are not next to each other.
  • T2 - The tumor is found only on three adjacent parts of the vertebrae
  • T3 - The tumor is found on four or more adjacent parts of the vertebrae or located on parts of the vertebrae that are not next.
  • T4 - The tumor has grown into the spinal canal or great vessels.
  • T4a - The tumor has grown into the spinal canal.
  • T4b - The tumor has grown into the great vessels or affects blood flow.
  • Pelvis
  • TX - The primary tumor cannot be evaluated.
  • T0 - No evidence of a primary tumor with no extraosseous extension.
  • T1 - The tumor is located only on 1 part of the pelvis.
  • T1a - The tumor is about 8 cm or smaller.
  • T1b - The tumor is more significant than 8 cm
  • T2 - The tumor is located on 1 part of the pelvis with an extraosseous extension or two parts of the extraosseous extension.
  • T2a - The tumor is 8 cm or smaller.
  • T2b - The tumor is greater than 8 cm
  • T3 - The tumor is found in two parts with extraosseous extension.
  • T3a - The tumor is 8 cm or smaller
  • T3b - The tumor is more significant than 8 cm.
  • T4 - The tumor is found on three parts of the pelvis or has crossed the sacroiliac joint (which connects the bottom of the spine with the pelvis).
  • T4a - The tumor involves the sacroiliac joint and has grown to the sacral neural foramen.
  • T4b - The tumor has grown around blood vessels and affects blood flow.

N categories

  • NX - The regional lymph node cannot be evaluated.
  • N0 - Cancer has not spread to regional lymph nodes.
  • N1 - Cancer has spread to regional lymph nodes, rare for primary bone sarcoma.

M categories

  • M0 - Cancer has not metastasized.
  • M1 - Cancer has metastasized
  • M1a - Cancer has spread to the lungs
  • M2b - Cancer has spread to other bones or another organ

Grade (G)

Additionally, doctors may talk about the Stages of Bone Cancer. The grade tells how much cancer cells look like healthy cells when viewed under a microscope. Cancer resembles healthy tissue and has different cell groupings; it is called 'well-differentiated or a 'low-grade tumor.' It is called 'poorly differentiated' or a 'high-grade tumor' if the cancerous tissue does not resemble healthy tissue."

  • GX - The tumor can't be identified
  • G1 - The cancerous cells are well differentiated that are low grade
  • G2 - The cancerous cells are moderately differentiated that is a high grade
  • G3 - The cancerous cells are poorly differentiated, which is high grade.

Stages of Bone Cancer

The cancer stage is determined by combining the T, N, M, and G classifications. No stage groupings are available for primary bone sarcoma in the spine or pelvis. These stage groupings are for the skeleton, trunk, skull, and facial bones ?2?:

Stage I

  • Stage IA - Tumour is either low grade or cannot be graded (GX or G0), is 8 cm or smaller (T1) and has not spread to lymph nodes(N0) or other parts(M0).
  • Stage IB:Tumour is low grade or cannot be graded(GX or G0), more significant than 8 cm(T2), or there is more than one tumour at the primary site (T3) and has not extended to lymph nodes(N0) or other parts (M0).

Stage II

  • Stage IIA - Tumor is high grade(G2 or G3) and 8cm or smaller (T1), has not extended to lymph nodes(N0) or other parts (M0).
  • Stage IIB: Tumor is high grade(G2 or G3) and more significant than 8 cm (T2), has not extended to lymph nodes(N0) or other parts (M0).

Stage III

There are multiple high-grade (G2 or G3) tumors in the primary bone site (T3), but they have not extended to any lymph nodes or other parts of the body (N0, M0).

Stage IV

  • Stage IVA - The tumor is of any size or grade and has extended to the lungs (any G, any T, N0, M1a).
  • Stage IVB:The tumor can be of any size or grade and has extended to the lymph nodes (any G, any T, N1, and any M), or the tumor can be of any size or grade and has spread to another bone or organ besides the lung (any G, any T, any N, M1b).

Recurrence:Cancer that returns after the treatment is recurrent cancer. The doctor performsanother round of tests to know the extent of the recurrence.

Reference

  1. 1.
    Steffner RJ, Jang ES. Staging of Bone and Soft-tissue Sarcomas. Journal of the American Academy of Orthopaedic Surgeons. Published online July 2018:e269-e278. doi:10.5435/jaaos-d-17-00055
  2. 2.
    Kundu ZS. Classification, imaging, biopsy and staging of osteosarcoma. IJOO. Published online June 2014:238-246. doi:10.4103/0019-5413.132491
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