How is this cancer staged?
TNM method: The TNM system is used to stage cancers that produce tumors, and the same procedure is used to stage gallbladder cancer. The TNM method can be used to define the size of the original tumor (T), the number of malignant lymph nodes (N), and the extent to which the disease has spread to other sections of the body (M).
Tumor(T): is a term that is typically used to describe the size of a primary tumor, but in this case, it was used to describe the extent to which the cancer has spread to the gallbladder's walls. The gallbladder is made up of multiple layers, which are outlined below in order of innermost to outermost:
- The epithelium is a thin layer of cells that lines the gallbladder's internal wall.
- A layer of loose connective tissues called the lamina propria.
- The muscularis is a layer of muscle tissue that assists the gallbladder in contracting in order to push bile into the bile duct.
- The perimuscular is a fibrous tissue layer that lines the muscularis.
- The serosa is the outer layer of the gallbladder that arises from the gallbladder.
The node (N) indicates whether or not the malignancy has spread to neighbouring lymph nodes. N0 indicates that the cancer has not spread to the lymph nodes, N1 indicates that the cancer has spread to one to three neighbouring lymph nodes, and N2 indicates that four or more lymph nodes have been affected by malignancy.
Metastasis(M): This indicates if the cancer has moved to other parts of the body; M0 indicates no metastasis, while M1 indicates tumors that have spread to other parts of the body.
The grade describes how closely cancer cells resemble normal gallbladder cells under a microscope. Gallbladder cancer is graded on a scale of 1 to 3:
Grade 1 (G1): The cancer cells resemble the normal cells of the gallbladder.
Grade 2 (G2): The cells appear to be somewhere between grades 1 and 3.
G3 (Grade 3): Cancer cells appear aberrant and unlike to normal cells.
Extent of resection: Resection refers to the surgical removal of the cancer tumor, and gallbladder cancers are classed as follows based on the extent of resection:
- Resectable tumors are those that doctors feel can be surgically removed completely.
- Unresectable: Cancers that have spread too far or in a site where surgery is not possible.
Even when first diagnosed, only a small percentage of gallbladder cancer cases are resectable.
Stage I- The cancer has not spread to the nearby lymph nodes or other parts of the body. The diagnosis of the cancer in this stage usually happens by accident, for example during some surgery.
Stage II- Most cases of gallbladder cancer, especially of stage II are detected during surgeries performed to remove gall stones.
The gallbladder is divided into stages as follows:
- Stage IIA: The cancer has advanced through the muscularis into the fibrous tissue on the peritoneum's side, but not to surrounding lymph nodes or distant organs, and the grouping is complete (T2a, N0, M0).
- Stage IIB: The cancer has advanced through the muscularis into the fibrous tissue on the side of the liver, but it has not yet penetrated the liver or spread to surrounding lymph nodes or distant organs, and the grouping is still in the early stages (T2b, N0, M0).
Stage III- In this stage, the cancer has spread to the nearby organs- like liver, colon, pancreas. However, it has not yet spread to distant organs.
Gallbladder cancer is separated into two stages in stage III:
- Stage IIIA: The cancer has progressed through the serosa and spread to the liver or neighbouring structures such as the stomach, duodenum, colon, pancreas, or bile ducts outside the liver, but not to nearby lymph nodes or distant organs (T3, N0, M0).
- Stage IIIB: The cancer has gone beyond the gallbladder into adjacent structures but has not yet reached the main blood arteries. The staging is (TX, N1, M0), with X ranging from 1 to 3. It has spread to no more than three adjacent lymph nodes but has not migrated to distant organs.
Stage IV- This is the most advanced stage of cancer. In this case, the cancer has spread to the nearby lymph nodes and in more complex cases, has spread to distant organs.
The most advanced stage of gallbladder cancer is stage IV, with the following sub stages:
- Stage IVA: The tumor has developed into one of the main blood veins connecting the liver or two or more tissues outside the liver; it may or may not have migrated to local lymph nodes, but it has not gone to distant organs, and the staging is IVA (T4, N0 or N1, M0)
- Stage IVB: The cancer may or may not have spread beyond the gallbladder but has affected four or more lymph nodes but has not spread to distant organs and the staging is (any T, N2, M0) or the cancer may or may not have spread beyond the gallbladder or to lymph nodes but has spread to distant organs and the cancer may or may not have progressed beyond the gallbladder, but it has spread to distant organs ( T, N2, M0). .