Overview of Adenoid Cystic Carcinoma

Executive Summary:

Adenoid Cystic Carcinoma is the malignant form of Adenocarcinoma that affects the head and neck region, mainly targeting the salivary glands. The stages and grades of Adenoid Cystic Carcinoma determine the extent of the disease condition that has affected the patients. This stage of the disease determines the location or suspect area of cancer growth. TNM staging system determines the stages of Adenoid Cystic Carcinoma (ACC).

In the TNM staging system, T’ stands for tumor, ‘N’ stands for node and ‘M‘ stands for metastasis. The letter T plus a letter or number from 0 (zero) to 4 represents the location and size of tumor growth and ranges from TX-T4. On the other hand, the letter N in TNM staging is for lymph nodes in and near the head and neck region and ranges from NX-N3. The letter M is the metastasis and ranges from MX- M1. Stages of Adenoid Cystic Carcinoma or tumor growth combine the results of the T, N, and M classifications and constitute Stage I, II, III, IVA, IVB, IVC.

Staging system of Adenoid Cystic Carcinoma

Adenoid Cystic Carcinoma is a cancerous growth that affects the body’s glandular tissue. ACC is a rare but malignant form of Adenocarcinoma. It mainly affects the head and neck region, particularly targeting the salivary glands ​1​.

The Stages and Grade of Adenoid Cystic Carcinoma cancerous growth plays a pivotal role in determining the gravity of the disease condition ​2​. Staging describes the location or spot of the cancerous growth or tumor. It also helps explain whether the tumor has spread to other body parts.

Diagnostic tools to evaluate the stage of a tumor

Doctors use different diagnostic tools to evaluate the stage of a tumor. All the required tests and scans finalize the tumor stage. Knowing the tumor stage is extremely important in deciding the treatment strategy. The doctors choose the best treatment plan that suits their patients as per the staging aids. It helps them predict a person’s prognosis and the chance of recovery and survival.

The stage description varies with different kinds of cancers. There are plenty of staging systems available, but the most preferred and appropriate way to describe the Stages of Adenoid Cystic Carcinoma (ACC) is by using the TNM staging system. 

TNM staging system

In the case of Adenoid Cystic Carcinoma affecting the salivary glands, a TNM staging system is used to accurately diagnose the tumor growth stage. The salivary glands can be divided into primary and minor salivary glands. The three pairs of major salivary glands include the parotid, submandibular, and sublingual salivary glands. Around 800-1000 minor salivary glands are dispersed across the oral cavity.

The staging system, appropriate for a major salivary gland, helps to diagnose a tumor in that region. A staging system suitable for that location or the primary site is used if the tumor develops in the minor salivary gland ​3​. For instance, if the tumor arises from the salivary glands in the tongue or palate, it will be staged as per the TNM staging system suitable to the oral cavity. Based on such tests and scans, doctors determine the stage of cancerous growth and communicate it with their patients.

In the TNM staging system, ‘T’ stands for tumor‘N’ stands for Node and ‘M‘ stands for Metastasis.

T (tumor): The staging system will look for the size of the tumor, how big it is and its location of origin. 

N (Node): In terms of Node, it checks whether the tumor has spread to the surrounding lymph nodes or not. If so, where and how many have been affected?

Metastasis (M): whether the cancerous growth has metastasized or spread to different body parts. If so, which all body parts have been affected and to what extent? 

All these results together determine a person’s cancer stage. Usually, a cancer condition has five Stages of Adenoid Cystic Carcinoma: Stage 0 (zero), Stage I, Stage II, Stage III and Stage IV. It is a common way of describing almost all types of cancers. Based on these stages from 0 to 4, doctors determine the best treatment plan suiting a person’s condition. 

Cancer staging can be clinical or pathological. The clinical stage of cancer or tumor growth is based on physical examinations or imaging tests before the surgical procedure. On the other hand, pathological staging is based on what is discovered during a surgical procedure (like a biopsy). The latter provides more accurate information regarding a patient’s cancer prognosis between clinical and pathological staging.

TNM STAGING SYSTEM IN DETAIL FOR ADENOID CYSTIC CARCINOMA 

Tumor (T)

The letter T plus a letter or number from 0 (zero) to 4 represents the location and size of tumor growth. The size of the tumor is measured in centimeters (cm). Staging based on tumors can be divided into many small groups. The following is a list of specific tumor stage information concerning Adenoid Cystic Carcinoma:  

TX: refers to the primary tumor without evaluation.

T0 (T plus zero): indicates no or zero evidence of tumor growth

T1: indicates a small tumor, about 2 centimeters (cm) at its widest dimension. Such tumors usually don’t grow or spread outside their area of origin or invade other body parts. They are non-invasive tumors.

T2: it refers to a large tumor. The size can range between 2 cm and 4 cm. but these are non-invasive.

T3: The tumor size is more significant than 4 cm but smaller than 6 cm. The tumor can be invasive. At this stage, it would have spread or metastasized beyond the salivary gland (point of origin). But it would not have affected the facial nerve, which happens to be the seventh nerve that controls expressions like frowns and smiles.

T4: it refers to the aggressive stage of tumor growth. The tumor in this stage would be highly invasive. T4 stage can be divided into:

T4a: refers to the tumor that has invaded parts like the jawbone, ear canal, skin or facial nerve.

T4b: indicates aggressive invasion. The tumor must have invaded the nearby bones skull base or encased the arteries.

Node (N)

The letter N in TNM staging stands for lymph nodes. Lymph nodes refer to the small, bean-shaped organs in our body which helps fight infections. In the case of Adenoid Cystic Carcinoma, the lymph nodes in and near the head and neck region are called regional lymph nodes. And those present in other parts of the body are distant lymph nodes.

NX: this stage refers that the neck having undergone an intervention; it prevents the evaluation of lymph nodes present in the region.

N0: indicates no evidence of CancerCancer or tumor in the regional nodes.

N1: indicates that CancerCancer has spread to a single node on the same side as the primary tumor (at the initial origin point). The tumor size found in the Node would be 3cm or less than that.

N2a: The cancer growth has also spread to a single lymph node on the same side as the primary tumor (origin point). The size is more significant than 3cm but smaller than 6cm. 

N2b: indicates that the tumor has spread to more than one lymph node on the same side as the primary tumor, and its size is not larger than 6 cm.

N2c: indicates that the tumor has spread to more than one lymph node on either side of the body, and the tumour size is not larger than 6 cm.

N3: aggressive stage, where the tumor found in the lymph nodes is more significant than 6 cm.

Metastasis (M)

The letter “M” in the TNM system indicates Metastasis. It describes whether Cancer has spread to other parts of the body. It is called distant Metastasis.

MX: This indicates a distant metastasis .

eM0: means that the tumor has not spread to other body parts.

M1: this indicates Metastasis. That is, the tumor has spread to other parts of the body.

Stage grouping of Adenoid Cystic Carcinoma Cancer

Doctors assign the stages of Adenoid Cystic Carcinoma or tumor growth by combining the results of the T, N, and M classifications ​4​.

Stage I: This stage of Adenoid Cystic Carcinoma indicates a non-invasive tumor (T1 or T2) that does not spread or metastasize to the lymph nodes (N0). Also, there happens no distant metastasis (M0).

Stage II: This stage is an invasive tumor (T3) stage with no spread or Metastasis to the lymph nodes (N0) or distant metastasis (M0).

Stage III: This indicates a smaller tumor (T1 or T2) spread to or invaded the regional lymph nodes (N1). It shows nil sign of Metastasis (M0).

Stage IVA: It is an invasive tumor (T4a) stage. It either has no lymph node involvement (N0) or has spread or metastasized to only a single, same-sided lymph node (N1) but with no metastasis (M0). The stag also describe a T3 tumor with one-sided nodal involvement (N1) but zero Metastasis (M0) or any tumor growth (any T) with extensive nodal involvement (N2) but no spread or Metastasis (M0).

Stage IVB: more aggressive stage, which describes any cancer (any T) with more extensive spread to lymph nodes (N2 or N3) and null Metastasis (M0).

Stage IVC: This stage describes any tumor (T, N) with distant metastasis (M1).

Recurrent Cancer: 

Recurrent cancer refers to cancer or tumor growth that comes or recurs back after treatment. If the tumor recurs once again in the body, it would require another round of tests scans to learn about it and the extent of the recurrence.

To learn about the extent of the recurrence, the tests and scans conducted would be similar to those carried out during the original cancer diagnosis.

References

  1. 1.
    Ko JJ, Siever JE, Hao D, Simpson R, Lau HY. Adenoid Cystic Carcinoma of Head and Neck: Clinical Predictors of Outcome from a Canadian Centre. Current Oncology. Published online February 1, 2016:26-33. doi:10.3747/co.23.2898
  2. 2.
    Seethala RR. An Update on Grading of Salivary Gland Carcinomas. Head and Neck Pathol. Published online February 25, 2009:69-77. doi:10.1007/s12105-009-0102-9
  3. 3.
    Szanto PA, Luna MA, Tortoledo ME, White RA. Histologic grading of adenoid cystic carcinoma of the salivary glands. Cancer. Published online September 15, 1984:1062-1069. doi:
    4.