Sarcoma – histological rank and stage affects recurrence, prognosis and life expectancy
2. Histological rank is the decisive factor of the chances of recovery from sarcoma.
Histology is a medical concept that describes the shape of a tissue with the help of microscopic observations. The determination of the histological level of the tumor consists in the content of various components of the sarcoma tissue and is determined by means of a microscope.
The determination of the histological level of the tumor has been demonstrated in several studies as an independent and powerful predictor of the chances of patient recovery. The histological level of the sarcoma is usually determined in accordance with the recommendations of the American Joint Committee on Cancer Control (AJCC), which were updated recently in 2017.
Histological examination of the tumor becomes possible after the patient has taken a tumor sample, also known as a biopsy.
After taking the sample from the tumor, the biopsy is sent to a pathological laboratory where the pathologist will have to evaluate four important characteristics of the sarcoma:
- • its histological type, degree of differentiation;
- • cytotoxic amount;
- • cells necrosis.
For each of the characteristics, the pathologist assigns an estimate of 0-3, and at the end of the process all scores for determining the histological level of the disease are evaluated.
The lower the score, the lower the histological level, and the chances of recurrence from sarcoma are higher.
Let’s look at each of the components that contribute to the histological level:
• Histological type of sarcoma:
At the first stage, the pathologist will have to decide to which of subspecies of the sarcoma fits the sample of the patient. This is done by determining the source tissue from which the sarcoma developed. For example, a well-differentiated sarcoma of adipose tissue will receive a low score, which will predict the best chances of recurrence, compared with a low degree of differentiation of the joint sarcoma.
• Degree of sarcoma differentiation:
The more tissue of the sarcoma is similar to the original tissue from which it was formed, the lower the score, and the better for the patient. Tissues that have lost their differentiated characteristics will receive higher scores and will be judged as reflecting lower chances of recurence.
• Chaotic amount of sarcoma:
Mitosis is a cell division. Since a cancer cell is a cell that is divided without control, the more mitoses, the more cancerous the tissue will be. Therefore, a tissue in which only a small number of dividing cells will be found will be considered less aggressive than a biopsy in which a large number of dividing cells will be found.
• Cell sarcoma necrosis:
Necrosis is an unplanned cell death. It is commonly said that when cancerous tumors are detected, extensive necrosis is a sign of rapid disease progression. This is due to the fact that the cells are so “busy” with the division that they consume a large number of nutrients. Tissues are not enough to provide all the cells with the nutrients they need, so some of them die in the process of necrosis.
After scoring for each of the four properties, all points are summarized on a scale of 2 to 8. The score between 2 and 3 gives the histological rank of G1, the score between 4 and 5 gives the histological rank of G2, and a score greater than 6 gives the histological rank of G3.
As already mentioned, a lower level is associated with better recovery rates in sarcoma.
3. Pathological stage of the disease – a combination of all the previous information.
Once the size of the tumor is determined, it is examined. All data are weighed to determine the pathological stage of the disease.
The pathological stage is known to patients as a scale 1-4 or as an indicator of TMN. In sarcoma, it is common to determine the stage of the disease in accordance with the guidelines of the American Joint Committee on Cancer Control (AJCC).
1. When the primary tumor is less than 5 cn in size, there is no metastasis and the histological level corresponds to G1, the sarcoma stage will be defined as IA or A1. When the tumor size is up to 15 cm, there is no metastasis, and the histological level is G1, the sarcoma stage will be defined as IB or B1. The average survival rate for patients with stage 1 is between 90% and 5 years, provided that the sarcoma began in the limbs.
2. When the primary tumor is less than 5 cm in size, no metastases and the histological level is G2 or G3, the stage of the disease will be determined as 2. The average survival rate for patients with sarcoma 2 stage was 81% within 5 years. These data are correct relative to the sarcoma that developed in the limbs.
3. When the main tumor size is 5 to 10 cm, no metastases and the histological level of G2 or G3, the stage of the disease will be defined as IIIA or A3. When the primary tumor is more than 10 cm, there are no metastases, and the histological level of the tumor is G2 or G3, the stage of the disease will be defined as IIIB or 3B. Any patient who has a metastatic lymph node but does not have metastases in distant organs, regardless of his histological stage, will refer to stage IIIB or 3B. The average survival rate of patients whose disease began with the limbs, and was defined as stage 3, was 56% within 5 years.
4. Any patient who has metastases in distant organs, regardless of the histological stage of the disease, will refer to stage IV.