Cancer Staging, Grouping, and Grading

The stage of the breast cancer patient is determined by the doctor based on the combination of the T, N, and M staging system along with the tumor size grading system in addition to the output of ER/PR and HER2 test. The present knowledge about the patient condition is used by health care professionals to determine diagnosis. The simpler and the most effective approach used in evaluating the condition of the patient is by using the T, N, and M staging. This analyses method is deployed in the research work.

The condition of the patient needs to be analyzed by the doctor to save the patient; this is done after the surgery, usually after the time span of five to seven days. Neoadjuvant therapy is the treatment given to the whole body before surgery. Healthcare professionals state that Stage I to Stage IIA cancer is a starting stage, and Stage IIB to Stage III is a bit advanced.

Stage 0: When the epidemic is present only in the ducts and lobules in and around the breast tissue but has not escalated to the neighboring tissues then it is considered as Stage zero (0) or noninvasive cancer(Tis.NO.MO).

Stage IA: The tumor grading is small, invasive, but it doesn't starts its origin in lymph nodes (Tl, N0, MO) is considered as Stage IA.

Stage IB: In this category sickness has been transferred to lymph nodes; further, the size of the lymph node is greater than 0.2 mm and lower than 2 mm in size. Absence of the symptoms of tumor cells in the human breast or the size of tumor cells is 20 mm or lower (TO or Tl, N1, M0).

Stage IIA: This category can fall under any of the following conditions: [1]

  • • The tumor is of size 20 mm or minor and the cancer has transferred to the auxiliary lymph nodes (Tl, N1, MO).
  • • The tumor of size larger than 20 mm yet not beyond 50 mm but the cancer has not extended to the auxiliary lymph nodes (T2, N0, MO).

Stage IIB: This level can fall on one of these two conditions:

  • • The tumor is of size larger than 20 mm yet not beyond 50 mm but the cancer has extended to one to three auxiliary lymph nodes (T2. N1, M0).
  • • The tumor is of size beyond 50 mm, yet it has not started its origin in auxiliary lymph nodes (T3, N0, M0).

Stage IIIA: In this level cancer started its origin in four to nine auxiliary lymph nodes or in internal mammary lymph nodes, but it can be of any size; the point to be noted is it has not moved to other parts of the body (TO. Tl. T2 or T3, N2, M0). In Stage IIIA tumor cells can be of size greater than 50 mm which has started its growth in one to three auxiliary lymph nodes (T3, N1. M0).

Stage IIIB: When the disease is diagnosed as inflammatory breast cancer. If this is the case, then the tumor has started to move to the chest wall with some symptoms like swelling or ulceration of the breast. There is a chance that it may not have been spread up to nine auxiliary or internal mammary lymph nodes, but it has started its origin in other organs.(T4; N0, N1 or N2; M0).

Stage IIIC: This is the condition where the cancer rate has increased, in which measurement of tumor cells constitutes any size and its growth has started in ten or more auxiliary lymph nodes, and also to the internal mammary lymph nodes, and further to the lymph nodes beneath the collarbone. Its origin has not started its growth in remaining areas of the body (any T, N3, M0).

Stage IV (metastatic): This category is the stage w'here the tumor cells constitute any size but it has started to move to other parts of the body like the bones, lungs, brain, etc. When this stage is diagnosed with no prior diagnosis(found to be 5% to 6%) it is termed de novo metastatic breast cancer.

Recurrent: The cancer that reappears even after treatment, which can be either local, regional, or distant. There are possibilities w'here the cancer may not reappear; if that is the case then further tests are conducted to determine the chances of reappearance. Tests or scans are carried out similarly over the period of diagnosis.

Staging and Grading

Staging and grading is the methodology used by doctors to explain to the patient how far the patient is affected with the breast cancer and how far the cancer grcws. The staging and grading process helps the healthcare professional team plan the best treatment for the patient. This methodology is useful even after surgery. Grading is the methodology that indicates w'hat the breast cancer cells look like. It is categorized in to 1, 2, 3 categories (Fig.11.2).

Grade 1 - In this classification type the cancer cells looks like normal cells, and the grow'th is generally moderate compared to the other categories.

Types of grade cells

FIGURE 11.2 Types of grade cells.

Grade 2 - In this classification type the cancer cells are moderately larger than natural cells, with different pattern and growth is rapid compared to normal cells.

Grade 3 - In this classification type the cancer cells look different from normal cells, and growth is usually faster.

Grading methodology for noninvasive breast cancers like DCIS is completely different. with the categories low, medium, or high.

Staging

Staging methodology is implemented to diagnose the volume of a tumor and to check the cancer infection as to how far and to what extend the problem has developed. Staging helps the doctor to plan the best treatment for an individual patient. One the best and most accurate methods to define the cancer is TNM system. The TNM system is implemented to identify the position or condition among four stages.

Stage 1 is considered to be small and less effected inside the breast (Fig. 11.3).

Stage 2 is considered to be category where the surrounding tissues are not affected in the breast, but larger than Stage 1 and moved to lymph nodes closer to tumor, even growth has not started in remaining organ in the human body (Fig. 11.4).

Stage 3 compared to Stage 1 and 2 the cancer is bit larger. In this stage the cancer cells have started moving into surrounding tissues and even to the lymph nodes in the area (Fig. 11.5).

Stage 4 is at high risk where the cancer cell has moved to rest of the organs of the body. Also termed has secondary or metastatic cancer (Fig. 11.6).

Stage 2 of tumor size

FIGURE 11.4 Stage 2 of tumor size.

Stage 3 of tumor size

FIGURE 11.5 Stage 3 of tumor size.

These are special kind of tests that are invented those that are used by the health care professionals in diagnosing the breast cancer. It is not necessary that all cases need these tests. Accuracy in diagnosis depends on the situations. All these are considered for non-cancerous the benign stage which changes as the pathologist observes under the microscope [I].

Evaluating and Implementing Naive Bayes Algorithm

In the world of data science one among the classification algorithms is the naive Bayes algorithm, which is based on Bayes’ theorem. The naive Bayes is a popular method for creating statistical predictive models. This algorithm is most commonly used for problems related to prediction for ease of implementation and usage. This classification algorithm is used to analyze the relationship between the attribute and various classes to determine the prediction or probability of the problem.

According to this study for the given patient record, every record is grouped based on the conditions as fit (“Recurrence event”) or unfit (“NO-Recurrence event”) for class.

The dataset is classified into two categories, the feature matrix and the response vector.

  • • The feature matrix represents each vector (row) of the datafile and each vector contains values which are dependent. Based on the dataset considered for the study, features are age, menopause, tumor-size, inv-nodes, nodecaps, deg-malig, breast, breast-quad, and irradiat.
  • • The response vector represents the actual value of the variable for each row in the feature matrix. Similarly, the name of the variable in the class is the class itself.

Assumptions

The naive Bayes algorithm assumes that each feature in the dataset is independent and contributes equally to the result.

Based on the relationship between features in the dataset, the assumptions can be understood as:

  • • Each feature is independent of each other.
  • • Equal importance is given to each feature.

Bayes Theorem

In terms of theoretical probability and event, given the probability of another event the Bayes theorem determines the probability for an event occurring. A mathematical representation of Bayes’ theorem:

Where A and В are events and P (B) [2] 0

P (A/В): Possibility of action A occurrence assuming that event В is true.

P (В/A): Possibility of action В occurrence assuming that event A is true.

P (A) and P (B) are actual possibilities that occur, which are independent of each other.

  • [1] Signs or symptoms of tumor cells are absent in the breast, but the abnormalcells have expanded to 1 to 3 auxiliary lymph nodes, but the cancer has notyet moved to other organs of the body. (TO, N1, M0).
  • [2] Gaussian: This model is implemented in classification techniques. It makesthe assumption that characteristics follow a normal distribution. • Multinomial: This model is implemented for discrete counts. For instance,consider, a classification problem. In this case Bernoulli trials are considered. In the example, in addition to “word reappearing in the document,”it is necessary to “keep track of how often the word reappears in the document.” Another example is “number of times resultant number x_i is determined in n trials”.
 
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