Cancer Disease

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Cancer Disease Cancer Cells

 Epidemiology

What cancer is?

 Classification of cancer

            Clinical assessment

            Radiological assessment

            Biopsy

            Pathological examination

            Genetic markers

 Treatment

 References and selected reading

                                              

Cancer Disease

 

Epidemiology

            Cancer is the second killer disease in the western world (after heart disease). In the USA, more than half million people were estimated to die from cancer in 2008 (1). Breast cancer is the most prevalent cancer among women; and prostate cancer is the most prevalent among men (1). Lung cancer, is the second most prevalent cancer both in men and women, but is the first killer cancer disease in both sexes (1).

 

What cancer is?

            The body organs are composed from cells, which divide and proliferate according to the body needs (e.g. when child grow, or in the process of wound healing…).  Tumors result from unnecessary proliferation of cells. Tumors can be benign or malignant. What makes tumors malignant and cancerous is the ability of some of the tumor cells to detach from the “tumor” masses, travel in the blood stream or the lymphatic system, reside in other organs and start dividing there. This process is called “metastasis”.

  

Classification of cancer

             The type of cancer is determined according to its origin: this means according to the organ from which the unnecessary cell proliferation initiated. There are several methods to determine the type of cancer:

1.      Clinical assessment:

a.       History taking: detailed history from the patient and his relatives regarding the disease symptoms is very important. The symptoms are usually non-specific, but they help in directing the clinician to the disease source. Symptoms that may help in assessing the type of cancer include: changes in skin color (melanoma); head and neck lumps (cancer of head and neck); changes in voice (laryngeal cancer); convulsions (brain cancer); breast lumps (breast cancer); hemoptysis, i.e. coughing up blood (lung cancer or metastasis to the lung); rectal bleeding and constipation (colon cancer); and vaginal bleeding (uterine cancer).

b.       Physical examination is a second and pivotal step. Physical examination should include:

I.       Inspection: looking to the patient is very important: Any skin discolorations, lumps, asymmetry (e.g. breast asymmetry- including differences in the breast skin texture) should be noted. Inspecting the patient while moving will help identifying neurological deficits. Special note should be given to the patient’s voice, as changes in the voice quality may hint to the source of the disease (e.g. laryngeal cancer).

II.    Palpation & percussion: palpating the patient will help in identifying disease that is difficult to assess by inspection only, and to further assess lesions inspected by the examiner’s eyes. Palpating lumps defines their size, consistency, and fixation to other organs. Palpating and percussion the abdomen may detect abdominal masses and evaluate the size of abdominal organs (liver and spleen size) and their consistency. Palpation may elicit pain; the location and quality of this pain allows the clinician to further define the disease process.

III. Auscultation: Is very important part of the physical examination. For example obstruction of bronchial airway (lung cancer) by cancer growth will results in wheezes when auscultating above the diseased bronchus. Auscultating the abdomen in a patient with bowel obstruction due to intestinal cancer will gives “metallic sounds”.

2.      Radiological assessment:

a.       X- ray: Plain x- ray films may give initial evaluation of caner disease and its complications. X -ray is essential in evaluating lung cancer and metastasis to the lung, bone lesions, and bowel obstructions due to cancer.  

b.      Mammography: It's a test that utilizes x- rays to detect lesions in the breast. 

c.       Ultrasonography: is a useful tool to assess tumors. It is usually used to assess metastasis to liver, blood flow in blood vessels and the presence of thrombus, and can guide clinicians while performing biopsy so that they can approach the desired location more precisely. Trans-esophageal ultrasonography is helpful in identifying pancreatic cancer. Trans-rectal ultrasound is useful in identifying prostate cancer. Breast ultrasonography is useful to define breast lesions detected by mammography more precisely, and to guide biopsy from suspicious lesions.

d.      Computerized Tomography (CT): CT scans are very important for evaluating primary cancer and its metastatic spread. Usually CT scans are enhanced with contrast (iodine based) to get better visualization of the cancerous spread (side effects of contrast include kidney injury, and hence it should used with caution in patients with preexisting kidney disease).

e.       Magnetic Resonance Imaging (MRI); Is more expensive, and time consuming test. MRI is needed for studying specific brain lesions, muscular and bone lesions, and in some other situations that CT scan gives insufficient information. Recently MRI is being utilized to examine breasts, especially in young women with dense breast tissue (where mammography is not usually inefficient).  

3.      Biopsy: Biopsy is the process in which a specimen from a suspected lesion/ lump/ mass is taken. Biopsy may be open or closed. “Open biopsy” is obtained through operation in which the surgeon makes incision and approaches the desired lesion directly. “Close Biopsy” is usually obtained under guidance of radiological facility (ultrasound or CT); and the lesion is approached via a fine needle (aspiration) or thicker needle that cuts part of the lesion (Tru-cut biopsy). Once material from the tumor is obtained, several tests may be performed; these include pathological evaluation under microscope, molecular cancer and genetic markers and microarray analysis.

4.      Pathological examination: pathological examination is the diagnostic step that usually supplies the final diagnosis of the disease. Following the acquisition of the biopsy materials, it is sectioned and stained with different methods and for different markers, and viewed under microscope. According to the picture obtained from the various staining, a diagnosis regarding the nature of the disease and the type of cancer is confirmed. In some highly malignant tumors, the origin of the tumor cells can’t be identified even under microscopic examination.   

5.      Genetic markers. Molecular markers may be studied from tumor specimens, and a microarray test can be performed to elucidate the gene expression profile in tumors. Tests for gene expression in tumor cells are performed today, but usually to test a limited number of genes (e.g. Oncotype Dx that test 21 genes). In the next decade such tests will probably become more widespread, and will incorporate much more genes.

 

Treatment

            The treatment of cancer includes multiple approaches: Surgery, Chemotherapy, Radiotherapy, Antibodies, and tumor vaccines.

 

 

 

References and selected reading.

 

  1. Jemal A, Siegel R, Ward E, Hao Y, Xu J, Murray T, Thun MJ. Cancer statistics, 2008. CA Cancer J Clin. 2008; 58: 71-96.

 

 

 

 

 

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