Small Cell Lung Cancer In Malaysia Biology Essay

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Basically, lung cancer can be defined as the rapidly growth of cells which is abnormal. The uncontrolled growth occurs in the lung. There are different types of lung cancer which are classified based on the main types of lung cancer involved. These include the small cell lung cancer (SCLC) and the other one is the non small cell lung cancer (NSCLC). The SCLC is also known as the 'oat cell cancer' due to the cell shape observed under the microscopic view. It is a fast growth spreading type if compare to the NSCLC.

According to the National Cancer Registry, Ministry of Health Malaysia (2006), there were ten most common cancers reported among Malaysian. These include: breast cancer, colorectal, lung, cervix, nasopharynx, thyroid gland, liver, stomach, prostate gland and lymphoma.

Figure 1: Percentage of Ten Most Common Cancers Occurred in Peninsular Malaysia 2006

(National Cancer Registry, Ministry of Health Malaysia, 2006)

From the figure 1, it can be conclude that the lung cancer take place as the third most cancer incidence occur in Peninsular Malaysia in 2006 which account for 9.4% over ten most common cancers.

There were 2048 lung cancer cases has been reported which is 1445 of the cases are from males (71%) and 603 of the cases are from females (29%). The incidences of lung cancer among males are two times higher if compared to the females.

Figure 2: Percentage Incident of All Cancers in Males of Peninsular Malaysia 2006

(National Cancer Registry, Ministry of Health Malaysia, 2006)

Based on the figure 2 above, lung cancer becomes the second most common cancer among man after the colorectal cancer which account for 14.5%.

The incidence of lung cancer is increase with age 50 years old and above (Figure 3). Common cancers occur among the young adult group (15-49 years old) of men are nasopharynx, colorectal, lung, brain and leukemia while in women include breast, cervix, thyroid gland, ovary and colorectal cancer. For the older age which is more than 50 years old, the common cancer are colorectal, lung, nasopharynx, prostate and liver for men and breast, colorectal, cervix, lung and ovary for women.

Figure 3: Lung Age Specific Cancer by Age and Gender in Peninsular Malaysia 2006

(National Cancer Registry, Ministry of Health Malaysia, 2006)

The incidence of lung cancer is differed on ethnicity. Chinese populations have the highest lung cancer incidences that are 16.1% for males and 6.4% in females. (This is based on the statistics of ten most frequent cancers according to ethnicity, Figure 4).


Male (%)

Female (%)










Figure 4: Incidents of Lung Cancer over All Cancers According to Ethnicity

(National Cancer Registry, Ministry of Health Malaysia, 2006)

Causes of lung cancer

There are several causes of lung cancer. These include by smoking habit, environmental factors, age and genetic risk. From all these factors, tobacco smoking contributes the most common factor the occurrence of lung cancer (UpToDate, 2010).

According to Health Information Publications (2004), smoking lead to lung cancer is due to the presence of carcinogen substances within tobacco which are able to cause the cancer. These carcinogens will cause damage to DNA of lung tissue cell which will cause it to mutate and lead to the development of uncontrolled cell growth. These cells may become cancerous over a period of time when it metastasize or move to other areas of the body via the bloodstream. It is believed that smoker's has 10 to 30 times greater risk of developing lung cancer than that of a non-smoker (UpToDate, 2010).

There are other causes of lung cancer which are include, the environmental factors due to the exposure of carcinogens such as asbestos, radon gas, secondhand smoke, radiation and other chemicals. According to the Center of Disease Control, about 126 million people are exposed to secondhand smoke (tobacco smoke that permeates outside environment) and are put at risk of lung cancer.

Based on National Cancer Registry, Ministry of Health Malaysia, 2006, the risk of developing lung cancer is increases with age which is most commonly occur after age 50. Meanwhile, person that has a family background of lung cancer has a higher risk of developing lung cancer in her/himself.

Symptoms of lung cancer

Lung cancer can be early detected by several symptoms such as cough, coughing up blood, shortness of breath and chest pain. As the cancer cell migrate to other part of body, hoarseness of voice, shortness of breath, difficulty swallowing and swelling of the face and hands can be seen in the suspected person. On the other hand, the severe case may cause back pain, paralysis and bone pain.

Sample Collection and Preparation

In detecting SCLC, there are few specimens collected. According to Kennedy, Miller, and Prindiville (2000), they stated that sputum cytology is useful in detection of lung cancer at an earlier stage. Sputum cytology is a primary screening test in diagnosing SCLC due to it lesion location which is at the central of the lung. Morning sputum specimen is the best sample and should be collected in three consecutive days. According to Byers, et al (2008), the fixative used to preserve the sputum sample is 2% carbowax and 50 % alcohol.

Bronchoscopic specimens which are bronchial brushing and bronchial washing that are obtained by bronchoscopy also valuable samples in detecting SCLC. Based on the journal by Rivera, Detterbeck, and Mehta (2003), pleural effusion taken by fine needle aspiration of supraclavicular nodes or metastatic sites can be done in diagnosis of SCLC.

Preservation Prior to Processing

Specimens received in laboratory should be examined and record their appearance. According to the manual of Non Gynae Preparation Techniques (n.d.), sputum must be carefully inspected by pouring into petri dish and examining on a dark background. Any bloody, discoloured, or solid particles are taken and spread on slide. Specimens are smeared on two adhesive coated slides and then fix in 95% ethanol, and two on plain slides for dried smear. The adhesive slide that is commonly used is albumen or polylysine coated slide.

Staining of the Smears

Based on the manual of Non Gynae Preparation Techniques, the smears that fixed in the 95% ethanol are stain using Papanicolaou staining. The Papanicolaou stain demonstrates nuclear details and giving cytoplasmic transparency. The Papanicolaou stain consists of Harris haematoxylin, Orange G-6 (OG-6), and eosin alcohol-50 (EA-50). Harris haematoxylin has strong affinity for nuclei, while OG-6 and EA-50 have polychrome properties.

The air dried smears are stained with May-Grunwald Giemsa staining. This stain demonstrates cytoplasmic detail and extracellular substances. It is also used to shows cell and nuclear size. It depends on two components which are azure B (trimethylthiomin) and eosin Y (tetrabromoflurescen).

Cytomorphology Features of Small Cell Lung Cancer

There are three types sample that are used in diagnosing SCLC in cytology, which are sputum, bronchiol brushing, and pleural fluid. Sputum is the most common sample used. According to the Kulawik, J. D., (2010) the significant characteristic of cells that shows SCLC are prominent nuclear molding, finely granular nuclear chromatin, scanty cytoplasm and high nuclear to cytoplasmic (N:C) ratio. In addition, Charles, D.S.,et al(2000) state that the other criteria that present in SCLC are basophilic cytoplasm, crush artifact, diathesis and the cells size 1.5 times lymphocyte size.


Figure 6: A pleural fluid smear shows salt and pepper chromatin and scanty cytoplasm (1).

(Brahm, et al., n.d.)

Figure 5: A pleural fluid smear show nuclear molding and high N:C ratio (1,3) and scanty cytoplasm (2)

(Brahm, et al., n.d.)

Figure 8: A bronchiol brushing smear shows high nuclear/cytoplasmic ratio. Scanty, delicate ,and basophilic cytoplasm. Nucleus show molding and finely granular "salt and pepper" chromatin.

(Brahm, et al., n.d.)

Figure 7: A sputum smear shows demonstrating cluster of small malignant cells-loosely arranged and finely granular chromatin (1), hyperchromatic nuclei and scanty cytoplasm

(Brahm, et al., n.d.)