Lung cancer (LC) which is also referred as lung carcinoma, is characterised by a malignant tumour in the lung which is due to the uncontrollable tissue cell growth (1). LC has two main types, small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC), and similar to other cancers, LC, is typically initiated by the activation of oncogenes or tumour suppressor genes (1). It is thought that approximately 10-30% of adenocarcinomas are due to K-ras proto-oncogene mutations. Individuals with this condition most often experience symptoms of hemoptysis, chest pains, weight loss and finally shortness of breath (1). Furthermore, LC is also responsible for majority of cancer related deaths (fig. 1).

Figure 1 (2)- This graph shows the estimated number of deaths (in 2011) from pancreas, prostate, breast and colon combined. The number of deaths from lung cancer alone is equal to the cumulation of the rest (2).

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In regard to the staging process (fig. 2), it refers to the spread from its original location; physicians often use this as a reference for both the treatment plan and prognosis of the cancer (1). NSCLC adopts the TNM classification, this system is effectively based on the size of the primary tumour, spread and potential lymph node involvement (1).

The stages of lung cancer

Figure 2 (3): This table shows the different stages of lung cancer and the Tumour, Node, Metastasis classifications (3). As shown, as the stages go up, the cancer gets more aggressive and thus its treatment becomes more difficult (3).

Molecular changes contributing to breast cancer

Furthermore, LC is amongst the leading causes of cancer-related deaths in western nations (fig. 1) (4). Its cause is greatly associated with smoking cigarette (which are mutagens) and 10% of long-term smokers are susceptible (4). The development of this disease is largely due to the build of various molecular abnormalities (fig. 3 and 4). The most common is genomic instability. These alterations are not restricted to one level of gene slicing (4). In NSCLC, the predominant changes that occur in the genome is the loss of the 3p and 9p regions, deletion of chromosomal arm on 5p and mutations of both K-ras and p53 (these have been recognised in later stages) (4). It is important to note that LC can also be caused by chromosomal alternations i.e. amplification and is not solely due to mutations (4). Amplification is mostly seen in chromosome 1q and 3q (4). Genomic instability and alternations are a crucial characteristic of the initiation of LC and it’s the accumulation of the changes that lead to its progression (4).

The loss of chromosome types and their prevalence in nasopharyngeal cancer

Chromosome type	Prevalence of loss (percentage %)
3p	75
11q	70
14q	65
9q	60
13q	50
16q	50

Figure 3 (5)- This table shows the chromosomal losses which may occur in primary nasopharyngeal carcinoma. Although this data is not for lung cancer directly, there have been several studies (one of which was conducted by Dr Hui EP in 1999 in Hong Kong titled “Detection of recurrent chromosomal gains and losses in primary nasopharyngeal carcinoma by comparative genomic hybridization.” This study discusses the spread of nasopharyngeal carcinoma to the lungs and this can be used as an early diagnostic factor, as it may be an early indication of development of the cancer to the lung (5).

Chromosomal deletions in small-cell lung cancer and their prevalence

Chromosome type	Prevalence of loss (percentage %)
3p	100
10q	94
4q	86
5q	86
13q	86
17q	86

Figure 4 (6)- This table shows details of the molecular changes that occur in lung cancer and specifically deletion of the chromosomes. It can be seen t