Systematic anti-cancer therapies
to identify the specific gene changes and indicate whether a particular patient is suitable for a targeted treatment.
Lung cancer
Lung cancer is known to be highly heterogeneous, with each patient presenting with different symptoms and responding individually to different treatments. 3 Lung cancer has the highest incidence and mortality rate for cancer, it is also the most expensive cancer in the world with a mortality rate of three times prostate cancer in men and nearly double breast cancer in women. Interestingly, the incidence rate of lung cancer and Human Development Index (HDI) and mortality rate of lung cancer and HDI both showed a significantly positive correlation for both sexes. 4 Lung cancer can be broadly split into two different types: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) which in turn can be further divided into large cell carcinoma, squamous cell carcinoma (epithelial cells) and adenocarcinoma (cells lining the alveoli and mucus producing cells). Treatment of lung cancer initially involves taking an image-guided biopsy of the tumour in which the DNA sequence of the cancer cells is then analysed to look for abnormalities in certain genes. Specific abnormalities in genes such as the KRAS gene require a specific form of treatment as they do not respond to other forms of targeted drugs. 5 A specific treatment plan can then be designed for the treatment. An example of this is EGFR (epidermal growth factor), which is a gene that codes for a glycoprotein on the surface of cells which enables cells to grow and divide. When there is an overexpression of this gene then a specific form of NSCLC occurs. EGFR inhibitors are used to stop the EGFR gene functioning and therefore block the production of the glycoprotein, slowing the growth of the cancer. 6 Another example of targeted therapy are inhibitors that target the ALK gene mutations, for which the main drug used is Crizotinib, which stops the ALK gene mutation from helping the tumour grow leading to the tumour shrinking. Crizotinib is often used instead of chemotherapy; however, often it is used in patients after the initial chemotherapy drugs have stopped having an effect on the tumour. 7 A major problem with all treatments is that the cancer mutates to become resistant to treatments over time, meaning repeat challenges with the same agent are not effective. A further advantage of targeted therapy is that instead of intravenous administration the majority of targeted therapy options involve an pill that is swallowed. 8 This means that treatment is easier to deliver and can be done from home instead of having to visit the hospital for intravenous infusions. 3 Wu, K. & House, L. (2012) ‘Personalized targeted therapy for lung cancer’, Int J Mol Sci 13(9): 11471-114969. 4 Goodarzi, E. (2018) ‘Geographical distriution global incidence and mortality of lung cancer and its relationship with the human development index (HDI); An ecology study in 2018’, World Cancer Research Journal 6: e1354. 5 Targeted drug therapy for non-small cell lung cancer at https://www.cancer.org/cancer/types/lung-cancer/treating-non-small-cell/targeted-therapies.html. Consulted:24/08/23 . 6 See Wu & House (note 3); see also Targeted drug therapy for non-small cell lung cancer at https://www.cancer.org/cancer/types/lung-cancer/treating-non-small-cell/targeted-therapies.html. Consulted:24/08/23.
7 See Targeted drug therapy for non-small cell lung cancer (note 6). 8 Sonett, J. Personalized medicine used for treatment of lung cancer at https://www.youtube.com/watch?v=1c9sKHtNuKQ. Consulted 23/08/23.
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