LUNG CANCER

Lung cancer (Malignant neoplasm of the trachea, bronchus and lung) was the 4th leading cause of death in Australia in 2015, accounting for 8,466 or 5.3% of all deaths. It is also the leading cause of cancer death, with the lung being the primary site in 18.4% of cancer fatalities.

Although lung cancer accounts for the most deaths, other types of cancer are more commonly diagnosed. Breast, prostate and colorectal cancers, as well as melanoma of the skin are the most commonly diagnosed cancer types (Endnote 4).

What is Lung Cancer?

Lung cancer refers to the uncontrolled growth of abnormal cells in one or both lungs which spreads (metastasises) to other parts of the body. Malignant tumours which originate in the lung are referred to as primary lung cancers. They are classified into two groupings based on how the cancerous cell type appears under a microscope: small cell lung cancer and non-small cell lung cancer.

The lung is also a common site for secondary cancers to establish, however this fact sheet discusses only primary lung cancers.

Lung cancer, sex and age

Lung cancer causes more deaths (30.5 per 100,000 persons) than sex-specific cancers such as breast (20.1 per 100,000 females) and prostate (25.5 per 100,000 males) cancers.

Historically, males have a higher death rate due to lung cancer than females. In 2015, males had a death rate 1.7 times higher than females (38.9 deaths per 100,000 and 23.5 deaths per 100,000 respectively). Over the last 10 years there has been a steady decrease in the lung cancer death rates in males, however female death rates have remained relatively stable (see graph below).



Lung cancer is more commonly diagnosed in those aged 60 years or older (Endnote 8), and the graph below shows that the rate of lung cancer deaths increases with age. The median age of death for persons who died of lung cancer was 73.5 years in 2015. Lung cancer is associated with premature mortality and on average a person who died prematurely from lung cancer lost a potential of 10.4 years off their life in 2015.



Risk factors

There are a number of risk factors relating to the development of lung cancer. Of these, tobacco smoking has been identified as being the greatest risk factor (Endnotes 3, 7 and 12). Current smokers have a 9 times higher risk of developing lung cancer than non-smokers (Endnote 7). The benefits of quitting smoking are widely known, and for those who quit, the risk of developing lung cancer decreases by more than half when compared to current smokers (Endnote 7). Other environmental and personal risk factors for lung cancer include: occupational exposure to particular substances; pollution; other specified lung diseases such as tuberculosis and chronic obstructive pulmonary disease; and having a personal or family history of lung cancer (Endnotes 3, 7 and 12).

Comorbidities and lung cancer

Understanding comorbidities which occur with lung cancer are important for medical practitioners when considering treatment options and survival rates. In 2015, 66.2% of lung cancer deaths were reported with one or more comorbid conditions on the death certificate. Lung and heart diseases were the most common chronic diseases to be reported with lung cancer, with: Chronic obstructive pulmonary disease (J44) seen on 13.8% of death certificates; other forms of heart disease (I30-I52) seen on 10.9%; and Ischaemic heart diseases (I20-I25) seen on 8.6%. These conditions also have similar risk factors to lung cancer, most notably, smoking and age (Endnotes 6, 10, 11 and 13).

Future Projections

While both the incidence and mortality rate of lung cancer are projected to decrease for males, the rates for females are forecast to increase (Endnotes 2 and 5). Although smoking rates have been steadily decreasing for both men and women, decreases for men began in the 1960s while for women they began in the late 1970s (Endnote 1). This may account for the differences seen today for lung cancer incidence and mortality between the sexes, as it can take decades for lung cancer to develop (Endnotes 1 and 9). Smoking rates are projected to continue decreasing for both males and females in all age groups (Endnote 14) which in time should see both the incidence and mortality rate for lung cancer also decrease.


Bibliography

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2. AIHW 2012. Cancer incidence projections: Australia, 2011 to 2020. Cancer Series no. 66. Cat. no. CAN 62. AIHW: Canberra.

3. AIHW, 2015. Lung cancer: What are the risk factors for lung cancer? Viewed 17th June 2017 <https://lung-cancer.canceraustralia.gov.au/risk-factors>

4. AIHW 2017. Cancer in Australia 2017. Cancer Series no. 101. Cat. no. CAN 100. AIHW: Canberra.

5. AIHW 2017. Supplementary data tables: 2014 to 2015. Cancer mortality trends and projections: 2014 to 2015. Viewed 16th June 2017 <http://www.aihw.gov.au/cancer/mortality-trends-projections/>

6. AIHW. Risk factors associated with COPD. Viewed 17th June 2017 <http://www.aihw.gov.au/copd/associated-comorbidities-and-risk-factors/risk-factors/>

7. Cancer Australia 2014. Risk factors for lung cancer: an overview of the evidence. Cancer Australia, Surry Hills, NSW.

8. Cancer Council 2014. Understanding Lung Cancer: A guide for people with cancer, their families and friends. Viewed 16th June 2017 <http://www.cancer.org.au/content/about_cancer/ebooks/understanding_lung_cancer_2015_rev1.pdf>

9. Cancer Research UK 2016. How smoking causes cancer. Viewed 15th June 2017 <http://www.cancerresearchuk.org/about-cancer/causes-of-cancer/smoking-and-cancer/how-smoking-causes-cancer>

10. Centers for Disease Control and Prevention 2014. High Blood Pressure Risk Factors. Viewed 15th June 2017 <https://www.cdc.gov/bloodpressure/risk_factors.htm>

11. Heart Foundation. Heart attach risk factors. Viewed 17th June 2017 <https://www.heartfoundation.org.au/your-heart/know-your-risks/risk-factors>

12. IARC, 2014. World Cancer Report 2014. WHO, Switzerland.

13. World Health Organisation. Risk factors for chronic respiratory diseases. Viewed 17th June 2017 <http://www.who.int/gard/publications/Risk%20factors.pdf>

14. World Health Organisation 2015. WHO global reports on trends in prevalence of tobacco smoking 2015. WHO: Geneva, Switzerland.