Lung cancer and genetics

What is lung cancer?

Lung cancer consists of the uncontrolled multiplication of malignant cells of the lung epithelium. It usually starts in these organs and can spread to different parts of the respiratory system, even reaching the lymph nodes or other organs, such as the brain. [1]

 

There are two types of lung cancer [2]:

Non-small cell carcinoma:

It is the most common type, accounting for 85% of all cases. This in turn is divided into three subtypes, which are as follows:

• Adenocarcinoma: the most common cancer in people who have not smoked. It originates in the cells that produce mucus in the respiratory tract and is usually more common in women than in men.
• Squamous cell carcinoma: appears in the flat cells that line the airways. It is related to smoking and tends to appear as a mass in the center of the lung.
• Large cell carcinoma: it stands out because it can appear in any part of the lung and because of the rapid growth of the tumor, which means that it tends to spread in much less time.

 

Small cell carcinoma:

It is less common but more aggressive, and is closely related to tobacco consumption. It is usually detected in advanced stages, so in many cases metastasis has already occurred.

 

Lung cancer symptoms

Symptoms may vary depending on the individual and the stage of the disease, but the most common are persistent cough, sometimes with blood or sputum, chest pain, shortness of breath, persistent fatigue, weight loss, wheezing and hoarseness [3].

In some cases, patients have also been seen to have repeated attacks of pneumonia, bronchitis or inflammation of the lymph nodes located between the lungs.

In addition, in more advanced stages, when the cancer has spread to other parts of the body, bone pain, alterations in the nervous system (triggering headache, numbness of the extremities or balance problems), jaundice, or swelling of the lymph nodes, especially those in the neck, may occur.

It has been shown that lung cancer can sometimes trigger the appearance of certain syndromes, which are associated with specific symptoms. These syndromes in question are as follows [3]:

• Horner’s syndrome: affects nerves of the eyes and face, causing drooping of the eyelid, heterogeneity in the size of one pupil with respect to the other and loss of perspiration on one side of the face.
• Superior vena cava syndrome: this vein is close to the right lung, so that tumors in that area can exert pressure on the vein and cause blood retention in that area, causing headache, dizziness or swelling of the neck and face.

 

Worldwide figures on lung cancer

Currently, this type of cancer is the second most common cancer in the world after breast cancer (Figure 1) and the one with the highest mortality rate worldwide (Figure 2). About 2.2 million new cases of this disease are diagnosed annually [4] and about 1.8 million deaths occur each year [5].

Figure 1: Global cancer prevalence in 2020. Source: https://gco.iarc.fr/

Figure 2: Cancer mortality in the world 2020. Source: https://gco.iarc.fr/

 

Since records have been kept of the incidence of this disease, it is known that it is much higher in men than in women. However, in recent years there has been a decrease in lung cancer cases in men, while in women it has increased, which may be related to the change in social habits over the last few decades. Despite this, it is still a disease more prevalent in men (Figure 3).

Figure 3: Evolution over time of lung cancer mortality in Spain, by sex. Source: https://gco.iarc.fr/

 

Causes and/or risk factors

The major trigger of lung cancer is smoking, since about 80% of the cases are related to this habit, including passive smokers. However, there are other risk factors such as exposure to environmental pollution; exposure to carcinogens, such as asbestos or radon; lung infections, such as pneumonia or tuberculosis; HIV infection; beta-carotene supplementation in heavy smokers; or family history.

In addition, there is growing evidence of an association between lung cancer and oral microbiota. For example, an increased concentration of Streptococcus bacteria, together with other changes in the oral microbiota (state of dysbiosis or bacterial imbalance), are associated with this type of cancer [2, 5].

 

Cancer prevention and treatment

Taking into account the health risks posed by prolonged exposure to harmful substances, particularly tobacco consumption, it can be stated that the best way to prevent this disease is not to smoke and to reduce exposure to agents that can trigger a malignant tumor in the long term. In addition, medical follow-up is recommended for those who have a family history of this pathology [5].

Since there are different types of lung cancer, there are also different treatments for each of them. People with non-small cell lung cancer can be treated with various therapies, such as surgery, chemotherapy, radiation therapy, targeted therapy (use of drugs to block tumor growth and spread) or a combination of these. However, patients diagnosed with small cell cancer usually receive only chemotherapy or radiotherapy treatments [6].

 

24Genetics and Lung Cancer

At 24Genetics we have been researching in depth about the oral microbiota and its relationship with certain diseases and we have recently been the first to discover that there is an association between certain imbalances in the oral microbiota and several diseases, including, specifically, lung cancer, although we have not yet demonstrated a causal relationship in this association.

As a result of this in-depth research, we have just launched an innovative microbiota test, unique worldwide, which consists of analyzing the current status of your oral microbiota with a simple saliva sample, as in our genetic tests. Thus, you can now have information about lung cancer taking into account the balance of your microbiota.

Thus, with our All in One Plus test, you can now obtain our 7 genetic reports and, in addition, your oral microbiota report.

 

Bibliography

[1] ¿Qué es el cáncer de pulmón? Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/spanish/cancer/lung/basic_info/what-is-lung-cancer.htm#:~:text=El%20c%C3%A1ncer%20es%20una%20enfermedad,del%20cuerpo%2C%20como%20el%20cerebro. 

[2] Zheng, M. (2016) ‘Classification and pathology of Lung Cancer’, Surgical Oncology Clinics of North America, 25(3), pp. 447–468. doi:10.1016/j.soc.2016.02.003. 

[3] Signos y síntomas del cáncer de pulmón. American Cancer Society. Available at: https://www.cancer.org/es/cancer/tipos/cancer-de-pulmon/deteccion-diagnostico-clasificacion-por-etapas/senales-sintomas.html. 

[4] The International Agency for Research on Cancer (IARC) Global cancer observatory, Global Cancer Observatory. Available at: https://gco.iarc.fr/. 

[5] Prevención del Cáncer de Pulmón. Instituto Nacional del Cáncer. Available at: https://www.cancer.gov/espanol/tipos/pulmon/paciente/prevencion-pulmon-pdq. 

[6] ¿Cómo se diagnostica y se trata El Cáncer de Pulmón? Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/spanish/cancer/lung/basic_info/diagnosis_treatment.htm#:~:text=se%20haya%20diseminado.-,Las%20personas%20con%20c%C3%A1ncer%20de%20pulm%C3%B3n%20de%20c%C3%A9lulas%20no%20peque%C3%B1as,general%20reciben%20radioterapia%20y%20quimioterapia.