Lung Cancer

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Introduction

Lung cancer refers to tumors originating in the lung parenchyma or within bronchi. It is:

• A broad term referring to the main histological subtypes of primary lung malignancies that are mainly linked with inhaled carcinogens, with cigarette smoke being a key culprit.
• The most common cancer worldwide, with 2 million new cases in 2018. 
• One of the leading causes of cancer-related deaths in the United States.

At the beginning of the 20th century, lung cancer was a relatively rare disease. Its dramatic rise in later decades is mostly attributable to the increase in smoking among both males and females

Epidemiology

Lung cancer

• Is a leading type of cancer, equal in prevalence with breast cancer.
• Is the leading cause of cancer mortality worldwide; accounting for ~20% of all cancer deaths
• Is dramatically rising with nearly half of new cases, 49.9%, diagnosed in the under-developed world.
• In the United States, mortality is high in men compared to women.
• Overall, there is no difference between blacks and whites, but age-adjusted mortality is higher in black males than their white counterparts.

Aetiology

Smoking is the most common cause of lung cancer.

• It is estimated that 90% of the cases of lung cancer are attributable to smoking.
• The risk is highest in males who smoke.
• The risk is further compounded with exposure to other carcinogens, such as asbestos.

Risk Factors

• There is no correlation between lung cancer and the number of packs smoked per year due to the complex interplay between smoking and environmental and genetic factors.
• The risk of lung cancer by passive smoking increases by 20% to 30%.
• asbestos: 5x increased risk
• occupational exposure: uranium, radon, arsenic, chromium
• diffuse lung fibrosis: 10x increased risk
• chronic obstructive pulmonary disease

Investigations

The overall goal is a timely diagnosis and accurate staging.

Only 26% and 8% of cancers are diagnosed at stages I and II, whereas 28% and 38% are diagnosed at stages III and IV respectively. Hence curative surgery is an option for a minority of patients.

Lung cancer evaluation can be divided in 2 ways:

1. Radiological staging
2. Invasive staging

Goals of Initial Evaluation

• Clinical extent and stage of the disease
• Optimal target site and modality of 1st tissue biopsy
• Specific histologic subtypes
• Presence of co-morbidities, para-neoplastic syndromes
• Patient values and preferences regarding therapy

Radiologic Staging

Every patient suspected of having lung cancer should undergo the following tests:

• Contrast-enhanced CT chest with extension to upper abdomen up to the level of adrenal glands
• Imaging with PET or PET-CT directed at sites of potential metastasis when symptoms or focal findings are present or when chest CT shows evidence of advanced disease
  

Clinical Manifestations

Patients with lung cancer may be asymptomatic in up to 50% of cases.

• Cough and dyspnoea are rather non-specific symptoms that are common amongst those with lung cancer.
• Central tumours may result in haemoptysis
• Peripheral lesions may result in pleuritic chest pain.
• Pneumonia, pleural effusion, wheeze, lymphadenopathy may be present.
• Other symptoms may be secondary to metastases (bone, contralateral lung, brain, adrenal glands, and liver particularly) or paraneoplastic syndromes.

Treatment/Prognosis

Treatment and prognosis vary not only with stage but also with cell type. In general, surgery, chemotherapy, and radiotherapy are offered according to the stage, resectability, operability, and functional status.

• Despite all the advances, the outcomes for lung cancer remain abysmal. The key reason is that most patients are diagnosed with advanced-stage disease. To improve outcomes, an interprofessional team approach with close communication between the members may perhaps lead to earlier diagnosis and treatment.
• The definitive diagnosis and management of lung cancer is done by the thoracic surgeon with collaboration with the radiologist and pathologist.
• After surgery, the patients are usually monitored by nurses for oxygenation, ventilation, and pain. Since many of these patients are smokers, they also have other comorbidities like heart disease and peripheral vascular disease, which often presents with symptoms in the post-operative period.
• After surgery, patients need prolonged rehabilitation. Some may need chemotherapy and radiation.
• Lung cancer is not curable and all clinicians should urge patients to quit smoking; screening may be useful in selective patients.

Physiotherapy and Other Management

Physiotherapy interventions vary depending on the stage in disease trajectory and timing relative to treatment.

• The cornerstone of physiotherapy management in lung cancer should be prescription and delivery of exercise intervention.
• Physical activity and exercise are vital components targeting three main aspects of the cancer continuum: prevention, mortality and morbidity.
• The American Cancer Society recommends that adults with cancer engage in at least 150 minutes of moderate-intensity aerobic exercise and two sessions of resistance exercise per week, which is the same as the guidelines for the general adult..

Exercise

Aerobic exercise and resistance training have a positive impact on lung functioning including a reduction in airflow obstruction and clearing of airways therefore the improved functional capabilities increase energy levels and the release of sputum. Exercise programs should be supervised by the treating clinical team and should also be discussed with the general practitioner before participating in any exercise program. Surgery involves resection of the tumor and some normal tissue around it. This is the first line of choice of treatment for non-small cell lung cancer patients who are medically fit to undergo surgery. An exploratory secondary trial data analysis suggests that breathlessness services must be easily accessible to patients and patients should be encouraged and assisted to attend. Research shows positive results of physical exercises on cancer-related fatigue, physical function, symptom distress, sarcopenia and health-related quality of life (HRQoL).

Radiation Therapy

Radiation therapy is a form of treatment that is indicated for patients with stage I, II or III of non-small cell lung cancer. With respect to lung cancer, stages I, II, and III determine various sizes of primary tumor and lymph node involvement without distant metastasis and any distant metastasis is automatically stage IV. It is also used in combination with surgery for non-small cell lung cancer and with chemotherapy for small cell lung cancer. Chemotherapy The first line of treatment for small cell lung cancer, which are often spread upon clinical presentation. It is also indicated for patients with more advanced stage of non-small cell lung cancer to improve prognosis, disease control or for palliative care.

Recent Updates and News

Prevention

Smoking cessation

The best way to prevent lung cancer is to quit smoking. The risk of getting diagnosed with lung cancer will decrease the sooner an individual quits smoking. After 10 years of not smoking, the chance of developing lung cancer decreases to half that of someone who smokes. Diet Research suggests that eating a low-fat, high-fibre diet, including at least five portions of fresh fruit and vegetables and whole grains every day, can help reduce the risk of developing lung cancer, as well as other types of cancer and heart disease.

Physical Activity/Exercise

Studies show that higher levels of physical activity may lower lung cancer risk. It is important to exercise regularly, attempting to perform at least 150 minutes of moderate intensity aerobic activity each week and incorporate muscle strengthening activities two days per week.

Aspirin

Some research has found that taking aspirin may reduce the risk of getting lung cancer. Other studies have found that aspirin may only reduce risk in people who take aspirin daily or may only reduce the risk in men. It is important to check with a doctor before taking aspirin every day as it can damage the lining of the stomach and potentially cause bleeding.

References

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