What is Lung Cancer?
Lung cancer, also known as bronchogenic carcinoma, is a type of cancer that begins in the lungs or its airways, called bronchi. It’s among the top causes of cancer-related deaths in the United States. In fact, since 1987, lung cancer has killed more women than breast cancer. It’s estimated that each year in the United States, 225,000 new cases of lung cancer are diagnosed, and about 160,000 people die from it. Interestingly, lung cancer was not common at the beginning of the 20th century. Its dramatic increase later on correlates mostly with increased smoking habits in both men and women.
What Causes Lung Cancer?
Smoking is the main cause of lung cancer. Around 90% of lung cancer cases are caused by smoking, and men who smoke are at the most risk. This risk is even higher when smokers are also exposed to other harmful substances like asbestos. However, the number of cigarette packs someone smokes in a year does not necessarily relate to their lung cancer risk. This is because the risk is also affected by other factors like environment and genetic factors.
Secondhand smoke, also known as passive smoking, can increase the risk of lung cancer by 20 to 30%. Other risks include exposure to radiation for treatment of other illnesses, such as non-Hodgkins lymphoma and breast cancer. Coming into contact with certain metals like chromium, nickel, and arsenic, as well as certain chemicals called polycyclic aromatic hydrocarbons, also increases the risk of lung cancer. If you have lung diseases like idiopathic pulmonary fibrosis, which is a type of lung disease that causes scarring of the lungs, you’re at a higher risk for developing lung cancer even if you’re a non-smoker.
Two other well-known risks for lung cancer are asbestos and radon exposure. Asbestos is a fibrous material that was once widely used in construction, and radon is a radioactive gas that forms naturally from the decay of uranium. Occupational exposure to asbestos, particularly for those in certain jobs like construction and shipbuilding, increases the risk for lung cancer. However, the risk for people who are exposed to asbestos in non-working environments is not as well defined. The U.S Environmental Protection Agency (EPA) has set safety standards for these low-level exposures.
Radon exposure has been linked to lung cancer in uranium miners. Furthermore, radon has also been shown to accumulate in homes, posing a significant risk, especially for smokers. It is held responsible for about 2% of all deaths from lung cancer in Europe.
Risk Factors and Frequency for Lung Cancer
Lung cancer is a major health issue worldwide – it’s the most frequently diagnosed cancer and the leading cause of cancer-related deaths. Each year, over 234,000 new cases of lung cancer are diagnosed, and more than 154,000 people die from it in the United States alone. Globally, lung cancer accounts for an estimated 1.8 million deaths annually.
While in the past lung cancer was mainly a problem in developed countries, it’s now becoming increasingly common in less developed parts of the world. Around half of all new lung cancer diagnoses occur in these regions. In the United States, more males die from lung cancer than females. When it comes to race, the rate of lung cancer is the same, but African American males are more likely to die from it than Caucasian males. This difference does not exist among females.
- Lung cancer is the most commonly diagnosed cancer worldwide.
- Each year in the U.S., there are over 234,000 new cases and more than 154,000 deaths from lung cancer.
- Globally, lung cancer causes about 1.8 million deaths annually.
- Half of the new diagnoses are in less developed parts of the world.
- In the U.S., males are more likely to die from lung cancer than females.
- While the lung cancer rate is the same among races, African American males have a higher mortality rate than Caucasian males.
- This racial difference in mortality does not exist in females.
Signs and Symptoms of Lung Cancer
Lung cancer is a disease that’s often advanced by the time it’s diagnosed, mainly because it doesn’t have specific signs or symptoms. When symptoms do occur, they could be due to effects of the tumor itself, or from the cancer spreading to other areas of the body (metastasizing).
- Coughing is seen in 50 to 75% of lung cancer patients, becoming productive of large amounts of thin, mucus-like secretions in certain cases.
- About 15 to 30% of patients experience hemoptysis, which is coughing up blood.
- Chest pain is present in about 20 to 40% of patients, and breathing difficulties occur in roughly 25 to 40% of cases at the time they’re diagnosed. These symptoms can be due to lung cancer itself, or due to pre-existing lung disease.
- Approximately 10 to 15% of patients develop pleural effusion, a condition where fluid accumulates in the space between the lungs and chest wall. This can be the only symptom for some patients.
Lung cancer can also lead to various syndromes such as Superior vena cava syndrome, which includes symptoms like swelling in the face, neck, and upper extremities – usually seen in small cell lung cancer patients. The condition called Pancoast syndrome, characterized by shoulder pain, drooping of one side of the face (Horner’s syndrome), and evidence of bone destruction, is another possible symptom.
Moreover, cancer often spreads or metastasizes to the bone causing bone pain, especially in cases of non-small cell lung cancer and small-cell lung cancer. Typical signs of this include high serum alkaline phosphatase levels and elevated calcium levels in the blood. Metastasis to the brain is another typical feature in both types of lung cancer.
Lastly, cancer can lead to other conditions, referred to as paraneoplastic syndromes, such as high calcium levels causing loss of appetite, nausea, constipation, and fatigue. These paraneoplastic syndromes also include many neurological disorders and Cushing’s syndrome, a condition caused by an excess of the stress hormone cortisol.
Testing for Lung Cancer
Lung cancer is a significant health issue, as it causes the most deaths in both men and women. Of all lung cancer cases diagnosed in the US, non-small cell lung cancer (NSCLC) accounts for 85%. Ideally, it’s important to diagnose and determine the stage of this cancer efficiently and accurately. According to guidelines from the American College of Chest Physicians (ACCP), a complete evaluation should ideally be done within six weeks for patients exhibiting tolerable symptoms and no complications. However, only a small proportion of lung cancers are detected early – specifically, only 26% are diagnosed at stage I and 8% at stage II, whereas a higher percentage of cases are diagnosed at later stages, notably stages III and IV. Consequently, surgical removal of the cancer, which can possibly cure the disease, is only possible for a small number of patients.
The evaluation process of lung cancer can be divided into two categories: radiological staging and invasive staging. The main goals for this initial evaluation are determining the stage and extent of the disease, deciding on the best method for the first tissue biopsy, identifying specific types of lung cancer cells, understanding the presence of co-existing health issues, and considering the patient’s values and therapy preferences.
Those suspected of having lung cancer should undergo specific imaging tests including a contrast-enhanced CT scan of the chest that extends to the upper abdomen level and PET or PET-CT scans to look for potential metastasis when symptoms, focal findings are present or in instances where chest CT scan indicates an advanced disease.
A contrast-enhanced CT scan distinguishes between the invasion of the primary tumor or metastatic lymph nodes from vascular structures. CT scans also provide an accurate layout of the tumor within the chest, which helps in deciding the best site for biopsy. Furthermore, CT scans help identify problems such as tumor-related collapse of a lung (atelectasis), post-obstructive pneumonia, spreading of the cancer within or outside the chest, and the presence of any other lung diseases. The aim is to understand the size, location, and lymph node involvement of the tumor. Lymph node involvement strongly influences the tumor’s classification into different stages (TNM staging). Enlarged lymph nodes, measuring 1 centimeter or more on short axis, are normally regarded as highly suspicious for cancer presence. The overall sensitivity and specificity of CT scans for identifying cancer are 55% and 81% respectively, making it not a very reliable tool for lung cancer staging on its own.
The ACCP groups patients based on tumor extent and lymph node involvement. Even though a CT scan isn’t the perfect tool for staging, it still helps doctors decide where to obtain a tissue biopsy for further assessment.
A PET scan examines the metabolic activity of the main tumor, mediastinal involvement, and potential distant metastases. This test has a higher sensitivity of 80% and specificity of 88% than a CT scan, but it’s still not considered sufficient to stage lung cancer independently. Despite these advantages, a PET scan doesn’t eliminate the need for lymph node sampling except for disease in group A.
After undergoing CT and PET scans, tissue samples or pathologic confirmation of malignancy is necessary to establish the stage and type of cancer cells present. This confirmation can be achieved through procedures like bronchoscopic endobronchial ultrasound-transbronchial needle aspiration (TBNA), Endoscopic-TBNA, Mediastinoscopy, or video-assisted thoracoscopy (VATS).
Take procedures such as bronchoscopic TBNA for example, which is a technique where a small convex ultrasound is attached to the tip of the bronchoscope. It allows doctors to see structures in the mediastinum or lung tissue through the bronchial wall, permitting them to perform a biopsy in real-time.
In conclusion, diagnosing and staging lung cancer involves a series of steps involving both radiological and invasive methods. It’s important to note that even the best imaging techniques are not completely accurate, and therefore tissue samples are often necessary to confirm a diagnosis.
Treatment Options for Lung Cancer
In the world of medicine, diagnosing and treating non-small cell lung cancer (NSCLC) is broken down into stages, each with its own approach. The specific choice of treatment often depends on the stage of the patient’s lung cancer.
For Stage I lung cancer, surgery is usually the first approach. The surgery may be either a lobectomy that removes one lobe of the lung, or a pneumonectomy that removes the entire lung. However, for patients who don’t have the stamina for this type of surgery, a smaller operation like a wedge resection or segmentectomy can be performed. These more minor surgeries raise the risk of the cancer returning, but they don’t change the patient’s overall chance of survival.
Following surgery for Stage II lung cancer, chemotherapy is usually recommended. If the tumor has spread to the chest wall, a surgery that removes both the tumor and the portion of the chest wall it has invaded may be necessary. In some cases, the patient may have a specific kind of tumor, called a Pancoast tumor, that arises from the top section of the lung. Treating this type of tumor typically involves a combination of chemotherapy, radiation, and surgery.
Stage III lung cancer treatment is unique as it considers the extent of the tumor spread and involvement of the lymph nodes. If the cancer has spread to lymph nodes close to the original tumor (N1 lymph nodes), surgery is usually the best course of action. After surgery, chemotherapy is generally recommended. However, if the cancer has spread to lymph nodes further from the original tumor (N2/N3 lymph nodes), the decision on treatment is less clear and may involve combinations of chemotherapy, radiation, and surgery.
For Stage IV lung cancer, which indicates that the cancer has spread extensively, the typical aim is to improve the patient’s quality of life and prolong survival, rather than to cure the disease. Some patients may respond to chemotherapy, and others may benefit from targeted therapies that harm cancer cells, but leave healthy cells unharmed. For instance, bevacizumab, which blocks the growth of new blood vessels in tumors, may be used in certain patients without potential brain metastasis or respiratory complications.
Advances in treatment have introduced targeted therapy and immunotherapy as effective strategies for managing NSCLC. Mutations that drive cancer development have been identified, and drugs have been developed to block these mutations, improving survival rates. Boosting the immune system to recognize cancer cells and increase immune responses has also shown promising results.
As for small cell lung cancer (SCLC), which is known for its high sensitivity to chemotherapy but also high risk of recurrence after treatment, the stage of the disease also determines its treatment found. Limited-stage small cell lung cancer (LS-SCLC) may involve a surgery called lobectomy that removes part of the lung, followed by chemotherapy. Extensive-stage small cell lung cancer (ES-SCLC), where the cancer has spread widely, is usually treated with chemotherapy, radiation therapy, and other supportive measures.
What else can Lung Cancer be?
When diagnosing respiratory diseases, several conditions are considered that may present with similar symptoms:
- Bacterial pneumonia
- Bronchitis
- Mycoplasmal pneumonia
- Pleural effusion
- Pneumothorax
- Tuberculosis
- Viral pneumonia
- Fungal pneumonia
What to expect with Lung Cancer
The chance of recovery from non-small cell lung cancer (NSCLC) depends largely on the TNM stage of the cancer when it’s first diagnosed. The TNM system is a way doctors describe the size and spread of cancer. The higher the stage, the more advanced the cancer is, meaning it has spread further and the chances for recovery are lower.
Other signs that suggest a poor chance of recovery include the patient’s health and activity levels at the time of diagnosis, loss of appetite, weight loss, and the cancer spreading to the liver or skin. Research has shown that patients with a certain type of NSCLC, called adenocarcinoma, who have mutations in a gene called EGFR often have a better chance of recovery than those without the EGFR mutations.
In the case of small cell lung cancer (SCLC), the chances of recovery are also greatly influenced by the extent of the disease and the stage at which it’s diagnosed. Those who are diagnosed with a lesser, or “limited”, stage of the disease have a 10 to 13% chance of surviving for at least 5 years. However, patients who are diagnosed with a more extensive stage of the disease only have a 1 to 2% chance.
Like with NSCLC, a patient’s health and activity levels, as well as weight loss, can also affect the chances of recovery from SCLC. Patients who are less healthy and active, and/or have lost weight at the time of diagnosis, may not survive as long.
Possible Complications When Diagnosed with Lung Cancer
People undergoing lung cancer treatment often face a variety of complications. This includes issues such as:
- Nausea and vomiting triggered by chemotherapy
- Constant fatigue
- Loss of appetite
- Unintended weight loss
- Reduced red blood cells or anemia
- Drop in a type of white blood cell, known as neutropenia
- Kidney damage, mainly in those on cisplatin-based treatments
- Harmful effects on the nervous system, referred to as neurotoxicities
Earlier, we also mentioned additional lung cancer complications, such as clot formation (thrombosis) and conditions indirectly caused by cancer (paraneoplastic syndromes).
Preventing Lung Cancer
Quitting smoking is the most effective way to prevent lung cancer. Doctors and healthcare professionals should take the time to educate their patients about the link between smoking and lung cancer during each visit. Another important step to reduce the risk and negative impact (morbidity and mortality) of lung cancer is timely and effective screening. A type of scan called a low-dose helical computed tomography (LDCT) is recommended for those at high risk of lung cancer.
This method of screening is particularly beneficial for smokers between the ages of 66 and 80 years, more so than those who are between 55 to 64 years old. However, it’s important to note that non-smokers do not benefit from lung cancer screening.
Additional risk assessment models have been created taking into consideration other health factors. These include a history of lung illnesses, a family history of lung cancer, and exposure to harmful substances like asbestos. These models help identify those who are at risk and could benefit from screening.
Current guidelines from the United States Preventive Services Task Force (as of 2021) advise an annual LDCT scan for those between 50 and 80 years old who are at high risk due to their history of smoking. Being at high risk is defined as having a history of smoking the equivalent of 20 packs of cigarettes per year or more, and are either still smoking or have quit less than 15 years ago.
