By Brillon Joseph, V Form

The Causes and Symptoms of Lung Cancer and the Treatments of the Two Main Types of Lung Cancer

Introduction

Choi, Clark, and Douglas (2012) state that “cancer is not a single disease but includes many different diseases. In cancer cells, mutations modify cell-cycle control and cells don’t stop growing as they normally would” (p 452). Cancer is a result of gene mutations in the cells that make up the tissues and organs of the human body. When normal cells undergo gene mutations, this can be a result of inheritance, aging, or damage to genes by factors such as radiation. These mutated cells form cancer cells, which grow and divide uncontrollably. Cancer has been a very prominent epidemic in the world in recent years. Every day, more and more people are diagnosed with cancer and suffer from the fatal effects of this disease. Statistics show that in 2018 alone, there were approximately 18 million new diagnoses of cancer and 9.6 million cancer-related deaths worldwide. One of the most common types of cancer is lung cancer. There are several types of lung cancer that involve different causes, symptoms, and treatment options.

What Is Lung Cancer?

Lung cancer is one of the most common types of cancer worldwide. According to the World Cancer Research fund, lung cancer constituted 12.3% of all new cases of cancer diagnosed in 2018. The Center for Disease Control (CDC) states that lung cancer is a medical condition that leads to cells in the lungs dividing uncontrollably. This causes tumors to grow and thus reduce a person’s ability to breathe (Nall 2018). When cells in the lungs are abnormal, they do not carry out the necessary functions as efficiently as a normal cell would. As these abnormal cells continue to grow and divide in an uncontrollable manner, they form tumors. Consequently, these tumors may impact the individual’s ability to breathe properly. Lung cancer can be broadly classified into Small-Cell Lung Cancer (SCLC) or Non-Small Cell Lung Cancer (NSCLC). “This classification is based upon the microscopic appearance of the tumor cells themselves, specifically the size of the cells” (Stöppler [date unknown]). The two types of lung cancer also differ in terms of spread, growth, aggression and applicable treatments.

What is Small-Cell Lung Cancer?

The Small-Cell Lung Cancer, also referred to as SCLC, is defined as “an aggressive (fast-growing) cancer that forms in tissues of the lung and can spread to other parts of the body. The cancer cells look small and oval-shaped when looked at under a microscope” (National Cancer Institute, [date unknown]). There are several sub-categories to SCLC, and the most common types include squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. Statistics show that approximately ten to fifteen percent (10-15%) of all lung cancer cases fall in the category of small-cell lung cancer. Therefore, SCLC is less common than NSCLC. 

SCLC comprises of two stages called the limited stage and the extensive stage. As the name suggests, the limited stage is when the cancer is limited to solely one side of the chest and involves only one part of the lung and the surrounding lymph nodes. The extensive stage of SCLC, on the other hand, is the stage when cancer has traveled to other sections of the chest and/or other parts of the body of the individual.

What is Non-Small Cell Lung Cancer?

“Non-small cell lung cancer is the most common type of lung cancer. It usually grows and spreads more slowly than small cell lung cancer” (Wake Forest Baptist Health [date unknown]). Similar to the SCLC, the most common types of NSCLC include squamous cell carcinoma, large cell carcinoma, and adenocarcinoma. There are four different stages of NSCLC. Stage I is when the cancer is only located in the lungs and has not spread to the surrounding lymph nodes, Stage II is when the cancer is in the lungs and nearby lymph nodes; Stage III is when the cancer is found in the lungs and the lymph nodes in the middle of the chest; and Stage IV is when the cancer has spread to both lungs, to fluid in the area around the lungs, or to another part of the body (most advanced stage). Stage III can be further broken down into Stage IIIA, when cancer has only spread to lymph nodes on the same side of the chest where the cancer originated, and Stage IIIB, when the cancer has spread to the lymph nodes on the opposite side of the chest or above the collarbone. 

Statistics show that Non-Small Cell Lung Cancer accounts for approximately eighty-five percent (85%) of all lung cancer cases. Contrary to small-cell lung cancer, NSCLC spreads at a slower rate. Therefore, the likelihood of cancer spreading to other organs or parts of the body before it is discovered by a medical professional is less than that of the SCLC. Consequently, an individual with NSCLC has a much greater chance of having a longer lifespan than an individual with SCLC due to the major difference in the aggression of the two.

 Symptoms of Lung Cancer

The most common symptoms of lung cancer include but are not limited to coughs that do not go away or get worse; coughing up blood or rust-colored sputum (spit or phlegm); chest pain that is often worse with deep breathing, coughing, or laughing; hoarseness; weight loss; loss of appetite; and shortness of breath (American Cancer Society 2016).

It is possible for an individual who has the disease to only experience less than a handful of the extensive list of possible symptoms. The symptoms that the individual experiences may also vary drastically depending on the exact location in the lung that the cancer is found. If the cancer is found in the upper section of the lungs, for example, it may result in the individual experiencing a group of symptoms referred to as Horner syndrome. Another syndrome is the superior vena cava syndrome which occurs when cancer (tumor) is found in the superior vena cava.

Causes of Lung Cancer

Certain actions, situations and/or being exposed to a specific environment put people at risk of developing lung cancer. Peto R, Lopez AD, Boreham J, et al. states that cigarette smoking, which is one of the leading etiologic agents, is the leading cause of lung cancer by far. It accounts for about 80% to 90% of lung cancer cases in the United States and other countries where cigarette smoking is a common practice (Alberg, Brock, Ford et al. 2013). The practice of smoking contributes to the development of SCLC, and it is the leading cause of lung cancer in general. Carcinogens, which are cancer-causing substances, are major components of the fumes that are produced when smoking cigarettes or other substances. These substances lead to the damage of cells within the lungs and therefore damage the tissues. When these cells are damaged and are no longer capable of performing their functions efficiently, they begin to act abnormally, and cancer may begin to develop. “Non-smokers who are exposed to second-hand smoke at home or at work increase their risk of developing lung cancer by 20– 30%” (Naeem 2015). Being constantly exposed to second-hand smoke also increases a person’s vulnerability to the disease as he or she is also exposed to the carcinogens that are produced, and the person’s lungs are being damaged. 

The U.S. Department of Health and Human Services states that Lung cancer can also be caused by occupational exposures to substances including asbestos, uranium, and coke (an important fuel used in the manufacturing of iron in smelters, blast furnaces, and foundries). The combination of asbestos exposure and smoking greatly increases the risk of developing lung cancer (American Lung Association 2018).

Asbestos, uranium, and coke are just a few of the carcinogens that are found in our environments. Asbestos, for example, may be found in homes and buildings since it was frequently used in construction when its harmful effects were not discovered. Therefore, these substances might be easily encountered, depending on the field of work, quality of workplaces, and the quality of houses. 

Another example of a carcinogen present in the environment is radon. The U.S. Environmental Protection Agency states that exposure to radon is estimated to be the second-leading cause of lung cancer, accounting for an estimated 21,000 lung cancer deaths each year. The majority of these deaths occur among smokers since there is a greater risk for lung cancer when smokers also are exposed to radon (American Lung Association 2018). Radon is a tasteless, colorless and odorless gas that is produced by decaying uranium and occurs naturally in soil and rock. Because of its physical nature and its presence in soil and rock, it is easy to be exposed to the substance unknowingly. Therefore, it is no surprise that it is the second leading cause of lung cancer since an individual may be frequently exposed to the gas without knowledge, which could lead to constant lung damage and the development of lung cancer.

Genetics may also play a role in the development of lung cancer. In lung cancer cells, scientists have found somatic mutations in several different genes. In rare cases, the genetic change is passed on through generations and present in all the cells of the body (germline mutations) (U.S. National Library of Medicine [date unknown]). Deoxyribonucleic acids, commonly known as DNA, are molecules found in the cells of the body and they carry all human genetic information. When these molecules undergo mutations, their entire structure and function change, which can sometimes have negative effects. In the case of lung cancer, for example, mutations in TP53, EGFR, and KRAS genes are commonly linked to the disease. Therefore, although not common, the probability of developing lung cancer can be increased due to inherited DNA mutations from one or both parents.

Treatments for Small-Cell Lung Cancer: Limited Stage SCLC

SCLC has several treatment options, and the treatment that an individual receives is based on the stage of cancer or whether it is limited or extensive. Due to the fast pace at which NSCLC progresses, treatment for the disease is rather complex. Having only a small tumor in the lung and absolutely no evidence of cancer in the lymph nodes or elsewhere, might prompt doctors to recommend that one undergoes a surgery to remove the tumor as well as the nearby lymph nodes (American Cancer Society [date unknown]). Although it is not a common occurrence among people diagnosed with the disease, there may be situations where the cancer has not spread and thus surgery may be a suitable option. Doctors will make sure cancer has not spread elsewhere by conducting a mediastinoscopy. In surgery, the doctors will remove the small, malignant tumor and the lymph nodes that are near the tumor. “Very few patients with SCLC are treated this way. This is only an option if you are in fairly good health and can withstand having all or part of a lung removed” (American Cancer Society [date unknown]). Therefore, the health of the patient is a pivotal factor when medical professionals are considering surgery as an option for a patient. This is because there is a chance that the individual may not survive the surgery or may not fully recover since his or her body is not strong enough.

 “In patients with Limited Stage SCLC, early chemoradiotherapy, with accelerated hyperfractionated radiation therapy concurrently with platinum-based chemotherapy, is recommended” (Rudin et al, 2015 p 4108). When the malignant tumor and nearby lymph nodes have been surgically removed, further treatments may be required. Chemotherapy and radiation therapy help to slow down or stop the growth of cancer cells. This is done in smaller doses several times a day as opposed to one large dose each day. This approach, however, does not guarantee that cancer will not return even if the tumors are removed after the treatment.

Surgery is not an option for most people who have limited stage SCLC due to circumstances such as the tumor being too large, being in a place that can’t be removed easily, or having already been spread to nearby lymph nodes or other places in the lung (American Cancer Society [date unknown]). Due to the size and spread of cancer, some diagnosed individuals are not eligible for the surgery. Therefore, their only options are to receive chemotherapy or radiation therapy. As previously mentioned, these treatments aim to slow down or stop the growth of the cancer cells. “The brain is a common site of tumor spread (termed metastasis) in people with small cell lung cancer” (Kalemkerian [date unknown]). The treatment for this, therefore, is a medical procedure known as Prophylactic Cranial Irradiation (PCI) which aims to prevent the spread to the brain. However, the dose that a patient receives is based on whether or not cancer has already spread to the brain and if it has, the patient receives a lower dose. As with other limited-stage SCLC, treatment does not guarantee that cancer will fully disappear and not return, even if the treatments are successful at first.

Treatments for Small-Cell Lung Cancer: Extensive Stage SCLC

Ayoola, Belani and Joshi, medical doctors, state that “[f]or patients with ESSCLC patients, current treatment recommendations include combination chemotherapy, radiation therapy, and prophylactic cranial irradiation” (Lemjabbar-Alaoui et al. 2015 p.22). Due to the rapid pace at which this stage of SCLC spreads to other places, individuals cannot be considered for the same treatments as an individual suffering from limited-stage SCLC. As with the limited stage, the treatment that an individual receives depends partly on their overall health. However, “[i]f you have extensive SCLC and are in fairly good health, chemotherapy (chemo), possibly along with an immunotherapy drug, is typically the first treatment” (American Cancer Society [date unknown]). An immunotherapy drug is used to stimulate the patient’s immune system to detect and kill cancer cells more effectively. If the initial treatment is successful, then the patient may be eligible to receive radiation in the chest and PCI to prevent the progression of cancer into the brain. Some patients may be deemed too unwell to receive chemotherapy, and as a result, palliative radiotherapy or supportive care may be their most suitable option (National Collaborating Centre for Cancer (UK) 2011).  In this case, doctors utilize a different approach. They may choose to give the patient a lower dose of chemotherapy or supportive care to treat pain, breathing difficulties, etc.

Treatments for Non-Small Cell Lung Cancer

As with SCLC, the treatment options for Non-Small Cell Lung Cancer depend on which stage of cancer the patient has. According to Zappa and Mousa (2016), “[p]atients who have stage I, II, and IIIA NSCLC typically have surgery to remove the tumor if the tumor is found to be resectable and the patient is able to tolerate surgery” (p 289). The doctor performs a lobectomy, where they remove the lobe that contains the tumor, a sleeve resection, wedge resection or segmentectomy, where they remove a smaller piece of the lung. Whether the doctor removes the entire lobe or a segment of the lung depends on the patient’s overall health and whether or not he or she is able to withstand the surgery and its effects. In order to reduce the chances of disease recurrence and improve the chances of survival after having received a surgical resection, adjuvant chemotherapy is considered the most logical approach (Wozniak & Gadgeel 2009). Adjuvant therapy is administered to patients after initial treatment (surgery) in an effort to eliminate any cancer cells that may have possibly lingered around after the tumor was removed.

“For stage IV NSCLC, cytotoxic combination chemotherapy is the first-line therapy, which might be influenced by histology, age vs. comorbidity, and performance status (PS)” (Zappa & Mousa 2016). For patients at stage IV of the disease, surgery is not an option. Therefore, the treatment aims to help with symptoms of the disease and to treat other complications. The chemotherapy aims at shrinking the tumor; however, this is not always guaranteed to work due to the progression and aggression of the disease.

Amini A, Yeh N, Gaspar LE, et al stated that “patients with NSCLC that is localized to the chest and who are not candidates for surgical resection may benefit from radiotherapy” (Zappa and Mousa 2016). Radiotherapy is used to eliminate the cancer cells and may also be used as a method to control or eliminate tumors at different parts of the body. In addition to these, radiotherapy may also be used as a backup form of treatment for the individuals that have gone through chemotherapy or had surgery but have not had much relief from the treatments.

Conclusion

The cancer epidemic is apparent in the world today, constituting 17.08% of all deaths worldwide. Lung cancer is one of the most common types of cancers, and it is the leading cause of cancer death in the United States for both men and women. In order to understand lung cancer in its entirety, it is pivotal that one fully examines the symptoms of the disease and analyzes the different treatment options available for the two most prevalent types of cancer: Small-Cell Lung Cancer (SCLC) and Non-Small Cell Lung Cancer (NSCLC). After this comprehensive analysis, one would undoubtedly have greater knowledge and understanding of the disease.

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