Lung Cancer Pathophysiology

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Table of Contents

Introduction
Diagnosis Etiology
Epidemiology
Pathophysiology
Clinical Manifestations
Diagnostic Possibilities
Patient Education
Reference Page

Introduction

Lung cancer is a disease manifested in malignant tumor located in lungs. Like any other type of cancer, tumors in lungs have a characteristic of an uncontrolled cell growth that takes places in lung tissues. Because of the effects of metastasis, lung tumors may spread far beyond tissues of lungs affecting other organs. Most of the lung cancers are categorized as carcinomas. There are two main types of lung cancer: small-cell lung carcinoma (SCLC) and non-small-cell lung carcinoma (NSCLC). There are also common symptoms associated with this disease; those symptoms are coughing (in particular cases, hemoptysis included), decrease in body weight, breath shortness, and severe or mild pain in chest (depends on progression of the disease). Long-term tobacco smoking causes most cases of lung cancer.

Diagnosis Etiology

According to Cruz, Tanoue and Matthay (2011), there are numerous factors contributing to lung cancer etiology: tobacco smoking (the most prominent cause), other types of smoking, genetic, racial, and ethnical predisposition, and even causes that do not relate to smoking. All in all, although smoking is the primary cause, there is no sure way to protect oneself from lung cancer. The types of smoking that do not relate to cigarettes consumption are cigar or pipe smoking. These are associated with increased risk of lung cancer. Lifetime nonsmokers and people who have smoked fewer than one hundred cigarettes during their life are called never smokers. These people, however, also may have lung cancer.

Epidemiology

Ridge, McErlean and Ginsberg (2013) describe a lot of factors that form the basis of medical sciences knowledge of lung cancer. Also, Alberg, Brock, Ford, Samet and Spivack (2013) conclude their research on epidemiology of lung cancer with stating that a consideration of the epidemiology of lung cancer consistently reinforces one major theme: The pandemic of lung cancer is a consequence of the tragic and widespread addiction to cigarettes (p. 18). All in all, the researchers state that regarding racial factors white Americans are less affected by lung cancer than African Americans, while white and black American women have equal chances of developing this condition. Survival rates for people of Asian descent are significantly higher.

Pathophysiology

The term normal lung structure is used if lungs are not affected by any diseases (including lung cancer) and function well. Normal lung structure and functionality are defined by bronchi, bronchioles, alveoli, and blood vessels running through alveoli. Naturally, as the tumor develops, lung functions are affected, and lungs can no longer operate properly. Bronchi and alveoli are blocked or disrupted by the growing tumor which may cause a cough, pneumonia, shortness of breath, blood coughing, etc. The symptoms caused by lung cancer are divided into local and systemic ones. Local symptoms relate to the tumors mass or ulceration. Systemic symptoms are not directly connected to the metastatic growth of the tumor (body weight decrease, fever, fatigue, etc.).

As already mentioned, lung cancer is categorized as carcinoma. Carcinomas name stems from their visible image under the microscope. The most general type of lung cancer in the US is adenocarcinoma. This type, in turn, may be described as papillary, micropapillary, acinar, mucinous, and solid. Again, the names are given based on the form that the cells appear in under the microscope (these are also referred to as growth patterns). Even in just one tumor, cell structure may differ. Depending on how the tumor looks, physicians are able to tell if it has good or bad prognosis. However, due to the possible mixture of various types of tumor growth patterns, it is not always possible to predict outcomes.

Should the tumor be removed in its entirety, pathologists are able to perform the so-called gross examination. This term refers to the measured size of tumor determined from the naked-eye perspective. The size of the tumor is mostly reported based on how big the tumor is across in the largest area. This part of the tumor is referred to as the tumors greatest dimension. Naturally, the significance of the tumors size often lies in the fact that smaller tumors have better outcomes. Nevertheless, the stage that lung cancer progresses to is vital as well. If the tumor is big enough, it is on a higher stage and is, therefore, harder to treat and recover from resulting in worse outcomes and predictions.

Clinical Manifestations

The typical symptoms that lung cancer causes are worsening cough, blood coughing, rust-colored sputum, pain in chest that gets worse with certain actions (deep breathing, coughing, laughing), hoarseness, weight and appetite loss, breath shortness, general exhaustion and weakness, repeating and worsening infections (pneumonia, bronchitis, etc.), wheezing. If lung cancer has already spread to distant organs, it may cause bone pain, headaches, numbness in limbs, dizziness, inability to correctly balance body position, seizures, skin and eyes turning yellow (jaundice), lumps near skin layers of the body. Moreover, tumor growing on top of lungs may cause a number of face and eye nerves-related symptoms (Horner syndrome). Other syndromes caused by lung cancer are superior vena cava syndrome, paraneoplastic syndromes, and others.

Pertinent history findings will be the most probable causes for a patient to consult a physician. The most significant findings include the symptoms mentioned above. These symptoms may be severe enough to alert a person to attend a hospital. Coughing, coughing up blood, skin and eyes jaundice, unyielding infections these are the most probable pertinent history findings. Physical examination may reveal additional symptoms that were not directly visible to a patient. These include undetected and unexplained body weight loss, low-grade fever. A more thorough examination will also reveal tumors presence or that of metastases in bones, liver, brain, spinal cord or lymph nodes and skin. These locations are the most common for metastases to manifest. The early-stage-lung-cancer often remains undetected and unreported.

There are numerous red flag symptoms that may manifest in patients. However, it is seldom that patients will immediately report these symptoms to doctors. There are at least eight red flag symptoms that require thorough examination despite their cause. These symptoms are constant or almost constant coughing, long-term coughing changing pattern, breath shortness, coughing up blood or rusty-colored phlegm (sputum), chest or shoulder pain, significant loss of appetite that lasts for an extended period of time, severe fatigue, and noticeable body weight loss. Naturally, it is especially important to take into account these symptoms for smokers and people that have genetic or racial predispositions to cancer. Family history may provide significant insight into how likely it is for a person to suffer from lung cancer.

Diagnostic Possibilities

The most common way to diagnose lung cancer is radiography. It is an imaging technique that is based on using x-rays to reveal the internal structures of various objects. The tumors density allows physicians to detect them on x-ray images. However, numerous researches were carried out to discover and develop new ways of diagnosing lung and other types of cancer, for example, studies by Cazzoli et al. (2013) and Oki et al. (2013). However, one of the most promising types of diagnosing lung cancer is elucidated in research by Oxnard et al. (2014). The authors provide a new quantitative assay for plasma-based tumor genotyping which has been technically optimized for translation into clinical practice (p. 1702).

The research has a purpose of ensuring that tumor genotyping using cell free plasma DNA (cfDNA) has the potential to allow noninvasive assessment of tumor biology, yet many existing assays are cumbersome and vulnerable to false positive results (Oxnard et al., 2014, p. 1). The researchers collected plasma from patients that developed advanced stages of lung cancer that they used as a basis for ddPCR assays for epidermal growth factor receptor (EGFR), KRAS proto-oncogene, and BRAF gene mutations. The results identified a reference range for EGFR L858R and exon 19 deletions in specimens from KRAS-mutant lung cancer (Oxnard et al., 2014, p. 1). Such results allowed the authors to reach 100% specificity with a significant level of sensitivity.

This type of research is so important because the research was a success even on theoretical stage. This allows authors to confidently state that their mean of lung cancer detection is ready to be transitioned into practice. The authors equipped their method of detecting lung cancer with a number of ways that maximize positive predictive value and ensure proper quality control. Thus, rather high levels of sensitivity are achieved. These precautions, as well as the nature of method itself, allow it to have a significantly high level of specificity as well. Due to the high levels of sensitivity and specificity, true positive and true negative predictive values dominate in measured results. Therefore, the research will most likely have a great impact on medical practices.

Patient Education

The most important piece of information that must be distributed amongst the patient is the fact that lung cancer is one of the most lethal of common diseases. Even amongst types of cancer, lung cancer is probably the most lethal one (25% of all cancer deaths). It is also important to know that more women die from lung cancer than from other types of cancer (breast, ovarian, uterine), and more men die from it than from, for instance, prostate and colon cancer. The patients need to know that the most important step to prevent lung cancer is ceasing to smoke and secondhand smoke. Also, it is important to remember that appropriate screening is most effective to prevent and detect lung cancer.

If lung cancer is, in fact, present, a patient may need hospitalization if any of the mentioned symptoms have already manifested in them. After receiving a proper physical examination, the patient will know if they need treatment. As with almost any other type of cancer, the patient is presented with a variety of treatment options depending on the tumors size, overall disease progression and various other conditions. These options include chemotherapy, surgical treatment, radiation therapy, targeted drug therapy, clinical trials (experimental treatment), and palliative care that will most likely be necessary. The safest way to treat cancer will probably be a surgery because other treatment options may result in lasting side-effects that may be rather severe. The treatment must be chosen wisely.

Reference Page

Alberg, A. J., Brock, M. V., Ford, J. G., Samet, J. M., & Spivack, S. D. (2013). Epidemiology of lung cancer. Chest, 143(5), 1-29.

Cazzoli, R., Buttitta, F., Nicola, M. D., Malatesta, S., Marchetti, A., Rom, W. N., & Pass, H. I. (2013). MicroRNAs derived from circulating exosomes as noninvasive biomarkers for screening and diagnosing lung cancer. Journal of Thoracic Oncology, 8(9), 1156-1162.

Cruz, C. S. D., Tanoue, L. T., & Matthay, R. A. (2011). Lung cancer: Epidemiology, etiology, and prevention. Clinics In Chest Medicine, 32(4), 1-61.

Oki, M., Saka, H., Kitagawa, C., Kogure, Y., Murata, N., Adachi, T., & Ando, M. (2013). Rapid on-site cytologic evaluation during endobronchial ultrasound-guided transbronchial needle aspiration for diagnosing lung cancer: A randomized study. Respiration, 85(1), 486-492.

Oxnard, G. R., Paweletz, C. P., Kuang, Y., Mach, S., OConnel, A., Messineo, M. M., & Jänne, P. A. (2014). Noninvasive detection of response and resistance in EGFRmutant lung cancer using quantitative next-generation genotyping of cell-free plasma DNA. Clinical Cancer Research, 20(6), 1698-1705.

Ridge, C. A., McErlean, A. M., & Ginsberg, M. S. (2013). Epidemiology of lung cancer. Seminars in Interventional Radiology, 30(2), 93-98.

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