Does Smoking Cause Lung Cancer - Research Paper Example

Smoking and lung cancer Whether active smoking causes lung cancer has been a of hot debate for a long time. Since lung cancer has been diagnosed among patients who have never smoked and many long-time smokers enjoy a full and disease-free life, it was difficult to correlate smoking as a cause for lung cancer. In particular, the tobacco industry and its lobbyists had tried long and hard to prove that there had not been any direct causal relationship between the two; whatever empirical relationship had been purely coincidental. In view of this, the research question is to establish beyond doubt the direct causal relationship between active smoking and lung cancer. It is difficult to establish such a relation genetically. It is much easier to consider the problem from an epidemiological point of view. It is enough to prove that the risk of developing lung cancer in the population of smokers is significantly higher than that in the population of non-smokers. In this respect we need to define the population of smokers. Naturally effect of smoking in the population who have been smoking more than a pack of cigarettes for the last 20 years is much more than the effect of smoking in a population who smoke at most 3 cigarettes a day for last five years. Probability of developing lung cancer is expected to be more in the former group than in the latter. Let us consider the population of long time smokers; e.g. the population consists of males or females who have been smoking more than a pack of cigarettes for the last 20 years or more. Let π1 be the probability of developing lung cancer in the group of smokers and let π2 be the probability of developing lung cancer in the group of non-smokers. Test the null hypothesis of equality of the two proportions versus the alternative that π1 > π2. Mathematically, we may write H0: π1 = π2 against Ha: π1 > π2. Equivalently we may say that under the null hypothesis the odds of developing lung cancer in the population of smokers is 1 against the alternative that the odds is greater than 1. Let the odds of developing lung cancer be denoted by θ. Hence, the equivalent hypothesis is H0: θ = 1 against Ha: θ > 1. To test the above null hypothesis data need to be collected from a sample of smokers and another sample of non-smokers. Recall that we have defined the smoker population as who have been smoking more than one pack of cigarettes for past 20 years or so. Those who had smoked for more than 20 years but are currently non-smokers, are not included in the study. Ordinarily such hypotheses may be tested by collecting data from a cross-section of the population. However, lung cancer is a rare disease and to have a good enough representation of diseased persons in the sample a retrospective study is recommended. In such design, a group of lung cancer patients, known as cases, and another group of controls (disease-free patients) are sampled. To improve efficiency of the testing procedure, and to eliminate confounding factors, the controls are matched with the cases in many important factors, like age, sex and other risk status. This is called a matched case-control study. How many controls are to be matched with the cases are open to consideration. If more than one control is matched with each case, it is known as a one-to-many matched case-control study. Once the cases and controls are sampled, their retrospective risk status is determined. Each of the subjects included in the study is categorized according to whether they have smoked for the past 20 years or not. Hence a 2 x 2 matched case-control study is designed. It is recommended that each of the 4 cells of the contingency table contains at least 5 observations. From the sample the sample odds ratio is computed. Depending on the sample size, a large sample normal test for odds ratio may be considered. If the sample is small, an exact test of Fisher type may be adopted. There are many reliable websites on the topic of lung cancer, or cancer, in general. We have chosen the following sites: 1. http://www.cancer.gov/ 2. http://www.who.int/en/ 3. http://www.cdc.gov/features/lungcancer/ 4. http://www.quit-smoking-stop.com/ 5. http://www.lungcancer.org/ 1. One of the most comprehensive website for information on lung cancer is the one by National Cancer Institute (NCI), a part United States National Institutes of Health (NIH). NCI is the Federal Government’s principal agency for cancer research and coordination of clinical trials, information dissemination, diagnosis, treatment and prevention programs. On their page for lung cancer, they start with definition for lung cancer and its different types. They also report on the number of new cases and deaths in a year (to date). This numbers, written simply, underscores the fatal nature of this cancer. From this page the links go to causes and prevention of lung cancer, treatment, screening and the information on the latest research and clinical trials on lung cancer. The information contained under each linked page is completely up-to-date and helpful for both the patients and the health professionals. In many cases these are the industry best practices recommended by the apex body. For patients the plethora of information serves to get an understanding of the diseases and available options. For researchers and epidemiologists also this site is extremely informative. Detailed research findings and statistics related to incidence and mortality and usefulness of statistics for prognosis is given. 2. Curiously enough the website of World Health Organization is not informative about lung cancer. It is not included among respiratory tract diseases, neither is it under cancer. If searched with the keyword ‘lung cancer’, the website points to several countries’ campaigns against tobacco as a carcinogenic agent. This neglect of one of the principal forms of cancer by the principal organization looking after world’s health causes concern. 3. Another federal government website containing information on lung cancer is Centers for Disease Control and Prevention. This site actively campaigns against smoking and second-hand smoking to stop lung cancer. The sections on risk factors, symptoms and treatments are written succinctly and are easy to understand. For more information on latest research and clinical trials the site refers to National Cancer Institute site. For information on radon and its protection, the site refers to the Environmental Protection Agency. 4. This site is not directly linked to lung cancer, but it deals with, as the name suggests, stopping smokings. The site is especially aimed for teens to stop smoking. While talking about ill-effects of smoking, the site points out that smoking is one of the primary causes of lung cancer, and it has been established beyond doubt. The site speaks about the carcinoma and its symptoms and signs in an easy to understand form. 5. Lungcancer.org is the website of CancerCare, a not for profit organization providing professional support to cancer patients and their family members. This organization has been around since 1944 and claims to have helped more than one hundred thousand cancer patients, family and friends and healthcare professionals last year. This site is very well designed and has a plethora of information on various aspects of lung cancer. They recognize that having been diagnosed with lung cancer can be a huge burden on the family, both emotionally and financially. CancerCare provides counselling and other support, information on available financial support and education. They have a staff of more than 50 oncology social workers. They are located in the Tri-State region where they can offer in-person services. One important service provided by CancerCare is the information regarding possible short and long term side effects for the treatment. They also highlight some of the latest cancer research and treatments so that a patient may make an informed choice. In addition CancerCare provides tips on how to manage common side-effects of treatment. Another wonderful service CancerCare offers is for the healthcare professionals so that they become more sensitive to the oncology related issues. Often families are devastated with the knowledge that one loved one has cancer and the other members do not understand how best to deal with this knowledge. Emotional support service is provided as well as answers to specific questions are posted on this website. From medical or epidemiological viewpoint these organizations may not be the most informative, but they also fill in a gap in the overall scheme of things. The sites by the National Cancer Institute and the Centers for Disease Control and prevention are the most reliable. The information and the statistics given there are up-to-date and complied with care. Also these sites being established by the federal government are most accountable. The site by World Health Organization contains hardly any information. The other two sites are, although useful, maintained by private bodies. Their access to information may be limited and possibly from the federal or other government sites. If any information posted in these sites are at variance to the official sites maintained by the federal government, the government sites must be trusted. Read More