FINALLY. We now know what causes lung cancer (and mouth cancer, throat cancer, larynx cancer, esophageal cancer, esophageal cancer, pancreas cancer, cervix cancer, bladder cancer, kidney cancer, emphysema, and heart disease - the list goes on and on). The Liggett Group has told us. AND, Phillip Morris and R.J. Reynolds have now come to the table to talk (and to cut their losses). Let us hope that we can get on with the job of compensating the victims and as importantly, preventing others from exposure and addiction.
The World Health Organization tells us that three million people die worldwide every year as a result of smoking. The American Cancer Society's Cancer Prevention Study II estimates that smoking is related to 419,000 US deaths each year. Although the number of cardiovascular deaths is declining, smoking-related cancer deaths continue to rise. The risks of dying from lung cancer are 23 times higher for male smokers and 11 times higher for female smokers than for people that have never smoked. Smoking accounts for 29% of all cancer deaths.
Approximately 87% of all lung cancer are related to cigarette smoking. Overall there has been a decrease in the incidence of smoking from 1974 through 1992. Smoking cessation decreases the risk of developing lung cancer but does not occur until 5 years after stopping and remains higher than the risk in non-smokers for 25 years. Second-hand smoke accounts for 3000 lung cancer deaths per year. Nonsmokers who live in a household with smokers have a 30% increase in the incidence of lung cancer compared to nonsmokers who do not live in such an environment. Asbestos exposure, radioactive dust and radon exposure are all risk factors for lung cancer, particularly if a person smokes as well.
The incidence of tobacco-related cancers in the United states is 360,000 new cases every year with 240,000 deaths. By far the most frequent tobacco-related cancer is lung cancer with 178,000 cases per year and 160,400 deaths. The survival for lung cancer is only 13%.
In 1984 there were 87 cases of lung cancer per 100,000 men and in 1993 this number decreased to 77 cases per 100,000 men. Unfortunately, for women the number has increased and in 1993 was 42 cases per 100,000. In California, the 25 cent increase in the tobacco tax in 1988 - Proposition 99 - resulted in a definite decrease in the incidence of smoking. Currently 16.7% of Californians smoke. Unfortunately in California, there is an increase in the rate of smoking for all ages but particularly among the youth of our state. In the United states 25% of the population or 48 million people smoke. The highest incidence of smoking is found in Hawaiians and African-Americans.
There are four major types of lung cancer: Adenocarcinoma (40%), Squamous (30%), Large Cell Carcinoma (10%) collectively designated non-small cell lung cancer (NSCLC)
and finally Oat Cell Carcinoma or small cell carcinoma. The NSCLC cases are considered together because their prognosis and survival is the same. Oat cell carcinoma is more treatable and carries longer survival compared to NSCLC. The median age for people with lung cancer is 60 years.
The clinical manifestations of lung cancer depend on the location and extent of the tumor. Cough is a major manifestation but one must remember that lung cancer patients are smokers and likely have a chronic cough associated with the irritation that results from tobacco smoke. Therefore, smokers should be asked whether or not there has been a change in the frequency or severity of their coughing. Increasing shortness of breath or coughing up of blood may be signs of lung cancer. Partial or complete obstruction of the bronchial tubes can result in pneumonia. The presence of pleural effusion is an ominous sign. Chest pain may occur if the tumor invades the chest wall and shoulder or arm pain may occur as a result of invasion of the tumor into the brachial plexus of nerves. Hoarseness may result from tumor or lymph node invasion of the nerve to the larynx resulting in paralysis of the vocal cords. Finally the tumor may cause compression of the bronchial tubes or esophagus causing difficulty in swallowing , wheezing or stridor.
Several randomized trials, conducted in the 1970's failed to demonstrate a survival advantage for those individuals who were screened with chest x-rays. Consequently, this has led some investigators to abandon the recommendation for regular chest x-rays and to concentrate instead on prevention. This is undergoing reconsideration and studies are evaluating long term trials for annual chest x-rays. Potentially, this could result in a 13% reduction in mortality. A 10% reduction in mortality would result in 14,000 lives saved annually.
As yet, no agent has been demonstrated to reduce the incidence of lung cancer. There is an ongoing trial of 13-cis-retinoic acid to determine if the incidence of a second primary lung cancer is reduced in patients who have had a completely resected stage I lung cancer. Cis-retinoic acid has reduced the incidence of second primaries in head and neck cancer. Recently, the FDA has recommended approval of the Lung Imaging Fluorescence Endoscope (LIFE-lung system) for the early diagnosis of lung cancer. This system uses blue light rather than white light and takes advantage of natural differences in fluorescence between normal and cancerous tissue. The device has been shown to improve a physician's ability to spot lung cancer by over 200% in those patients with lung cancer.
Researchers at the University of Texas Southwestern Medical Center have reported that alteration in the genes of chromosome 3p may reveal the earliest stages of lung cancer. It is possible that a simple test will be developed that would predict who would get lung cancer.
In the meantime, all is not gloom and doom. Since 1990 US scientists have demonstrated a 3.1% decrease in mortality overall. This equates to 18,000 fewer deaths from cancer generally. The major reasons for this decline has been early diagnosis from cancer screening and cancer prevention from the reduction in tobacco use. If the projected improvement in cancer mortality continues at 2% per year as expected, there will be a 15% reduction in the age-adjusted death rate in 20 years, by the year 2013, the 100th anniversary of the American Cancer Society . With increased strategies and efforts we can reach a 50% reduction in mortality. We are winning the war on cancer.
To obtain low-cost cancer screening examinations you may call the Cancer Detection Center at (213-481-2511) or (800) 92-CANCER. For more information on cancer you may call the American Cancer Society, Central Los Angeles Unit at (213)-386-6102.
Lowell E. Irwin, M.D.
Cancer Detection Center
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