Cigarette smoking and PULMONARY EFFECTS

Dr:HALVANIDr:HALVANIYazd University Medical Yazd University Medical

SchoolSchool

IN THE NAME OF GOD

PREVALENCE OF CIGARETTE SMOKING

• The prevalence of cigarette smoking in the United States has decreased since 1964, when the first Surgeon General's Report on Smoking and Health was published

• In 1965, 52 percent of men and 34 percent of women over age 18 were cigarette smokers.

• By 1991, these percentages had decreased to 28 percent for men and 24 percent for women.

• Nearly all first use of tobacco occurs before high school graduation, and each day 3000 teenagers start to smoke.

The WHO estimates 1.1 billion smokers worldwide, increasing to 1.6 billion by 2025. In low- and middle-income countries, rates are increasing at an alarming rate.

The WHO estimates 1.1 billion smokers worldwide, increasing to 1.6 billion by 2025. In low- and middle-income countries, rates are increasing at an alarming rate.

COST OF SMOKING

• Cigarette smoking is very costly to both the individual and society.

• In 1993 the estimated smoking-attributable costs for medical care were $50 billion.

• When lost work and productivity were added, the total cost to society was estimated to exceed $97 billion

Cigarette smokers and MORTALITY

• Cigarette smoking is a major contributor to mortality in the United States.

• Recenly, approximately 5,000,000 died from diseases directly related to cigarette smoking.

• more than one out of every five deaths was the result of smoking

• New long-term studies estimate that about half of all regular cigarette smokers will eventually be killed by their habit.

Cigarette smokers and MORTALITY

• Cigarette smoking remains the most preventable cause of premature death in the United States.

• heavy smoker at age 25 can expect a life expectancy at least 25 percent shorter than a nonsmoker

Cigarette smokers and morbidity

Current smokers have:

• more acute and chronic illness • more restricted activity days• more bed disability days• more school and work absenteeism

than former smokers or those who never smoked

GENERAL PULMONARY EFFECTS

• Cigarette smoking alters both the structure and function of central and peripheral airways, alveoli and capillaries, and the immune system of the lung.

• Multistep transformation from normal epithelium to squamous metaplasia, carcinoma in situ, and eventually invasive bronchogenic carcinoma has been reported

Pulmonary function abnormalities

• current smokers have a lower FEV1 and an accelerated decline in FEV1

• Both of these associations show a dose response relationship and are more dramatic in men than women.

• A relatively low FEV1, by middle age and a faster-than-expected annual fall in FEV1 identifying smokers who are likely to develop severe pulmonary impairment

Respiratory symptoms

• A dose-response relationship exists for chronic cough and phlegm production, wheeze, and dyspnea

• Smoking-induced changes in airway epithelium underlie the development of these respiratory symptom

COPDCOPD• COPD is the 4th leading cause of death in

the United States (behind heart disease, cancer, and cerebrovascular disease).

• In 2000, the WHO estimated 2.74 million deaths worldwide from COPD.

• In 1990, COPD was ranked 12th as a burden of disease; by 2020 it is projected to rank 5th.

• COPD is the 4th leading cause of death in the United States (behind heart disease, cancer, and cerebrovascular disease).

• In 2000, the WHO estimated 2.74 million deaths worldwide from COPD.

• In 1990, COPD was ranked 12th as a burden of disease; by 2020 it is projected to rank 5th.

Leading Causes of DeathsU.S. 1998

Leading Causes of DeathsU.S. 1998

All other causes of death 469,314All other causes of death 469,314

10.10. Chronic liver disease 24,936Chronic liver disease 24,936

9.9. Nephritis 26,295Nephritis 26,295

8.8. Suicide 29,264Suicide 29,264

7. 7. Diabetes 64,574Diabetes 64,574

6.6. Pneumonia and influenza 93,207Pneumonia and influenza 93,207

5.5. Accidents 94,828Accidents 94,828

4.4. Respiratory Diseases (COPD) 114,381Respiratory Diseases (COPD) 114,381

3.3. Cerebrovascular disease (stroke) 158,060Cerebrovascular disease (stroke) 158,060

2. 2. Cancer 538,947Cancer 538,947

1.1.

Cause of Death Number Cause of Death Number

Heart Disease 724,269

Percent Change in Age-Adjusted Death Rates, U.S., 1965-1998Percent Change in Age-Adjusted Death Rates, U.S., 1965-1998

00

0.50.5

1.01.0

1.51.5

2.02.0

2.52.5

3.03.0

Proportion of 1965 Rate Proportion of 1965 Rate

1965 - 19981965 - 1998 1965 - 19981965 - 1998 1965 - 19981965 - 1998 1965 - 19981965 - 1998 1965 - 19981965 - 1998

–59%–59% –64%–64% –35%–35% +163%+163% –7%–7%

CoronaryHeart

Disease

CoronaryHeart

Disease

StrokeStroke Other CVDOther CVD COPDCOPD All OtherCauses

All OtherCauses

Chronic obstructive pulmonary disease

• Cigarette smoking is the principal risk factor for COPD

• The exact mechanism not been firmly established:

imbalance between proteolytic and antiproteolytic activity in the lung

smoking as a cause of heightened airway responsiveness, which in turn may be a risk factor for the development of COPD.

• An estimated 10 to 15 percent of all smokers develop clinically significant airflow obstruction.

• Alpha-l-antiprotease deficiency remains the only known determinant of susceptibility for cigarette smokers.

Lung cancer• the most common cause of cancer death caused

approximately 154,900 deaths in the United States during 2002

• 127,000 deaths will result from the combined mortality of colorectal, breast, and prostate cancer

• lung cancer mortality Stabilized in men but continues to rise dramatically in women

• bronchogenic carcinoma is undoubtedly the most preventable of the common forms of cancer

LUNG CANCER • The possibility that inhalation of cigarette smoke might be a common cause

of lung cancer was first suggested by Adler in 1912

• In 1920, lung cancer comprised only one percent of all malignancies in the US.

• The first scientific report associating cigarette smoking with an increased risk of premature death appeared in 1938

• It was not until 1950, however, that Doll and Hill clearly demonstrated an epidemiologic association between cigarette smoking and lung cancer mortality

• The 1964 Surgeon General's report concluded that cigarette smoking was causally related to lung cancer

• smoking responsible for 87 percent of cases of lung cancer, including 90 percent of cases in men and 79 percent of cases in women

• Cigarette smoking is the major cause of lung cancer of each of the principal histologic types

Amount and duration of smoking and risk of lung cancer

• smoke > or =40 cigarettes/day e twice the lung cancer risk of who smoke < or =20 cigarettes/day.

• start before the age of 15 years are four times more likely to than those who begin after the age of 25 year.

• Epidemiologic studies have shown that brands of cigarettes that contain less tar and nicotine only marginally reduce the risk of lung cancer mortality.

• Similarly, little difference in mortality has bean found for lifelong filter versus nonfilter smokers and for persistent smokers who switch from non filter to filter cigarettes

Mechanism by which cigarette smoking causes lung cancer

• Not fully understood

• A multistage model in sequentially transforms cells from normal to malignant is widely accepted

• The components of tobacco smoke have been proven capable of initiating and promoting carcinogenesis.

Host and environmental factors and risk of lung cancer in cigarette smokers

• A family history of lung cancer and exposure to radon or asbestos greatly increase the likelihood of lung cancer in smokers.

• The effects of genetic susceptibility and vitamin A deficiency on the risk of lung cancer in smokers are unknown

• the risk associated with ambient air pollution appears to be small.

Carcinoma of the larynx and sinus

• Smoking dramatically increase the risk for squamous cell carcinoma of the larynx and cancer of sinus

Prenatal exposure to maternal smoking

• smoking enhances airway-parenchymal dysanapsis (disproportionately small airways compared to the size of the pulmonary parenchyma).

• Pulmonary function was lower in infants whose mothers smoked

• Reduced pulmonary function early in life increases the risk for wheezing and subsequently for asthma later in life.

Asthma

• There is a growing body of evidence that passive smoke associated with the development of asthma in early life.

• Maternal smoking is the most important

• children of smoking mothers were 2.1 times more likely to develop asthma

• Passive exposure to tobacco smoke was associated with increases in the risks of doctor-diagnosed asthma, wheezing, bronchitis, and dyspnea and middle ear disease

Current asthma

• Smoking trigger current asthma

Occupational asthma

• Smokers increases risk of sensitisation by occupational allergens

Interstitial lung disease

some diseases occur largely among current or former smokers :

• pulmonary Langerhans cell histiocytosis• desquamative interstitial pneumonitis• IPF• respiratory bronchiolitis• Active smoking can lead to complications in

Goodpasture's syndrome

Interstitial lung disease

some diseases occur largely among never or former smokers:

• Sarcoidosis

• hypersensitivity pneumonitis

Primary spontaneous pneumothorax

• The pathogenesis of the subpleural blebs and PSP is probably related to airway inflammation due at least in part to cigarette smoking in many cases.

• the relative risk of a pneumothorax in men is seven times higher in light smokers (one to 12 cigarettes per day), 21 times higher in moderate smokers (13 to 22 cigarettes per day), and 102 times higher in heavy smokers (more than 22 cigarettes per day).

• For women, the relative risk is four, 14, and 68 times higher in light, moderate, and heavy smokers, respectively

Pneumonia

• Among cigarette smokers compared with nonsmokers mortality increased from pneumonia, and influenza

Pulmonary embolism• Although the Leiden group and the ARIC

and CHS studies found no relation between smoking and VTE, at least two other studies have detected a relationship between the two, with relative risks ranging from 1.9 to 3.3 (especially in women)

Obstructive sleep apnea

• A higher incidence of OSA may occur in smokers

• Whether a causal relationship exists is not known

Postoperative pulmonary complications

• Current smokers have increased risk for postoperative pulmonary complications even in the absence of chronic lung disease

• Patients undergoing elective surgery should be advised to :

stop smoking at least eight weeks before surgery

• patients who had stopped smoking for more than six months had rates similar to those who had never smoked

Asbestosis

• The disease is characterized by slowly progressive, diffuse pulmonary fibrosis

• Cigarette smoking increase risk of Asbestosis

Malignancy and asbestos exposure

• Asbestos exposure was associated with a relative risk of lung cancer of 3.5 -6

• The increased risk of lung cancer associated with asbestos is greatly magnified by coexisting exposure to tobacco smoke

Malignancy and asbestos exposure

• Asbestos exposure in the absence of a smoking history was associated with a 3.5 -6 fold relative risk.

• Cigarette smoking without a history of asbestos exposure was associated with an 11-fold increase in risk.

• The relative risk for cigarette smokers with a history of asbestos exposure was 59.

Mesothelioma

Sudden infant death syndrome

• There are two major maternal risk factors for SIDS that are independent of birth weight:

• Maternal smoking

• Age of the mother under 20 years

Passive inhalation

• Associated with many of the same health consequences as active smoking, albeit with much smaller degrees of increased risk

• classified by the Environmental Protection Agency as a Class A (known human) carcinogen.

Thank you for your attention

• A number of other risk factors for lung cancer have also been identified, including exposure to asbestos, haloethers, polycyclic aromatic hydrocarbons, nickel, and arsenic.

• Interest has also focused on the potential roles of exposure to environmental tobacco smoke (ie, passive exposure to "second-hand" smoke) and to radon.

• Other potential risk factors include dietary factors, genetic factors, and the presence of underlying benign forms of parenchymal lung disease, especially pulmonary fibrosis.

The American Cancer Society's Cancer Prevention Study II

• prospective evaluation of almost 1.2 million men and women from 1982 to 1986, found that the overall mortality ratio (ie, deaths from all causes in current smokers compared to deaths in those who never smoked) was 2.22 for men smoking 1 to 20 cigarettes/day and 2.43 for men smoking > or =21 cigarettes/day. Similarly, the mortality ratio was 1.60 and 2.10, respectively, for women smoking 1 to 19 and > or =20 cigarettes/day.