Occupational Cancer
By : Dr. Aliraza Safaiyan M.D.
Occupational Medicine Specialist
Introduction
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One of every two or three individuals in the
industrialized world will develop some type of
cancer during their lifetimes
Approximately 3-10% of all human cancers are
thought to be caused by occupational exposure to
carcinogens
It is estimated that approximately 20,000 cancer
deaths and 40,000 new cases of cancer each year
in the U.S. are attributable to occupation
The most common cancers associated
with occupational exposure:
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lung and pleura
bladder
skin
laryngeal
nasal cavity
leukemia
throat
lymphoma
soft-tissue sarcomas
liver
Risk of developing a particular cancer
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Personal characteristics such as age, sex, and race
Family history of cancer
Diet and personal habits such as cigarette smoking
and alcohol consumption
The presence of certain medical conditions
Exposure to cancer-causing agents in the environment
Exposure to cancer-causing agents in the workplace
Stages in tumor development
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Initiation (irreversible changes in DNA)
Promotion (facilitate tumor development)
Progression (development to malignant tumor &
metastases)
Examples
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(PAH) & (croton oil) in skin cancers in mice
(Nitrosamine) & (PCB) in liver tumor in mice
Complete carcinogens (cigarette smoke)
Induction-Latency period
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3-5 years for radiation or toxin induced Leukemia
40 or more asbestos-induced Mesothelioma
For most tumors about 12-25 years
Initiators VS Promoters
Initiators
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Genotoxic
Carcinogenic alone
Covalently bind to
DNA (irreversible)
Single exposure (may
be)
Promoters
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Not genotoxic
Act after initiation
Act by cellular
proliferation (may be
reversible)
Repeated exposure
required
IARC
International Agency of
Research on Cancers
Problems in testing
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Prolonged high exposure is uncommon
Usually mix of exposures
Epi: expensive, long, past exposures, poor
exposure data
Animal: high dose (Validity in humans ?!)
In vitro: mutagens, not carcinogens
IARC Evaluations
Dimensions and Groups
11
Types of evidence
Human
Animal
Other
- mutagenicity
- genotoxicity
- metabolism
- etc.
Group
1
Carcinogenic to humans
2A
Probably carcinogenic
to humans
2B
Possibly carcinogenic
to humans
3
Not classifiable
4
Not carcinogenic
to humans
Numbers of occupational carcinogens and high risk
occupations and industries designated by the IARC
Monograph Programme, 1971-2003
Mixtures
& Agents
Groups
Occupations
& Industries
1
(definite)
28
12
2A
(probable)
27
3
2B
(possible)
113
4
Siemiatycki et al, Environ Hlth Persp, 2004, http://www.ehponline.org
12
Lung cancer (Exposures)
General
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Tobacco smoking is
responsible for nearly 90%
of all lung cancers.
Second-hand smoke
Byproducts of fossil fuel
Air pollution
Insufficient consumption of
fruits and vegetables
High doses of ionizing
radiation
workplaces
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Asbestos
Radon
chloromethyl ethers
Polycyclic aromatic
hydrocarbons
Inorganic arsenic
Chromium
Nickel
Mustard Gas
Lung cancer (findings)
Symptoms & Signs
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Cough
Hemoptysis
Wheezing
Dyspnea
Weight loss
Anorexia
Fatigue
Paraclinics
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CXR
CT-scan
Sputum cytology
Fiberoptic Bronchoscopy
Biopsy
Lung cancer (prevention)
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Avoidance of exposure
Medical monitoring
Mesothelioma (exposure)
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Asbestosis (trivial contact)
Crocidolite: the most potent carcinogen
Mesothelioma (findings)
Symptoms & signs
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Chest pain
Dyspnea
Dry cough
Weight loss
Pleural effusion
Friction rub
paraclinics
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CXR
CT-scan
Thoracentesis
Thotacotomy & thoracoscopy
Sputum cytology
SI-ADH
LDH
Mesothelioma (prevention)
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OSHA PEL (1970) :5 Fiber/cm3
(1986):2 fiber/cm3
now: 0.1 fiber/cm3
Asbestos ban : since 1989 by EPA
Asbestos Ban (1989)
Bladder cancer (exposure)
General
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The most important risk factor is
cigarette smoking .
Heavy coffee consumption
(Possible risk factors )
Bladder infection with
schistosoma
Cyclophosphamide
Long-term use of pain killers
containing phenacetin,
Urinary tract infections or low
urine flow
Genetic factors
workplace
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Benzidine
2-naphthylamine
Occupations in the dye,
leather or rubber
industry
Chlornaphazine
4 chlorotoluidine
Phenacetine
Bladder cancer (findings)
Symptoms & signs
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Hematuria (Painless, gross,
intermittent) 80%
Vesical irritability alone
20%
In advance cases:
 Anemia
 Uremia
 Leg edema
Paraclinics
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Urinary cytology (in up
to 75% of patients is
positive)
Ultrasonography
Excretory urography
Cystoscopy & biopsy
(definitive diagnosis)
Bladder cancer (prevention)
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Avoidance of exposure
Medical monitoring :
Urinary cytology (75% Sen. 99.9 Spes.)
Immunocytology
Liver cancer
(hepatic angiosarcoma) (exposure)
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Vinyl chloride
Arsenic
Copper, Lead, Zinc
Thorotrast (thorium dioxide) 1930-1955
Liver cancer
(hepatic angiosarcoma) (findings)
Symptoms & sings
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Asymptomatic (some time)
RUQ abdominal pain
Weight loss
Fatigue
Hepatomegaly with ascitis
Jaundice
Splenomegaly
Paraclinics
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Ultrasonography
Radionuclide liver scan
Hepatic angiography
Liver biopsy (hemorrhage)
Lab data:
Mild anemia (target cell &
schistocyt), Leukocytosis,
thrombocytopenia
LFT
LDH
Liver cancer
(hepatic angiosarcoma) (prevention)
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Avoidance of exposure
Medical monitoring (history, Ph/E, CBC, LFT,
Ultrasonography)
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