LUNG TUMOURS

Question 1

Introduction

Answer 1

Introduction
• A variety of benign and malignant tumours may arise in the lung
:90% to 95% are carcinomas
:about 5% are bronchial carcinoids
: 2% to 5% are mesenchymal and other miscellaneous neoplasms.

Question 2

carcinomas

Answer 2

Carcinomas
• Currently the most frequently diagnosed major cancer in the
world (estimated 1.6 million new cases in 2008) and the
most common cause of cancer mortality worldwide
(1,380,000 deaths in 2008).

Question 3

Aetiology and Pathogenesis

Answer 3

Environmental and genetic factors
• Most lung cancers are associated cigarette

Tobacco Smoking
• About 80% of lung cancers occur in active smokers or
those who stopped recently.
• Nearly linear correlation between the frequency of lung
cancer and pack-years of cigarette smoking.
• Lung cancer develops in only 11% of heavy smokers.
• Women have a higher susceptibility to carcinogens in
tobacco than men
• Second-hand smoke, or environmental tobacco smoke

Industrial Hazards
Certain industrial exposures increase the risk of developing lung cancer.
( Asbestos Arsenic Chromium Uranium Nickel Vinyl chloride Mustard gas)

Air Pollution.
• Uncertain effect
• Chronic exposure to air particulates in smog may cause lung irritation,
inflammation and repair, and chronic inflammation and repair
increases the risk of a variety of cancers

Molecular Genetics
Smoking-related carcinomas of the lung arise by a stepwise
accumulation of oncogenic “driver” mutations that result in the
neoplastic transformation of pulmonary epithelial cells.

Question 4

Squamous cell carcinoma

Answer 4

• Shows the highest frequency of TP53 mutations.
• p53 protein overexpression (as seen by immunohistochemical
staining), a marker of TP53 mutations.
• The cyclin-dependent kinase inhibitor gene CDKN2A is
inactivated and its protein product, p16, is lost in 65% of
tumors.

Question 5

Small cell carcinoma

Answer 5

• shows the strongest association with smoking, only about 1% occurs in
nonsmokers.
• shows frequent loss-of-function aberrations involving TP53 (75% to 90% of
tumors), RB (close to 100% of tumors), and chromosome 3p deletions.
• Also common is amplification of genes of the MYC family.

Question 6

Adenocarcinoma

Answer 6

• These include gain-of-function mutations in multiple genes
encoding receptor tyrosine kinases, including EGFR, ALK,
ROS, MET, and RET, which are all also mutated in other
forms of cancer.

Question 7

Lung cancer in Never Smokers

Answer 7

• Accounts for 25% of lung cancers cases.
• More common in women and most are adenocarcinomas.
• Cancers in nonsmokers are more likely to have EGFR mutations, and
almost never have KRAS mutations; TP53 mutations are not
uncommon, but occur less frequently than in smoking related cancers.

Question 8

Classification of lung tumours

Answer 8

Classification
Primary
• - Benign
• - Malignant
Secondary

Adenocarcinoma (38%)
Squamous cell carcinoma (20%)
Small cell carcinoma (14%)
Large cell carcinoma (3%)
Other (25%)

Question 9

MORPHOLOGY

Answer 9

• Lung carcinomas may arise in the peripheral lung (more
often adenocarcinomas) or in the central/hilar region (more
often squamous cell carcinomas)

Question 10

Staging

Answer 10

• A uniform TNM system for staging cancer according to its anatomic
extent at the time of diagnosis is useful, particularly for comparing
treatment results from different centers

Question 11

Clinical Course

Answer 11

• Insidious and aggressive neoplasms. 
• Age: 50s or older whose symptoms are of several months’ duration. 
• The major presenting complaints are:
cough (75%),
weight loss (40%)
chest pain (40%), 
dyspnea (20%).

Question 12

Treatment

Answer 12

• Targeted treatment of patients with adenocarcinoma and activating
mutations in EGFR (present in about 15% of all patients) or in other
tyrosine kinases with specific inhibitors of the mutated kinases
prolongs survival.
• Untreated, the survival time for patients with small-cell carcinoma is 6
to 17 weeks. This cancer is particularly sensitive to radiation therapy
and chemotherapy, and cure rates of 15% to 25% for limited disease
have been reported in some centers.

Question 13

Paraneoplastic Syndromes

Answer 13

• May antedate the development of a detectable pulmonary lesion.
• The hormones or hormone-like factors elaborated include:
• Antidiuretic hormone (ADH),
• Adrenocorticotropic hormone (ACTH)
• Parathormone, parathyroid hormone-related peptide, Prostaglandin E,
and some cytokines, all implicated in the hypercalcemia
• Calcitonin, causing hypocalcemia

Question 14

Carcinoid Tumors

Answer 14

• Represent 1% to 5% of all lung tumors.
• Most patients with these tumors are younger than 40 years of age,
and the incidence is equal for both sexes.
• Approximately 20% to 40% of patients are nonsmokers.
• Carcinoid tumors are low-grade malignant epithelial neoplasms
that are subclassified into typical and atypical carcinoids

Question 15

morphology of carcinoids

Answer 15

• Carcinoids may arise centrally or may be peripheral. On gross
• examination, the central tumors grow as fingerlike or spherical
• polypoid masses that commonly project into the lumen of the
• bronchus and are usually covered by an intact mucosa

Question 16

Malignant Mesothelioma

Answer 16

• Rare
• Increased incidence among people with heavy exposure to asbestos
• There is a long latent period of 25 to 45 years

Question 17

Morphology of malignant mesothelioma

Answer 17

• Malignant mesothelioma is a diffuse lesion arising either from the
visceral or parietal pleura,
• Associated with extensive pleural effusion and direct invasion of
thoracic structures.
• The affected lung becomes ensheathed by a thick layer of soft,
gelatinous, grayish pink tumor tissue
• Microscopically, malignant mesotheliomas may be epithelioid
• (60%), sarcomatoid (20%), or mixed (biphasic) type (20%).

Question 18

morphology of asbestos

Answer 18

• Asbestos bodies are found in increased numbers in the lungs of
patients with mesothelioma.
• Another marker of asbestos exposure, the asbestos plaque