Lung cancer

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Lung cancer
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Definition

• The term lung cancer is used for tumors arising
  from the respiratory epithelium (bronchi,
  bronchioles, and alveoli).
• Bronchial carcinoma accounts for 95 of all
  primary tumours of the lung.
• Alveolar cell carcinoma accounts for 2 of lung
  tumours, and other less malignant or benign
  tumours account for the remaining 3.

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Bronchial carcinoma

• This is the most common malignant tumour in the
  West and is the third most common cause of death
  in the UK after heart disease and pneumonia.
• Male-to-female ratio of 3 1. Although the
  mortality rate from this disease has started to
  decrease in men, it continues to rise in women,
  and now causes more deaths from malignant disease
  in women than any other tumour.

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• Aetiological factors
• cigarette smoking, passive smoking (the frequent
  inhalation of other people's smoke by
  non-smokers) increases the risk of bronchial
  carcinoma by a factor of 1.5.
• Occupational factors include exposure to
  asbestos, and an association is also claimed for
  workers in contact with arsenic, chromium, iron
  oxide, petroleum products and oils, coal tar,
  products of coal combustion, and radiation.
• Tumours associated with occupational factors are
  mostly adenocarcinomas and appear to be less
  related to cigarette smoking.

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• there is a higher incidence of bronchial
  carcinoma in urban compared with rural areas,
  even when allowance is made for cigarette
  smoking.
• Pathology
• Four major cell types make up 88 of all primary
  lung neoplasms according to the WHO
  classification.
• These are
• squamous or epidermoid carcinoma
• small cell (also called oat cell) carcinoma
• adenocarcinoma (including bronchioloalveolar)
• large cell carcinoma.

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• The remainder include
• undifferentiated carcinomas
• carcinoids
• bronchial gland tumors (including adenoid cystic
  carcinomas and mucoepidermoid tumors)
• Based on the characteristics of the disease and
  its response to treatment bronchial carcinoma may
  be divided into
• small-cell carcinoma .
• non-small-cell carcinoma.

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Small-cell carcinoma

• This tumour, often called oat-cell carcinoma,
  accounts for 20-30 of all lung cancers.
• It arises from endocrine cells .These cells are
  members of the APUD system, which explains why
  many polypeptide hormones are secreted by these
  tumours. Some of these polypeptides act in an
  autocrine fashion they feed back on the cells
  and cause cell growth.
• The tumour is rapidly growing ,highly malignant
  and spreads early so,it is almost always
  inoperable at presentation.
• It responds to chemotherapy but the prognosis
  remains poor.

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Non-small-cell carcinoma

• Squamous or epidermoid carcinoma
• It is the commonest type, accounting for
  approximately 40 of all carcinomas.
• Most present as obstructive lesions of the
  bronchus leading to infection.
• It occasionally cavitates (10) at presentation.
• The cells are usually well differentiated but
  occasionally anaplastic.
• Local spread is common but widespread metastases
  occur relatively late.

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• Adenocarcinoma
• Arises from mucous cells in the bronchial
  epithelium.
• Invasion of the pleura and the mediastinal lymph
  nodes is common, as are metastases to the brain
  and bones.
• It accounts for approximately 10 of all
  bronchial carcinomas.
• It is the most common bronchial carcinoma
  associated with asbestos and is proportionally
  more common in non-smokers, in women, and in the
  elderly.
• Large cell carcinomas
• Are less-differentiated forms of squamous cell
  and adenocarcinomas.
• These account for about 25 of all lung cancers
  and metastasize early.

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• Bronchoalveolar cell carcinoma (also termed
  bronchiolar carcinoma)
• accounts for only 1-2 of lung tumours and
  occurs either as a peripheral solitary nodule or
  as diffuse nodular lesions of multicentric
  origin.
• Occasionally this tumour is associated with
  expectoration of very large volumes of mucoid
  sputum.

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Clinical features

• Symptom
• Chest pain and discomfort are often described as
  fullness and pressure in the chest.
• The pain may be pleuritic owing to invasion of
  the pleura or ribs.
• signs
• Often there are no abnormal physical signs.
• Enlarged supraclavicular lymph nodes may be
  present.
• There may be signs of a pleural effusion or of
  lobar collapse.
• Signs of an unresolved pneumonia or of associated
  underlying disease (e.g. diffuse pulmonary
  fibrosis in asbestosis) may be present.

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The frequency of the common presenting symptoms
of bronchial carcinoma .
Frequency () Symptom
41 Cough
22 Chest pain
15 Cough and pain
7 Coughing blood
lt5 Chest infection
lt5 Malaise
lt5 Weight loss
lt5 Shortness of breath
lt5 Hoarseness
lt5 Distant spread
lt5 No symptoms
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• Direct spread
• The tumour may directly involve the pleura and
  ribs.
• Carcinoma in the apex of the lung can erode the
  ribs and involve the lower part of the brachial
  plexus (C8, T1 and T2), causing severe pain in
  the shoulder and down the inner surface of the
  arm (Pancoast's tumour).
• The sympathetic ganglion can also be involved,
  producing Horner's syndrome.
• Hilar tumours may involve the recurrent
  laryngeal nerve, causing unilateral vocal cord
  paresis with hoarseness and a bovine cough.

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• Bronchial carcinoma can also directly invade the
  phrenic nerve, causing paralysis of the
  ipsilateral hemidiaphragm. It can involve the
  oesophagus, producing progressive dysphagia, and
  the pericardium, producing pericardial effusion
  and malignant dysrhythmias.
• Superior vena caval obstruction causes early
  morning headache, facial congestion and oedema
  involving the upper limbs the jugular veins are
  distended, as are the veins on the chest that
  form a collateral circulation with veins arising
  from the abdomen.

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• Metastatic complications
• Bony metastases are common, giving rise to
  severe pain and pathological fractures.
• There is frequent involvement of the liver.
• Secondary deposits in the brain present as a
  change in personality, epilepsy or as a focal
  neurological lesion.
• Spinal cord compression is not uncommon and
  requires urgent treatment .
• Secondary deposits in the adrenal gland are a
  very frequent post-mortem finding but are often
  asymptomatic.
• .

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• Non-metastatic extrapulmonary manifestations
• Although approximately 10 of small-cell tumours
  produce ectopic hormones at some stage, clinical
  extrapulmonary manifestations are relatively rare
  apart from finger clubbing.
• Hypertrophic pulmonary osteoarthropathy (HPOA)
• occurs in approximately 3 of all bronchial
  carcinomas, particularly squamous-cell carcinomas
  and adenocarcinomas.
• Symptoms include joint stiffness and severe pain
  in the wrists and ankles, sometimes associated
  with gynaecomastia.
• X-rays show a characteristic proliferative
  periostitis at the distal ends of long bones,
  which have an onion-skin appearance.
• HPOA is invariably associated with clubbing of
  the fingers.
• It may regress after resection of the lung
  tumour.

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• Investigations
• Chest X-ray
• Asymptomatic tumours may be seen on chest X-ray
  if they are more than 1 cm in diameter.
• Lateral views are useful to assess the hilum and
  masses behind the heart.
• Although investigation of isolated haemoptysis
  with chest X-ray is often negative, a normal
  chest X-ray should not stop further
  investigation, especially in smokers over the age
  of 40y .
• About 70 of all primary lung cancers present
  with a mass, including all small-cell lung
  cancers and most squamous cell carcinomas.
• Adenocarcinoma occurs more often in the periphery
  than the other cell types.

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• Carcinomas causing partial obstruction of a
  bronchus interrupt the mucociliary escalator, and
  bacteria are retained within the affected lobe.
  This gives rise to the so-called secondary
  pneumonia that is commonly seen on the chest
  X-ray.
• Bronchial carcinoma can also appear as round
  shadows on a chest X-ray , characteristically the
  edge of the tumour has a fluffy or spiked
  appearance, though sometimes it may be entirely
  smooth with cavitation.
• The hilar lymph nodes on the side of the tumour
  are frequently involved.
• Bronchial carcinoma is also a common cause of
  large pleural effusions.

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• Carcinoma can spread through the lymphatic
  channels of the lung to give rise to lymphangitis
  carcinomatosa in bronchial carcinoma this is
  usually unilateral and associated with striking
  dyspnoea. The chest X-ray shows streaky shadowing
  throughout the lung.

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• Computed tomography CT
• It is useful for identifying disease in the
  mediastinum, such as enlarged lymph nodes or
  local spread of the tumour, and for identifying
  secondary spread of carcinoma to the opposite
  lung by detecting masses too small to be seen on
  the chest X-ray.
• CT scanning should include the liver, adrenal
  glands and the brain since these are common sites
  for metastases.

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• Fibreoptic bronchoscopy
• This technique is used to define the bronchial
  anatomy and to obtain biopsy and cytological
  specimens.
• If the carcinoma involves the first 2 cm of
  either main bronchus, the tumour is inoperable as
  there would be insufficient resection margins for
  pneumonectomy.
• Widening and loss of the sharp angle of the
  carina indicates the presence of enlarged
  mediastinal lymph nodes, either malignant or
  reactive. These can be biopsied by passage of a
  needle through the bronchial wall.
• Vocal cord paresis indicates involvement of the
  recurrent laryngeal nerve and inoperability.

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• Percutaneous aspiration and biopsy
• Peripheral lung lesions cannot be seen by
  fibreoptic bronchoscopy and samples may be
  obtained by direct aspiration or biopsy through
  the chest wall under appropriate X-ray or CT
  screening.
• Fine-needle aspiration samples can be obtained
  from 75 of peripheral lesions that could not be
  biopsied transbronchially. Although useful if
  positive, negative FNA is not very helpful.
• Biopsies obtained with Trucut needles are usually
  diagnostic.

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• Other investigations
• Full blood count for the detection of anaemia.
• biochemistry for liver involvement.
• hypercalcaemia and hyponatraemia.
• Bone scane for detection of bony metastases.

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Treatment

• Treatment of lung cancer involves several
  different modalities and is best planned by a
  multidisciplinary team.
• Treatment decisions need to reflect the poor
  overall survival rates only 20 of patients are
  alive 1 year after diagnosis and only 6-8 after
  5 years . Patients are staged according to the
  TNM classification for non-small-cell cancer but
  small-cell cancer is treated according to whether
  it is limited or extensive .

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• Surgical treatment
• Preoperative assessment includes exclusion of
  metastatic disease by blood tests and imaging.
• Lung function tests, including walking oximetry,
  are used to predict postoperative potential.
• 1- Curative
• All operable and resectable cases .
• 2-Palliative
• a) Infectionhaemoptysis
• b)Osteoarthropathy
• c)Pain
• d)Debulking of the tumour size

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• Non surgical lines of therapy could be used in
  Non-small-cell carcinoma
• Radiotherapy.
• Radiotherapychemotherapy
• Laser therapy, endobronchial irradiation and
  tracheobronchial stents

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Secondary tumours

• Metastases in the lung are very common and
  usually present as round shadows (1.5-3.0 cm
  diameter). They may be detected on chest X-ray in
  patients already diagnosed as having carcinoma.
• Typical sites for the primary tumour include the
  kidney, prostate, breast, bone, gastrointestinal
  tract, cervix and ovary.
• Metastases nearly always develop in the
  parenchyma and are often relatively asymptomatic
  even when the chest X-ray shows extensive
  pulmonary metastases.
• Rarely metastases may develop in the bronchi,
  when they may present with haemoptysis.

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• Carcinoma, particularly of the stomach, pancreas
  and breast, can involve mediastinal glands and
  spread along the lymphatics of both lungs
  (lymphangitis carcinomatosa), leading to
  progressive and severe breathlessness. On the
  chest X-ray, bilateral lymphadenopathy is seen
  together with streaky basal shadowing fanning out
  over both lung fields.
• Occasionally a pulmonary metastasis may be
  detected as a solitary round shadow on chest
  X-ray in an asymptomatic patient(e.g. renal cell
  carcinom).

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• The differential diagnosis of solitary round
  shadow on chest X-ray includes
• primary bronchial carcinoma
• tuberculoma
• benign tumour of the lung
• hydatid cyst.

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• SCREENING FOR LUNG CANCER
• Screening programme (yearly chest X-ray,
  4-monthly sputum cytology) have been tried in
  high-risk groups but the success rate is minimal,
  underlining the need for prevention.
• CT screening is currently being evaluated.

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