LUNG CANCER

Classification of lung cancer

There are two types of lung cancer: Non-small cell lung cancer and small cell lung cancer. Non-small cell lung cancer is more common and it tends to grow and spread slowly.   On the other hand, small cell lung carcinoma is less common, and it tends to grow more quickly and spread to other organs.

 

Risk Factors for Lung Cancer

1.       Cigarette smoke

2.       Environmental tobacco smoke (Second hand smoke)

3.  Other causes include exposure to asbestos, scarred lung from previous tuberculosis infection and past history of previous lung cancer. 

 

Symptoms

Lung cancer may be picked up in an asymptomatic patient who has undergone routine health screening with a chest X ray. Otherwise, the most common presenting symptoms include:

  • Chronic cough                          
  • Blood in sputum            
  • Chest pain
  • Shortness of breath                   
  • Hoarse voice                
  • Loss of weight and/or appetite. 

 

However, the presence of these symptoms does not confirm lung cancer, as other causes eg. Chest infections, may have the same symptoms too.

 

Diagnosis of Lung Cancer

If a patient is suspected of having lung cancer, a lung specialist or a thoracic surgeon will evaluate him. Apart from the history and physical examination, chest X rays and CT scans are performed. Often, a biopsy is done to confirm the cancer, and the procedure performed is either of the following:

1.       Bronchoscopy: A small, lighted flexible tube is inserted into the nose down the windpipe to obtain some tissue for examination. The 20-minute procedure is done under mild sedation and does not require admission.

2.       Needle aspiration: A fine needle is passed through the chest under local anesthesia into the tumour to remove a tissue sample.   It may require an overnight admission after the procedure.

 

Staging

Once a diagnosis has been made, the extent of tumour is determined by the staging process. This includes CT scans of the chest, abdomen, brain and an isotope bone scan. Sometimes a bone marrow biopsy in case of small-cell lung cancer is also done. The most recent advance in imaging is PET scanning using radiolabelled glucose to detect small populations of cancer cells.

 

Non-small cell lung cancer is staged according to the extent and size of the primary tumour, the site of lymph node involvement, and sites of distant spread (metastases). Stages 1 and 2 are considered early stage, whereas stages 3 and 4 are advanced stages.

 

The staging of small cell lung cancer is similar:
Limited Stage
Cancer is found in one lung, the tissues between the lungs, and nearby lymph nodes only.

Extensive Stage
Cancer has spread outside of the lung where it began or to other parts of the body.

 

Treatment of Lung Cancer

The treatment of lung cancer depends on the type of lung cancer, size, location, extent of the tumour and the general health of the patient. 

SURGERY

Surgery is the best option of cure for non small cell lung cancer if the tumour can be removed and the operation performed safely.  After considering the tumour stage, surgical candidacy depends on the severity of comorbidities, most of which are tobacco-related lung, heart, and peripheral vascular diseases. Such factors could be as simple as 6-minute walk ability to more complex spirometric and functional lung capacity assessments. If the patientís lung function is poor, he may not survive removal of any lung tissue. Three types of surgery can be performed: Wedge resection , lobectomy or pneumonectomy, depending on how much lung tissue needs to be removed.

After surgery, most patients should undergo further treatment with chemotherapy, radiotherapy or both. This is called adjuvant therapy, and its main aim is to prevent further relapses of the cancer. It is now standard therapy.

CHEMOTHERAPY

Chemotherapy drugs are injected into a vein and work against cancer cells that have migrated to other parts of the body. This modality is either used with radiation, before surgery or in cases where surgical treatment is not feasible. Chemotherapy has been proven to improve survival rates of all stages of patients, be it early stage 1 and 2 disease when it is called adjuvant therapy, to more advanced stages such as stage 3A NSCLC when used preoperatively (major response rates of 50% to 75%). Chemotherapy, combined with radiation for unresectable stage 3 disease, has also improved survival rates. Major response rates which result in palliation of symptoms and prolongation of survival are also reported in cases of stage 4 disease.

 

New drugs used in the treatment of lung cancer include Taxol, Taxotere, Gemcitabine, Navelbine, Campto, and Carboplatin. These new drugs have the benefit of improved response rates and survival at the same time being manageable in side effects. Many patients return to work during chemotherapy.

 

In patients with small cell lung cancer, chemotherapy is successful in achieving response in patients with limited disease, and 5-year survival rates as high as 10% to 15%. Further increases in the 5-year survival rate will depend on improved chemotherapeutic treatment of non-surgical disease. Research in the 1990s has presented a number of new chemotherapeutic agents with promising activity against this recalcitrant disease

TARGETED THERAPIES

There are now a new group of drugs which have the unique properties of being able to target the cancer cell proteins specifically. These have the advantage of minimal toxicity and significant effect. Examples of these drugs are Iressa, Tarceva and Avastin.

RADIATION THERAPY

 

Radiation therapy is the third treatment option to destroy the cancer cells. It is effective, but is only a localized therapy. It is therefore generally used in treating lung cancer limited to the lung only for patients too frail for an operation or situations where the cancer is beyond surgical treatment.

 

It can often be combined with chemotherapy either with or without surgery to improve local control. It is also used in situations where the cancer has spread to certain organs eg. Brain, bone, where chemotherapy has less of an effect.

 

Important: Public awareness

           

In conclusion, lung cancer is still a serious problem. Lung cancer can largely be prevented if cigarette smoking can be reduced or stopped altogether. This hinges on public awareness of the dangers of smoking, and the government contribution in tobacco advertising, public awareness campaigns, warning labels on cigarette packets etc has helped. However, it is also the duty of each member of the public to educate family and friends who are still smoking to quit the habit for the sake of themselves and their families, especially in view of the data on second hand smoke.