Family doctor

What is lung cancer?

Lung cancer is a very common condition and is highly related to cigarette smoking (it can also occur in non-smokers or passive smokers).

Lung cancer refers to a malignant growth in the lung itself. A malignant growth can begin in the lung (primary tumour) or it can represent spread to the lung from a cancer somewhere else in the body (secondary tumour). It is important to understand the difference between primary and secondary tumours as the treatment for each can differ significantly. Secondary tumours will not be discussed in this article.

Primary Lung Cancer is divided into two main types:

1. Small cell lung cancer

2. Non-small cell lung cancer e.g. large cell cancer, squamous cell cancer and adenocarcinoma of the lung are common varieties.

It is important for the doctor/specialist to find out which type of tumour is present as it will help decide what other treatment is appropriate.

Note: There are other many more rare tumours of the lung and the contents of this article do not apply to these.

How is cancer discovered?

These tumours can be discovered in a number of ways. Some are picked up as a result of a routine chest x-ray and many patients have no symptoms at all. Some patients have a persistent cough or cough blood as the first sign of the tumour. Pneumonia can occur behind a tumour that is blocking an airway. Chest pain is unusual unless the tumour has spread into the tissues outside the lung. Sometimes it is the secondary deposits of lung cancer in various parts of the body that bring the tumour to notice (e.g. spread to the brain or bone).

What investigations will be necessary?

A medical history, physical examination, chest x-ray and blood tests are the most common initial investigations.

If a tumour is seen or suspected then a CT scan is performed to assess the entire lungs and upper abdomen in much more detail than can be achieved with a routine chest x-ray. This is a painless test where the patient lies on a table while the x-ray machine scans the target areas.

If the tumour looks like it is in the major windpipes of the lung a bronchoscopy may be advised. This is where under sedation a fine tube (bronchoscope) is passed down into the windpipes and the tumour sampled (i.e. a biopsy). This tissue is looked at under the microscope to check for cancer cells.

If the tumour cannot be reached by a bronchoscope then often the patient will be sent for a fine needle aspiration test. This is when a needle is passed through the chest wall into the tumour and cells sampled. This will often give the diagnosis.

With these investigations complete the doctor/specialist is often in a position to decide the next most appropriate step.

Surgery

Surgery is the only known reliable way of achieving a cure for lung cancer. Only about 15-25% of all patients that are diagnosed with lung cancer will be able to undergo surgery. The two main reasons why surgery is not appropriate for the majority are:

1. The lung cancer is of a type not responsive to surgery (if the tumour is a small cell lung cancer then surgery is of no benefit), or

2. The tumour is too far advanced for surgery to have a beneficial effect (this is often demonstrated by CT scanning or mediastinoscopy (see below).

If a patient has a non-small cell lung cancer (see above) then surgery would be advised as long as the tumour is confined to the lung and has not spread to the lymph nodes around the main windpipe or beyond this into the rest of the body.

If the lymph nodes around the main windpipe look enlarged on the CT scan a minor surgical procedure is often advised. This operation is called a mediastinoscopy. It is performed under general anaesthetic where a telescope is passed into the chest through a very small 1-2 cm incision at the lower part of the front of the neck just above the breastbone. If the lymph glands are free of tumour when looked at under the microscope then it is likely that further surgery would be recommended to remove the lung cancer.

Who is fit to have surgery?

As a general rule if a patient has no major heart problems and can walk up two flights of stairs without difficulty then they will tolerate having the tumour removed. Breathing tests are usually performed by the specialist to confirm fitness for surgery.

The surgery is performed through a cut around the side of the chest (thoracotomy) and the lung is reached by going in between the ribs. It is very unusual these days to remove any ribs as part of the surgery unless they are involved with the tumour. The part of the lung containing the tumour is then removed and sent to the laboratory for further analysis. This usually involves taking half of the lung (lobectomy) but occasionally the whole lung (pneumonectomy). Taking less than half the lung (wedge excision) does not appear to be an adequate cancer operation in the majority of circumstances. We normally leave tubes in the chest leading down to bottles beside the bed and these drain any fluid or air from the chest and helps keep the lung fully expanded. When all drainage from the chest stops the tubes are removed. It is common to go home within the first week of surgery (usually 3-7 days). At this stage patients are walking freely around the ward, showering and dressing themselves and are usually able to manage stairs.

Overall the recovery period is 4-8 weeks. Many can return to work after 3-4 weeks, although if their work is physically heavy then 6-8 weeks off is usually required.

How many are cured by surgery?

Around 50% of patients are cured (alive at 5 years) by surgery. If cancer comes back after surgery it is usually incurable. This is most likely to occur within the first 1-2 years and is increasingly unlikely as time passes.

Although a 50% cure rate with surgery may not sound good it is important to remember that without surgery the chances of being alive 5 years after diagnosis are reduced to around 5%.

Future trends

With the increasing unacceptability of cigarette smoking in the community hopefully fewer people will take up the habit and more will give it up. This should reduce the number of people presenting with lung cancer. There is some early evidence that CT scanning rather than chest x-rays may be an effective way of picking up early cancers in smokers at a stage when they are still able to be removed surgically. If further research demonstrates that CT scanning is a useful screening tool then patients who are smokers may be advised to undergo this investigation as a routine.