Case of the Month

Cough in a 72 year old man

Diagnosis:   Lung Cancer

Investigation

The left image is the initial Chest X-ray which shows a mass (arrowed) situated centrally in the left lung, causing apparent enlargement of the left lung hilum

The middle image is from the subsequent CT scan.  It confirms the mass, which involves the apical segment of the left lower lobe. The obstructed bronchus can be seen (arrowed), running into the abnormal lung segment.

The right image is from the same CT scan, with the image settings adjusted to display the mediastinum.  There are some lymph nodes present (arrowed) but these are not clearly enlarged. 

 

Discussion

The challenge posed by this patient is to determine the best form of treatment.  If the central lymph nodes are involved with cancer, then curative surgery will not be an option.  Palliative radiotherapy and/or chemotherapy will be the likely choices.

If the lymph nodes are not involved, then the patient would be a candidate for surgery, with the aim of a permanent cure.

So the question is how to determine if the nodes are involved or not.  Previously, nodes were sometimes sampled by a preliminary operation called mediastinoscopy.  In other situations, it was commonly assumed that lymph nodes were normal unless they were very enlarged.  The patient would undergo surgery, only to find that in reality the cancer had spread and could not be removed.

The current standard of care is for these patients to undergo PET-CT scanning, where the metabolic activity of the nodes can be measured. Involvement by cancer can often be determined even in normal sized nodes.  This spares the patient from having unnecessary surgery.

 

Lung Cancer

Lung cancer is a disease of uncontrolled cell growth in tissues of the lung. This growth may lead to metastasis, which is the invasion of adjacent tissue and infiltration beyond the lungs. The vast majority of primary lung cancers are carcinomas of the lung, derived from epithelial cells. 85% of lung cancers are due to cigarette smoking.

Over 1500 men and women are diagnosed with lung cancer each year in New Zealand. Lung cancer is the most common cause of death from cancer in New Zealand men, and the second most common for women, although it is increasing in women as more of them are smoking. The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss.

Lung cancer may be seen on chest radiograph and computed tomography (CT scan). The diagnosis is confirmed with a biopsy. This is usually performed by bronchoscopy or CT-guided biopsy. Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Possible treatments include surgery, chemotherapy, and radiotherapy. Depending on the stage and treatment, the five-year survival rate is 14%.

 

PET-CT

This is an imaging technique where we are able to image areas of high metabolic activity.  It involves an injection of a sugar compound that has been labeled with radioisotope.  The active cells take up this compound, and can be seen using a very sensitive camera.  The images of high activity are superimposed on CT images that are taken at the same time, resulting is a composite view that has been called "CT with Traffic Lights".

PET is mainly used to diagnose cancer and also to monitor whether treatment is working or not.  However, there is enormous research taking place in its use in other conditions.