Every physician has a few patients during their practice who stand out; Mr Stevens (not his real name) was one of them for me.

He was a 6’ 4” Texan with a very distinct Southern accent. He was a retired financial officer, a very knowledgeable and articulate person.

At age 66, he loved travelling and reading, and was always ready to share his interesting experiences and was a pleasure to listen to.

One day, after he had just returned from vacation, Stevens came unscheduled to my clinic with complaints of sharp chest pains.

My initial assessment was that it might be a pulled muscle; however, due to his history of travelling and heavy smoking, I sent him for a computed tomography scan (CT scan) of his chest to make sure he did not have a blood clot.

A couple of hours later, I received a call from the radiologist regarding the results. It was not a blood clot; he had a 2cm mass, suspected to be lung cancer. It was quite unexpected and the poor patient was in complete shock.

After confirmation of lung cancer through a lung biopsy, it took us couple more scans to make sure that his cancer had not spread anywhere else in the body.

He was immediately referred to a thoracic surgeon, who did an excellent job removing the cancer. After surgery not only Steven's lung cancer was gone, but he finally got the message that he had to quit smoking.

Stevens was lucky to be diagnosed and treated in time, unlike many others in the US as well as in Pakistan. In the US, where smoking prevalence is less than Pakistan (16% vs 24%), more people die of lung cancer than any other cancer each year.

Exact numbers of lung cancer patients are not available in Pakistan due to lack of centralised tumor registry.

What often fools patients and physicians is that lung cancer starts and spreads unnoticed. By the time signs or symptoms appear, it has usually spread out to other parts of the body, making it incurable.

Treatment at a later stage is costly and usually carries poor outcomes. People who have seen their relatives or loved ones suffering from this cancer know the misery that patients go through during the last few months of their lives.

Early diagnosis of cancers can be achieved by screening people who are at high risk for developing cancers. The aim of a screening test is to catch a disease at an early stage, before it has any opportunity to spread. Usually, catching the disease early on makes it amenable to curative treatment.

However, all screening tests have pros and cons. An ideal screening test should be cost-effective, least harmful, and provide maximum benefit.

Mammography is an excellent example of a good screening test, which has significantly decreased the disease burden of breast cancer in western societies.

Historically, lung cancer lacked any effective screening test, making it one of the deadliest cancers. Chest X-ray and sputum tests were tried in the past, but failed to meet criteria for a good screening test.

CT scans were always known to diagnose lung cancer at an early stage, but due to concerns of high radiation exposure, the scan was not recommended for screening purposes.

Keeping this concern in mind, medical scientists designed a clinical study utilising CT scans with minimal possible dose of radiation.

In a landmark study, researchers studied low-dose CT scan (LDCT) for screening for lung cancer. After an extensive evaluation of benefits and harms, LDCT was found to be an effective screening test for lung cancer as it minimised the harms of radiation exposure.

Currently, this test is recommended by major physician organisations in the world such as United States Preventive Services Task Force, European Respiratory Society, European Society of Radiology, and the European Society of Medical Oncology.

Lung cancer starts as a small nodule that grows in size over period of months. At an early stage, cancer can be treated with surgery, which usually results in complete cure from this otherwise fatal disease.

However, if left untreated or undiagnosed, the cancer grows bigger and spreads to other parts of the body. At this stage, a complete cure is not possible and treatment is focused on containing the cancer with help of chemotherapy and radiation therapy.

An LDCT of the chest in a high-risk population can catch cancer at an early stage, hence decreasing lung cancer-related mortality by 20 percent.

LDCT screening should be done only for people who are at high risk of developing lung cancer. So if you have been a heavy smoker and are between 55 to 75 years of age, you should discuss lung cancer screening with your doctor.

However if you have quit smoking for more than 15 years, your cancer risk decreases significantly, hence this test may not be recommended for you.

Lung cancer screening programmes have been successfully adopted in many countries, including the United States, for last few years. During my recent visit to Pakistan, however, I found that the awareness about this valuable screening test was lacking among the general public and health care providers.

It should be noted that this scan is done with a regular CT scan machine and does not require any new equipment. Only the amount of radiation exposure is changed to an astounding 90% less than regular CT scan.

Major hospitals with cancer prevention programmes such as Shaukat Khanum Hospital are already using this modality for cancer screening, but a broader implementation, especially in public sector, is needed to get maximum benefit from this test.

There is no doubt that smoking cessation remains the cornerstone for preventing lung cancer and its importance should never be undermined.

But LDCT, along with smoking cessation, can significantly decrease the burden of this disease in our society.

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