Lung Cancer Screening Tests – when does one need it?

February 21 07:26 2023 Print This Article

Overview

Lung Cancer Screening is a minimally-invasive procedure to detect the presence of lung cancer in people whose general health is good, but who are at high risk of lung cancer. The risk comes from being a long-time smoker, or other reasons, and is only done for adults who are currently not showing any signs of lung cancer. The technique used for screening is called LDCT and once cancer is suspected after the screening, more tests are carried out to confirm the condition, and treatment meted out thereafter.

Introduction

It is no secret that tobacco smoking in the form of cigarette, beedi, cheroot, cigarillo, cigar, hookah and smoking-pipe increases the risk of lung cancer. Longer the history of smoking, the higher the risk of lung cancer. However, lung cancer doesn’t show prominent symptoms in the initial stages, other than occasional cough. So, it’s important to get screening done, based on certain parameters described below.

In the past, chest X-ray and sputum cytology were the methods used for lung-cancer screening. Sputum cytology involves collecting the sputum from coughing and analysing the same under a microscope to detect the presence of cancer cells. However, these methods were not effective in detecting all cases of lung cancer. This means, they did not reduce the risk of people dying from undetected lung cancer.

In recent years, a more effective method called Low Dose Computed Tomography (LDCT) scan has emerged as a more effective technique to detect lung cancer and minimize the risk of death. As the name implies, this is similar to a regular CT scan, but uses a lower dose of radiation compared to a regular CT scan, but a higher dose compared to a chest X-ray.

When does one need LDCT?

• Older adults who smoked/smoke now: The screening is only done in the age-group of 50 to 80 years where the person smoked in the past or smokes till date. Once the person has crossed 80 years, such a screening is not recommended.
• A history of smoking equal to 20 pack-years or more: Smoking is measured by a factor called pack-years which is a product of number of packs smoked in a day and number of years. So, a history of 20 pack-years means, the person has smoked 1 pack a day for 20 years, or 2 packs a day for 10 years or half a pack a day for 40 years. All such people will require lung cancer screening.
• People who used to smoke heavily but quit: Quitting after a long history of smoking does not reduce the risk of lung cancer immediately. The risk reduces only if the gap is fairly long. So, quitters will also need this screening.
• People whose general health is good: LDCT and follow-up tests involve exposure to radiation and even a lung biopsy. And once cancer is confirmed, surgery may be required as treatment. Because of these reasons, people who have poor lung function, who need a continuous supply of oxygen for breathing, who coughed up blood recently, who had a chest CT scan in the last year (for some other condition), who experienced weight-loss in the past year for no reason, or who has any serious condition that rules out surgery for them – none of these people are prescribed this form of screening.
• People with a history of lung cancer: If one has had lung cancer in the past, there is always the risk of a relapse. So, the screening is done for such people too, no matter how long back they were treated.
• People with other risk factors for lung cancer: As explained below

Other risks for Lung Cancer

Smoking is not the only risk factor for lung cancer and there are other factors too. All the below people will require LDCT.

• Secondary smoke: Being a partner or family member of a long-time smoker exposes the person to significant risk of lung cancer, so such people must also get screened, irrespective of whether they smoked or not.
• People with lung conditions: Patients suffering from Chronic Obstructive Pulmonary Disease (COPD) are at a high risk of lung cancer, irrespective of whether they or their partner is/was a long-time smoker. And if they were smokers, the risk increases multi-fold.
• Exposure to toxic chemicals: People who are constantly exposed to asbestos, radon and other toxic industrial chemicals are at a high risk of lung cancer.
• Other exposures: People who work in quarries, mines, do wood-work (exposure to saw-dust) constantly, are at a high risk of silicosis and lung-cancer. Even automobile mechanics and traffic police who are constantly exposed to vehicle smoke are at high risk. People living in highly polluted cities are also at risk. And if such people have smoked or do smoke, the risk increases multi-fold.
• A family history of lung cancer: If one or more family member related by blood has or had lung cancer, the risk increases. This is because there could be a genetic mutation in the family that makes the person develop lung cancer irrespective of whether they or their partner smoke/smoked.

Benefits of Lung Cancer Screening

• LDCT can detect even nodules that are very small, which makes it a very effective technique for early detection of lung cancer. Early detection means quick treatment and hence minimized risk of death. Treatment methods include minimally-invasive techniques to remove the cancerous tissue. This reduces collateral damage to lung tissue as in surgery.
• Safe and effective: LDCT produces high-quality or high-resolution cross-section images of the chest region including the lungs. This is good enough to show any abnormality in the lung. At the same time, it uses 90-percent lesser ionizing radiation than regular CT scans.
• Speed: CT scan is a procedure, in which patients must hold their breath. However, LDCT is quick, which comes as a relief to people who have trouble holding their breath.
• Hassle-free: LDCT is non-invasive, painless and does not use contrast dye, so there is no risk of nausea.
• No residual radiation: Since LDCT uses a lower-dose of radiation, there is no radiation remaining in the patient’s body after scanning.

Risks

• False positives: Sometimes the screening may show a possibility of lung cancer. To confirm the findings, the doctors will have to undertake additional CT scans and even lung biopsy. This can lead to unnecessary hassle, cost and anxiety for the patient.
• False negatives: Sometimes the screening may not show up lung-cancer although it is present. Such patients will not seek medical care till the symptoms of lung cancer start showing up.
• Overdiagnosis: Such screening exams may detect certain cancers which later on turn out to be harmless or not requiring treatment. But in the process, the patient goes through unnecessary hassle and cost, while also increasing the risk of complications.
• Inadequate: Although LDCT is supposed to detect lung cancers in their early stage, this doesn’t happen always. The cancer is already at an advanced stage sometimes, and may have even metastasized (spread) to nearby organs and tissues.
• Radiation risks: Although the screening uses low dose of radiation, once cancer is suspected, more scans are required. These increase the risk of radiation. So, even a healthy person may develop cancer, sometimes.

When is the screening stopped?

Lung Cancer Screening using LDCT is an annual affair. It must and should be done every year. However, the screening is stopped when the person:

• Turns 81 years of age
• Has not smoked in the last 15 years, or more. Such a gap is good enough to reduce the risk of lung cancer that requires screening. Lung cancer may still develop but that will be treated effectively.
• Develops any health problem that rules out surgery once lung cancer is detected.

How is the procedure done?

The procedure is like that of any regular CT scan. The person must inform the doctor about current medication being taken. The doctors will advise stopping the medication for a few days before the screening. On the day of the screening, the person must leave all metal items such as jewellery, dentures, glasses, etc., at home. It is preferable not to eat or drink anything for 2 hours before the scan.

At the hospital or diagnostic clinic, the person will change into a gown. He/she must lie on the back, on a table. The table is then wheeled into the CT-scan chamber, with head first. When the technician mentions it, the person must hold his/her breath for as long as possible. Once the technician has captured adequate number of images, the person is wheeled out of the scanning chamber.

The person then changes back into his/her clothes and is discharged immediately. Since there is no pain, no incision, no nausea, there is no medication or extra care to be taken. Once the results arrive, the doctors will call the patient for a discussion.

Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

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