Cancer of the lung is not the easiest to diagnose in its early stages, primarily due to generic symptoms that could be mistaken for any other respiratory disease.
Another hindrance in timely diagnosis is the patient himself/herself, who blames his/her own lifestyle for the ‘side effects’, and avoids timely diagnosis. However, it’s not all bad news for lung cancer patients – early diagnosis can result in an effective treatment with cancer-free years ahead.
When Is Lung Cancer Suspected?
The initial diagnostic tool is a physical exam that may lead a doctor to suspect the disease. The following signs may point towards cancer in the lungs:
- Abnormal lung sounds
- Swollen lymph nodes over the collarbone
- Weakened breathing; face swelling
- Arm weakness
- Enlarged veins in chest, neck and arms
- Drooping eyelids, differently sized pupils
Based on the results from the physical examination, the doctor will ask the patient to undergo the following tests:
- Chest X-ray – Chest x-ray can show an abnormal shadow or mass or nodule(s) in the lungs, which may or may not be lung cancer. Any abnormal mass or nodule should further be evaluated by the doctor.
- CT scan or MRI Chest –These tests provide more detailed information than an x-ray as they can reveal the precise location & size of the tumour along with local extension/lymph node spread.
- Sputum Cytology – Persistent cough brings up sputum, which can be looked at under the microscope as they may contain cancerous lung cells.
- Bronchoscopy – A bronchoscope, which is a thin, flexible tube with a tiny, lighted camera at its tip, is inserted through the mouth down the windpipe and into the lung airways (bronchi). The patient is given a local anaesthetic that numbs the mouth and throat to relieve discomfort while the bronchoscope examines the lower airways and collects sample of suspected tumour growth.
- Needle Biopsy – Needle biopsy is useful in cases when the tumour sits on the lung periphery or pleura (thin lining outside lungs) or lymph node (which are positive on CT/PET CT), where a bronchoscope cannot reach. A fine needle is inserted through the chest wall to directly reach the tumour and collect tissue sample for analysis. A CT scan or endoscopic ultrasound may be used to direct the needle, called as CT guided lung tissue biopsy or EUS guided lung biopsy, respectively. Tissue collect via biopsy is studied for pathology evaluation, IHC marker studies, receptor studies & mutation studies, such as – EGFR mutation, ALK mutation, KRAS mutation.
- Thoracoscopy – This procedure is conducted under general anaesthesia. Two to three small incisions are made to allow a tube to pass into the chest, using which the doctor looks for cancerous growths and takes samples. Overnight hospital stay may be needed to drain out any remaining fluids from the lungs.
- Mediastinoscopy – This procedure allows a careful examination of the mediastinum or the centre of the chest. The doctor makes a small incision at the bottom of the patient’s neck to pass a thin tube into the chest. Fitted with a camera, this tube allows the doctor to look inside the chest and draw samples of suspicious growths in the lung and lymph nodes. This test is conducted under general anaesthesia and the patient may require hospital stay for couple of days.
- Thoracentesis – Also called as thoracocentesis or pleural tap is an invasive procedure of removing fluid from space in between the two layers of pleura (lining covering lungs).
- PET CT/PET Scan – Also called as Positron Emission Tomography is an imaging technique that is used to assess the primary site of cancer & cancer spread to lymph nodes, bones, and other organs.
- Bone Scan – Bone scan is done to assess spread of cancer in bones.
- Brain MRI – Brain MRI may be required to assess the spread of cancer in the brain.
An important step in the diagnostic process is determining the stage of cancer, i.e. the extent of spread. Knowing which stage the cancer is at is useful in deciding the right treatment. Various tests that help determine the cancer stage are MRI, CT scans, positron emission tomography (PET) and scanning of bone. Based on these tests, cancer in the lung is divided into the following stages:
- Stage I – Limited to lungs; smaller than two inches.
- Stage II – Grown more than two inches or is smaller but spread to chest wall, diaphragm or lung lining, or lymph nodes.
- Stage III – Large tumour and spread to nearby organs, or small tumour but spread far from lungs.
- Stage IV – Cancer spread to other lung too &/or distant organs &/or bones.
It is important for patients to take worsening lung symptoms seriously and consult the doctor at the earliest for timely lung cancer treatment.
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“Diagnosing Lung Cancer,” Lung.org, American Lung Association, https://www.lung.org/lung-disease/lung-cancer/learning-more-about-lung-cancer/diagnosing-lung-cancer/
“Lung cancer – Diagnosis,” NHS.uk, https://www.nhs.uk/Conditions/Cancer-of-the-lung/Pages/Diagnosis.aspx
“Lung cancer tests,” CancerResearchUK.org, https://www.cancerresearchuk.org/about-cancer/type/lung-cancer/diagnosis/lung-cancer-tests
“Lung cancer – Tests and diagnosis,” MayoClinic.org, Mayo Clinic Staff, https://www.mayoclinic.org/diseases-conditions/lung-cancer/basics/tests-diagnosis/con-20025531