A 50-year-old woman walked into my clinic seeking a second opinion. For several weeks, she had been treated for asthma because of an occasional cough and episodes of breathlessness. She had faithfully used her inhalers, yet her symptoms showed no sign of improvement. Instead of simply changing her medication, we decided to start from the beginning. A routine chest X-ray revealed something completely unexpected—massive fluid accumulation around the lung. Further investigations confirmed the real diagnosis: lung cancer that had spread to the pleura, the membrane surrounding the lungs.The diagnosis came as a shock to the patient and her family. They had never imagined that symptoms resembling asthma could actually be masking lung cancer. This case reinforces an important lesson in medicine — not every persistent cough or episode of breathlessness is asthma, bronchitis or an infection. When symptoms continue despite appropriate treatment, they deserve a fresh evaluation rather than repeated prescriptions.Fluid accumulation around the lung or pleural effusion itself may be the first sign of an underlying lung cancer. Patients often present with progressive breathlessness, chest heaviness or a persistent dry cough, symptoms that can easily be mistaken for more common respiratory illnesses. We are also witnessing a significant shift in the profile of lung cancer patients. It is no longer a disease seen only in older male smokers. In our own practice, we diagnose nearly two to three new cases of primary lung cancer every three months, and almost 40% of these patients are either women or people who have never smoked.Lung cancer doesn’t always present with typical symptomsWhen most people think of lung cancer, they associate it with a persistent cough, coughing up blood, chest pain or breathlessness. These remain the most common warning signs. However, lung cancer does not always follow a textbook presentation.Breathlessness itself can occur for several reasons. It may result from airway obstruction caused by the tumour, fluid around the lungs, collapse of a portion of the lung, or reduced lung function. In some patients, breathlessness develops even before a persistent cough appears.In many cases, the first symptoms appear in completely different parts of the body and are often mistaken for stress, ageing, nutritional deficiencies, infections or common health conditions. Sometimes these symptoms occur because the tumour affects nearby nerves, blood vessels or surrounding structures. In other cases, they develop after the cancer has spread to other organs.Story continues below this adAdding to the challenge, early-stage lung cancer often causes very few noticeable symptoms. As a result, many patients ignore subtle warning signs until the disease has progressed.Unusual symptoms that shouldn’t be ignoredA prolonged change in your voice may not immediately suggest a lung problem. However, a tumour in the chest can affect the recurrent laryngeal nerve, which controls the vocal cords, leading to persistent hoarseness. Although allergies, acid reflux and throat infections are far more common causes, any voice change lasting more than a few weeks should be medically evaluated.Difficulty or discomfort while swallowing, medically known as dysphagia, can occur when a tumour in the chest presses against the oesophagus. Patients may initially notice difficulty swallowing solid foods before liquids become affected.Unexplained swelling around the face, neck or upper chest can occur when a lung tumour compresses the superior vena cava, the large vein responsible for returning blood from the upper body to the heart. This condition, known as Superior Vena Cava (SVC) syndrome, requires prompt medical attention.Story continues below this adA painless swelling or lump above the collarbone or in the neck may occasionally be the first visible sign of lung cancer that has spread to nearby lymph nodes. While enlarged lymph nodes can occur with infections and other illnesses, persistent or unexplained swelling should always be medically assessed.Lung cancer can sometimes present as a deep, persistent ache in the back, shoulders or bones. This may happen due to cancer spreading to the spine and compressing the spinal cord or surrounding nerves, leading to persistent neck or back pain, numbness, stiffness or weakness that may radiate to the arms or legs. Sudden weakness in the limbs requires immediate medical evaluation. In some advanced cases, cancer cells spread to the protective membranes surrounding the brain and spinal cord. This can cause back pain along with headaches, limb weakness and other neurological symptoms.When lung cancer spreads to the bones, it can raise calcium levels in the blood. Along with bone or back pain, patients may experience excessive thirst, nausea, vomiting, constipation, weakness or headaches.Neurological symptomsSometimes, lung cancer is diagnosed only after it has spread to the brain. Persistent headaches, dizziness, seizures, blurred vision, difficulty maintaining balance, confusion or weakness affecting one side of the body may be warning signs that require urgent medical evaluation. Although these symptoms can have many causes, they should never be ignored, particularly when accompanied by respiratory symptoms or unexplained weight loss.Story continues below this adFinger clubbingOne of the lesser-known signs of lung cancer is finger clubbing. The fingertips gradually become broader while the nails appear more rounded and curved. Although clubbing can occur in several lung and heart diseases, any new or unexplained changes in the fingers should be evaluated by a doctor.Recurrent chest infectionsRepeated episodes of bronchitis or pneumonia, especially affecting the same area of the lung, may signal an underlying blockage. A tumour can partially obstruct an airway, making it difficult to clear mucus and increasing the risk of recurring infections. Rather than repeatedly treating infections with antibiotics, it is important to identify the underlying cause.Unusual hormonal or neurological changesIn some patients, lung cancer causes symptoms that are not directly related to the tumour itself. Known as paraneoplastic syndromes, these occur when the cancer produces hormone-like substances or triggers an abnormal immune response. Patients may experience unexplained muscle weakness, low sodium levels, electrolyte imbalances or neurological symptoms before the lung tumour is even detected.Who is at risk?While smoking remains the single biggest risk factor for lung cancer, it is important to understand that the disease can affect people who have never smoked.Story continues below this adExposure to second-hand smoke, indoor biomass fuel smoke, cooking fumes, radon gas, asbestos fibres, diesel exhaust, air pollution, volatile organic compounds (VOCs) and other aerosolised chemicals may also increase the risk. In addition, a family history of lung cancer or previous radiation therapy to the chest can make some individuals more susceptible.When should you see a specialist?If you have a persistent cough lasting more than three weeks, unexplained breathlessness, coughing up blood, recurrent chest infections, or any of the unusual symptoms described above that do not improve with routine treatment, it is important to consult a pulmonologist or specialist for a thorough evaluation.The earlier lung cancer is diagnosed, the greater the chances of successful treatment and better long-term outcomes.(The author is Director, Pulmonology & Critical Care Medicine, Sakra World Hospital, Bengaluru)