[Click! Health] 'Lung Cancer,' the Leading Cause of Cancer Deaths... Early Detection Is the Key to Effective Treatment

The leading cause of cancer death in South Korea is lung cancer. Although the survival rate for lung cancer was only 10% in the early 2000s, advances in treatment have recently improved it to 30-40%. However, compared to stomach and colorectal cancers, where over 70% of patients survive for five years, lung cancer still has a poor prognosis.

[Photo by Seoul National University Hospital]

In particular, lung cancer survival rates vary depending on the stage, making early detection critically important. Professor Park Saemina of the Department of Cardiovascular and Thoracic Surgery at Seoul National University Hospital said, "The appropriate treatment plan for lung cancer varies depending on the stage, type, and the patient's condition," adding, "Various medical professionals collaborate for optimal diagnosis and treatment, and patients who have concerns or questions about lung cancer are encouraged to consult their attending medical staff to obtain accurate information."

Lung cancer is classified into small cell lung cancer, characterized by small-sized cells under the microscope, and non-small cell lung cancer, which has larger cells. About 8 out of 10 lung cancer patients are diagnosed with non-small cell lung cancer. Non-small cell lung cancer grows slowly and can be completely cured by surgery if detected early. The problem is that early diagnosis is difficult, and even if initial treatment is successful in advanced cases, more than half of patients experience recurrence. Recurrence typically appears around two years after surgery. Small cell lung cancer is more aggressive and has a much shorter survival period than non-small cell lung cancer. Chemotherapy is the primary treatment rather than surgery.

The biggest risk factor for lung cancer is smoking. Direct smoking increases the risk of lung cancer by up to 13 times, and long-term exposure to secondhand smoke can increase the risk by about 1.5 times. Occupational exposure to carcinogens and underlying lung diseases are also considered risk factors for lung cancer. However, despite a decrease in smokers recently, the number of lung cancer patients is increasing. This is interpreted as an increase in non-smoking lung cancer patients or patients detected early due to the introduction of low-dose chest computed tomography (CT) scans.

Low-dose chest CT scans have been used in the government's lung cancer screening pilot project since 2017. The target group is smokers aged 55 or older with a smoking history of 20 years or more. According to the Korean Association for Lung Cancer, the early detection rate through screening reaches 68.4%. The greatest advantage of low-dose chest CT is its ability to detect small nodules measuring 3 to 5 mm that are difficult to find with chest X-rays, and to examine areas obscured by the heart, blood vessels, or bones.

Low-dose chest CT scan [Photo by Seoul National University Hospital]

Lung cancer initially shows almost no symptoms, and symptoms such as cough, hemoptysis, chest pain, and shortness of breath occur only after the cancer has progressed to some extent. However, cough and hemoptysis can occur regardless of the progression stage. When metastasized to the bones, it can cause persistent pain. Weight loss may also occur. Since these symptoms can accompany not only lung cancer but other malignant tumors as well, screening is recommended.

Treatment methods for lung cancer can be divided into local treatments targeting the tumor directly, such as surgery and radiation therapy, and systemic treatments using drugs, including chemotherapy, targeted therapy, and immunotherapy. Surgery involves removing the lung cancer lesion and the surrounding metastasized areas. If detected early, the cure rate is very high. However, not all patients with early-stage cancer undergo surgery. Surgery is selectively performed after evaluating the patient's various conditions in advance. Recently, surgical techniques have advanced to minimize the resection area, preserving more lung tissue, and reducing incision size, enabling faster recovery for patients.

Lung cancer stages are classified from stage 1 to 4, and treatment strategies vary completely depending on the stage. Surgery is recommended for stages 1 through early stage 3. Surgery is especially effective for stage 1 lung cancer. For stage 2 and 3 lung cancers, chemotherapy and immunotherapy are mainly used to reduce tumor size before surgery. Stage 4 lung cancer, which accounts for the majority of lung cancer patients, is primarily treated with chemotherapy. Radiation therapy is sometimes combined.