It’s not uncommon to find a nodule in the lung during a medical examination. Lung nodules are small lesions (three centimeters or less in diameter) inside the lungs that are usually benign, such as granulomas or hyperplasia caused by infections.

However, they can also be caused by malignant diseases, such as lung cancer or metastatic cancer.

So, what are the chances of a small lung nodule being a malignant tumor, including lung cancer or metastatic cancer?

"The likelihood of malignancy ranges from 2 percent to 23 percent, and the risk increases dramatically if you are a smoker," said Professor Lee Seung-hun of the Department of Family Medicine at Pusan National University Hospital on the YouTube channel with the same name as the hospital.

If a lung nodule is found, a chest CT scan is performed first to check the shape and size of the nodule and determine the risk of malignancy. "If the risk of malignancy is high, it can be confirmed by bronchoscopy, percutaneous fine needle aspiration, or video thoracoscopic biopsy, depending on the location of the lesion," Professor Lee explained.

The rate of lung nodules that are biopsied because of the high risk of malignancy is lower than expected, and because of their small size, diagnosis and treatment are done simultaneously, according to Lee.

"Statistically, the percentage of nodules that require biopsy is reported to be around 2 to 4 percent, and if there is a strong suspicion of malignancy, video thoracoscopy is used for diagnosis and surgical treatment simultaneously," he said.

Periodic checkups are essential for those with lung nodules.

"The management of lung nodules leads to early detection of lung cancer. Depending on the degree of malignancy, follow-up examinations are performed every three to 12 months, and the degree of malignancy is reevaluated at each examination based on the size of the nodule and changes in shape. Whether there are new nodules," Professor Lee said.

If a lung nodule is more likely to be malignant during follow-up, a biopsy is performed, and a medical approach is taken, so there is no need to be overly concerned about lung nodules.

"Not all lung nodules that are detected lead to lung cancer, so it's important not to worry too much, see a specialist and develop a treatment plan," Lee said.

Another reason lung nodule follow-up is important is the nature of lung cancer.

"Lung cancer is the most common cancer along with stomach cancer, except for thyroid cancer, but the survival rate is the lowest along with pancreatic and biliary cancers," Professor Lee said.

If lung cancer has not metastasized, the survival rate is high at about 75 percent. However, if it has metastasized to the surrounding area, the survival rate drops sharply to 11 percent. Therefore, early diagnosis is even more important, Lee added, emphasizing the importance of lung nodule follow-up screening.