Is the sudden increase in lung nodules a precursor to lung cancer? How to diagnose and treat it?

Since this winter, due to the high incidence of respiratory infections, many people have found lung nodules during lung examinations in hospitals. And with the widespread development of low-dose spiral CT screening technology, more and more asymptomatic lung nodules have been found, of which more than 97% are benign lesions, and the detection rate of lung cancer is only 0.7% to 2.3%.

However, many people are afraid of "nodules" and are afraid that they may develop into lung cancer. Some even mistakenly equate lung nodules with lung cancer. Most people become anxious and even panic after accidentally discovering lung nodules. Under great psychological pressure, they usually choose to have repeated CT scans or choose treatment. In fact, repeated CT scans in the short term are of no benefit. A study also showed that the mis-resection rate of lung nodules in China is nearly 20%. The high detection rate leads to overdiagnosis, overtreatment and increased anxiety in the examinees.

1. Have the number of lung nodules suddenly increased?

Many people feel that there are suddenly more people around them being diagnosed with lung nodules, but this is not the case.

First of all, as the public pays more and more attention to lung health, more people have taken the initiative to undergo lung CT examinations in recent years than before, and thus lung nodules have been discovered "incidentally" during the examination process.

Secondly, the widespread application of new detection technologies, especially the widespread development of artificial intelligence lung nodule auxiliary diagnosis system technology and low-dose spiral CT screening technology, has been introduced to the medical imaging departments of hospitals at all levels, which has not only improved the diagnostic efficiency of doctors, but also simultaneously increased the detection rate of lung nodules. Some views on the trend of younger lung nodules are actually because more and more young people are participating in physical examinations and early cancer screening.

In short, the above factors superimposed in the same period have caused many people to have the illusion that "lung nodules suddenly increased" and "lung nodules became younger."

2. Is the appearance of lung nodules related to “excessive yang”?

Some patients reported that after they were infected with the new coronavirus, they were always out of breath during activities and felt that their endurance had decreased. When they went to the hospital for a check-up, they found nodules on their lungs. So, are lung nodules really related to "excessive positive"? Experts say that any infection may form nodules, and the new coronavirus infection is no exception. Indeed, a very small number of patients will form nodules due to inflammation that cannot be completely absorbed. However, these nodules are basically benign nodules and there is almost no possibility of malignant transformation. Even if they are found, there is no need to panic. Just follow the doctor's advice and have regular check-ups. In addition, some people originally had lung nodules, but only discovered them after a CT scan after being infected with the new coronavirus.

In fact, shortness of breath during activities, poor endurance or the appearance of nodules are related to airway hyperresponsiveness and inflammatory changes in the lungs after infection with the new coronavirus. Some patients with more serious conditions will have imaging manifestations such as ground-glass shadows and flaky shadows in the lungs. The latter can be absorbed by themselves during the recovery process, but the degree of absorption varies from person to person. Some patients, especially those with combined underlying lung diseases and poor lung function, may not be completely absorbed and remain in the lungs to form local fibrotic scars, and appear on CT images in the form of lung nodules. However, for most mild patients with "positive over-exposure", the infection with the new coronavirus will not leave any marks in the lungs after recovery, nor will it affect lung function, let alone cause lung nodules.

3. Classification and follow-up of nodules

1. Single solid pulmonary nodule

(1) Diameter < 6 mm

Low-risk group: No follow-up is required.

High-risk groups: No follow-up is required. However, if the morphology is suspicious or located in the upper lobe, a reexamination can be conducted once every 12 months. **High-risk groups:**Age ≥ 45 years; smoking (smoking ≥ 20 pack-years); history of secondhand smoke or environmental fume inhalation; history of occupational carcinogen exposure (long-term exposure to radon, arsenic, beryllium, chromium, cadmium and its compounds, asbestos, silica and coal smoke); personal tumor history (previous exposure to other malignant tumors); family history of lung cancer in direct relatives (individuals with first-degree relatives diagnosed with lung cancer); history of chronic lung disease (chronic obstructive pulmonary disease, tuberculosis and pulmonary fibrosis, chronic inflammation of bronchial and lung tissue).

(2) Diameter 6-8 mm

Low-risk group: Repeat CT scan every 6 to 12 months. The specific time interval depends on the size, morphology, and patient preference of the nodule. In most cases, one follow-up is sufficient. For patients with suspicious morphology and uncertain stability, a second CT scan can be performed at 18 to 24 months.

High-risk groups: The first CT scan should be performed at 6 to 12 months; the second CT scan should be performed at 18 to 24 months. Most patients only need two follow-ups, but the total follow-up time can be appropriately extended for those with uncertain stability.

(3) Solid nodules with a diameter of more than 8 mm

Repeat CT every 3 months. Perform PET-CT, tissue biopsy, or both, depending on the size, morphology, concomitant diseases, and other factors of the nodule.

2. Multiple solid nodules

(1) Maximum nodule diameter <6 mm

Low-risk population: No routine CT follow-up is required.

High-risk group: A CT scan can be considered every 12 months. Prerequisite: No known or suspected primary tumor lesions (no possibility of metastasis).

(2) At least one nodule has a diameter ≥ 6 mm

The first CT scan is performed at 3 to 6 months (mandatory); the second CT scan is performed at 18 to 24 months depending on the results (optional).

3. Single pure ground glass nodule

(1) Nodule diameter <6 mm

Routine CT follow-up is not required. However, if there is a suspicious morphology or other risk factors, reexamination should be performed at 2 and 4 years.

(2) Nodule diameter ≥ 6 mm

Repeat CT scans at 6 to 12 months, and then every 2 years, with a follow-up of 5 years.

4. Single partially solid nodule

(1) Nodule diameter <6 mm

Routine CT follow-up is not required (similar to pure ground glass nodules).

(2) Nodule diameter ≥ 6 mm but solid component < 6 mm

CT scans were performed every 3 to 6 months and then once a year for a total of 5 years.

(3) Solid component ≥ 6 mm

Repeat CT scans at 3 to 6 months to evaluate whether the nodules persist. For nodules with suspicious morphology, increased solid components, or solid components >8 mm, PET-CT is recommended for further examination to clarify the nature or surgical resection.

5. Multiple partially solid nodules

(1) Maximum nodule diameter <6 mm

First, infectious lesions should be considered, and then CT scans should be repeated every 3 to 6 months. If the disease persists, CT scans should be repeated every 2 and 4 years thereafter.

(2) At least one nodule has a diameter ≥ 6 mm

The decision is made based on the most suspicious nodule. If the nodule still exists after CT scan 3 to 6 months, multiple primary adenocarcinomas should be considered. Recommendations for the management of pulmonary nodules found by low-dose CT screening: baseline screening (see Figure 1) and annual screening (see Figure 2)

Note: LDCT is low-dose spiral CT; HRCT is high-resolution CT; NS is non-solid nodule; S is solid nodule; PS is partially solid nodule; negative result means no non-calcified nodules are detected in the lungs

Figure 1 Management process for nodules detected in baseline lung cancer screening

Note: LDCT is low-dose spiral CT; HRCT is high-resolution CT; negative result means no non-calcified nodules are detected in the lungs

Figure 2 Management process of nodules found in annual lung cancer screening

With the widespread use of high-resolution, low-dose CT, especially the increase in the number of people participating in lung cancer screening programs or health examinations, the number of lung nodules detected is increasing. Therefore, the diagnosis and treatment of lung nodules should adopt a multidisciplinary consultation work model and joint decision-making between doctors and patients, which should not only reduce the rate of overdiagnosis and treatment but also make up for the problem of insufficient diagnosis and treatment, reduce the psychological burden of patients, and increase the rate of early diagnosis and treatment of lung cancer.

References

[1] Chinese Medical Association Oncology Branch, Chinese Medical Association Journal. Chinese Medical Association Guidelines for Clinical Diagnosis and Treatment of Lung Cancer (2023 Edition) [J]. Chinese Journal of Oncology, 2023, 45(7): 539-574.

[2] Chinese Medical Education Association Lung Cancer Medical Education Committee "Chinese Expert Consensus on Multidisciplinary Minimally Invasive Diagnosis and Treatment of Pulmonary Nodules". Chinese Expert Consensus on Multidisciplinary Minimally Invasive Diagnosis and Treatment of Pulmonary Nodules. Chinese Journal of Clinical Thoracic and Cardiovascular Surgery, 2023, 30(8): 1061-1074.