What is a safe lung function test for patients undergoing radical radiotherapy?

From the Guidelines

Pulmonary function tests (PFTs), particularly spirometry, are safe and recommended for patients undergoing radical radiotherapy. These tests are essential for evaluating lung function and can help clinicians adjust treatment plans to minimize pulmonary complications. According to the European Respiratory Society (ERS) guidelines, pulmonary function testing includes spirometry and diffusion capacity of the lung for carbon monoxide, split function studies, and exercise tests 1.

Key Parameters

• Spirometry measures key parameters like forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), providing essential information about lung function without interfering with radiation treatment.
• Diffusion capacity testing (DLCO) can also be safely performed to assess gas exchange efficiency.

Test Administration

These non-invasive tests require patients to breathe into a mouthpiece connected to a spirometer, typically taking only 15-30 minutes to complete.

Test Timing

The tests should ideally be conducted before starting radiotherapy to establish baseline lung function and may be repeated during or after treatment to monitor for radiation-induced lung toxicity.

Patient Considerations

PFTs are particularly important for patients with pre-existing lung disease or those receiving thoracic radiotherapy, as they help clinicians adjust treatment plans to minimize pulmonary complications. The tests pose minimal risk to patients, with no radiation exposure or interference with the therapeutic radiation dose to the tumor.

Additional Considerations

While the evidence from 1 provides guidance on preoperative risk assessment for patients undergoing surgery, the principles of evaluating lung function and minimizing pulmonary complications can also be applied to patients undergoing radical radiotherapy. However, it is crucial to prioritize the most recent and highest quality study, which in this case is 1, to ensure that the recommended tests are safe and effective for patients undergoing radical radiotherapy.

From the Research

Safe Lung Function Tests for Radical Radiotherapy

• The safety of lung function tests for patients undergoing radical radiotherapy can be assessed through various studies, including those that evaluate the effects of irradiation on lung function and perfusion 2.
• One study found that lung irradiation results in some loss of lung function in patients with lung cancer, with a decrease in diffusion capacity (DLCO) of 14% at 6 months and 12% at 12 months 2.
• Another study found that the reduction of lung function within 7.5 months after 3D conformal radiotherapy was small, with only 15% of patients showing a pulmonary function reduction of more than 20% 3.
• Stereotactic body radiotherapy (SBRT) has also been found to be well-tolerated, with minimal changes in pulmonary function tests (PFTs) after treatment 4.
• A study on whole breast radiotherapy found that lung function and radiological changes were minimal, with no significant reduction in FEV1, FVC, FEV25, FEV50, and DLCO at 3 and 6 months after completion of radiotherapy 5.
• The use of SPECT lung perfusion scans has been found to be useful in minimizing and assessing the physiologic consequences of thoracic irradiation, providing a unique quantitative 3-dimensional map of the distribution of functioning pulmonary vascular/alveolar subunits 6.

Key Findings

• Lung function tests such as DLCO, FEV1, and FVC can be used to assess the safety of radical radiotherapy for patients with lung cancer.
• The use of 3D conformal radiotherapy and SBRT can help minimize the loss of lung function.
• SPECT lung perfusion scans can be used to assess regional lung function and detect changes in lung function secondary to radiotherapy.
• Patients with poor pulmonary function pre-treatment may benefit from the use of pre-treatment SPECT scans to design radiation portals that minimize irradiation of functioning lung.

Lung Function Tests

• DLCO: a measure of the lung's ability to transfer gas from the air we breathe into the bloodstream.
• FEV1: a measure of the amount of air that can be exhaled in one second.
• FVC: a measure of the total amount of air that can be exhaled from the lungs.
• SPECT lung perfusion scans: a type of imaging test that provides a 3-dimensional map of the distribution of functioning pulmonary vascular/alveolar subunits.