Outcome After Stereotactic Radiotherapy in 'High-Risk' Patients With Stage I Non-small Cell Lung Cancer (NSCLC)
Stage I non-small cell lung cancer is optimally treated with surgery, but some patients may not be candidates for surgery due to other medical health issues. Stereotactic radiotherapy (SRT) is a very precise form of radiation therapy that is being used to treat inoperable, early stage lung cancers. There has been concern that this therapy may lead to unacceptable toxicity for patients with tumors that are classified as T2, or for T1 or T2 tumors that are close to the heart or spinal cord. This analysis looked at the side effects experienced by such patients.
247 patients who were treated with SRT were analyzed. Radiation doses depended upon the location and size of the tumors, which were classified as low or high risk based on these factors. No patients received chemotherapy in this study. Patients experienced mild side effects, including fatigue, nausea, pain and pneumonitis (inflammation of the lungs).
The average overall survival was 34 months for high-risk patients and 36 months for low-risk patients. Disease-free survival rates at one year were 59% for high-risk patients and 76% for low-risk.
Local failure rates (tumor recurred in the original tumor location) were 12% for high-risk patients and 3% for low-risk, and rates of distant metastases (tumor recurred in another part of the body) were 32% for high-risk patients and 19% for low-risk.
The rates of acute toxicity were acceptable, as the researchers noted; however, one of the concerns with use of SRT for larger or centrally located tumors is late toxicity. Use of SRT is known to result in increased late damage to normal tissues, much of which may not be seen for 10 – 20 years after completion of treatment. The limited follow-up of 20 months in this study does not allow for assessment of potential late effects from the high radiation doses given to normal tissue or vital organs such as the heart, esophagus, and spinal cord. Only time will allow full assessment of these effects; however, when SRT is used, particular attention should be paid to the amount of organ tissue receiving radiation. Having said that, because this is a selected patient population with significant underlying health issues (which is why they did not receive surgery in the first place), the patients may not live long enough to demonstrate late toxicity.
Partially funded by an unrestricted educational grant from Bristol-Myers Squibb.