Guidelines for treating early stage non-small-cell lung cancer with stereotactic body radiotherapy

The authors reviewed data from recent clinical trials to update guidelines on treating early stage inoperable non-small-cell lung cancer (NSCLC). This article provided a summarized account of the updates included in the American Society for Radiation Oncology guidelines for treating NSCLC.

For patients with early stage NSCLC, surgery is usually the first treatment option. However, some patients are not eligible for surgery and therefore other treatments are required. Stereotactic body radiotherapy (SBRT) is a cancer treatment which involves high dose radiation targeted to specific tumors. It has been shown to result in high survival rates in patients who are ineligible for surgery. The American Society of Clinical Oncology (ASCO) has provided updates to existing guidelines that recommend how to treat patients with SBRT. The guidelines make it clear when to treat patients with SBRT and the types of patients who will benefit from this method of treatment.

This review summarizes updates of the guidelines based on recent clinical trials and studies. The recommendations outlined below focus on patients with early stage non-small-cell lung cancer (NSCLC) that are ineligible for surgery.

For patients with stage 1 NSCLC who are eligible for surgery, SBRT is not recommended.

For patients who are ineligible for surgery, SBRT should be considered as an alternative treatment. The location of the tumor in the lung will affect whether a patient should receive SBRT treatment or not. SBRT should be used for peripherally located tumors. Physicians should be more cautious when treating centrally located tumors with SBRT as there is the potential for high toxicity (negative effects). In the case of centrally located tumors that are too high risk for SBRT, alternative radiotherapy involving more spread out treatments of lower doses should be considered. Similarly, physicians should be cautious when treating tumors close to the esophagus and heart with SBRT. Treatment should be altered to deliver more fractions of lower doses of radiation to reduce toxicity. Physicians should be aware that SBRT used to treat tumors invading the chest wall may result in chest wall toxicity that presents as rib pain due to fracture.

Currently, tumors greater than 4 cm in diameter are treated with chemotherapy. There is some weak evidence to suggest that SBRT may be beneficial for tumors greater than 5 cm in diameter however it may be necessary to optimize the treatment to reduce toxicity.

Ideally, a biopsy should be obtained prior to SBRT. SBRT can be given to a patient if they are unable to provide a biopsy if the treating physicians recommend.

Some patients can have more than one initial tumor the same time, which is called multiple primary lung cancer (MPLC). This needs thorough diagnosis to differentiate it from cancer that has spread from the one area. There is low level evidence to support SBRT as a treatment for MPLC as it does not have the same survival rates as SBRT for single tumors.

Metachronous primary lung cancer occurs when a second primary cancer develops after the first. SBRT is recommended for this and has comparable effectiveness as SBRT for single tumors.

Some patients have recurring cancer after treatment with conventional radiation. While treating physicians may decide to use SBRT to treat this cancer, patients should be advised on potential severe toxicities. Treating these patients with SBRT is a highly individualized process and patients should be assessed by a multidisciplinary cancer care team.

The authors concluded that SBRT could be beneficial to patients with early stage NSCLC who are ineligible for surgery. 

Several of the recommendations were based off of weak evidence and therefore more research is needed to validate these.