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| Stephen Hahn, MD |
Dr. Hahn recently answered a series of questions related to lung cancer and radiation therapy for TalkAboutHealth.com.
Why is spot radiation so frowned upon in advanced non-small cell lung cancer?
This is a good question and I am assuming by ‘spot radiation’ you mean very focused radiation to a tumor (what radiation oncologists refer to as stereotactic body radiotherapy or SBRT). SBRT is a highly effective and safe treatment for early stage non-small cell lung cancer (NSCLC) when the cancer is small and surrounded by normal lung.In patients with advanced NSCLC, the tumors are typically larger and more centrally located toward the middle of the chest. When cancers get bigger and are located near the middle of the chest, we are limited in the dose that we can deliver because of the risk of serious side effects.
Therefore, often in patients with advanced NSCLC, SBRT could be unsafe. Of course, every patient is different and therefore, every patient should be evaluated by a qualified radiation oncologist who has experience in using SBRT.
What factors determine if radiation treatment is recommended instead of surgery for stage 1 and 2 lung cancer?
The biggest determining factor is whether surgery is safe for a patient.The safety of surgery is determined by a thoracic surgeon often in collaboration with the patient’s primary care doctor. More and more patients are electing to receive radiation (typically stereotactic radiation) for early stage lung cancer rather than surgery.
Studies are being performed now to determine if radiation should be considered a routine treatment for early stage lung cancer.
How is radiation adjusted accordingly to cause maximum damage to cancer cells while keeping normal tissue within its tolerance?
There are a couple of ways that we maximize radiation dose to the tumor and minimize dose to the normal tissues.First, radiation oncologists have a lot of experience with understanding the doses that are required to control tumors and the doses that could cause side effects. Therefore, most treatment regimens are designed with these doses in mind.
Second, we use advanced imaging to help guide the treatments. At Penn Medicine, we have CT scans, MRI scans and PET CT to help determine exactly where the tumor is and exactly where the normal tissues are. Not only do we use these advanced forms of imaging to identify tumor and normal tissue, but we also use advanced imaging during the treatment to ensure that the radiation is delivered as precisely as possible.
Third, it is very important that experience physicians and staff use the best devices to keep the patient in the same position every day for treatment. These are typically casts that the patient is able to comfortably lie in on a daily basis.
Fourth, we select the correct type of radiation for the patient’s type of cancer and location. At Penn Medicine, we can choose among advanced conventional types of radiation such as SBRT and intensity modulated radiation therapy (IMRT) or proton therapy. Proton therapy is a type of radiation beam that can allow a physician to reduce the dose that is delivered to normal tissues compared to conventional radiation therapy. It is a highly precise form of radiation.
We are particularly enthusiastic about the use of proton therapy for lung cancer patients and are currently evaluating its use in this setting.
How do you measure if the radiation treatment is working for lung cancer?
Radiation therapy works over a period of time after the radiation is delivered. We obtain scans typically three and six months after a course of radiation to look for shrinkage and/or disappearance of the tumor.
The scans can be regular CT scans of the chest or a PET CT scan.
A PET CT scan often gives us more information about a patient’s response to treatment. It can be difficult to distinguish treatment-related changes in the lung which are benign and related to the effects of radiation on lung versus tumor.
Therefore, such studies should be carefully evaluated by experienced radiologists and radiation oncologists.
What potential issues should a lung cancer patient going through radiation treatment look for?
A patient should always let his doctor know when there are changes in symptoms that he or she is concerned about. When we treat the chest with radiation, a patient would want to watch out for fatigue, skin redness on the chest, and sore swallowing. Sore swallowing is more common when radiation is combined with chemotherapy.
After radiation, there are side effects that can occur.
Radiation pneumonia can occur one to three months after treatment is complete and can cause cough, fever, and shortness of breath. Other much less common late side effects include damage to the heart, thyroid gland, and spinal cord. Side effects from treatment are typically related to the site of treatment, the doses used and the amount of normal tissue in the radiation field.
An experienced radiation oncologist with the most advanced equipment will design the radiation fields to maximize the doses to the tumor and minimize the doses to the normal tissues such as the lung, heart and spinal cord.
How does radiation therapy help as a palliative treatment for advanced lung cancer?
Radiation therapy is a highly effective treatment for patients who need palliation.
Some examples include the treatment of pain if the cancer has spread to the bones, reducing any bleeding that occurs when patient’s cough, and treatment of symptoms related to cancer that has spread to the brain.
The course of such treatment typically occurs over one to three weeks and the side effects are mild.
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