GRACE :: Radiation Oncology


Repeating Chest Radiation Therapy: Feasible or Foolhardy?

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Very often when cancer patients consult with me regarding radiation therapy, they inquire, “Is it true that after a full course of radiation therapy that a second course cannot be repeated?” My answer is similar to that for many questions about radiation: “It depends.”

The key concern regarding repeat radiation therapy is that it could potentially do more harm than good. Various structures and organs in the body have differing tolerances to radiation therapy – if these are exceeded there is a possibility that significant damage could be done.

However, radiation therapy, even in the setting of recurrent cancer can at times be effective in controlling disease or in helping to reduce a symptom, such as pain or bleeding. In three general scenarios, repeating radiation therapy is considered:

1) Prior radiation therapy was well below normal tissue tolerance. This scenario is possible among patients that initially undergo stereotactic body radiation therapy (SBRT) for an initial early stage lung cancer (e.g., T1N0 or T2N0), but then have a recurrence or cancer progression in the chest. SBRT delivers a highly focused, high radiation dose to the tumor only and may largely spare the critical organs of the chest, including the majority of the lungs, the esophagus, the spine, and the heart. This scenario is also possible among patients treated with traditional external beam irradiation to a lower dose – perhaps the initial course of therapy was delivered to a specific area to try to alleviate a specific symptom.

2) Re-irradiation will employ techniques which limit additional radiation exposure to vital organs to a level not expected to cause vital organ injury. Radiation planning and delivery have become increasing sophisticated, such that it may be feasible to target recurrent or progressive lung cancer guided by 3-dimensional imaging, while avoiding the delivery of significantly high dose radiation to nearby critical anatomic structures. Modern imaging also is able to better characterize the extent of recurrent cancer after an initial course of radiation therapy – which helps determine if repeat treatment is likely to be of benefit.

3) The benefits outweigh the risks. Unfortunately, lung cancer is a difficult diagnosis. Recurrent lung cancer is even more difficult. In general, patients with recurrent lung cancer may expect to live in measures of months, or sometimes weeks. Typically, with sufficiently high doses the most dreaded radiation related vital organ toxicities such as spinal cord damage take over a year after re-irradiation to develop. For patients with symptoms from recurrent or progressive lung cancer that do not have effective alternative therapies, the short term benefits may often outweigh the long terms risks. In my experience, I have seen repeat radiation therapy dramatically help a patient that was repeated coughing up large amounts of blood – the treatment stopped the bleeding and despite the long term risks, in the short term, dramatically improved quality of life.

A recent article written by Drs. Branislav Jeremic and Gregory Videtic in the International Journal of Radiation Oncology, Biology, and Physics (generally referred to as the “red journal”, because who would want to say the full name?) reviews studies published over the last three decades in the medical literature with regard to chest re-irradiation for lung cancer. Their article summarizes the reported responses to treatment across multiple studies.

On average, 50% to 80% of patient undergoing repeat chest irradiation had decreased symptoms of cough, coughing blood, chest pain or shortness of breath. Side effects experienced by patients were in largest part related to the esophagus or to the lungs. Although rates of side effects varied widely across studies, irritation of the esophagus occurred in approximately 20% of patients undergoing re-irradiation to the chest, and irritation of lungs in about 8% of patients. By and large, these side effects tended to be mild to moderate. Severe side effects were less common, although at least one study reports a 5% rate of spinal cord damage, and it appears that at least one of the approximately 250 patients may have died related to radiation re-treatment.

The study also identifies a number of factors that may predict for longer patient survival after repeat chest radiotherapy. These factors are radiation dose, time interval to recurrence and re-irradiation, and the patients overall health status and level of activity (overall health status and level of activity are often referred to as performance status). While some of the data are conflicting, in general, patients with better performance status, longer time interval to recurrence and re-irradiation, and those treated to higher repeat radiation dose tended to live longer. These factors are highly inter-related.

Overall, in some circumstances of lung cancer recurrence or progression, repeat chest irradiation may be the best available treatment option. I hope this commentary highlights some of the key factors are involved in assessing potential risks and benefits.

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