Cardiac events following radical radiotherapy for lung cancer
Fei Sun - Leeds Cancer Centre, Leeds, UK
I’ll be presenting the results of a multicentre study looking into the characteristics of cardiac events following radical radiotherapy for lung cancer. This is a very large study and we’re looking into the results of thousands of patients so it’s one of the largest studies conducted looking into this setting.
We’re looking into a number of cardiac events so ischemics or heart attacks, also arrhythmias, so problems with the conduction of the heart and the heart rate, and heart failures and also pericardial effusions where you have a ring of fluid that surrounds the heart which can also lead to problems.
What have you found?
The biggest thing that people have found in recent years is that in comparison to previous findings where cardiac events happen much longer after thoracic radiotherapy, perhaps decades earlier when people followed up patients who had radiotherapy for breast cancer or lymphoma where cardiac events happen ten or twenty years down the line, after lung cancer radiotherapy we’ve seen a much sooner onset of cardiac events after radiotherapy, so probably in the first year or two. This is very significant because a lot of them are ischemic events and they negatively impact on patients’ survival outcomes.
How can you determine that these events are specifically because of the radiotherapy?
That, again, is a very good question. Currently there is little understanding of the mechanism of cardiac damage induced by radiation. There have been some laboratory studies but there is no consensus on exactly how things happen. A lot of the observations we’ve made clinically is that obviously this is a very complex area with lots of confounding because a lot of these patients have a heavy smoking history, they have a high prevalence of cardiac disease at baseline and therefore any association becomes quite challenging. But we have found that significant patients who develop a cardiac event didn’t have a cardiac history previously so that in itself is very interesting. So whether the radiotherapy process accelerated aging in the heart, accelerated the arteriosclerosis process in the heart, that’s something that is well worth looking into.
What does this mean for administering radiotherapy now?
Again, that’s very interesting because there have been a lot of studies looking into this and again there is no clear consensus on how low the radiotherapy needs to be to the heart before we see a protective effect. We are starting to look into this and we are trying to get more data and we’re trying to use our computer software to see which areas of the heart are more sensitive to radiation damage. Rather than talking about radiation to the whole of the heart, we’re trying to identify vulnerable areas where we can perhaps shield in the future because you’d want to treat lung cancer adequately as well. So there’s always a compromise if you try to lower the dose to one particular area.
Is there anything else important to mention?
This will be an important upcoming area because we’re now looking to use more radiotherapy and we’re treating a greater number of patients. It’s not just radiotherapy for more advanced disease, we’re using more stereotactic radiotherapy for early stage lung cancer and oligometastatic disease as well. So this topic will be more relevant in the future and also we’re seeing improved survival with the addition of immunotherapy. So the more we know about this the more we can do to further improve the outcomes of patients.