Cardiac Problems after Radiation
Posted 3/2/2012
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I actually have debated about this entry as I do not want to contribute to anyone's anxiety or worries about possible long-term side effects from treatment. This is an editorial from the Journal of Clinical Oncology that discusses an article in the same issue. The topic is cardiac stenosis after radiation therapy, almost always to the left breast. (Note: I, too, have had radiation to the left breast, so read this with interest.) My eventual conclusion, after several careful readings of both articles, is that this is a relatively rare situation, and very dependent on the exact radiation field. I decided that it is something that, for some of us, is a piece of knowledge to tuck away. At the time of a breast cancer diagnosis, the entire focus must be on treating that disease with less worry about possible distant consequences. This goes along with earlier postings about survivorship issues, and we are fortunate to live long enough to think about them.
Here is the beginning and then a link. If you want to read the research article itself, it will be evident how to do so:
Breast Cancer Radiotherapy and Coronary Artery Stenosis: Location, Location, Location
Timothy M. Zagar and Lawrence B. Marks, University of North Carolina, Chapel Hill, NC
Radiation therapy (RT) plays an integral role in the treatment of breast cancer. Lumpectomy followed by whole breast RT provides equivalent outcomes to mastectomy. In a meta-analysis of nearly 42,000 women who were treated within clinical trials, the use of RT after mastectomy or lumpectomy improved local control, breast cancer-spe- cific survival, and overall survival. Unfortunately, the use of RT also has a dark side. In that same Oxford meta-analysis, the hazard ratio for death secondary to heart disease, presumably radiation related, was 1.27. Although the incidence of cardiac events was low in the first 5 years of follow-up, it increased over time and persisted after year 15.
In the article that accompanies this editorial, Nilsson et al. provide the oncology community with another useful and elegantly performed study that addresses radiation-associated heart disease. Previous studies from this group and others have suggested that RT for breast cancer can clearly increase the risk of cardiovascular disease, including pericarditis, coronary artery disease (CAD), conduction abnormalities, congestive heart failure, and valvular disease.3-6 In ad- dition, essentially all of the increased risk of clinically meaningful cardiac events is not manifest until more than 10 years after RT. Given this long latency, prospective studies with clinical end points have been difficult; therefore, much of the current data is derived from population-based studies and a few clinical trials with long follow-up. Additionally clouding the issue is that RT techniques have been im- proved during the last several decades and much of the cardiac toxicity data come from older series. RT is also associated with reductions in regional perfusion as assessed by single photon emission computed tomography (SPECT) scans, in a manner consistent with microvascular injury, relatively soon after RT (eg, 6 months to 5 years). These perfusion defects seem to largely persist with longer follow-up, but their clinical relevance is not yet known.
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