A Journey of Recovery Post-Remission – Radiation Treatment Induced Coronary Artery Disease

by Astrid Kühn

With breast cancer accounting for 23.11% of all cancers reported in women in South Africa in 2017, there is no doubt as to how important breast cancer research is in our society. One may be tempted to think that remission marks the hoped-for end of a battle with breast cancer, but with aggressive treatments, such as radiation therapy (RT), can breast cancer survivors expect long-term pathology associated with treatment? What factors may predispose an individual to developing treatment-related pathologies?

Correa et al. addresses these questions by analyzing the prevalence of radiation-associated coronary damage in women who had received RT, following breast-conservation surgery, by laterality of treatment (I.e., left or right-side treated). The study found that at a median time of 12 years, post-RT, 56% participants who had undergone left-sided RT were found to have a disproportionately higher risk of presenting with cardiac abnormalities following stress-testing, compared to only 8% of right-sided RT participants.

In addition to stress-testing, some left-side RT participants underwent cardiac catherization. Of the resulting data, 92% of these participants were found to present with coronary stenoses (narrowing) of which 82% occurred in the left anterior descending artery. Below is a summarization of where these stenoses were located in the aforementioned participants:

Fig 1. (A) Lateral and (B) medial views of left-side irradiated patient’s catheterization findings. Counts in locations of coronary stenoses: proximal left circumflex (LCx), n _ 1; distal LCx, n _ 1; proximal left anterior descending (LAD), n _ 2; mid LAD, n _ 6; distal LAD, n _ 4; proximal right coronary artery (RCA), n _ 1; mid RCA, n _ 2; distal RCA, n _ 0.

Insights such as these, are essential in preventing and treating long-term RT induced cardiac stress in radiation-treated patients.

The authors cite improved RT planning as a potential tool against excessive, erroneous radiation of the heart during RT. Suggested methods include computerized tomography (CT) scans for “visualization of cardiac structures and potential avoidance of cardiac irradiation via field border modification, modulation of dose around critical structures, placement of heart blocks, breathing techniques, and intensity-modulated RT.” Together with long-term, post-RT monitoring of breast cancer patients for signs of cardiac distress, as well as the protective precautions mentioned, patients are more likely to avoid this potential legacy of RT treatment.

References:

  1. Correa CR, Litt HI, Hwang WT, Ferrari VA, Solin LJ, Harris EE 2007, ‘Coronary artery findings after left-sided compared with right-sided radiation treatment for early-stage breast cancer’, Journal of clinical oncology, vol. 25, no. 21, pp. 3031-3037.
  2. National Cancer Registry of South Africa, 2021. 2017 National Cancer Registry. National Cancer Registry of South Africa, p.1. Available at: https://cansa.org.za/files/2021/01/Cancer-Registry-2017-NCR-2017-Final-02dec2020.pdf.

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