Heart Changes Noted After Radiation Therapy for Left-sided Breast Cancer

Cancer Connect

A study that followed women for three to six years after radiation therapy for left-sided breast cancer reported that more than half the women had abnormalities in blood flow to the heart. Changes in heart wall motion or ejection fraction were less common. These results were published in the journal Cancer.

Radiation therapy plays an important role in the treatment of many women with breast cancer. Nevertheless, radiation therapy for left-sided breast cancer may expose areas of the heart to radiation.

To explore the effects of radiation therapy on the heart, researchers conducted a study among 160 women who received radiation therapy for left-sided breast cancer. The study evaluated three measures of heart function: 1) cardiac perfusion (blood flow to the heart); 2) motion of the heart wall; and 3) ejection fraction (the fraction of blood that is pumped out of a ventricle with each beat of the heart).

An initial report from this study indicated that during the first two years after radiation therapy, 50% to 60% of women experienced an abnormality in blood flow to the heart. The current report provides longer follow-up. It includes information about 44 of the women from the original study who have now been followed for between three and six years.

  • The frequency of perfusion defects during the three to six years after radiation therapy was 80% among women who had experienced earlier perfusion defects (consistently noted defects during the first two years after radiation therapy) and 63% among women who had not experienced earlier perfusion defects. This suggests that perfusion defects can persist over time, but can also develop later in women with initially normal results.
  • Abnormalities in heart wall motion were less common. These abnormalities were noted in 17% of the women with perfusion defects and 7% of the women without perfusion defects.
  • A drop in ejection fraction of at least 5% was noted in 27% of the women with perfusion defects and 36% of women without perfusion defects.

Although this analysis suggests that perfusion defects are common in women who have received radiation therapy for left-sided breast cancer, the clinical significance of these defects remains uncertain. Nevertheless, the researchers conclude that every effort should be made to minimize incidental irradiation of the heart while maintaining adequate coverage of target volumes.

Reference: Prosnitz RG, Hubbs JL, Evans ES et al. Prospective assessment of radiotherapy-associated cardiac toxicity in breast cancer patients: analysis of data 3 to 6 years after treatment. Cancer. 2007;110:1840-50.

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