Radiation Therapy Is Safe in the Management of Ductal Carcinoma In Situ: No Increase in Risk of Cardiovascular Disease 


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Radiation therapy as part of the management of ductal carcinoma in situ (DCIS) did not increase the risk of cardiovascular disease 10 years after treatment, according to a large retrospective study presented at a press conference held just prior to the 2013 Breast Cancer Symposium.1 Longer follow-up is required to establish with certainty the lack of increased cardiotoxicity risk, but the study provides a degree of reassurance to physicians and patients who have opted for radiation therapy in addition to surgery in the treatment DCIS.

Late Effects of Radiation

The study comes at a time when some experts question the classification of DCIS as a cancerous lesion. Recently, a working panel convened by the National Cancer Institute called for the removal of the word “cancer” with regard to nonlethal cancers that include DCIS.2 However, in about 5% of patients, DCIS can herald the eventual development of invasive breast cancer. Since, currently, it is not possible to determine which patients with DCIS will progress to invasive disease, DCIS is typically treated with surgery plus or minus radiation therapy to control local recurrence. The present study sought to determine whether radiation as part of DCIS management increases the risk of cardiovascular disease in light of concerns about the late effects of radiation.

This is the first large population-based study to evaluate long-term effects of radiotherapy for DCIS on both the incidence of cardiovascular disease and associated deaths. The authors compared the 10-year risk of developing cardiovascular disease in patients with DCIS treated with radiation and surgery vs those treated with surgery alone vs the general population.

“The late effects of radiation are of great importance. Over time, radiation techniques have been adjusted to reduce exposure to the heart, and currently, radiation exposure for DCIS is relatively low,” said lead author of the study Naomi B. Boekel, MSc, a PhD student at the Netherlands Cancer Institute in Amsterdam, Netherlands. “We found no increased risk of [cardiovascular disease] morbidity and mortality after radiation compared to surgery alone in patients with DCIS. However, longer follow-up of about 5 to 10 years is needed.”

Study Methods and Results

The retrospective study was based on data from 10,468 women diagnosed with DCIS before the age of 75 between 1989 and 2004. Surgery alone was performed in about 71% (43% had mastectomy and the remaining women had lumpectomy), and 28% underwent both surgery and radiotherapy. At a median follow-up of 10 years, compared with the general population in the Netherlands, survivors of DCIS had a similar risk of dying from any cause and a 30% lower risk of dying of cardiovascular disease.  Women treated with surgery alone and women treated with surgery and radiotherapy had a similar risk of developing cardiovascular disease: 9% vs 8%, respectively. The risk of cardiovascular disease was similar in those who received left-sided radiotherapy (includes a portion of the heart in the radiation field) or right-sided radiotherapy (the heart is not included in the radiation field); in these subgroups, the incidence of cardiovascular disease was 7% vs 8%, respectively. ■

Disclosure: Ms. Boekel reported no potential conflicts of interest.

References

1. Boekel NB, Schaapveld M, Gietema JA, et al: Cardiovascular morbidity and mortality in patients treated for ductal carcinoma in situ of the breast. ASCO Breast Cancer Symposium, September 7-9, 2013, San Francisco, CA. Abstract 58.

2. Esserman L, Thompson IM, Reid B. Overdiagnosis and overtreatment in cancer. JAMA. July 29, 2013 (early release online).


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