Role of Radiation and Imaging in DCIS Explained

October 2013, Vol 4, No 8

San Francisco, CA—Management of ductal carcinoma in situ (DCIS) was the focus of 2 studies highlighted at a press conference before the 2013 Breast Cancer Symposium. These studies showed that:

  • Radiation to the breast as part of treatment of patients with DCIS does not increase cardiovascular toxicity, including the risk for cardiovascular disease (CVD) and death from CVD or from other causes
  • Perioperative magnetic resonance imaging (MRI) does not reduce the risk of locoregional recurrence or contralateral breast cancer in patients with DCIS who are undergoing surgery as part of their treatment program.

Women and their physicians can gain reassurance from the first study that radiation for DCIS does not increase cardiotoxicity, and the second study indicates that MRI should not be part of routine presurgical or surgical planning in this patient population.

Radiation Does Not Increase CVD Risk in DCIS
DCIS is a precancerous lesion that, if left untreated, may progress to invasive cancer in a small percentage of patients. At present there is no way to identify which patients with DCIS are at risk of progression, so DCIS is typically treated with surgery plus or minus radiation to reduce the risk of locoregional recurrence.

Concern has been raised about increased cardiotoxicity with radiation to the breast area, and modern protocols have been adjusted to reduce exposure to the breast, as well as radiation dose. The risk of CVD was not increased in women with DCIS who received radiotherapy in a large population-based study compared with women who had surgery alone and with women in the general population.

This is the first large study to evaluate long-term effects of radiotherapy for DCIS on the incidence of CVD and associated deaths, said lead investigator Naomi B. Boekel, MSc, a PhD candidate at the Netherlands Can­cer Institute, Amsterdam. However, longer follow-up is needed to confirm the cardiovascular safety of radiation in patients with DCIS. Ms Boekel said that 5 or 10 more years of follow-up should be sufficient.

The study included 10,468 women diagnosed with DCIS younger than 75 years of age between 1989 and 2004. Approximately 71% had surgery only, and 28% underwent surgery and radiotherapy. DCIS survivors had similar death rates, as well as a 30% lower risk of dying from CVD compared with the general population. Patients treated with surgery alone had a similar risk for CVD as those undergoing surgery and radiotherapy; no difference in risk was observed between patients who received left-sided radiotherapy or right-sided radiotherapy (which does not include the heart in the radiation field); in these subgroups, the incidence of CVD was 7% versus 8%, respectively.

It is not clear why DCIS survivors had a slightly lower risk of CVD compared with the general population, but Ms Boekel suggested that cancer survivors may be more concerned about a healthy lifestyle than the general population.

Perioperative MRI Often Unnecessary
Perioperative MRI may not be necessary in all patients undergoing surgery for DCIS, according to results of the second study. The risk of loco­regional recurrence or contralateral breast cancer was not lower in women who underwent MRI around the time of surgery, according to this retrospective study.

Although no official guidelines for MRI in DCIS are available, many medical centers routinely order perioperative MRI with the hope of improving outcomes by finding additional cancers not detected by mammograms or other imaging studies. “Our findings indicate that MRI is not necessary for every patient with DCIS,” stated lead investigator Melissa L. Pilewskie, MD, Surgical Breast Oncologist, Memorial Sloan-Kettering Cancer Center (MSKCC), New York. Dr Pilewskie noted that perioperative MRI may be useful in specific patients with DCIS, such as those with a palpable mass and nipple discharge not found on mammography screening.

The study included 2321 women who underwent a lumpectomy between 1997 and 2010 at MSKCC; 596 had an MRI before or immediately after surgery and 1725 did not. At a median follow-up of 59 months, 5-year locoregional recurrence rates were 8.5% in those who had an MRI versus 7.2% for those who did not. In addition, no significant differences were seen in the 5-year rates of contralateral breast cancer. The rates were still similar at 8 years.

MRIs are typically ordered for women who have risk factors for breast cancer, such as younger age or family history. Dr Pilewskie said that this may explain the higher recurrence rates in these women.

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