Improving risk outcomes: Invasive breast cancer after DCIS

July 8, 2020

Women with ductal carcinoma in situ (DCIS) may experience higher risk of developing invasive breast cancer (IBC) and of death from breast cancer than the general population, according to new research.

The study, published in the BMJ, also found that the risks were more than twice those of the general population, even for women diagnosed with low or intermediate-grade DCIS.1

DCIS can increase a woman’s risk for developing IBC later in life,2 but the long-term risks of IBC and of death from breast cancer after surgery for DCIS had not been previously studied.

This investigation is a result of that. The study’s purpose was to evaluate the long-term risks and explore how those risks may vary in relation to different patient, tumor, and treatment characteristics.

The findings are based on data from 35,024 women in England who had initially been diagnosed with DCIS by the National Health Service (NHS) Breast Screening Program from its inception in 1988 until March 2014. The data included patient-related factors (screening date, date of DCIS diagnosis, age at DCIS diagnosis, any previous cancer diagnoses, and region of residence).

For women screened from April 2000 forward, the data also included tumor-related factors (DCIS tumor size, grade, laterality, estrogen receptor status) and details of treatment (type of surgery, radiotherapy, endocrine treatment).

Researchers found that by December 2014, 2,076 women had developed IBC, an incidence rate of 8.82 per 1,000 per year. That result was more than double the number expected from national rates.1

Of the women with IBC, 310 died from breast cancer with a death rate of 1.26 per 1,000 per year, which was 70% more than expected from national rates. These increases continued for at least 20 years.

This study also showed that breast conserving surgery was associated with a lower rate of invasive breast cancer in women who also had radiotherapy. The lowest rates of IBC were seen in women who had undergone mastectomy.

Larger final surgical margins may also decrease risks of IBC and of death, according to researchers. “Although guidelines recommend that margin widths do not need to be more than 1-2 mm, our study suggests that having margins greater than this may confer some further benefit,” the authors wrote, calling for further studies on margin distances in DCIS.

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References

  1. Mannu G, Wang Z, Broggio J, et al. Invasive breast cancer and breast cancer mortality after ductal carcinoma in situ in women attending for breast screening in England, 1988-2014: population based observational cohort study. BMJ. 2020;369:m1570. doi: https://doi.org/10.1136/bmj.m1570
  2. American Cancer Society. Ductal Carcinoma in Situ (DCIS). July 2, 2020. www.cancer.org/cancer/breast-cancer/understanding-a-breast-cancer-diagnosis/types-of-breast-cancer/dcis.html.