DCIS (ductal carcinoma in situ) is the most common form of non-invasive breast cancer and is considered stage 0 cancer. While DCIS isn’t considered life threatening, it does increase the risk of developing invasive breast cancer later in life.
DCIS usually is treated with surgery to remove the cancer -- lumpectomy in most cases. After surgery, hormonal therapy may be recommended if the DCIS is hormone-receptor-positive (most are). Radiation therapy also is recommended for many women. Both hormonal therapy and radiation help reduce the risk of the DCIS recurring (coming back), as well as the risk of invasive cancer.
Routine radiation therapy after DCIS surgery was common in the past, but some newer DCIS treatment guidelines say that women at low risk for recurrence may be able to skip radiation therapy after surgery. Still, the definition of low risk isn't always clear.
A study has found that a prognostic score, calculated from a set of risk factors that are easy to measure, may help figure out which women get survival benefits from radiation therapy after DCIS surgery and which women do not.
The study was published online on Feb. 1, 2016 by the Journal of Clinical Oncology. Read the abstract of “Patient Prognostic Score and Associations With Survival Improvement Offered by Radiotherapy After Breast-Conserving Surgery for Ductal Carcinoma In Situ: A Population-Based Longitudinal Cohort Study.”
This study was a retrospective study, which means the researchers analyzed information that was collected before the study was designed. Some doctors think that the results of retrospective studies aren’t as strong as studies that are designed first and then collect new information specifically for that study.
The researchers looked in the SEER databases to identify 32,144 women diagnosed with DCIS between 1988 and 2007 who had lumpectomy (also called breast-conserving surgery):
- 20,329 women (63.2%) had radiation therapy after lumpectomy
- 11,815 women (36.8%) didn’t have radiation therapy after lumpectomy
SEER databases are large registries of cancer cases from sources throughout the United States maintained by the National Institutes of Health.
The women in the study ranged in age from 20 to more than 80 years old. Most of the women (82%) were white and more than 50% were married.
In women who didn’t get radiation therapy after lumpectomy:
- 60% of the DCIS was between 1 mm and 9 mm in size; about 24% was between 10 and 19 mm in size
- 47.4% of the DCIS was grade 2 and 30.4% was grade 3
- 4.7% of the DCIS was estrogen-receptor-negative, 29.1% was estrogen-receptor-positive, and 66.2% had an unknown estrogen-receptor status
In women who did get radiation therapy after lumpectomy:
- 48.5% of the DCIS was between 1 mm and 9 mm in size; about 32% was between 10 and 19 mm
- 39% of the DCIS was grade 2 and 48.5% was grade 3
- 8.4% of the DCIS was estrogen-receptor-negative, 39.1% was estrogen-receptor-positive, and 52.5% has an unknown estrogen receptor status
Overall, 304 women died from breast cancer during about 8 years of follow-up:
- 1.8% of the women in the radiation group died from breast cancer
- 2.1% of the women who didn’t get radiation died from breast cancer
The researchers assigned each woman a prognostic score from 0 to 6 calculated from three risk factors:
- nuclear grade (how abnormal the cells look under a microscope)
- the woman’s age
- the size of the DCIS
Women with a higher nuclear grade, younger age, and/or larger sized DCIS had a higher prognostic score. Women with a lower nuclear grade, older age, and/or smaller DCIS had a lower prognostic score.
Earlier research has shown that this prognostic score can help predict the likelihood of recurrence, but until this study, no one had looked at whether the prognostic score could help make treatment decisions based on long-term survival.
The researchers found that women with higher prognostic scores got survival benefits from radiation therapy after lumpectomy. Women with prognostic scores of 4 or 5 were about 70% less likely to die from breast cancer if they received radiation therapy compared to women with similar prognostic scores who didn’t get radiation.
This difference was statistically significant, which means that it was likely because of the difference in radiation therapy and not just due to chance.
Radiation therapy after lumpectomy in women with lower prognostic scores (0-3) didn’t seem to make a difference in whether or not the women died from breast cancer.
"Using three factors that are routinely measured, we can predict whether there will be a survival benefit or no survival benefit for patients receiving radiation therapy," said co-lead author Yasuaki Sagara, M.D. of the Dana Farber/Brigham and Women's Cancer Center, who is also chief of breast oncology at Hakuaikai Medical Cooperation in Japan. "Our finding suggests, for the first time, that patients with more aggressive cancer who are at higher risk may actually live longer if they are treated with radiation therapy."
"This is the first time it's ever been shown that there are women with DCIS whose survival could be improved by getting radiation after lumpectomy, but that many women -- most women -- probably won't live longer by getting radiation therapy," added co-lead author Mehra Golshan, M.D., also of the Dana Farber/Brigham and Women's Cancer Center. "Patients should know the pros and cons of different treatment options. What we are trying to do is make [the treatment decision] much more patient-centric, where patients and oncologists work together to come up with the best path of care."
Several other large, randomized studies have shown that radiation after lumpectomy for DCIS reduces the risk of recurrence in the same breast by about half. Other studies have shown that taking tamoxifen after lumpectomy for hormone-receptor-positive DCIS reduces the risk of both DCIS recurrence and invasive disease in both breasts.
How DCIS considered to have a low risk of recurrence should be treated is somewhat controversial right now. Some women and their doctors prefer careful monitoring instead of surgery, some prefer lumpectomy alone, and some prefer lumpectomy followed by radiation and hormonal therapy.
While the study had 8 years of follow-up, which is a long time, the research did have some weaknesses. It’s important to know that the study didn’t look at whether the women diagnosed with DCIS had other breast cancer risk factors, such as a strong family history of breast cancer or a known abnormal gene. To accurately develop a treatment plan for DCIS, doctors have to look at ALL risk factors.
Also, the study was non-randomized, which means the women weren’t randomly assigned to a specific treatment group. We also don’t know how many women took hormonal therapy to reduce the risk of DCIS recurrence or invasive disease, so it's not clear if this affected the study’s outcomes.
It’s also important to know that there have been new developments in testing since this study was started. The Oncotype DX DCIS test is a genomic test that analyzes 12 genes in a DCIS and assigns a Recurrence Score that estimates the risk of both DCIS coming back and invasive disease in the future. It gives women and their doctors more information so they can make more informed decisions about whether treatment is needed after DCIS has been surgically removed.
Still, the results of this study are encouraging. It may be that this prognostic score is used along with the Oncotype DX DCIS score to help make DCIS treatment decisions.
If you’ve been diagnosed with DCIS, the goal is to provide you with the best treatment for your unique situation. This takes into account:
- your family history of breast cancer and other diseases
- your personal health history
- any other breast cancer risk factors you may have
- your preferences
- the characteristics of the DCIS
- any genomic test results
Together, you and your doctor will develop a DCIS treatment plan that makes the most sense for you.
For more information, visit the Breastcancer.org DCIS pages.