BARCELONA, Spain — Women with ductal carcinoma in situ (DCIS) currently undergo treatment as if they have breast cancer, because even though this early form of the disease is not invasive, it has been unclear which cases are most likely to progress.
New clues come from an Italian study that followed more than 1000 DCIS cases. The study was presented here at the 11th European Breast Cancer Conference.
“A diagnosis of DCIS can be frightening but also confusing. Although we know that very few patients will go on to develop invasive cancer, we don’t know which ones they will, and so we offer treatments such as surgery and radiotherapy, and sometimes hormone therapy,” commented lead researcher Icro Meattini, MD, consultant clinical oncologist, University Hospital of Florence, Italy.
“We wanted to look in detail at women treated for DCIS to see if there are any clues about who is most at risk of a recurrence, and to understand the risks and benefits of different treatments,” he explained.
The researchers therefore conducted a retrospective analysis of 1072 patients with DCIS who were treated with breast-conserving surgery and adjuvant radiotherapy between 1997 and 2012 at nine Italian centers. The use of adjuvant endocrine therapy (ET) was based on the center’s policy.
Of 557 patents whose hormonal status was positive, 51.9% received adjuvant ET.
During a mean follow-up of 8.4 years, there were 67 cases of local recurrence in the 1072 DCIS cases (6.25%).
Among the 67 cases of local recurrences, 25 (37.3%) were in situ, and 42 (62.7%) were invasive.
The mean time to local recurrence was 7.0 years — 5.4 years for in situ, and 8.0 years for invasive recurrence, yielding overall local recurrence rates at 5 and 10 years of 3.4% and 7.6%, respectively.
There were 47 deaths during follow-up, of which 11 (23.4%) were related to breast cancer.
The overall survival rates at 5 and 10 years were 98.5% and 97.0%, respectively. The breast cancer–specific survival rates were 99.7% and 99.1%, respectively.
These results “should offer all DCIS patients reassurance that the risk of their cancer returning is very low, if they are treated with breast-conserving surgery followed by radiotherapy,” Meattini said in a statement.
A multivariate analysis revealed that being postmenopausal and having estrogen receptor–positive disease were associated with a substantially reduced risk of having a local recurrence (hazard ratios [HRs], 0.40 [P = .03] and 0.35 [P = .045], respectively).
In contrast, having a fine surgical margin of <1 mm was associated with a markedly increased risk for local recurrence (HR, 3.3; P = .024).
The use of adjuvant ET in women with a positive hormonal status was found to have no significant effect on overall local recurrence (P = .34), in situ recurrence (P = .92), invasive recurrence (P = .25), and overall survival (P = .81).
None of the clinical variables studied had an effect on overall and breast cancer–specific survival rates.
“Now we need to do more research to find out if lower-risk patients can safely be given less treatment, or even no treatment, as well as studies on how best to treat higher-risk patients,” Meattini commented.
“In the meantime, it’s vital that each patient receives treatment that is best suited to their individual cancer and their particular circumstances,” he added.
Speaking to Medscape Medical News, Meattini said that the findings underline those of previous studies indicating that there is a group of low-risk women “for whom the deescalation of treatment is possible.” The study also “confirms the importance of a clear fine surgical margin >1 mm.”
He noted that the effect of postoperative radiotherapy “seems to be stable over time,” but that, “once again, adjuvant endocrine therapy seems not to be crucial in recurrence prevention.”
“In the real world, where endocrine treatment, in many centers, is routinely given, probably endocrine therapy omission could represent the deescalation of treatment,” he said in an interview.
Meattini pointed to several ongoing randomized controlled trials that are investigating specific deescalation strategies, such as the LORIS trial in the United Kingdom, which is examining the omission of radiotherapy, and the LORD trial in Europe, in which surgery is being compared to observation for low-risk patients.
Another option in surgical low-risk patients, he said, is accelerated partial breast radiotherapy to treat just the tumor bed of the affected breast. This was the subject of a recent American Society for Radiation Oncology guideline.
On the other hand, Meattini does not think that women with a fine surgical margin of <1 mm should undergo additional therapy to compensate for their substantially increased risk for recurrence.
“Personally, I think that women with surgical margins <1 mm should be simply considered for reintervention; so, no extras, just surgery,” he said.
He pointed out that higher doses of radiation do not seem to improve the prognosis of patients whose surgical margins are unsatisfactory, and that the toxicity profile of adjuvant chemotherapy is “absolutely higher and not comparable to simple reintervention.”
Meattini concluded: “This is obviously my personal opinion, but there is no space for extra adjuvant therapy, just surgery.”
Isabel Rubio, MD, cochair of the 11th European Breast Cancer Conference and director of the Breast Surgical Unit at Clinica Universidad de Navarra, in Madrid, Spain, who was not involved in the study, welcomed the findings.
“This study provides more reassurance to patients that their risk of recurrence is low. It also provides doctors with more information on which patients have a higher chance of a recurrence, and points the way to further research on how to tailor treatments to individual patients,” she added.
The researchers have disclosed no relevant financial relationships.
European Breast Cancer Conference. Abstract 215, presented March 22, 2018.
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