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Breast-conserving surgery plus radiation therapy (RT) could be a treatment option for selected patients with extensive, pure ductal carcinoma in situ (DCIS), according to a retrospective study.

Among women with DCIS ≥4 cm who received lumpectomy plus RT, 8% had local recurrence at 10 years compared with 2% of those who received standard mastectomy, reported Sarah Hamilton, MD, of the University of British Columbia in Canada, and colleagues.

Still, relative to mastectomy, breast-conserving treatments were all associated with a higher risk of recurrence:

• Lumpectomy alone (HR 7.87, 95% CI 2.82-21.92, P<0.0001)
• Lumpectomy with RT (HR 3.80, 95% CI 1.56-9.28, P=0.003)
• Lumpectomy with RT plus boost (HR 5.76, 95% CI 2.59-12.83, P<0.0001)

Mastectomy remains a local treatment option for extensive DCIS, the authors wrote in the , "but breast-conserving surgery and RT may also be considered in patients with careful consideration of benefits, treatment-related side effects, and patient preferences."

Patients with DCIS ≥4 cm are typically treated with mastectomy, but little data exist to demonstrate an unacceptably high risk of relapse with different treatment methods, they explained, and whether there are significant mortality differences between the two options is unclear.

The , for example, reported that 65% of DCIS patients ≥4 cm did not experience relapse at 3 years follow-up, but that data set included only a small number of these patients. And in two trials, which randomly assigned patients to either lumpectomy or lumpectomy followed by RT, 90% of the patients had tumors <2 cm.

Janna Andrews, MD, of the Northwell Health Cancer Institute in New York, said this study is important because it is one of the first to examine whether patients with extensive DCIS could do just as well with a lumpectomy and RT as they would with a mastectomy.

"It may not change their decision to move forward with a mastectomy, but historically these patients haven't even been given the option, or that information may have just never been presented to them," Andrews told 名媛直播.

"I think it's important as the breast cancer oncology field evolves that we include patients in these treatment decisions," she said. "A woman may still hear that her rates of recurrence are potentially higher with lumpectomy and radiation if she has a large focus of DCIS, but that number may be completely acceptable to her when compared to mastectomy."

The study collected data from 720 patients, diagnosed between 1989 and 2010, with extensive DCIS (≥4 cm) treated with breast-conserving surgery or mastectomy. Those with contralateral breast cancer and lobular carcinoma in situ (LCIS) were excluded. Median tumor size was 5.5 cm in the 490 women who underwent mastectomy (median age 52).

And median tumor size was 4.6 cm in the 230 women who had breast-conserving surgery (median age 58). Of these, 192 received lumpectomy plus RT, while 38 were treated with lumpectomy alone (16% of this group relapsed at 10 years).

Lumpectomy patients were more likely to receive RT after surgery than patients who underwent mastectomy (84% versus 6%, P<0.0001). Additionally, 21% of breast-conserving surgery patients received adjuvant hormone therapy, compared to 9% of mastectomy patients.

They were also more likely to have positive or close (<2 cm) margins (P=0.006). Positive margins were associated with a higher relapse rate (HR 3.55, 95% CI 1.56-8.05, P=0.002).

Relative to estrogen receptor (ER)-positive disease, ER-negative disease was associated with an increased risk of local relapse (HR 3.32, 95% CI 1.08-10.18, P=0.04).

Year of diagnosis, tumor size and grade, comedocarcinoma, and close margins were not associated with risk of relapse (all P>0.05). Endocrine therapy was also not associated with reduced local recurrence risk, although the authors reported that only a small number of patients underwent hormonal therapy, and ER status was not available for the majority.

The authors cited several limitations to their study, including patient- and treatment-selection bias due to its retrospective design. In terms of pathology, they noted the possibility that some occult microinvasive carcinomas were missed and that not all cases of distant metastases were reported. Additionally, it lacked data on race and ethnicity, which can be associated with breast cancer mortality in DCIS.

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