Mastectomy Not Always Needed in DCIS

December 13, 2016

By Brian Hoyle

SAN ANTONIO, Tex -- December 13, 2016 -- Contrary to conventional wisdom, a retrospective analysis presented here at the 39th Annual San Antonio Breast Cancer Symposium (SABCS) has indicated that ductal carcinoma in situ (DCIS) can respond positively to primary chemotherapy.

“Selected patients could be offered breast conserving surgery even in the presence of biopsy proven DCIS or in the presence of micro-calcification in sites distant from the primary tumour,” said Ruhe Chowdhury, MD, Guys and St. Thomas’ NHS Trust, London, United Kingdom, on December 8.

The current standard therapy for patients with large primary breast cancer along with widespread DCIS is a mastectomy. This decision is made even though primary chemotherapy might act exclusively to reduce the size of the invasive tumour, with no effect on DCIS.

Data on the benefit of primary chemotherapy would be a good thing, since it could help defer or eliminate mastectomy. With this goal, the researchers took a retrospective look at 1,526 patients with primary invasive cancer with radiologically- or histologically-proven DCIS who were treated at their institution. Of these, treatment involved primary systemic therapy in 156 patients.

Of the 156 patients, DCIS was confirmed by biopsy prior to chemotherapy in 46, with 30 also having confirmation provided radiologically; 26 others displayed microcalcification that was likely DCIS.

Of the 46 patients with biopsy-proven DCIS, DCIS was not detected in resection in 12 patients, 9 had received a mastectomy, 5 had a pathological complete response, and 4 had a complete radiological response.

Of the 26 patients with microcalcification detected prior to chemotherapy, DCIS was not detected in resection in 15 patients. Of these, 10 had received a mastectomy, 6 had a pathological complete response, and 3 had complete radiological response.

“Despite differing opinions that suggest DCIS is not responsive to chemotherapy, our dataset has shown that DCIS and microcalcification can resolved with primary chemotherapy,” said Dr. Chowdhury. “A significant proportion of patients underwent a mastectomy as planning for definitive surgery traditionally takes place earlier in the management timeline.”

“Although there were patients with radiological evidence of DCIS, without a confirmatory biopsy we cannot be sure that these were malignant,” she said. “This highlights the need to ensure that all suspicious areas distant from the primary tumour should be biopsied before treatment.”

The researchers opined that the data argue for a biopsy done after primary chemotherapy in cases where DCIS or microcalcification has traditionally been the determining factor for a mastectomy and where the radiological response is excellent. These patients may be spared a mastectomy.

[Presentation title: Resolution of DCIS in Patients With Early Breast Cancer Receiving Primary Chemotherapy for Invasive Breast Cancer. Abstract P3-17-09]

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