Postoperative radiotherapy omission in selected patients with early breast cancer following preoperative breast MRI (PROSPECT): primary results of a prospective two-arm study.

BACKGROUND: Adjuvant breast radiotherapy as a standard component of breast-conserving treatment for early cancer can overtreat many women. Breast MRI is the most sensitive modality to assess local tumour burden. The aim of this study was to determine whether a combination of MRI and pathology findings can identify women with truly localised breast cancer who can safely avoid radiotherapy. METHODS: PROSPECT is a prospective, multicentre, two-arm, non-randomised trial of radiotherapy omission in patients selected using preoperative MRI and postoperative tumour pathology. It is being conducted at four academic hospitals in Australia. Women aged 50 years or older with cT1N0 non-triple-negative breast cancer were eligible. Those with apparently unifocal cancer had breast-conserving surgery (BCS) and, if pT1N0 or N1mi, had radiotherapy omitted (group 1). Standard treatment including excision of MRI-detected additional cancers was offered to the others (group 2). All were recommended systemic therapy. The primary outcome was ipsilateral invasive recurrence rate (IIRR) at 5 years in group 1. Primary analysis occurred after the 100th group 1 patient reached 5 years follow-up. Quality-adjusted life-years (QALYs) and cost-effectiveness of the PROSPECT pathway were analysed. This study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12610000810011). FINDINGS: Between May 17, 2011, and May 6, 2019, 443 patients with breast cancer underwent MRI. Median age was 63·0 years. MRI detected 61 malignant occult lesions separate from the index cancer in 48 patients (11%). Of 201 group 1 patients who had BCS without radiotherapy, the IIRR at 5 years was 1·0% (upper 95% CI 5·4%). In group 1, one local recurrence occurred at 4·5 years and a second at 7·5 years. In group 2, nine patients had mastectomy (2% of total cohort), and the 5-year IIRR was 1·7% (upper 95% CI 6·1%). The only distant metastasis in the entire cohort was genetically distinct from the index cancer. The PROSPECT pathway increased QALYs by 0·019 (95% CI 0·008-0·029) and saved AU$1980 (95% CI 1396-2528) or £953 (672-1216) per patient. INTERPRETATION: PROSPECT suggests that women with unifocal breast cancer on MRI and favourable pathology can safely omit radiotherapy. FUNDING: Breast Cancer Trials, National Breast Cancer Foundation, Cancer Council Victoria, the Royal Melbourne Hospital Foundation, and the Breast Cancer Research Foundation.

Benign papilloma on core biopsy requires surgical excision.

BACKGROUND: When a papillary lesion is identified on core biopsy of an impalpable breast lesion, standard practice involves excisional biopsy. Recent literature has questioned the need for surgical excision in patients with benign core biopsy and radiological concordance. Our aim was to assess whether surgical excision is required by targeting this concordant group in a large screen-detected population. METHODS: A retrospective review of a prospectively collected database of all benign papillary core biopsies between February 1995 and September 2007 at North Western Breast Screen and Monash Breast Screen in Melbourne, Australia was performed. All patients had surgical excision, enabling correlation between core and final excisional biopsy results on all lesions. All histology reports were reviewed and the radiology was reassessed. RESULTS: During a 14-year period, 5783 core biopsies were performed from 633,163 screening mammograms. Eighty patients (0.01%) had benign papilloma on core biopsy, no patients had atypia on core biopsy, and all patients had benign radiological features. Of the 80 patients, 15 patients were found to have ductal carcinoma in situ (8) or invasive ductal carcinoma (7) on final pathology, yielding a 19% malignant rate. CONCLUSION: Core biopsy showing benign papillary lesion, even where radiology is also suggestive of a benign process, cannot exclude malignancy, and therefore surgical excision is required.