Clinical and patient-reported outcomes in women offered oncoplastic breast-conserving surgery as an alternative to mastectomy: ANTHEM multicentre prospective cohort study.

Background: Oncoplastic breast-conserving surgery may be a better option than mastectomy, but high-quality comparative evidence is lacking. The aim of the ANTHEM study (ISRCTN18238549) was to explore clinical and patient-reported outcomes in a multicentre cohort of women offered oncoplastic breast-conserving surgery as an alternative to mastectomy with or without immediate breast reconstruction.

Methods: Women with invasive/pre-invasive breast cancer who were offered oncoplastic breast-conserving surgery with volume replacement or displacement techniques to avoid mastectomy were recruited prospectively. Demographic, operative, oncological, and 3- and 12-month complication data were collected. The proportion of women choosing oncoplastic breast-conserving surgery and the proportion in whom breast conservation was successful were calculated. Participants completed the validated BREAST-Q questionnaire at baseline, 3 months after surgery, and 12 months after surgery. Questionnaires were scored according to the developers' instructions and scores for each group were compared over time.

Results: In total, 362 women from 32 UK breast units participated, of whom 294 (81.2%) chose oncoplastic breast-conserving surgery. Of the oncoplastic breast-conserving surgery patients in whom postoperative margin status was reported, 210 of 255 (82.4%) had clear margins after initial surgery and only 10 (3.9%) required completion mastectomy. Major complications were significantly more likely after immediate breast reconstruction. Women having oncoplastic breast-conserving surgery with volume displacement techniques reported significant improvements in baseline 'satisfaction with breasts' and 'psychosocial well-being' scores at 3 and 12 months, but both oncoplastic breast-conserving surgery groups reported significant decreases in 'physical well-being: chest' at 3 and 12 months.

Conclusion: Oncoplastic breast-conserving surgery allows greater than 95% of women to avoid mastectomy, with lower major complication rates than immediate breast reconstruction, and may improve satisfaction with outcome. Oncoplastic breast-conserving surgery should be offered as an alternative to mastectomy in all women in whom it is technically feasible.