Ultrasound Measurement of the Distance between the Breast Tumor and the Skin: A Cut-Off Value for Safe Skin Preservation - Diagnostic Accuracy Study.

Background: In superficial tumors of the breast, it is necessary to plan the thickness of surgical skin flaps, and whether skin can be preserved for esthetics results. This study aimed to find an ultrasound-measured cut-off distance between tumor and skin (TSD) that allows patients to have the skin over the tumor spared. Methods: This is a diagnostic accuracy study comparing preoperative ultrasound TSD with pathological TSD and the thickness of the skin flaps. We recruited all consecutive women diagnosed with breast cancer between January 2017 and December 2019 whose surgical planning allowed to have the tumor and overlying skin to be removed in bloc (reconstruction procedures, situations where skin removal would not lead to esthetic problems, and superficially located tumors). Measurements were made: preoperatively (by ultrasound), during surgery (using a metal caliper to obtain the thickness of surgical skin flap), and after surgery (pathological). A pathological tumor-skin distance greater than surgical skin flap thickness would indicate preservation of skin above the tumor. Results: We evaluated 95 consecutive patients with 102 lesions. The average surgical flap thickness was 5.5 mm (3-10 mm). The ultrasound-measured cut-off TSD of 2.1 mm obtained 96.0% accuracy in predicting free anterior margin, considering a 5-mm-thick surgical flap. Conclusion: In breast superficial tumors, a cut-off distance of 2.1 mm or more measured preoperatively by ultrasound allows safe preservation of the skin above the tumor. Future studies need to follow up for longer the women submitted to skin preservation surgeries, especially those not undergoing radiotherapy.