Efficacy of radiation therapy in Japanese patients with positive margins after breast-conserving surgery.

Publisher: Oxford University Press Country of Publication: England NLM ID: 0313225 Publication Model: Print Cited Medium: Internet ISSN: 1465-3621 (Electronic) Linking ISSN: 03682811 NLM ISO Abbreviation: Jpn J Clin Oncol Subsets: MEDLINE

Publication: Oxford : Oxford University Press
Original Publication: Tokyo, Foundation of Clinical Oncology.

Mastectomy, Segmental* ; Breast Neoplasms*/radiotherapy ; Breast Neoplasms*/surgery ; Breast Neoplasms*/pathology ; Neoplasm Recurrence, Local*/epidemiology ; Margins of Excision*; Humans ; Female ; Middle Aged ; Retrospective Studies ; Aged ; Adult ; Japan/epidemiology ; Radiotherapy, Adjuvant ; Aged, 80 and over ; Treatment Outcome ; East Asian People

Background: Additional surgical resection is recommended after breast-conserving surgery if the surgical margin is pathologically positive. However, in clinical practice, radiation therapy is sometimes used instead for several reasons. Irradiation may be appropriate for some patients, but real-world data is still insufficient to establish it as standard treatment. We retrospectively investigated the status of local control in patients who received irradiation for positive margins.
Methods: We investigated 85 patients with positive margins after curative partial mastectomy who were treated with irradiation instead of additional excision during the period 2006-2013. The patients received whole-breast irradiation (43.2-50 Gy) using photon beams and additional tumour-bed boost (8.1-16 Gy) using electron beams. Intrabreast tumour recurrence was defined as secondary cancer within the ipsilateral conserved breast. Surgical margin was defined as positive if tumour cell exposure was pathologically confirmed on the margin.
Results: Seven patients (8.2%) developed intrabreast tumour recurrence during a mean observation period of 119 months. As to components of positive margin, 76 cases were positive for an intraductal component, of which seven (9.2%) developed intrabreast tumour recurrence. Meanwhile, all nine cases positive for an invasive component were free from intrabreast tumour recurrence. Two of the intrabreast tumour recurrence cases seemed to develop new lesions rather than recurrence, considering tumour location. The cumulative incidence of intrabreast tumour recurrence over 10 years was 6.1%. Limited to true recurrence, intrabreast tumour recurrence incidence was 4.9%.
Conclusion: Our real-world data supports irradiation as an alternative to additional surgical intervention for positive margins after breast-conserving surgery and offers a basis for further research.
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Keywords: breast cancer; breast-conserving surgery; intrabreast tumour recurrence; irradiation; surgical margin

Date Created: 20240122 Date Completed: 20240507 Latest Revision: 20240507

20240507

10.1093/jjco/hyad196

38251759