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26-05-2020 | Oncology | News | Article

Long-term results of delayed intraoperative radiotherapy for breast cancer reported

Hannah Kitt

medwireNews: A phase 3 trial has failed to demonstrate the noninferiority of delayed targeted intraoperative radiotherapy (TARGIT-IORT) to whole-breast external beam radiotherapy (EBRT) in terms of local control at 5 years in patients with early-stage breast cancer, but other long-term outcomes were comparable.

Noting that the previously published TARGIT-A trial showed the noninferiority of TARGIT-IORT given during the same operation immediately after lumpectomy by inserting the radiotherapy applicator directly into the open wound, Jayant Vaidya (University College London, UK) and colleagues say: “[I]t is clear that the preferred timing of using TARGIT-IORT is immediately–during the initial surgical excision of breast cancer.

“However, when immediate TARGIT-IORT has not been possible, the long-term data presented in this article may help inform discussions by clinicians and patients who wish to avoid a prolonged postoperative course of EBRT.”

Speaking to medwireNews, Vaidya pointed out that “these results could be of special relevance during the current COVID-19 pandemic.”

Among the 581 patients with invasive ductal breast carcinoma (≤3.5 cm) who were randomly assigned to receive delayed second-procedure TARGIT-IORT by re-opening the wound – at a median of 37 days after the original procedure – 3.96% had a local recurrence at 5 years.

By comparison, the rate among the 572 patients who received EBRT was 1.05%, giving a between-group difference of 2.91%, with an upper 90% confidence interval limit of 4.40%. This crossed the “stringent” prespecified margin of 2.50%, and therefore the noninferiority of delayed TARGET-IORT was not proven, say the researchers in JAMA Oncology.

Nevertheless, after a median follow-up of 9 years, there was no statistically significant difference between the treatment groups with respect to local recurrence-free survival. And other outcomes, such as mastectomy-free survival, distant disease-free survival, breast cancer-specific survival, and overall survival were similarly comparable.

Vaidya commented: “From the patient’s perspective, the standard treatment for local recurrence after lumpectomy and whole-breast radiotherapy is mastectomy. However, patients who develop a local recurrence after TARGIT-IORT can still have a lumpectomy. So, the good news from this study is that even though the local recurrence was slightly higher, by 2.9%, patients could still preserve their breast.”

The investigators notes that TARGIT-IORT has been shown to be superior to EBRT in terms of patient-reported outcomes, such as breast pain and cosmesis, and quality of life, and patient preference studies have shown that many patients prefer TARGIT-IORT “even in the face of a hypothetically higher local recurrence risk.”

The current data “may mitigate some of the patient concerns, and results of further patient preference research would help these discussions,” they add.

medwireNews is an independent medical news service provided by Springer Healthcare. © 2020 Springer Healthcare part of the Springer Nature Group

JAMA Oncol 2020; doi:10.1001/jamaoncol.2020.0249

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