Rates of Adverse Events Similar Regardless of IMRT Boost Type

For women treated with breast conservation surgery for early breast cancer in the IMPORT HIGH trial (CRUK/06/003), the adverse events (AEs) experienced by participants were roughly similar for all those who subsequently underwent radiotherapy, regardless of whether the intensity modulated radiotherapy (IMRT) were delivered by dose-escalated simultaneous integrated boost (SIB) or sequential boost. The results of the study were presented at the 2018 San Antonio Breast Cancer Symposium (SABCS) in San Antonio, Texas.¹

Patients aged 18 years and older who had undergone breast conservation surgery for pT1-3 pN0-pN3a M0 invasive carcinoma were included in the trial. The median age of patients was 49 years (range, 44-56). Across participants, 9%, 38%, and 53% had tumors that were grade 1, 2, and 3, respectively; 30% of patients were deemed node-positive; 66% had received prior chemotherapy, while 73% had received prior endocrine therapy. 

Patients were randomly assigned in a 1:1:1 ration to be in 1 of the following groups: 40Gy/15F to whole breast (WB) + 16Gy/8F sequential photon boost to tumor bed (40+16Gy); 36Gy/15F to WB, 40Gy to partial breast + 48Gy (48Gy); or + 53Gy (53Gy) in 15F SIB to tumor bed.

Between March 2009 and September 2015, 2617 women provided consent to participate in the study across 39 radiotherapy centers in the United Kingdom. AEs across 2017 patients were assessed by clinicians annually. Photograph review and evaluation of AEs was planned in a subset of 840 patients at 3 years (ultimately, 641 photographs were evaluated). AEs were also assessed by way of 842 patient self-reports that were collected at 6 months, 1 year, and 3 years.

Researchers determined that by the conclusion of the study, at 3 years, the proportion of patients who experienced marked AEs across all cohorts was low overall. Rates of moderate/marked AEs at 3 years were broadly similar between the study groups. There was a trend toward a slightly increased risk for breast induration for patients in the 53Gy group compared with the control group, but this finding only had “borderline significance,” according to study presenters.

Read more of Cancer Therapy Advisor‘s coverage of the SABCS 2018 meeting by visiting the conference page.

Reference

1. Coles CE, Griffin CL, Kirby AM, et al. Dose escalated simultaneous integrated boost radiotherapy for women treated by breast conservation surgery for early breast cancer: 3-year adverse effects in the IMPORT HIGH trial (CRUK/06/003). Presented at: 2018 San Antonio Breast Cancer Symposium; December 4-8, 2018; San Antonio, TX. Abstract GS4-05.