Abstract
BackgroundTo date, there are no reports of intraoperative radiotherapy (IORT) use with long-term follow up as a method of accelerated partial breast irradiation (APBI) in Asian countries. We initiated a prospective phase I/II clinical trial of IORT in Japan in 2007, and herein, we report the 5-year follow-up results.Materials and methodsThe following inclusion criteria were used for enrollment in the trial: (1) tumor size < 2.5 cm, (2) desire for breast-conserving surgery, (3) age >50 years, and (4) negative margins after resection. In February 2009, the eligibility criteria were changed to include only patients with sentinel lymph node-negative disease. In phase I, the radiotherapy dose was escalated from 19 Gy/fr to 21 Gy/fr, incremented by 1 Gy per step, with 3 patients in each step. Doses were escalated after all patients in the preceding cohort had completed treatment and exhibited only grade 1 or 2 toxicities at a given dose level. The recommended phase II dose was set at 21 Gy at 90 % isodose. The primary endpoint was early toxicity. Secondary endpoints were long-term efficacy and late toxicity. In addition, Hypertrophic scarring was evaluated retrospectively as a cosmetic outcome by a radiation oncologist.ResultsBetween December 2007 and March 2010, 32 women with breast cancer were enrolled in the trial. The median age was 65 years (51–80 years), and the median follow-up time was 6 years. No recurrence or metastasis was observed in any patient. Grade 2 fibrosis was detected in 3 patients as an acute adverse event and in 2 patients as a late adverse event. Ten patients developed a hypertrophic scar 1 year after the IORT; the number of patients decreased to 7 in the 3 years of follow-up.ConclusionThe first group of female Asian patients tolerated the treatment with IORT in this Phase I/II study and remained recurrence-free for more than 5 years after treatment. However, 24 % of the patients developed hypertrophic scarring, an event that is being further examined in our ongoing multi-center Phase II trial of IORT for early breast cancer.
Highlights
The standard treatment for early breast cancer is breastconserving therapy (BCT) with whole-breast external irradiation therapy (WBI) [1]
The first group of female Asian patients tolerated the treatment with intraoperative radiotherapy (IORT) in this Phase I/II study and remained recurrence-free for more than 5 years after treatment
24 % of the patients developed hypertrophic scarring, an event that is being further examined in our ongoing multi-center Phase II trial of IORT for early breast cancer
Summary
The standard treatment for early breast cancer is breastconserving therapy (BCT) with whole-breast external irradiation therapy (WBI) [1]. Local recurrences after BCT with or without WBI arise most often in the same quadrant as the primary cancer [2], which has led to Despite the positive results from clinical trials around the world, the Japanese Breast Cancer Society has stated in their guidelines regarding the APBI technique that there is “not enough evidence to perform in clinical use”. They state, "to start APBI, we need to solve the technical problems arises from breast and body size difference from Western women" [4] because the same target dose would result in a higher skin, heart, Kawamura et al Radiation Oncology (2015) 10:150 and lung dose for patients with smaller breasts, making it difficult to increase the fractional dose. We initiated a prospective phase I/II clinical trial of IORT in Japan in 2007, and we report the 5-year follow-up results
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