Acute adverse events of ultra-hypofractionated whole-breast irradiation after breast-conserving surgery for early breast cancer in Japan: an interim analysis of the multi-institutional phase II UPBEAT study

BACKGROUND

The applicability of ultra-hypofractionated (ultra-HF) whole-breast irradiation (WBI) remains unknown in Japanese women. This study aimed to evaluate the safety and efficacy of this approach among Japanese women and report the results of an interim analysis performed to assess acute adverse events (AEs) and determine whether it was safe to continue this study.

METHODS

We enrolled Japanese women with invasive breast cancer or ductal carcinoma in situ who had undergone breast-conserving surgery, were aged ≥ 40 years, had pathological stages of Tis-T3 N0-N1, and had negative surgical margins. Ultra-HF-WBI was delivered at 26 Gy in five fractions over one week. When the number of enrolled patients reached 28, patient registration was paused for three months. The endpoint of the interim analysis was the proportion of acute AEs of grade ≥ 2 (Common Terminology Criteria for Adverse Events v5.0) within three months.

RESULTS

Of the 28 patients enrolled from seven institutes, 26 received ultra-HF-WBI, and 2 were excluded due to postoperative infections. No AEs of grade ≥ 3 occurred. One patient (4%) experienced grade 2 radiation dermatitis, and 18 (69%) had grade 1 radiation dermatitis. The other acute grade 1 AEs experienced were skin hyperpigmentation (n = 10, 38%); breast pain (n = 4, 15%); superficial soft tissue fibrosis (n = 3, 12%); and fatigue (n = 1, 4%). No other acute AEs of grade ≥ 2 were detected.

CONCLUSIONS

Acute AEs following ultra-HF-WBI were within acceptable limits among Japanese women, indicating that the continuation of the study was appropriate.

Incidence of Radiation-induced Nausea and Vomiting: A Prospective Single-institution Pilot Study

Radiation-induced nausea and vomiting (RINV) is a frequent adverse event that occurs in patients undergoing radiotherapy. However, research on RINV is underrepresented. This prospective single-institution exploratory pilot study investigated the incidence of RINV according to the irradiation site and observed the efficacy of symptomatic antiemetic treatment in controlling symptoms of RINV. The primary outcomes were the proportions of emesis-free days and nausea-free days. The secondary endpoints included the time to the first episode of RINV, frequency of vomiting, and severity of nausea, including its impact on eating habits and weight loss. Fifteen patients were enrolled in each group (minimal, low, and moderate emetogenic risk). All patients received greater than 20 Gy in five fractions. Evaluation was based on weekly questionnaires completed by patients during routine clinic visits. Nausea and vomiting occurred in 11 and 0 patients, respectively. Six of 15 patients in the minimal-risk group, 1 in the low-risk group, and 4 in the moderate-risk group experienced nausea. Although all 11 symptomatic patients were offered antiemetics, only 3 used them, who reported satisfactory control of nausea. The percentage of emesis-free days for all patients was 100% and the percentage of nausea-free days for the 11 patients who developed RINV was 38%. An unexpectedly high percentage of patients in the minimal-risk group experienced nausea; all had breast cancer. Future studies should investigate factors beyond the irradiation site, including the characteristics of the patient and the treatment, to better predict an individual's risk of RINV.

A Case of Hypofractionated Radiation Therapy for Early-Stage Breast Cancer in a Patient With Fabry Disease

Fabry disease is a metabolic disorder caused by a deficiency in lysosomal enzymes and is inherited as an X-chromosomal disorder. Patients with Fabry disease have a low incidence of cancer, and reports of malignant tumors, especially in the thoracic region, are rare. In this case report, we describe our experience with radiation therapy following breast-conserving surgery in a patient with left breast cancer and Fabry disease, and we review the existing literature. The patient, a woman in her 40s, required postoperative irradiation for left breast cancer (pT1N0M0). There were several patients with Fabry disease in her family, and the diagnosis of Fabry disease was made five years ago. Cardiac function evaluation revealed no significant abnormalities, but a myocardial biopsy had suggested the presence of Fabry disease. Due to the relatively preserved distance between the heart and the chest wall, the patient received heart-shielded three-dimensional conformal radiation therapy at a dose of 53.2 Gy in 20 fractions, without the use of deep-inspiration breath-hold or intensity-modulated radiotherapy. After treatment was completed, only mild radiation dermatitis was observed. Six months have passed since treatment, and there have been no serious adverse events.

VMAT with DIBH in hypofractionated radiotherapy for left-sided breast cancer after breast-conserving surgery: results of a non-inferiority clinical study

The purpose of this study was to show the safety of volumetric modulated arc therapy (VMAT) with deep inspiration breath-hold (DIBH) in hypofractionated radiotherapy for left-sided breast cancer after breast-conserving surgery in a clinical setting. Twenty-five Japanese women, aged 20-59 years, who were enrolled in this prospective non-inferiority study received VMAT under the condition of DIBH with 42.4 Gy/16 fractions for whole-breast irradiation (WBI) ± boost irradiation for the tumor bed to show the non-inferiority of VMAT with DIBH to conventional fractionated WBI with free breathing. The primary endpoint was the rate of occurrence of radiation dermatitis of Grade 3 or higher or pneumonitis of Grade 2 or higher within 6 months after the start of radiotherapy. This study was registered with UMIN00004321. All of the enrolled patients completed the planned radiotherapy without interruption. The evaluation of adverse events showed that three patients (12.0%) had Grade 2 radiation dermatitis. There was no other Grade 2 adverse event and there was no patient with an adverse event of Grade 3 or higher. Those results confirmed our hypothesis that the experimental treatment method is non-inferior compared with our historical results. There was no patient with locoregional recurrence or metastases. In conclusion, VMAT under the condition of DIBH in hypofractionated radiotherapy for left-sided breast cancer after breast-conserving surgery can be performed safely in a clinical setting.

Hypofractionated radiotherapy after breast-conserving surgery: Clinical and dosimetric factors predictive of acute skin toxicity

PURPOSE

The purpose of this study was to evaluate acute skin toxicity in early breast cancer patients treated with hypofractionated radiotherapy (HFRT) after breast-conserving surgery and to identify factors predictive for grade ≥ 2 acute skin toxicity.

MATERIALS AND METHODS

A monocentric retrospective study was carried out using cases treated between December 2017 and November 2020. We analyzed data from 202 patients with early breast cancer treated with 3D hypofractionated RT (40.05 Gy in 15 fractions) to the whole breast with or without regional lymph nodes, followed by 13.35 Gy in 5 fractions to the tumor bed. Acute skin toxicity was monitored during RT according to CTCAE (common toxicity criteria for adverse events) scale. Univariate and multivariate analyses were performed to assess predictive factors of acute skin toxicity.

RESULTS

Overall, there was no erythema in 9%, grade 1 erythema in 64.5%, grade 2 in 24%, and grade 3 in 2.5%. No grade 4 erythema was seen. Median delay between RT initiating and maximum skin reaction was 22 days (range 4-44 days). No patient interrupted treatment. In univariate analysis, the rate of acute skin toxicity grade 2---3 (G2-3) was significantly higher for patients with larger tumor size (p = 0.02), body mass index > 27 (p = 0.04), and time between chemotherapy (CT) and RT less than 20 days (p = 0.01). Dosimetric risk factors for acute skin toxicity G2‑3 were breast volume > 800 cc (p = 0.000), boost volume > 18 cc (p = 0.002), V105% > 40 cc (p = 0.03), and Dmax > 56 Gy (p = 0.007). CT, trastuzumab, regional lymph node radiation, and age were not correlated with increased skin toxicity. In multivariate analysis, acute skin toxicity correlated with T stage (p = 0.032), breast volume > 800 cc (p = 0.012), boost volume > 18 cc (p = 0.04), and Dmax > 56 Gy (p = 0.035).

CONCLUSION

Our results confirm that whole breast with or without lymph nodes hypofractionated RT is safe and well tolerated. The factors strongly associated with a decreased risk of G2‑3 skin toxicity are T1, breast volume < 800 c, boost volume < 18 cc, and Dmax < 56 Gy. Long-term follow-up is needed to evaluate late toxicity.

Multi-institutional phase II study of ultra-hypofractionated whole-breast irradiation after breast-conserving surgery for breast cancer in Japan: Kyoto Radiation Oncology Study Group (UPBEAT study)

PURPOSE

The UK-FAST-Forward study showed that ultra-hypofractionated whole-breast irradiation (ultra-HF-WBI) involving five fractions of 26 Gy radiation over 1 week was not inferior to HF-WBI. However, it is not used in Japan due to safety concerns. In April 2022, we commenced a multi-institutional, single-arm, phase II trial. Our aim is to confirm the safety of ultra-HF-WBI after breast-conserving surgery (BCS) for breast cancer in Japanese women.

METHOD

We plan to enroll 98 patients from 13 institutions. The primary endpoint is the proportion of late adverse events of grades ≥2 within 3 years.

DISCUSSION

We believe that this highly promising clinical study can positively impact the Japanese guidelines for breast cancer treatment. The results will help us decide whether or not ultra-HF-WBI can be used as a more convenient alternative to WBI.

REGISTRATION NUMBER AND DATE

This trial was registered in the UMIN Clinical Trials Registry (UMIN000047080) on March 4, 2022.

Evaluation of breast cosmetic changes with a computer-software; the breast cancer conservative treatment cosmetic results (BCCT. core) in hypofractionated whole breast irradiation after breast-conserving surgery-supplementary analysis of multicenter single-arm confirmatory trial: JCOG0906

BACKGROUND

A good cosmetic outcome has been defined as an important endpoint in breast-conserving therapy (BCT). Various evaluation methods have been studied, but the optimal method has yet to be identified. The present supplementary analysis of JCOG0906 focused on comparing evaluation methods for breast cosmetic outcomes following hypofractionated whole breast irradiation (HFWBI) to examine whether a computer-software (the Breast Cancer Conservative Treatment cosmetic results [BCCT. core])-based program evaluation (CE) can be used for Asian women in clinical trials of BCT.

METHODS

Of 306 women, 292 underwent institutional evaluation (IE) for breast cosmetic outcomes before (pre) and 3 years after (post) HFWBI using a 4-point scale (excellent/good/fair/poor), and they were evaluated by CE and a central panel evaluation (PE) on the same scale using 292 pairs of pre/post-HFWBI photographs. PE was performed twice by consensus of the same two experts with a 3-year interval. CE was assessed individually by two radiation oncologists, an expert and a non-expert. Intra-observer variability and inter-observer variability were calculated using the kappa (k) and weighted kappa (wk) statistics.

RESULTS

The agreement between the first and second PE using pre/post-HFWBI photographs was moderate (k = 0.60, wk = 0.64. k = 0.53, wk = 0.60). The agreement between the expert and non-expert on CE was substantial (k = 0.72, wk = 0.76. k = 0.72, wk = 0.77). The inter-observer variability of CE was smaller than the intra-observer variability of PE.

CONCLUSION

CE with BCCT. core was considered a reproducible and an appropriate evaluation method for Asian women in clinical trials of BCT, when breast cosmetic changes were compared between pre/post therapy.

Interstitial lung disorders following postoperative radiotherapy with concurrent or sequential hormonal therapy for breast cancer: a nationwide database study in Japan

BACKGROUND

Hormonal therapy and radiotherapy are conducted concurrently or sequentially after breast cancer surgery. It remains unclear whether concurrent or sequential treatment is safer in terms of lung complications. Using a Japanese nationwide database, this study aimed to compare the occurrence of severe lung complications between concurrent and sequential treatments.

METHODS

We identified patients who underwent partial mastectomy for stage 0-III breast cancer from July 2010 to March 2020 and received adjuvant hormonal therapy and radiotherapy concurrently (n = 1851) or sequentially (n = 18,429). Two propensity score analyses (1:4 matching and overlap weighting) were conducted to compare hospitalization for radiation pneumonitis and pneumonia within 1 year after surgery, and intensive care unit admission and mortality during the hospitalization. We conducted additional analyses stratified by hormonal drugs (aromatase inhibitors and tamoxifen).

RESULTS

The propensity score-matched analysis showed no significant differences in occurrence of hospitalization for radiation pneumonitis (0.27 vs. 0.58%, p = 0.10) and pneumonia (0.16 vs. 0.58%, p = 0.05) between the concurrent and sequential treatments. The overlap propensity score-weighted analysis also showed no significant differences (0.25 vs. 0.56%, p = 0.08 and 0.15 vs. 0.44%, p = 0.06, respectively). Intensive care unit admission and in-hospital mortality did not differ significantly between the two treatments. The stratified analysis showed similar results.

CONCLUSION

Our propensity score analyses revealed no significant differences in severe lung complications between concurrent and sequential hormonal therapy with radiotherapy following breast cancer surgery, regardless of the type of hormonal drugs. Clinicians can provide concurrent or sequential treatment with equivalent attention to early lung complications.

Final analysis of a Multicenter Single-Arm Confirmatory Trial of hypofractionated whole breast irradiation after breast-conserving surgery in Japan: JCOG0906

OBJECTIVE

To evaluate the safety and efficacy of hypofractionated whole breast irradiation for Asian women after breast-conserving surgery. This is an updated report with 5-year follow-up.

METHODS AND MATERIALS

Asian women who had invasive breast cancer with clinical tumor size ≤3 cm, pN0-1c and negative inked margins were enrolled. Hypofractionated whole breast irradiation of 42.56 Gy/16 fractions was delivered, and boost irradiation of 10.64 Gy/4 fractions was added when the surgical margin was ≤5 mm. The primary endpoint was the proportion of grade ≥ 2 late adverse reactions within 3 years. Secondary endpoints included early adverse events, overall survival, disease-free survival, ipsilateral breast relapse-free survival, late adverse reactions and cosmetic outcome. Toxicities were evaluated using CTCAE ver3.0. Cosmetic outcomes were assessed using a 4-point scale and CTCAE ver3.0 for hyper/hypopigmentation, breast nipple/areolar deformity and breast volume/deformity.

RESULTS

Between February 2010 and August 2012, 312 patients were enrolled, and 306 received hypofractionated whole breast irradiation. Median follow-up was 70.5 (range 7.6-88.9) months. The proportion of grade ≥ 2 late adverse reactions within 3 years was 4.3% (90% confidence interval 2.5-6.7%). Grade 2 early adverse events occurred in 38 (12.4%); none had grade 3/4. Five-year overall survival, disease-free survival and ipsilateral breast relapse-free survival were 98.7, 95.4 and 98.0%, respectively. Of the 304 evaluable patients, 29 (9.5%; 95% confidence interval 6.5-13.4%) had grade 2/3 late adverse reactions; none had grade 4/5. At 5 years, 70/289 (24.2%) showed any worsening of breast cosmetic changes.

CONCLUSIONS

Hypofractionated whole breast irradiation is considered a standard treatment for Asian women with margin-negative invasive breast cancer after breast-conserving surgery.

An overview of the medical-physics-related verification system for radiotherapy multicenter clinical trials by the Medical Physics Working Group in the Japan Clinical Oncology Group-Radiation Therapy Study Group

The Japan Clinical Oncology Group-Radiation Therapy Study Group (JCOG-RTSG) has initiated several multicenter clinical trials for high-precision radiotherapy, which are presently ongoing. When conducting multi-center clinical trials, a large difference in physical quantities, such as the absolute doses to the target and the organ at risk, as well as the irradiation localization accuracy, affects the treatment outcome. Therefore, the differences in the various physical quantities used in different institutions must be within an acceptable range for conducting multicenter clinical trials, and this must be verified with medical physics consideration. In 2011, Japan's first Medical Physics Working Group (MPWG) in the JCOG-RTSG was established to perform this medical-physics-related verification for multicenter clinical trials. We have developed an auditing method to verify the accuracy of the absolute dose and the irradiation localization. Subsequently, we credentialed the participating institutions in the JCOG multicenter clinical trials that were using stereotactic body radiotherapy (SBRT) for lungs, intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for several disease sites, and proton beam therapy (PT) for the liver. From the verification results, accuracies of the absolute dose and the irradiation localization among the participating institutions of the multicenter clinical trial were assured, and the JCOG clinical trials could be initiated.

Current status and comparison of national health insurance systems for advanced radiation technologies in Korea and Japan

PURPOSE

This study aimed to compare the current status of the national health insurance system (HIS) for advanced radiation technologies in Korea and Japan.

MATERIALS AND METHODS

The data of the two nations were compared according to the 2019 guidelines on the application and methods of medical care benefit from the Ministry of Health and Welfare of Korea and the 2020 medical fee points list set by the Ministry of Health, Labor and Welfare of Japan.

RESULTS

Both countries have adopted the social insurance system and the general payment system which is fee-for-service for radiotherapy. However, for proton and carbon ion therapy, the Japanese system has adopted a bundled payment system. Copayment for radiotherapy is 5% in Korea and 30% (7-69 years old) in Japan, with a ceiling system. A noticeable difference is that additional charges for hypofractionation, tele-radiotherapy planning for an emergency, tumor motion-tracking, purchase price of an isotope purchase price, and image-guided radiotherapy are allowed for reimbursement in the Japanese system. There are some differences regarding the indication, qualification standards, and facility standards for intensity-modulated radiation therapy, stereotactic body radiation therapy, and proton therapy.

CONCLUSION

Patterns of cancer incidence, use of radiotherapy and infrastructure, and national HIS are very similar between Korea and Japan. However, there are some differences in health insurance management systems for advanced radiation technologies.

Hypofractionated Versus Conventional Fractionated Radiotherapy After Breast-Conserving Surgery in the Modern Treatment Era: A Multicenter, Randomized Controlled Trial From China

PURPOSE

No randomized trials have compared hypofractionated radiotherapy (HFRT) with conventional fractionated radiotherapy (CFRT) after breast-conserving surgery in the Asian population. This study aimed to determine whether a 3.5-week schedule of HFRT is noninferior to a standard 6-week schedule of CFRT in China.

PATIENTS AND METHODS

Patients from 4 Chinese institutions who had undergone breast-conserving surgery and had T1-2N0-3 invasive breast cancers participated this study. Patients were randomly assigned (1:1) using a computer-generated central randomization schedule, without stratification, to receive whole-breast irradiation with or without nodal irradiation, followed by tumor-bed boost, either at a dose of 50 Gy in 25 fractions over 5 weeks with a boost of 10 Gy in five fractions over 1 week (CFRT) or 43.5 Gy in 15 fractions over 3 weeks with a boost of 8.7 Gy in three daily fractions (HFRT). The primary endpoint was 5-year local recurrence (LR), and a 5% margin of 5-year LR was used to establish noninferiority.

RESULTS

Between August 2010 and November 2015, 734 patients were assigned to the HFRT (n = 368) or CFRT (n = 366) group. At a median follow-up of 73.5 months (interquartile range, 60.5-91.4 months), the 5-year cumulative incidence of LR was 1.2% in the HFRT group and 2.0% in the CFRT group (hazard ratio, 0.62; 95% CI, 0.20 to 1.88; P = .017 for noninferiority). There were no significant differences in acute and late toxicities, except that the HFRT group had less grade 2-3 acute skin toxicity than the CFRT group (P = .019).

CONCLUSION

CFRT and HFRT with a tumor-bed boost may have similar low LR and toxicity.

Ipsilateral breast tumor control following hypofractionated and conventional fractionated whole-breast irradiation for early breast cancer: a long-term follow-up

PURPOSE

Long-term follow-up of Japanese women with breast cancer who underwent hypofractionated whole-breast irradiation (HF-WBI) has not been well documented. Therefore, we compared the treatment results of HF-WBI and conventional fractionated (CF)-WBI.

METHODS

Patients with stage 0-II breast cancer receiving partial mastectomy were eligible for this prospective observational study. The HF-WBI consisted of 43.2 Gy in 16 fractions to the whole breast, with an additional tumor-bed boost of 8.1 Gy in three fractions for patients with positive or less than 5 mm surgical margins. A total of 615 patients (400: HF-WBI and 215: CF-WBI) who were treated between 2006 and 2008 were investigated. Propensity score matching was conducted based on age, tumor grade, and margin status, and 372 matched cases were investigated for examining factors relating to intrabreast tumor recurrence (IBTR).

RESULTS

With a median follow-up period of 9.4 years, age and margin status were independent factors associated with IBTR occurrence (P = 0.006 and 0.016, respectively). The 10-year ipsilateral breast tumor control (IBTC) rates after HF-WBI and CF-WBI were 96.5% and 95.3%, respectively (P = 0.606). The 10-year IBTC rates according to margin status were 88.0% with positive margins, 94.9% with 5 mm margins, and 98.0% with negative margins (P = 0.014).

CONCLUSIONS

There was no difference in IBTC between CF-WBI and HF-WBI in our patients. Positive surgical margin was a risk factor independently associated with IBTC rates after CF-WBI and HF-WBI. Further investigation is required to establish adequate treatment strategies for patients with positive surgical margins.

A phase I/II trial of intraoperative breast radiotherapy in an Asian population: 10-year results with critical evaluation

Although phase III trials have been published comparing whole breast irradiation (WBI) with accelerated partial breast irradiation (APBI) using intraoperative radiotherapy (IORT), long-term follow-up results are lacking. We report the 10-year follow-up results of a prospective phase I/II clinical trial of IORT. The inclusion criteria were as follows: (i) tumor size <2.5 cm, (ii) desire for breast-conserving surgery, (iii) age >50 years, (iv) negative margins after resection and (v) sentinel lymph node-negative disease. A single dose of IORT (19-21 Gy) was delivered to the tumor bed in the operation room just after wide local excision of the primary breast cancer using a 6-12 MeV electron beam. Local recurrence was defined as recurrence or new disease within the treated breast and was evaluated annually using mammography and ultrasonography. A total of 32 patients were eligible for evaluation. The median patient age was 65 years and the median follow-up time was 10 years. Two patients experienced local recurrence just under the nipple, out of the irradiated field, after 8 years of follow-up. Three patients had contralateral breast cancer and one patient experienced bone metastasis after 10 years of follow-up. No patient experienced in-field recurrence nor breast cancer death. Eight patients had hypertrophic scarring at the last follow-up. There were no lung or heart adverse effects. This is the first report of 10-year follow-up results of IORT as APBI. The findings suggest that breast cancer with extended intraductal components should be treated with great caution.

The Japanese Breast Cancer Society Clinical Practice Guideline for radiation treatment of breast cancer, 2018 edition

PURPOSE

The Japanese Breast Cancer Society (JBCS) Clinical Practice Guideline was revised in 2018. This article describes the revise points in the section on radiation therapy (RT).

METHODS AND MATERIALS

The JBCS formed task force to update the JBCS Clinical Practice Guideline 2015 edition. Background questions (BQs) deal with standard treatments of breast cancer in clinical practice. Clinical questions (CQs) highlight the important treatments in which controversy remains. The task force for RT section addressed the 10 BQs, the 10 CQs, and the 4 Future reseach questions (FQs). For each CQ, systematic literature reviews and meta-analyses were conducted, and recommendations, strength of recommendation and strength of evidence were determined according to the protocol in Morizane et al. (Minds Handbook for Clinical Practice Guideline Development, 2014).

RESULTS

The recommendations, the strength of recommendation and the strength of evidence were determined based on the systematic literature reviews and the meta-analyses for each CQ.

CONCLUSION

The JBCS updated the Clinical Practice Guideline. RT represents a significant portion of the breast cancer treatment, and these recommendations regarding RT will be useful in individualized, shared decision making between physicians and patients.

Surgical excision and postoperative radiotherapy for keloids

Keloids can be treated in a number of ways, including by surgery. Multiple studies now show that while surgical monotherapy associates with extremely high rates of recurrence (50%-80%), postoperative radiotherapy can significantly reduce these recurrence rates. Ongoing improvements in radiation technology have further increased the safety and efficacy of this combination protocol. Of the various radiotherapies that have been used in this setting, electron beam (β-ray) irradiation is currently the best due to its excellent dose distribution and safety. The maximal biologically effective dose (BED) for keloids is 30 Gy (using an estimated α / β ratio of 10); increasing the dose has no further benefits and elevates side effects. Over the last two decades, we have modified and then fine-tuned our radiotherapy protocol for keloid excision wounds. Thus, our early protocol was used for all body sites and consisted of 15 Gy/3 fr/3 days. We then customised the radiotherapy protocol so that body sites that are highly prone to recurrence (e.g. the anterior chest) receive higher doses while low recurrence sites like the earlobe receive a much smaller dose. More recently, we tweaked this body site-customised protocol so that fewer fractions are employed. Therefore, we currently apply 18 Gy/3 fr/3 days to high-recurrence sites, 8 Gy/1 fr/1 day to earlobes and 15 Gy/2 fr/2 days to other body sites. These radiotherapy protocol changes were accompanied by the evolution of body site-customised surgical approaches. As a result of these developments, our overall keloid recurrence rate is now below 10%.