Phase 2 Trial of Accelerated, Hypofractionated Whole-Breast Irradiation of 39 Gy in 13 Fractions Followed by a Tumor Bed Boost Sequentially Delivering 9 Gy in 3 Fractions in Early-Stage Breast Cancer

A Comparison Between Sequential Conventional and Hypofractionated Boost Following Whole-Breast Radiotherapy: A Propensity Score-Matched Analysis

BACKGROUND

The majority of local relapses after breast conservation therapy occur in the proximity of the primary lesion. Studies have shown that boost radiotherapy (RT) following conventional whole-breast radiotherapy (WBRT) of 50 Gy in five weeks improves outcomes. Boost RT also increases the risk of moderate skin reactions and fibrosis. The ideal boost RT dose and timing (sequential versus simultaneous) after hypofractionated radiotherapy schedules remain unclear. This retrospective propensity score-matched analysis assessed the outcome of sequential hypofractionated boost compared to conventional fractionated boost.

METHODS

The study was approved by the Institutional Review Board of the Regional Cancer Centre, Thiruvananthapuram, India. Patients with stage I-III breast cancer who have received adjuvant radiotherapy with a sequential boost of either hypofractionated RT (8 Gy in three fractions) or conventional fractionated RT (10 Gy in five fractions) after conservative breast surgery were identified from the radiotherapy planning records and included in this study. A 1:1 case matching was performed using a propensity score incorporating four known prognostic factors, namely, clinical and pathological composite stage, tumor grade, tumor biology (based on estrogen and/or progesterone and HER2 neu expression), and boost technique, which may have an impact on acute toxicity to make the two boost groups more homogenous.

RESULTS

After propensity score matching (PSM), there were a total of 166 patients, with 83 patients each in both conventional and hypofractionated boost RT groups. The median follow-up period was 30.7 months. At two years, locoregional recurrence-free survival (LRFS) was 98.8% in both groups. Disease-free survival (DFS) at two years for the hypofractionated group and conventional group was 91.5% and 96.3% (hazard ratio (HR): 2.5, 95% confidence interval (CI): 0.664-9.4, p = 0.161), respectively, with no statistically significant difference. Patients with grade 3 tumors who received hypofractionated boost had a statistically significant increased risk of recurrence (DFS: 88.9% versus 100%, HR: 60.559, 95% CI: 0.138-26613.2, p = 0.011). The overall survival (OS) at two years was 100% in both groups. There was no difference in acute skin toxicity between the two groups.

CONCLUSION

The present interim analysis shows similar locoregional recurrence-free survival, overall survival, and disease-free survival and acute skin toxicity for hypofractionated boost RT of 8 Gy in three fractions compared to the conventional boost of 10 Gy in five fractions. Hypofractionated boost is a feasible alternative option following hypofractionated whole-breast radiotherapy for women with breast conservation treatment. However, longer follow-up is required before forming definite conclusions.

Hypofractionated whole breast irradiation in association with hypofractionated or normofractionated boost to the tumor bed in early breast cancer: tolerance and efficacy analysis

BACKGROUND

The boost to the tumor bed improves local control in breast cancer and it is an important part of the breast conserving therapy. However, information about the use of a hypofractionated boost is sparse, thus further studies are needed. We conducted a retrospective study with the aim of comparing hypofractionated boost (HB) and normofractionated boost (NB) on skin toxicity and local control.

MATERIALS AND METHODS

A total of 96 women with early breast cancer undergoing breast-conserving surgery and hypofractionated whole breast irradiation (WBI) were retrospectively analyzed divided into hypofractionated boost group and conventional fractionation boost group. Forty-nine patients were treated with NB with 16 Gy in 8 fractions and 47 patients were treated with HB with 13.35 Gy in 5 fractions. We examined acute and chronic toxicity with CTCAE version 5.

RESULTS

The median follow-up was 49.5 months (26-67). Median age was 57 years (36-82). Sixty-six patients (68.7%) were younger than 60 years at the time of boost and 30 (31.2%) were older than 60 years who received the boost due to poor prognostic factors. No differences were found between the two groups in terms of patient, tumor or treatment characteristics. Grade 2 acute skin toxicity was 6.3% in the NB group and 4.2% in the HB group. Chronic skin induration was 4.2% in the NB group and 1% in the HB group. They did not show grade 3 skin toxicity. There were also no differences in acute or late skin toxicity between the two groups. No local recurrences were evidenced.

CONCLUSIONS

Hypofractionated WBI associated with HB treatment is a viable option in the management of conservative breast therapy given the good tolerance and similar local control.

Early Toxicity and Patient-Reported Cosmetic Outcomes in Patients Treated With Adjuvant Proton-Based Radiotherapy After Breast-Conserving Surgery

INTRODUCTION

To evaluate the dosimetric data, early toxicity, and patient-reported cosmetic outcomes in breast cancer patients treated with adjuvant proton-based radiotherapy (RT) after breast-conserving surgery.

MATERIALS AND METHODS

We performed a retrospective review of our institutional database to identify breast cancer patients treated with breast-conserving surgery followed by proton-based RT from 2015 to 2020. Patient-reported cosmetic outcomes were graded as excellent, good, fair, or poor. Early toxicity outcomes were graded by the treating physician during treatment. Dose-volume histograms were reviewed to obtain dosimetry data.

RESULTS

We identified 21 patients treated with adjuvant proton-based RT. Median whole breast dose delivered was 46.8 Gy (range, 40.0-50.4 Gy). Target volumes included the regional lymph nodes in 17 patients (81%). Seventeen patients (81%) received a lumpectomy boost. The median planning target volume V95 was 94% (range, 77%-100%), V100 71% (range, 60%-97%), V110 2% (range 0%-18%), and median max point dose was 115% (range, 105%-120%). The median ipsilateral breast V105 was 367.3 cc (range, 0-1172 cc) and V110 was 24.1 cc (range, 0-321.3 cc). Grade 2 and 3 dermatitis occurred in 62% and 14% of patients, respectively. Grade 2 and 3 pain was reported by 33% and 10% of patients, respectively. Median follow-up at the time of cosmetic evaluation was 27 months (range, 5-42 months). Four patients (21%) reported fair cosmetic outcome and 15 patients (79%) reported good or excellent cosmetic outcome. No poor cosmesis was reported.

CONCLUSION

Adjuvant proton-based radiotherapy after breast-conserving surgery is well tolerated with acceptable rates of acute toxicities and a high rate of good-to-excellent patient-reported cosmetic outcomes.

The Role of Hypofractionation in Proton Therapy

Hypofractionated radiotherapy is an attractive approach for minimizing patient burden and treatment cost. Technological advancements in external beam radiotherapy (EBRT) delivery and image guidance have resulted in improved targeting and conformality of the absorbed dose to the disease and a reduction in dose to healthy tissue. These advances in EBRT have led to an increasing adoption and interest in hypofractionation. Furthermore, for many treatment sites, proton beam therapy (PBT) provides an improved absorbed dose distribution compared to X-ray (photon) EBRT. In the past 10 years there has been a notable increase in reported clinical data involving hypofractionation with PBT, reflecting the interest in this treatment approach. This review will discuss the reported clinical data and radiobiology of hypofractionated PBT. Over 50 published manuscripts reporting clinical results involving hypofractionation and PBT were included in this review, ~90% of which were published since 2010. The most common treatment regions reported were prostate, lung and liver, making over 70% of the reported results. Many of the reported clinical data indicate that hypofractionated PBT can be well tolerated, however future clinical trials are still needed to determine the optimal fractionation regime.

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.

Accelerated whole breast irradiation in early breast cancer patients with adverse prognostic features

Purpose

Accelerated whole breast irradiation (AWBI) and conventional whole breast irradiation (CWBI) were compared to determine whether AWBI is as effective as CWBI in patients with early breast cancer and adverse prognostic features.

Patients and methods

We included 330 patients who underwent breast-conserving surgery (BCS) and post-operative radiation therapy (RT) using AWBI for pT1-2 and pN0-1a breast cancer from 2007 to 2010. These patients were matched with 330 patients who received CWBI according to stage, age (±3 years), and the year of BCS. AWBI of 39 Gy and CWBI of 50.4 Gy were given in 13 and 28 fractions, respectively.

Results

Median follow-up time was 81.9 months. There were no statistically significant differences between the AWBI and CWBI groups in terms of age, stage, tumor grade, or molecular subtype. More patients with Ki-67 index ≥ 14% were present in the AWBI group (AWBI 47.0% vs. CWBI 10.3%; P<0.01). The 5-year ipsilateral breast tumor relapse (IBTR) rates for the AWBI and CWBI groups were 0.8% and 1.8%, respectively (P=0.54). High tumor grade was a statistically significant risk factor for IBTR (5-year IBTR rate: 2.9%; P=0.01). Ki-67 ≥ 14% was marginally related to IBTR (5-year IBTR rate: 2.2%; P=0.07). There were no statistically significant differences in the hazard ratios between the AWBI and CWBI groups according to any of the risk factors. There were no acute grade 3 toxicities in the AWBI group. There were no late grade 3 toxicities in either group.

Conclusions

AWBI is comparable to CWBI in early breast cancer with adverse prognostic features.

Hypofractionated whole breast irradiation: new standard in early breast cancer after breast-conserving surgery

Hypofractionated whole breast irradiation (HF-WBI) has been proved effective and safe and even better for late or acute radiation toxicity for early breast cancer. Moreover, it improves patient convenience, quality of life and is expected to be advantageous in the medical care system by reducing overall cost. In this review, we examined key randomized trials of HF-WBI, focusing on adequate patient selection as suggested by the American Society of Therapeutic Radiology and Oncology (ASTRO) guideline and the radiobiologic aspects of HF-WBI in relation to its adoption into clinical settings. Further investigation to identify the current practice pattern or cost effectiveness is warranted under the national health insurance service system in Korea.

A Comparative Study of Daily 3-Gy Hypofractionated and 1.8-Gy Conventional Breast Irradiation in Early-Stage Breast Cancer

We retrospectively compared accelerated hypofractionation (AHF) with conventional fractionation (CF) in the radiation therapy (RT) for early-stage breast cancer patients.Three hundred seventy-nine early-stage (pT1-2 and pN0-1a) breast cancer patients who received RT with AHF after breast-conserving surgery (BCS) were included. These patients were matched with 379 corresponding patients who received BCS and RT with CF at a different center with respect to the year BCS was performed, patient age (±3 years), and cancer stage. The AHF regimen consisted of 39 Gy in 13 fractions to the whole breast and a consecutive boost of 9 to 12 Gy in 3 to 4 fractions to the tumor bed. CF comprised whole-breast irradiation up to 50.4 Gy in 28 fractions and a boost of 9 to 14 Gy in 5 to 7 fractions to the tumor bed.The median follow-up period was 75 months (range, 3.8-110.8 months). There was no statistically significant difference between the AHF and CF groups in terms of age distribution, T and N stage, resection margin, and histologic grade. There were 5 ipsilateral breast tumor relapse (IBTR) cases in the AHF group compared with 7 cases in the CF group. Seven and eight locoregional relapse (LRR) cases were observed in the AHF and CF groups, respectively. The 7-year rates of IBTR-free survival, LRR-free survival, and disease-free survival were 98.9%, 98.4%, and 97.1% in the AHF group and 98.1%, 97.9%, and 96.0% in the CF group, respectively (P > 0.05). The incident rates of grade 3 edema, hyperpigmentation, or wet desquamation at the end of RT were higher in the CF group than in the AHF group (16.4% vs 0.2%, respectively; P < 0.01).AHF RT of 39 Gy to the whole breast plus a 9-Gy boost in 16 fractions showed excellent tumor control and tolerable skin toxicity, a finding that is comparable to CF RT in patients with early-stage breast cancer.

Hypofractionated radiotherapy for breast cancer acceleration of the START A treatment regime: intermediate tolerance and efficacy

Purpose

Prospective evaluation of accelerated hypofractionated radiotherapy (RT) in breast cancer patients treated with 41.6 Gy in 13 fractions plus boost delivered five times a week.

Patients and methods

Between 03/2009 and 10/2012 98 consecutive patients aged >55 years presenting with breast cancer (invasive cancer: n = 95, ductal carcinoma in situ (DCIS): n = 3) after breast conserving surgery were treated in our institution with the following schedule: 41.6 Gy in 13 fractions 4 times a week and 9 or 12 Gy boost in 3 or 4 fractions (on day 5 each week), cumulative dose: 50.6 Gy in 3.2 weeks or 53.6 Gy in 3.4 weeks, respectively depending on resection status. 56 patients had a T1 tumor, 39 a T2 tumor. N-status was as follows: N0: n = 71, N1: n = 25, N2/3: n = 2. 23 patients (24%) received chemotherapy before RT. A prospectively planned follow-up (FU) visit with objective and subjective assessment of treatment tolerance (questionnaires) was performed 0 and 8 weeks after RT completion, and one, two and four years later, respectively.

Results

Mean/median follow-up was 32/28 months (range: 12-56). After 2 years local control, loco-regional control and disease-free survival was 100%, 100%, and 98%, respectively. Overall survival was 96% at 2 years. Cosmetic outcome was very good with patients being satisfied or very satisfied in 99% (n = 86/87), 97% (n = 55/57) and 100% (n = 25/25) after one, two and four years after RT, respectively. No grade ≥ 2 pain was described in the 25 patients with a FU of at least 4 years. Fibrosis, telangiectasia and edema were found in 7-15%, 0-22% and 0-11% at one, two, and four years, respectively, and are comparable to other trials.

Conclusion

The applied hypofractionated RT regime with single doses of 3.2 Gy plus boost doses of 9-12 Gy in 3–4 fractions applied in 5 sessions a week was effective and well tolerated on intermediate term FU.