Acute toxicity and 2-year adverse effects of 30 Gy in five fractions over 15 days to whole breast after local excision of early breast cancer

One versus three weeks hypofractionated whole breast radiotherapy for early breast cancer treatment: the FAST-Forward phase III RCT

Background

FAST-Forward aimed to identify a 5-fraction schedule of adjuvant radiotherapy delivered in 1 week that was non-inferior in terms of local cancer control and as safe as the standard 15-fraction regimen after primary surgery for early breast cancer. Published acute toxicity and 5-year results are presented here with other aspects of the trial.

Design

Multicentre phase III non-inferiority trial. Patients with invasive carcinoma of the breast (pT1-3pN0-1M0) after breast conservation surgery or mastectomy randomised (1 : 1 : 1) to 40 Gy in 15 fractions (3 weeks), 27 Gy or 26 Gy in 5 fractions (1 week) whole breast/chest wall (Main Trial). Primary endpoint was ipsilateral breast tumour relapse; assuming 2% 5-year incidence for 40 Gy, non-inferiority pre-defined as < 1.6% excess for 5-fraction schedules (critical hazard ratio = 1.81). Normal tissue effects were assessed independently by clinicians, patients and photographs.

Sub-studies

Two acute skin toxicity sub-studies were undertaken to confirm safety of the test schedules. Primary endpoint was proportion of patients with grade ≥ 3 acute breast skin toxicity at any time from the start of radiotherapy to 4 weeks after completion. Nodal Sub-Study patients had breast/chest wall plus axillary radiotherapy testing the same three schedules, reduced to the 40 and 26 Gy groups on amendment, with the primary endpoint of 5-year patient-reported arm/hand swelling.

Limitations

A sequential hypofractionated or simultaneous integrated boost has not been studied.

Participants

Ninety-seven UK centres recruited 4096 patients (1361:40 Gy, 1367:27 Gy, 1368:26 Gy) into the Main Trial from November 2011 to June 2014. The Nodal Sub-Study recruited an additional 469 patients from 50 UK centres. One hundred and ninety and 162 Main Trial patients were included in the acute toxicity sub-studies.

Results

Acute toxicity sub-studies evaluable patients: (1) acute grade 3 Radiation Therapy Oncology Group toxicity reported in 40 Gy/15 fractions 6/44 (13.6%); 27 Gy/5 fractions 5/51 (9.8%); 26 Gy/5 fractions 3/52 (5.8%). (2) Grade 3 common toxicity criteria for adverse effects toxicity reported for one patient. At 71-month median follow-up in the Main Trial, 79 ipsilateral breast tumour relapse events (40 Gy: 31, 27 Gy: 27, 26 Gy: 21); hazard ratios (95% confidence interval) versus 40 Gy were 27 Gy: 0.86 (0.51 to 1.44), 26 Gy: 0.67 (0.38 to 1.16). With 2.1% (1.4 to 3.1) 5-year incidence ipsilateral breast tumour relapse after 40 Gy, estimated absolute differences versus 40 Gy (non-inferiority test) were -0.3% (-1.0-0.9) for 27 Gy (p = 0.0022) and -0.7% (-1.3-0.3) for 26 Gy (p = 0.00019). Five-year prevalence of any clinician-assessed moderate/marked breast normal tissue effects was 40 Gy: 98/986 (9.9%), 27 Gy: 155/1005 (15.4%), 26 Gy: 121/1020 (11.9%). Across all clinician assessments from 1 to 5 years, odds ratios versus 40 Gy were 1.55 (1.32 to 1.83; p < 0.0001) for 27 Gy and 1.12 (0.94-1.34; p = 0.20) for 26 Gy. Patient and photographic assessments showed higher normal tissue effects risk for 27 Gy versus 40 Gy but not for 26 Gy. Nodal Sub-Study reported no arm/hand swelling in 80% and 77% in 40 Gy and 26 Gy at baseline, and 73% and 76% at 24 months. The prevalence of moderate/marked arm/hand swelling at 24 months was 10% versus 7% for 40 Gy compared with 26 Gy.

Interpretation

Five-year local tumour incidence and normal tissue effects prevalence show 26 Gy in 5 fractions in 1 week is a safe and effective alternative to 40 Gy in 15 fractions for patients prescribed adjuvant local radiotherapy after primary surgery for early-stage breast cancer.

Future work

Ten-year Main Trial follow-up is essential. Inclusion in hypofractionation meta-analysis ongoing. A future hypofractionated boost trial is strongly supported.

Trial registration

FAST-Forward was sponsored by The Institute of Cancer Research and was registered as ISRCTN19906132.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 09/01/47) and is published in full in Health Technology Assessment; Vol. 27, No. 25. See the NIHR Funding and Awards website for further award information.

From 25 Fractions to Five: How Hypofractionation has Revolutionised Adjuvant Breast Radiotherapy

There is a sound empirical basis for hypofractionation in radiotherapy for breast cancer. This article reviews the radiobiological implications of hypofractionation in breast cancer derived from a series of clinical trials that began when 50 Gy in 25 fractions over 5 weeks was commonplace. These trials led first to 40 Gy in 15 fractions over 3 weeks and, subsequently, to 26 Gy in five fractions over 1 week being adopted as standards of care for many patients prescribed whole- or partial-breast radiotherapy after primary surgery.

Final Analysis of a Phase II Trial of Once Weekly Hypofractionated Whole Breast Irradiation for Early Stage Breast Cancer

INTRODUCTION

We hypothesized that five-fraction once weekly hypofractionated whole breast irradiation (WH-WBI) would be safe and effective following breast conserving surgery for medically underserved patients with breast cancer. We report the protocol-specified primary endpoint of in breast tumor recurrence (IBTR) at five years.

METHODS

After signing informed consent, patients were treated with WH-WBI after breast conserving surgery were followed prospectively on an IRB-approved protocol. Women included in this study had stage 0-II breast cancer treated with negative surgical margins and met pre-specified criteria for being underserved. WH-WBI was 28.5 or 30Gy delivered to the whole breast with no elective coverage of lymph nodes. The primary endpoint was IBTR at 5 years. Secondary endpoints were distant disease-free survival (DDFS), recurrence free survival (RFS), overall survival (OS), adverse events, and cosmesis.

RESULTS

158 patients received WH-WBI on protocol from 2010 to 2015. Median follow-up was 5.5 years (range, 0.2-10.0). Stage distribution was ductal carcinoma in situ (DCIS) 22%; invasive pN0 68%; invasive pN1 10%. 28% of patients had grade 3 tumors, 10% were estrogen receptor negative and 24% required adjuvant chemotherapy. There were six IBTR events. The 5-, 7- and 10-year risks of IBRT for all patients were 2.7% (95% CI 0.89-6.34), 4.7% (95% CI 1.4-11.0) and 7.2% (95% CI 2.4-15.8) respectively. The 5, 7 and 10-year rates of DDFS were 96.4, 96.4 and 86.4%, RFS were 95.8%, 93.6 and 80.7%, and OS were 96.7, 88.6 and 76.7%, respectively. Improvement in IBTR-free time was seen in DCIS, lobular histology, low-grade tumors, T1 stage, Her2 negative tumors and receipt of a radiation boost to the lumpectomy bed.

CONCLUSION

Postoperative WH-WBI had favorable disease-specific outcomes that were comparable to those seen with conventional and moderately hypofractionated radiation techniques. WH-WBI may improve access to care for underserved patients with stage 0-II breast cancer.

Weekly radiotherapy in elderly breast cancer patients: a comparison between two hypofractionation schedules

PURPOSE

Weekly irradiation in breast cancer in elderly patients is a treatment option, whose tolerance may be influenced by the fractionation used. The objective of this study is to compare the tolerance and long-term side effects of two different fractionations.

MATERIALS AND METHODS

47 elderly patients were recruited after conservative or radical treatment that also received irradiation with a dose per fraction of 6.25 Gy or 5 Gy for one session per week, 6 sessions in total. The long-term tolerance results are compared by assessing toxicity using CTCAE version 5.0 scales for dermatitis, telangectasia, fibrosis and pain of the irradiated breast. In addition, objective parameters of skin status (erythema, hyperpigmentation, elasticity and hydration) by a multi-probe MultiSkin Test-Center system were obtained and compared between groups.

RESULTS

After an average follow-up of 5 years, all patients were free of disease and with complete local control. A total of 20 patients with 6.25 Gy fractionation and 27 patients with 5 Gy fractionation have been included. Patients treated with lower fractionation had a lower incidence of dermatitis, telangectasia, fibrosis, or local pain. The decrease in elasticity measured by the multi-probe system was smaller with the fractionation of 5 Gy. No differences were observed in the other objective parameters.

CONCLUSION

Weekly irradiation with 5 Gy fractionation is better tolerated than with higher fractionation.

Does breast composition influence late adverse effects in breast radiotherapy?

BACKGROUND

Large breast size is associated with increased risk of late adverse effects after surgery and radiotherapy for early breast cancer. It is hypothesised that effects of radiotherapy on adipose tissue are responsible for some of the effects seen. In this study, the association of breast composition with late effects was investigated along with other breast features such as fibroglandular tissue distribution, seroma and scar.

METHODS

The patient dataset comprised of 18 cases with changes in breast appearance at 2 years follow-up post-radiotherapy and 36 controls with no changes, from patients entered into the FAST-Pilot and UK FAST trials at The Royal Marsden. Breast composition, fibroglandular tissue distribution, seroma and scar were assessed on planning CT scan images and compared using univariate analysis. The association of all features with late-adverse effect was tested using logistic regression (adjusting for confounding factors) and matched analysis was performed using conditional logistic regression.

RESULTS

In univariate analyses, no statistically significant differences were found between cases and controls in terms of breast features studied. A statistically significant association (p < 0.05) between amount of seroma and change in photographic breast appearance was found in unmatched and matched logistic regression analyses with odds ratio (95% CI) of 3.44 (1.28-9.21) and 2.57 (1.05-6.25), respectively.

CONCLUSIONS

A significant association was found between seroma and late-adverse effects after radiotherapy although no significant associations were noted with breast composition in this study. Therefore, the cause for large breast size as a risk factor for late effects after surgery and optimally planned radiotherapy remains unresolved.

Once-weekly hypofractionated breast irradiation: fool's gold or diamond in the rough?

Daily conventionally fractionated breast irradiation over 5-7 weeks is costly and inconvenient. Its use is associated with disparities in both the delivery of quality care and outcomes for vulnerable populations. Alternatively, daily hypofractionated breast irradiation delivered over 3 weeks exhibits equal efficacy and toxicity profiles. Today, a new generation of accelerated radiotherapy for breast cancer has emerged. Once-weekly hypofractionated breast irradiation has been tested in pilot and large randomized studies and the initial data appear promising. As the data mature, this new approach has implications for cost-efficacy and provision of radiotherapy services. The purpose of this review is to explore the evolution of once-weekly hypofractionated breast irradiation including our ongoing institutional clinical trial at the University of Louisville.

Hypofractionated radiation therapy for early stage breast cancer: outcomes, toxicities, and cost analysis

A French prospective randomized trial comparing whole breast radiotherapy with 45 Gy in 25 fractions versus 23 Gy in four fractions demonstrated equivalent 5-year local control and survival. On the basis of this data, we offer the hypofractionated regimen to women who refuse to undergo standard radiotherapy. We report our outcomes and a cost analysis. Between 2000 and 2012, 84 patients participated in this IRB-approved study and underwent whole breast radiation to 23 Gy in four fractions. Local control and survival were analyzed using the Kaplan-Meier method. Acute toxicities and overall long-term cosmetic results were assessed. Costs were estimated from 2012 Medicare reimbursement data and compared to costs from standard courses of 25 and 16 fractions. All 84 patients are included in this report. Median age was 83 (range 42-98). Most patients had stage I (80%), hormone receptor positive (90%) breast cancer. Fifty-eight patients (69%) were treated prone and 26 (31%) supine. At a median follow-up of 3 years, one local recurrence has occurred, of ductal carcinoma in situ histology. Among the 13 patients deceased, two died of metastatic breast cancer. Five-year actuarial local control is 99%, breast cancer-specific survival is 98%, and overall survival is 79%. Toxicities were limited to grade 1 dermatitis in 32 patients (38%) and grade 2 fatigue in three (4%). Sixty-three patients (75%) reported good or excellent cosmetic outcome at their last follow-up. Collected Medicare reimbursement was $4,798 for the hypofractionated course. Compared to the projected reimbursement of standard regimens, $10,372 for 25 fractions and $8,382 for 16 fractions, it resulted in a difference of $5,574 and $3,584, respectively. At a follow-up of 3 years, this hypofractionated regimen appears to be a promising approach, primarily for elderly women who are unable to undergo longer treatment courses but have indications for whole breast radiotherapy.

Adjuvant chemotherapy and acute toxicity in hypofractionated radiotherapy for early breast cancer

AIM: To evaluate the effect of chemotherapy to the acute toxicity of a hypofractionated radiotherapy (HFRT) schedule for breast cancer.

METHODS: We retrospectively analyzed 116 breast cancer patients with T1, 2N0Mx. The patients received 3-D conformal radiotherapy with a total physical dose of 50.54 Gy or 53.2 Gy in 19 or 20 fractions according to stage, over 23-24 d. The last three to four fractions were delivered as a sequential tumor boost. All patients were monitored for acute skin toxicity according to the European Organization for Research and Treatment of Cancer/Radiation Therapy Oncology Group criteria. The maximum monitored value was taken as the final grading score. Multivariate analysis was performed for the contribution of age, chemotherapy and 19 vs 20 fractions to the radiation acute skin toxicity.

RESULTS: The acute radiation induced skin toxicity was as following: grade I 27.6%, grade II 7.8% and grade III 2.6%. No significant correlation was noted between toxicity grading and chemotherapy (P = 0.154, χ² test). The mean values of acute toxicity score in terms of chemotherapy or not, were 0.64 and 0.46 respectively (P = 0.109, Mann Whitney test). No significant correlation was also noted between acute skin toxicity and radiotherapy fractions (P = 0.47, χ² test). According to univariate analysis, only chemotherapy contributed significantly to the development of acute skin toxicity but with a critical value of P = 0.05. However, in multivariate analysis, chemotherapy lost its statistical significance. None of the patients during the 2-years of follow-up presented any locoregional relapse.

CONCLUSION: There is no clear evidence that chemotherapy has an impact to acute skin toxicity after an HFRT schedule. A randomized trial is needed for definite conclusions.

A phase 2 trial of once-weekly hypofractionated breast irradiation: first report of acute toxicity, feasibility, and patient satisfaction

PURPOSE

To report on early results of a single-institution phase 2 trial of a 5-fraction, once-weekly radiation therapy regimen for patients undergoing breast-conserving surgery (BCS).

METHODS AND MATERIALS

Patients who underwent BCS for American Joint Committee on Cancer stage 0, I, or II breast cancer with negative surgical margins were eligible to receive whole breast radiation therapy to a dose of 30 Gy in 5 weekly fractions of 6 Gy with or without an additional boost. Elective nodal irradiation was not permitted. There were no restrictions on breast size or the use of cytotoxic chemotherapy for otherwise eligible patients. Patients were assessed at baseline, treatment completion, and at first posttreatment follow-up to assess acute toxicity (Common Terminology Criteria for Adverse Events, version 3.0) and quality of life (European Organization for Research and Treatment of Cancer QLQ-BR23).

RESULTS

Between January and September 2011, 42 eligible patients underwent weekly hypofractionated breast irradiation immediately following BCS (69.0%) or at the conclusion of cytotoxic chemotherapy (31.0%). The rates of grade ≥2 radiation-induced dermatitis, pain, fatigue, and breast edema were 19.0%, 11.9%, 9.5%, and 2.4%, respectively. Only 1 grade 3 toxicity-pain requiring a course of narcotic analgesics-was observed. One patient developed a superficial cellulitis (grade 2), which resolved with the use of oral antibiotics. Patient-reported moderate-to-major breast symptoms (pain, swelling, and skin problems), all decreased from baseline through 1 month, whereas breast sensitivity remained stable over the study period.

CONCLUSIONS

The tolerance of weekly hypofractionated breast irradiation compares well with recent reports of daily hypofractionated whole-breast irradiation schedules. The regimen appears feasible and cost-effective. Additional follow-up with continued accrual is needed to assess late toxicity, cosmesis, and disease-specific outcomes.

Breast radiotherapy: less is more?

A 3 week schedule of whole breast radiotherapy is firmly established in the UK and is becoming more accepted internationally, especially as accelerated partial breast radiotherapy regimens become more common. It seems that a 3 week schedule is unlikely to be the lower limit of whole breast hypofractionation and the partial breast may even be adequately treated with just a single treatment. It is, however, essential that these hypotheses are rigorously tested within well-designed trials to ensure the highest quality of radiotherapy. This overview will address the rationale for hypofractionation in breast cancer, discuss past trials and outline the design of current studies.

Abbreviated course of radiotherapy (RT) for breast cancer

The use of RT as a component of breast-conserving therapy or after mastectomy has been proven to reduce the risk of local-regional recurrence (LRR) and to improve long-term breast cancer-specific and overall survival. As has been the common practice in the United States and Continental Europe, the majority of studies that demonstrated these benefits utilized daily radiation doses ranging from 1.8-2 Gray (Gy). However, due to geographic limitations, patient preferences and financial considerations, there have been continued attempts to evaluate the efficacy and toxicity of abbreviated courses of breast RT. Two key factors in these attempts have been: (1) advances in radiobiology allowing for a more precise estimation of equivalent dosing; and (2) advances in the delivery of RT that have resulted in substantially improved dose homogeneity in the target volume. As an alternative to approximately five weeks of daily treatment at 1.8-2 Gy, delivering radiobiologically-equivalent total doses in hypofractionated, abbreviated schedules has been evaluated in five randomized controlled trials, as well as many prospective and retrospective experiences. These studies have generally demonstrated equivalent rates of LRR, disease-free survival and overall survival with the use of hypofractionated regimens. Despite theoretical and historic concerns that hypofractionated regimens could increase damage to normal tissue, the rates of acute and long-term toxicities have generally not been increased in most recent series. Some toxicities, however, may take years to decades to manifest. Questions still remain regarding which patients are appropriate for abbreviated treatment. The majority of patients included in the studies supporting hypofractionated treatment were of older age with early-stage invasive ER+ disease of predominantly lower histological grade. This favorable subset of patients is also the most eligible for other alternative treatment approaches, such as partial-breast irradiation or hormonal therapy alone. Additionally, few to none of the patients included in most studies were treated with mastectomy, lymph node irradiation, a lumpectomy cavity radiation boost, or adjuvant chemotherapy. The existing evidence prompted the American Society for Radiation Oncology (ASTRO) to convene a task force to issue an evidence-based guideline in 2010 delineating the patients for whom an abbreviated radiation course is most supported by the current evidence [Smith et al. 2010, Int J Radiat Oncol Biol Phys]. Ongoing and future studies will further clarify the suitability of a hypofractionated treatment approach for the patient subgroups underrepresented in available trials. Additionally, alternative abbreviated treatment regimens, including those in which treatment is given once weekly and treatments that include an integrated lumpectomy cavity boost, are actively being investigated. Finally, innovative radiation techniques, such as the use of higher energies, prone treatment, and breathing-adapted therapy have further increased the homogeneity of breast irradiation and minimized dose delivered to nearby critical normal structures. Consequently, increasing experience with these techniques may expand the population of patients amenable to hypofractionated therapy.

First results of the randomised UK FAST Trial of radiotherapy hypofractionation for treatment of early breast cancer (CRUKE/04/015)

BACKGROUND AND PURPOSE

Randomised trials testing 15- or 16-fraction regimens of adjuvant radiotherapy in women with early breast cancer have reported favourable outcomes compared with standard fractionation. To evaluate hypofractionation further, two 5-fraction schedules delivering 1 fraction per week have been tested against a 25-fraction regimen.

MATERIALS AND METHODS

Women aged ⩾50years with node negative early breast cancer were randomly assigned after microscopic complete tumour resection to 50Gy in 25 fractions versus 28.5 or 30Gy in 5 once-weekly fractions of 5.7 or 6.0Gy, respectively, to the whole breast. The primary endpoint was 2-year change in photographic breast appearance.

RESULTS

Nine hundred and fifteen women were recruited from 2004 to 2007. Seven hundred and twenty-nine patients had 2-year photographic assessments. Risk ratios for mild/marked change were 1.70 (95% CI 1.26-2.29, p<0.001) for 30Gy and 1.15 (0.82-1.60, p=0.489) for 28.5Gy versus 50Gy. Three-year rates of physician-assessed moderate/marked adverse effects in the breast were 17.3% (13.3-22.3%, p<0.001) for 30Gy and 11.1% (7.9-15.6%, p=0.18) for 28.5Gy compared with 9.5% (6.5-13.7%) after 50Gy. With a median follow-up in survivors of 37.3months, 2 local tumour relapses and 23 deaths have occurred.

CONCLUSIONS

At 3years median follow-up, 28.5Gy in 5 fractions is comparable to 50Gy in 25 fractions, and significantly milder than 30Gy in 5 fractions, in terms of adverse effects in the breast.

Preliminary safety and efficacy results of laser immunotherapy for the treatment of metastatic breast cancer patients

We report our preliminary results of a pilot clinical trial of late-stage breast cancer patients treated by laser immunotherapy (LIT), a local intervention using an 805 nm laser for non-invasive irradiation, indocyanine green for selective thermal effect, and immunoadjuvant (glycated chitosan) for immunological stimulation. Ten breast cancer patients were enrolled in this study; all patients were considered to be out of other available treatment options. Toxicity was individually evaluated through physical exams and laboratory tests. Adverse reactions only occurred in the area of treatment due to photothermal injury and local administration of immunoadjuvant. No grade 3 or 4 side effects were observed. Treatment efficacy of LIT was also evaluated by physical examination and tomography. In 8 patients available for evaluation, the objective response rate was 62.5% and the clinical beneficial response rate was 75%. While the study is still ongoing, the initial outcomes of this clinical trial show that LIT is well tolerated and is promising in the treatment of metastatic breast cancer.

Hypofractionated breast radiotherapy: financial and economic consequences

A large amount of clinical evidence has recently accumulated supporting the efficacy and safety of hypofractionated radiotherapy for post-operative breast cancer. These schedules, typically delivering a lower total dose in fewer, but larger than 2 Gy fractions, are more convenient for the patients by limiting the number of treatment attendances. Moreover, the reduced resource use in terms of personnel and machine time is advantageous for radiotherapy departments and translates into lower treatment costs. In order to formally validate this therapeutic approach from a societal perspective, however, cost-effectiveness evaluations weighing long-term outcome against the societal costs incurred until many years after treatment are needed.

Hypofractionated radiotherapy in the treatment of early breast cancer

Radiotherapy (RT) after tumorectomy in early breast cancer patients is an established treatment modality which conventionally takes 6-7 wk to complete. Shorter RT schedules have been tested in large multicentre randomized trials and have shown equivalent results to that of standard RT (50 Gy in 25 fractions) in terms of local tumor control, patient survival and late post-radiation effects. Some of those trials have now completed 10 years of follow-up with encouraging results for treatments of 3-4 wk and a total RT dose to the breast of 40-42.5 Gy with or without boost. A reduction of 50% in treatment time makes those RT schedules attractive for both patients and health care providers and would have a significant impact on daily RT practice around the world, as it would accelerate patient turnover and save health care resources. However, in hypofractionated RT, a higher (than the conventional 1.8-2 Gy) dose per fraction is given and should be managed with caution as it could result in a higher rate of late post-radiation effects in breast, heart, lungs and the brachial plexus. It is therefore advisable that both possible dose inhomogeneity and normal tissue protection should be taken into account and the appropriate technology such as three-dimensional/intensity modulated radiation therapy employed in clinical practice, when hypofractionation is used.

Accelerated partial breast irradiation with IMRT: new technical approach and interim analysis of acute toxicity in a phase III randomized clinical trial

PURPOSE

To evaluate with a randomized clinical trial the possibility of treating the index quadrant with external intensity-modulated radiotherapy (IMRT) in a selected group of patients with early-stage breast cancer and to analyze the acute toxicity.

METHODS AND MATERIALS

From September 2005, a randomized Phase III clinical trial has been conducted to compare conventional (tangential field) fractionated whole breast treatment (Arm A) with accelerated partial breast irradiation plus intensity-modulated radiotherapy (Arm B). For intensity-modulated radiotherapy, the clinical target volume was drawn with a uniform 1-cm margin around the surgical clips in three dimensions. The ipsilateral and contralateral breast, ipsilateral and contralateral lung, heart, and spinal cord were contoured as organs at risk. All the regions of interest were contoured according to the International Commission on Radiation Units and Measurements reports 50 and 62 recommendations.

RESULTS

In September 2008, 259 patients were randomized and treated. The mean clinical target volume in Arm B was 44 cm(3) and the mean planning target volume was 123 cm(3). The mean value of the ratio between the planning target volume and the ipsilateral breast volume was 21%. The rate of Grade 1 and Grade 2 acute skin toxicity was 22% and 19% in Arm A (Radiation Therapy Oncology Group scale), respectively. The tolerance in Arm B was excellent with only 5% Grade 1 and 0.8% Grade 2 acute skin toxicity. The planning constraints were fully satisfied in most patients. In a very few cases, this was not possible because of very unfavorable anatomy. Quality assurance procedures were performed according to our internal quality assurance protocol, with excellent results.

CONCLUSION

In the present preliminary analysis, we have demonstrated that accelerated partial breast irradiation is feasible, with very low acute toxicity.

Biologically effective dose-response relationship for breast cancer treated by conservative surgery and postoperative radiotherapy

PURPOSE

To find a biologically effective dose (BED) response for adjuvant breast radiotherapy (RT) for initial-stage breast cancer.

METHODS AND MATERIALS

Results of randomized trials of RT vs. non-RT were reviewed and the tumor control probability (TCP) after RT was calculated for each of them. Using the linear-quadratic formula and Poisson statistics of cell-kill, the average initial number of clonogens per tumor before RT and the average tumor cell radiosensitivity (alpha-value) were calculated. An alpha/beta ratio of 4 Gy was assumed for these calculations.

RESULTS

A linear regression equation linking BED to TCP was derived: -ln[-ln(TCP)] = -ln(No) + alpha(*) BED = -4.08 + 0.07 (*) BED, suggesting a rather low radiosensitivity of breast cancer cells (alpha = 0.07 Gy(-1)), which probably reflects population heterogeneity. From the linear relationship a sigmoid BED-response curve was constructed.

CONCLUSION

For BED values higher than about 90 Gy(4) the radiation-induced TCP is essentially maximizing at 90-100%. The relationship presented here could be an approximate guide in the design and reporting of clinical trials of adjuvant breast RT.

Hypofractionated radiotherapy for breast cancer patients treated by breast-conserving surgery: short-term morbidity and preliminary results

BACKGROUND

Hypofractionated adjuvant radiotherapy (RT) in breast cancer patients treated by conservative surgery has been increasingly used in recent years. We present our experience regarding tolerance/acute toxicity of a hypofractionated RT schedule.

METHODS AND MATERIALS

We report on 339 patients treated for 4 years (March 2003-2007) by 42.5 Gy/16 fractions at the RT Department of Larissa University Hospital. Electron boost of 9-10 Gy/3-4 fractions was given to 104/339 (31%). Axillary/supraclavicular RT was given to the node-positive patients with the same fractionation schedule. Median follow-up time was 24 months.

RESULTS

RTOG grades 0, 1, 2, 3, and 4 for acute skin toxicity were 9.7, 68.7, 17.5, 4, and 0.3%, respectively. Radiation pneumonitis (resolved promptly by steroids) was suspected/diagnosed in 11/339 (3.2%). A total of 8/11 had been treated by regional lymphatics RT. In the univariate analysis, the following variables were examined as predictive of skin (grade >1) and lung (any grade) reactions: age, chemotherapy, endocrine treatment, RT of regional lymphatics, and boost RT. The only significant correlation was that of radiation pneumonitis and RT of regional lymphatics (Fisher's exact test, P = 0.000).

CONCLUSION

Our current results are similar to those from other centers, although they need to be evaluated for a longer time. This fractionation seems to be effective with acceptable side effects, while it facilitates the treatment for both patients and RT centers.