Radiation therapy of the primary tumour and oligometastatic sites in patients with breast cancer with synchronous metastases: A literature review

De novo metastatic breast cancer represents 5 to 8% of all breast cancers (2500 new cases per year in France). Systemic treatment is the cornerstone of treatment, whereas radiation therapy usually has a palliative intent. Advances in systemic and local treatments (surgery and radiation therapy) have substantially improved overall survival. In the recent breast cancer statistics in the United States, the 5-year relative survival for patients diagnosed during 2012-2018 was 29% for stage IV (Breast Cancer Statistics). Thus, an increasing proportion of metastatic breast cancers present a prolonged complete response to systemic therapy, which raises the question of the impact of local treatment on patient survival. Radiation therapy has shown its value for early breast cancer, but its place in the local management of the primary tumour or oligometastatic sites for de novo metastatic breast cancer remains under debate. This article is a literature review assessing the role of radiation therapy directed to the primary tumour and oligometastatic sites of breast cancer in patients with synchronous metastases, in order to highlight clinicians in their therapeutic decision.

[Predictive factors assessment of pathological response to neoadjuvant radiotherapy of soft tissue sarcomas]

PURPOSE

Conserving surgery combined with radiotherapy in presence of local recurrence risk factors is standard treatment of soft tissue sarcomas, a group of rare and heterogeneous tumours. Radiotherapy is performed before or after surgery. In neoadjuvant setting, late radiation-induced toxicity is reduced and pathological response to radiotherapy could be achieved. A complete pathological response to radiotherapy has recently been shown to predict better survival. Our study aims at identifying predictive factors of pathological response to neoadjuvant radiotherapy (clinical, radiological or histological) of soft tissue sarcomas.

PATIENTS AND METHODS

Clinical, imaging (MRI: perilesional oedema, necrosis, tumour heterogeneity, vasculonervous relationships) and pathological (pathological subtype, tumour grade, anticipated/obtained resection quality) data were retrospectively collected. Tumour response (imaging and pathological), patient outcome, acute and late radiation-induced toxicity, predictive factors of pathological response to neoadjuvant radiotherapy were studied. The 2-test or exact-Fisher test (qualitative variables) and by Student's t-test or Kruskal-Wallis test (quantitative variables) were used for statistical analysis.

RESULTS

From April 2017 to April 2021, neoadjuvant radiotherapy (50Gy in 25 fractions) followed by surgical excision was performed to 36 consecutive patients with liposarcomas (n=17/36), or undifferentiated sarcomas (n=8/36). MRI response was complete in 1 patient, partial in 9 patients (n=9/36, 25%), stable in 21 patients (n=21/36, 58%) or in progression in 5 patients (n=5/36, 14%). Pathological response was observed in 22 patients (61%). No grade 3-4 acute radiation-induced toxicity was observed. Regarding late toxicity, 28% of patients had grade 1-2 oedema (n=10/36), 39% had a grade 1 fibrosis (n=14/36), and 30% grade 1 pain (n=11/36). No predictive factors of response to radiotherapy was statistically significant.

CONCLUSIONS

Neoadjuvant radiotherapy is well-tolerated. No clinical, radiological or pathological predictive factors was identified for radiotherapy tumour response.

CANTO: Skin Toxicities Evaluation of a Multicenter Large Prospective Cohort of Irradiated Patients for Early-Stage Breast Cancer

PURPOSE/OBJECTIVE(S)

Skin damage is a common toxicity during oncology management. Its assessment and understanding of the factors influencing its occurrence, is a major issue in the management of patients treated for an early breast cancer (BC).

MATERIALS/METHODS

CANTO (NCT01993498) is a prospective, multicentric, clinical cohort study of 11 400 patients with stage I-III BC, treated in 26 French cancer centers. In this study, we will evaluate the 8561 patients during their overall management for a BC. We are focus on specifical skin toxicities: Erythema, fibrosis, telangiectasia and skin color (CTCAE v4.0). These toxicities were assessed at 3-6 (M0), 12 (M12), 36 (M36), 60 (M60) months.

RESULTS

The prevalence of toxicities of interest varied over time, so at M0, 30.4% of patients had erythema while 17.7% of patients had fibrosis. At M12, M36 and M60, the prevalence of erythema decreased from 5.5 % to 2.5 % then to 2 %, respectively, while fibrosis remained stable at about 19 %. The prevalence of telangiectasia increased from 0.8 % to 7 % from M0 to M60. While the modification of skin color was 51.1 % at M0, and 10.6 % at M60. After adjustments, at M0, there was a statistically significant association between the onset of cutaneous erythema and obesity, the presence of axillary dissection, the type of surgery the age of the patient as well as the tumor phenotype RH+/HER2+ [OR: 0.79 [0.67; 0.93]]. Concerning fibrosis, a statistically significant association was found, at M12, with the age of the patient, obesity, tumor grade, Charlson score, type of surgery and mitotic index. Obesity and the age of the patient represent at M12 and M36 a risk significantly associated with the onset of telangiectasia. Concerning the modification of skin color at M12, we find a link between the age of the patient, obesity, tobacco consumption, tumor grade, Charlson score, type of surgery, and alcohol consumption [OR: 0.69 [0.51; 0.91]].

CONCLUSION

In this study we identified several risk factors for acute and late skin toxicity. The knowledge of its predictive factors allows a personalized management of the patient by adapting our treatments and our monitoring according to these different factors.

Genome-wide association study of treatment-related toxicity two years following radiotherapy for breast cancer

BACKGROUND AND PURPOSE

Up to a quarter of breast cancer patients treated by surgery and radiotherapy experience clinically significant toxicity. If patients at high risk of adverse effects could be identified at diagnosis, their treatment could be tailored accordingly. This study was designed to identify common single nucleotide polymorphisms (SNPs) associated with toxicity two years following whole breast radiotherapy.

MATERIALS AND METHODS

A genome-wide association study (GWAS) was performed in 1,640 breast cancer patients with complete SNP, clinical, treatment and toxicity data, recruited across 18 European and US centres into the prospective REQUITE cohort study. Toxicity data (CTCAE v4.0) were collected at baseline, end of radiotherapy, and annual follow-up. A total of 7,097,340 SNPs were tested for association with the residuals of toxicity endpoints, adjusted for clinical, treatment co-variates and population substructure.

RESULTS

Quantile-quantile plots showed more associations with toxicity above the p < 5 × 10-5 level than expected by chance. Eight SNPs reached genome-wide significance. Nipple retraction grade ≥ 2 was associated with the rs188287402 variant (p = 2.80 × 10-8), breast oedema grade ≥ 2 with rs12657177 (p = 1.12 × 10-10), rs75912034 (p = 1.12 × 10-10), rs145328458 (p = 1.06 × 10-9) and rs61966612 (p = 1.23 × 10-9), induration grade ≥ 2 with rs77311050 (p = 2.54 × 10-8) and rs34063419 (p = 1.21 × 10-8), and arm lymphoedema grade ≥ 1 with rs643644 (p = 3.54 × 10-8). Heritability estimates across significant endpoints ranged from 25% to 39%. Our study did not replicate previously reported SNPs associated with breast radiation toxicity at the pre-specified significance level.

CONCLUSIONS

This GWAS for long-term breast radiation toxicity provides further evidence for significant association of common SNPs with distinct toxicity endpoints.

Early Results of the French Multicenter, Randomized SHARE Trial Comparing Whole Breast Irradiation vs. Accelerated Partial Breast Irradiation in Postmenopausal Women with Early-Stage Breast Cancer

PURPOSE/OBJECTIVE(S)

The aim is to report toxicity and cosmetic outcomes at 3 and up to 9 years of follow-up of post-menopausal patients randomized to receive either standard whole breast irradiation (WBI), including hypofractionated options, versus accelerated partial breast irradiation (APBI).

MATERIALS/METHODS

From December 2010 to July 2015, 1006 patients were enrolled in 34 French centers. Among the whole population, 28 patients who did not meet the final selection criteria or withdrew consent were excluded leading to a modified intention to treat analysis dataset of 978 patients (WBI: n = 488; APBI: n = 490). Median age (65y) and tumor stage pT1 (99%) rates were similar in both arms. Patients had conservative surgery with clip placement in the tumor bed. Clear margins (> 2mm) were observed in 99% of the patients. In both arms, 96-97% of the patients had negative sentinel lymph node biopsy. The median time interval between surgery and radiotherapy was 57d in WBI vs 62d in APBI. WBI schedules consisted of 50 Gy in 25 fr+16 Gy (n = 212) or 40 Gy in 15 fr (n = 156) or 42.5 Gy in 16 fr (n = 120). APBI arm consisted of 38.5 Gy or 40 Gy in 10 fr, 2 fr/day. Overall, 94 patients from the APBI arm finally received standard WBI. For statistical considerations, SHARE trial, sponsored by UNICANCER (NCT01247233) is a non-inferiority randomized controlled trial comparing APBI versus WBI in terms of local control as primary objective. Secondary endpoints were severe toxicity (NCI-CTCAE v4 grade ≥ 2), and cosmetic results. For both outcomes, we estimated the cumulative incidences (CI) using Kalbfleish and Prentice method, considering disease relapse, secondary cancer or death as competing events. Treatment effect (APBI vs WBI) was estimated by cause-specific Hazard Ratios (cs-HR) from Cox models.

RESULTS

Median follow-up was 5.8y (range, 0.13-9.5). The number of deaths was 27, and the number of local relapses was 8. Among the 978 patients, 582 and 396 had finally WBI and APBI, respectively. The rates of post-operative hematoma, edema and infection were low: 8-9%, 2%, 3-2%, respectively. When considering any type of severe toxicity, we observed a significant reduction rate in APBI compared to WBI: cs-HR = 0.73 (95% confidence interval: 0.61-0.88); p = 0.001, and 3-year CI of severe toxicity at 45% in WBI vs 36% in APBI arm. The difference was also in favor of APBI when considering breast skin toxicity alone: cs-HR = 0.55 (0.44-0.70), p<0.001 and 3-year CI at 36% in WBI vs 21% in APBI arm. Conversely, for breast other toxicities, WBI was found less toxic than APBI with a 3-year CI of 8% vs 15%, respectively. When considering cosmetic results, we observed no significant difference between the two arms in both evaluations by physicians and patients.

CONCLUSION

Historically SHARE is the first APBI trial that included hypofractionated schedules in the standard arm. We report increased risk of severe toxicity and skin breast toxicity in standard arm as compared with APBI arm without any difference in terms of cosmetic results. Longer follow-up is needed.

Economic evaluation and budget-impact of accelerated partial breast irradiation (APBI) versus standard or hypofractionated whole breast irradiation (WBI) in postmenopausal women with early-stage breast cancer. Results from the French SHARE randomized trial

PURPOSE

This economic evaluation reports the incremental cost-utility ratio and national budget impact in France of accelerated partial breast irradiation (APBI) vs standard or hypofractionated whole breast irradiation (WBI) in breast cancer patients at low risk of local recurrence.

MATERIALS AND METHODS

We compared 490 women randomized to the APBI (ten fractions delivered twice daily over one week) with 488 women in the WBI arm (one fraction per day delivered five days per week over three or six weeks). We took the perspective of the French national health insurance with a three-year time horizon. The outcome was quality-adjusted life years (QALYs). The incremental cost-effectiveness ratio was estimated and uncertainty was explored by probabilistic bootstrapping. Transportation and sick leave costs were added in a sensitivity analysis and a national budget impact analysis based on the incidence of breast cancer estimates in France performed.

RESULTS

At three years, the average cost per patient was €2,549 (±1,954) in the APBI arm and €4,468 (±1,586) in the WBI arm (p-value < 0.001), radiotherapy was the main driver of the difference between the two arms. No significant difference was found in QALYs. For an average of 60,000 new cases of breast cancer diagnosed annually in France, 28,000 would be eligible for treatment with APBI. A 100% uptake of APBI would result in a yearly30 million€ cost saving.

CONCLUSION

APBI for the treatment of postmenopausal women with early-stage breast cancer is cost saving, with no difference in outcome measured by QALYs.

[Breast cancer radiation therapy: Current questions in 2023]

Radiation therapy is a corner stone of breast cancer treatment as it has been shown postoperatively that it improves local control and overall survival. In recent years, multidisciplinary therapeutic strategies have evolved considerably for early-stage breast cancer, both surgically and in terms of systemic treatments or radiation therapy. Each of these developments affects other treatment components and open up new questions allowing even more personalized treatments. Essentially normofractionated a few years ago, breast radiation therapy is today very largely moderately or even ultra hypofractionated. De-escalation of the surgery of the axilla has changed the indications for lymph node radiation therapy keeping similar efficacy with reduced toxicity. Indications for radiation therapy after neoadjuvant chemotherapy remain based on pre-chemotherapy staging pending the results of ongoing randomized studies. The addition of a boost to the tumor bed significantly reduces the risk of local recurrence, but the magnitude of this benefit decreases with increasing age. The main risk factors for local recurrence are young age, the associated extended ductal in situ component, hormone receptor negative and high-grade status. The results of the simultaneous integrated boost (SIB) seem similar with normo- or moderately hypofractionated radiation therapy regimen.

Comparison of prone and supine positioning for breast cancer radiotherapy using REQUITE data: dosimetry, acute and two years physician and patient-reported outcomes

OBJECTIVE

Most patients receive whole breast radiotherapy in a supine position. However, two randomised trials showed lower acute toxicity in prone position. Furthermore, in most patients, prone positioning reduced doses to the organs at risk. To confirm these findings, we compared toxicity outcomes, photographic assessment, and dosimetry between both positions using REQUITE data.

METHODS

REQUITE is an international multi-centre prospective observational study that recruited 2069 breast cancer patients receiving radiotherapy. Data on toxicity, health-related quality of life (HRQoL), and dosimetry were collected, as well as a photographic assessment. A matched case control analysis compared patients treated prone (n = 268) versus supine (n = 493). Exact matching was performed for the use of intensity-modulated radiotherapy, boost, lymph node irradiation, chemotherapy and fractionation, and the nearest neighbour for breast volume. Primary endpoints were dermatitis at the end of radiotherapy, and atrophy and cosmetic outcome by photographic assessment at two years.

RESULTS

At the last treatment fraction, there was no significant difference in dermatitis (p = .28) or any HRQoL domain, but prone positioning increased the risk of breast oedema (p < .001). At 2 years, patients treated in prone position had less atrophy (p = .01), and higher body image (p < .001), and social functioning (p < .001) scores. The photographic assessment showed no difference in cosmesis at 2 years (p = .22). In prone position, mean heart dose (MHD) was significantly lower for left-sided patients (1.29 Gy vs 2.10 Gy, p < .001) and ipsilateral mean lung dose (MLD) was significantly lower for all patients (2.77 Gy vs 5.89 Gy, p < .001).

CONCLUSIONS

Prone radiotherapy showed lower MLD and MHD compared to supine position, although the risk of developing breast oedema during radiotherapy was higher. At 2 years the photographic assessment showed no difference in the cosmetic outcome, but less atrophy was seen in prone-treated patients and this seems to have a positive influence on the HRQoL domain of body image.

[Radiation therapists shortage in France: Organizational consequences and difficulties in deploying new missions and/or tasks delegation]

PURPOSE

Radiation therapists shortage has been evaluated at national level in France, specifically in oncology radiotherapy, in terms of: (i) organizational adaptations, (ii) impact on patients care, and (iii) difficulties in deploying new missions and/or tasks delegation.

MATERIALS AND METHODS

French professional organisations representing radiation therapists - SFRO, SNRO and AFPPE - sent their members a national survey (ten questions on 32 items).

RESULTS

From 18 November 2022 to 31 December 2022, 55 responses were received (response rate: 31%) from radiotherapy managers or department heads; 51% had a structure comprising three to five treatment rooms (receiving 500 to 1000 patients per year [36%], or 1500 to 2000 patients per year [33%]). Activities performed were intensity-modulated radiotherapy (100%), stereotaxic radiotherapy (85%), brachytherapy (40%), adaptive radiotherapy (34%). These structures described consequences in closing machine time for 25% of them (reduction of the hourly volume greater than 10% in 57%) with the following consequences in the last 6 months: (i) an extension of the period of medical care (78%), a closing of one or more accelerators (50%) and the development of moderate hypofractionation scheme or extreme hypofractionation (50%). In current functioning, linear accelerators can deliver treatments with a team of two radiation therapists per room for a short day (43%) or two to four radiation therapists per room teams for a long day (40%). During the last 6 months, there has been a 10% increase in linear accelerators operating with a single team. (ii) regarding treatment planning: 16.4% reported a decrease in the opening amplitude (less than 20% in 44% of cases, from 20 to 50% in 33 % of cases). The initial scheduling of appointments for radiotherapy sessions was carried out by radiation therapists in 84% of the departments in current functioning (0.1 to 1 FTE dedicated to this activity in 62% of the departments). Over the last 6 months, there has been a clear reduction in the number of dedicated FTEs: [FTE=0.1 to 1]=-8%; [FTE=0]=+7%. (ii) Regarding tasks delegation (excluding the decree on acts and activities carried out by the radiation therapist): organ at risk delineation is partially performed by radiation therapist in 26% of the centres; caregiver support time in 78% (56% totally or 22% partially). This activity has been reduced by 42%. Seventy-five percent of departments want to develop new techniques, patient-centered approaches (44%), implement task delegation (organ at risk delineation: 58%; weekly consultations: 67%; positioning imaging validation: 71%), and 78% of departments are interested in developing advanced radiotherapy practice. However, the number of radiation therapists is considered insufficient in their implementation in 76% of cases (one to two FTE missing for 72% of structures).

CONCLUSION

This survey shows a significant impact of radiation therapist shortage in radiotherapy oncology care (treatment delays, access to caregiver support time, workload on treatment teams), and represents a major obstacle to the development of radiotherapy structures.

Radiation-induced lung injury after breast cancer treatment: incidence in the CANTO-RT cohort and associated clinical and dosimetric risk factors

Purpose

Radiation-induced lung injury (RILI) is strongly associated with various clinical conditions and dosimetric parameters. Former studies have led to reducing radiotherapy (RT) doses to the lung and have favored the discontinuation of tamoxifen during RT. However, the monocentric design and variability of dosimetric parameters chosen have limited further improvement. The aim of our study was to assess the incidence of RILI in current practice and to determine clinical and dosimetric risk factors associated with RILI occurrence.

Material and methods

Data from 3 out of the 10 top recruiting centers in CANTO-RT, a subset of the CANTO prospective longitudinal cohort (NCT01993498), were retrospectively analyzed for RILI occurrence. This cohort, which recruited invasive cT0-3 cN0-3 M0 breast cancer patients from 2012 to 2018, prospectively recorded the occurrence of adverse events by questionnaires and medical visits at the end of, and up to 60 months after treatment. RILI adverse events were defined in all patients by the association of clinical symptoms and compatible medical imaging.

Results

RILI was found in 38/1565 (2.4%) patients. Grade II RILI represented 15/38 events (39%) and grade III or IV 2/38 events (6%). There were no grade V events. The most frequently used technique for treatment was 3D conformational RT (96%). In univariable analyses, we confirmed the association of RILI occurrence with pulmonary medical history, absence of cardiovascular disease medical history, high pT and pN, chemotherapy use, nodal RT. All dosimetric parameters were highly correlated and had close predictive value. In the multivariable analysis adjusted for chemotherapy use and nodal involvement, pulmonary medical history (OR=3.05, p<0.01) and high V30 Gy (OR=1.06, p=0.04) remained statistically significant risk factors for RILI occurrence. V30 Gy >15% was significantly associated with RILI occurrence in a multivariable analysis (OR=3.07, p=0.03).

Conclusion

Our study confirms the pulmonary safety of breast 3D RT in CANTO-RT. Further analyses with modern radiation therapy techniques such as IMRT are needed. Our results argue in favor of a dose constraint to the ipsilateral lung using V30 Gy not exceeding 15%, especially in patients presenting pulmonary medical history. Pulmonary disease records should be taken into account for RT planning.

The 2022 Assisi Think Tank Meeting: White paper on optimising radiation therapy for breast cancer

The present white paper, referring to the 4th Assisi Think Tank Meeting on breast cancer, reviews state-of-the-art data, on-going studies and research proposals. < 70% agreement in an online questionnaire identified the following clinical challenges: 1: Nodal RT in patients who have a) 1-2 positive sentinel nodes without ALND (axillary lymph node dissection); b) cN1 disease transformed into ypN0 by primary systemic therapy and c) 1-3 positive nodes after mastectomy and ALND. 2. The optimal combination of RT and immunotherapy (IT), patient selection, IT-RT timing, and RT optimal dose, fractionation and target volume. Most experts agreed that RT- IT combination does not enhance toxicity. 3: Re-irradiation for local relapse converged on the use of partial breast irradiation after second breast conserving surgery. Hyperthermia aroused support but is not widely available. Further studies are required to finetune best practice, especially given the increasing use of re-irradiation.

Different meaning of the mean heart dose between 3D-CRT and IMRT for breast cancer radiotherapy

Background

Previous studies in 2D and in 3D conformal radiotherapy concludes that the maximal heart distance and the mean heart dose (MHD) are considered predictive of late cardiac toxicities. As the use of inverse-planned intensity modulated radiation therapy (IMRT) is increasing worldwide, we hypothesized that this 3D MHD might not be representative of heart exposure after IMRT for breast cancer (BC).

Methods

Patients with left-sided BC and unfavorable cardiac anatomy received IMRT. Their treatment plan was compared to a virtual treatment plan for 3D conformal radiotherapy with similar target volume coverage (study A). Then, a second 3D conformal treatment plan was generated to achieve equivalent individual MHD obtained by IMRT. Then the heart and left anterior descending (LAD) coronary artery exposures were analyzed (study B). Last, the relationship between MHD and the heart volume or LAD coronary artery volume receiving at least 30Gy, 40Gy and 45Gy in function of each additional 1Gy to the MHD was assessed (study C).

Results

A significant decrease of heart and LAD coronary artery exposure to high dose was observed with the IMRT compared with the 3D conformal radiotherapy plans that both ensured adequate target coverage (study A). The results of study B and C showed that 3D MHD was not representative of similar heart substructure exposure with IMRT, especially in the case of high dose exposure.

Conclusions

The mean heart dose is not a representative dosimetric parameter to assess heart exposure following IMRT. Equivalent MHD values following IMRT and 3DRT BC treatment do not represent the same dose distribution leading to extreme caution when using this parameter for IMRT plan validation.

Treatment time and circadian genotype interact to influence radiotherapy side-effects. A prospective European validation study using the REQUITE cohort

BACKGROUND

Circadian rhythm impacts broad biological processes, including response to cancer treatment. Evidence conflicts on whether treatment time affects risk of radiotherapy side-effects, likely because of differing time analyses and target tissues. We previously showed interactive effects of time and genotypes of circadian genes on late toxicity after breast radiotherapy and aimed to validate those results in a multi-centre cohort.

METHODS

Clinical and genotype data from 1690 REQUITE breast cancer patients were used with erythema (acute; n=340) and breast atrophy (two years post-radiotherapy; n=514) as primary endpoints. Local datetimes per fraction were converted into solar times as predictors. Genetic chronotype markers were included in logistic regressions to identify primary endpoint predictors.

FINDINGS

Significant predictors for erythema included BMI, radiation dose and PER3 genotype (OR 1.27(95%CI 1.03-1.56); P < 0.03). Effect of treatment time effect on acute toxicity was inconclusive, with no interaction between time and genotype. For late toxicity (breast atrophy), predictors included BMI, radiation dose, surgery type, treatment time and SNPs in CLOCK (OR 0.62 (95%CI 0.4-0.9); P < 0.01), PER3 (OR 0.65 (95%CI 0.44-0.97); P < 0.04) and RASD1 (OR 0.56 (95%CI 0.35-0.89); P < 0.02). There was a statistically significant interaction between time and genotypes of circadian rhythm genes (CLOCK OR 1.13 (95%CI 1.03-1.23), P < 0.01; PER3 OR 1.1 (95%CI 1.01-1.2), P < 0.04; RASD1 OR 1.15 (95%CI 1.04-1.28), P < 0.008), with peak time for toxicity determined by genotype.

INTERPRETATION

Late atrophy can be mitigated by selecting optimal treatment time according to circadian genotypes (e.g. treat PER3 rs2087947C/C genotypes in mornings; T/T in afternoons). We predict triple-homozygous patients (14%) reduce chance of atrophy from 70% to 33% by treating in mornings as opposed to mid-afternoon. Future clinical trials could stratify patients treated at optimal times compared to those scheduled normally.

FUNDING

EU-FP7.

Radiotherapy of breast cancer

Adjuvant radiotherapy is an essential component of the treatment of breast cancer. After conservative surgery for an infiltrating carcinoma, radiotherapy must be systematically performed, regardless of the characteristics of the disease, because it decreases the rate of local recurrence and by this way, specific mortality. A boost dose over the tumour bed is required if the patient is younger than 50 years-old. Partial breast irradiation could be routinely proposed as an alternative to whole breast irradiation, but only in selected and informed patients. For ductal carcinoma in situ, adjuvant radiotherapy must be also systematically performed after lumpectomy. After mastectomy, chest wall irradiation is required for pT3-T4 tumours and if there is an axillary nodal involvement, whatever the number of involved lymph nodes. After neoadjuvant chemotherapy and mastectomy, in case of pN0 disease, chest wall irradiation is recommended if there is a clinically or radiologically T3-T4 or node positive disease before chemotherapy. Axillary irradiation is recommended only if there is no axillary surgical dissection and a positive sentinel lymph node. Supra- and infraclavicular irradiation is advised in case of positive axillary nodes. Internal mammary irradiation must be discussed case by case, according to the benefit/risk ratio (cardiac toxicity). Hypofractionation regimens (42.5Gy in 16 fractions, or 41,6Gy en 13 or 40Gy en 15) are equivalent to conventional irradiation and must prescribe after tumorectomy in selected patients. Delineation of the breast, the chest wall and the nodal areas are based on clinical and radiological evaluations. 3D-conformal irradiation is the recommended technique, intensity-modulated radiotherapy must be proposed only in specific clinical situations. Respiratory gating could be useful to decrease the cardiac dose. Concomitant administration of chemotherapy in unadvised, but hormonal treatment could be start with or after radiotherapy.

Quality assurance program and early toxicities in the phase III BONBIS randomized trial evaluating the role of a localized radiation boost in ductal carcinoma in situ

PURPOSE

To describe the quality assurance (QA) program and early toxicities in the phase III randomized trial BONBIS (NCT00907868) on the role of a localized radiation boost in ductal carcinoma in situ (DCIS).

MATERIALS AND METHODS

From November 2008 to July 2014, 2004 patients were randomized in arm A (only whole breast radiotherapy, WBRT) and arm B (WBRT + boost). The QA program involved 44 participant centers that performed the dummy run (DR). Compliance and uniformity of clinical target volume (CTV) delineations, and dose prescription and delivery according to the BONBIS trial radiotherapy guidelines were analyzed. Acute toxicities (during and up to 3 months after radiotherapy completion, NCI-CTCAE v3.0 classification) were evaluated in 1929 patients.

RESULTS

The differences in whole breast CTV (CTV1) and planning target volume (PTV1) were ≤10%, and the differences in boost CTV (CTV2) and PTV (PTV2) were ≥20% compared with the reference DR values; 95% of the prescribed dose encompassed 98.7% and 100% of the median CTV1 and CTV2. Grade ≥2 breast erythema (38.3% vs. 22.4% of grade 2 and 5.4% vs. 2.1% of grade 3, p < 0.001), grade ≥2 dermatitis (2.8% vs. 0.7%, p < 0.001), and grade 2 hyperpigmentation (6.9% vs. 3.6%, p = 0.005) were more frequent in arm B than arm A. No acute lung or cardiac toxicity was observed. Smoking history, large breast size, and large breast CTV were strong predictive factors of grade ≥2 acute skin toxicities.

CONCLUSIONS

The QA program showed deviations in breast and tumor bed delineation. The boost significantly increased acute skin toxicities.

Radio-induced cardiotoxicity: From physiopathology and risk factors to adaptation of radiotherapy treatment planning and recommended cardiac follow-up

Cancer and cardiovascular disease (CVD) are the leading cause of mortality worldwide, and breast cancer (BC) the most common malignancy affecting women worldwide. Radiotherapy is an important component of BC treatment and participates in CVD occurrence. It seems, therefore, crucial to gather both radiation oncology and cardiology medical fields to improve the follow-up quality of our BC patients. This review aims at updating our knowledge regarding cardiotoxicities risk factors, and consequently, doses constraints in case of 3D-conformal and IMRT treatment planning. Then we will develop how to reduce cardiac exposure and what kind of cardiac follow-up we could recommend to our breast cancer patients.

[Treatment of primary disease with irradiation in case of de novo metastatic breast cancer]

Synchronous metastatic breast cancer accounts for 5 to 6% of all breast cancers in Western countries, which corresponds to nearly 2500 new cases per year in France. Irradiation of the primary tumour in cases of metastatic disease at diagnosis was historically reserved for palliative indications. However, progress in systemic treatments, a better understanding of the biological basis of metastatic dissemination, the genesis of the concept of oligometastatic disease and ablative treatments directed towards metastases are revolutionizing the management of patients with de novo stage IV breast cancer. Survival of these patients has improved markedly over the years, and several studies have investigated the carcinological benefit of local treatment of the breast tumour in patients with advanced diseases at diagnosis. This article provides an update on the role of irradiation of the primary tumour in breast cancer with synchronous metastases, and discusses its interest through published or ongoing trials.

Intraoperative partial irradiation for highly selected patients with breast cancer: Results of the INTRAOBS prospective study

PURPOSE

To evaluate our long-term experience on one-day breast intraoperative radiotherapy (IORT) given as sole radiation treatment to selected patients with breast cancer.

METHODS AND MATERIALS

Inclusion criteria of INTRAOBS study (prospective observational study) were: ER+ T1N0 unifocal ductal carcinoma; absence of lymphovascular invasion or of extensive intraductal component (Scarff-Bloom-Richardson grade III and HER2+++ excluded). Two different linacs were used (20Gy/1 fraction): one dedicated electron linac (<October 2011), and afterwards a mobile linac (50kV photons). The primary endpoint was the local recurrence rate (=ipsilateral breast cancer recurrences number). Secondary endpoints were recurrence-free survival (RFS), overall and specific survival, cosmetic results, and patient satisfaction.

RESULTS

Of the present pre-planned analysis for the first 200 patients (median age: 68 years; range, 59-87 years) who received IORT between January 2010 and October 2014 (median follow-up of 53.4 months). A total of 193 patients were still alive. The local recurrence rate was 2.5% (n=5). The 1- and 5-year local RFS rates were 100% and 95.2%, respectively. At 12 months post-surgery, satisfaction about IORT was excellent for 86.9% of patients. Cosmetic results were considered by patients and physicians as good or very good in 89.4% and 97.3% of cases, respectively.

CONCLUSIONS

IORT for selected patients with breast cancer shows low recurrence rates, good cosmetic outcomes and excellent satisfaction.

[From fibrogenesis towards fibrosis: Pathophysiological mechanisms and clinical presentations]

Fibrogenesis is a universal and ubiquitous process associated with tissue healing. The impairment of tissue homeostasis resulting from the deregulation of numerous cellular actors, under the effect of specific cytokine and pro-oxidative environments can lead to extensive tissue fibrosis, organ dysfunction and significant morbidity and mortality. This situation is frequent in internal medicine, since fibrosis is associated with most organ insufficiencies (i.e. cardiac, renal, or hepatic chronic failures), but also with cancer, a condition with common pathophysiological mechanisms. Finally, fibrosis is a hallmark of numerous systemic autoimmune diseases such as connective tissue disorders (in particular systemic sclerosis), vasculitides, granulomatoses, histiocytoses, and IgG4-associated disease. Although the process leading to tissue fibrosis may be in part irreversible, new pharmacological approaches or cell therapies bring hope in the field of fibrotic conditions.

Five-Year Results of the Preoperative Accelerated Partial Breast Irradiation (PAPBI) Trial

PURPOSE

In this multicenter phase 2 feasibility study, we investigated the impact of preoperative accelerated partial breast irradiation (PAPBI) on local control, breast fibrosis, and cosmetic outcome.

METHODS AND MATERIALS

Women aged >60 years with an invasive, unifocal (mammography and magnetic resonance imaging), nonlobular adenocarcinoma of the breast were treated with PAPBI. Six weeks after radiation therapy, a wide local excision was performed. Radiation therapy consisted of 10 × 4 Gy (2010-2013) or 5 × 6 Gy (after 2013) to the tumor (gross target volume) with a 25 mm margin (20 mm from gross target volume to clinical target volume, 5 mm planning target volume).

RESULTS

One hundred thirty-three patients treated between 2010 and 2016 were analyzed with a median follow-up of 5.0 years (0.9-8.8 years). Seventy-eight (59%) patients were treated with 10 × 4 Gy in 2 weeks and 55 (41%) patients with 5 × 6 Gy in 1 week. Eighteen postoperative complications (14%) occurred in 15 patients (11%). The proportion of patients with no to mild fibrosis in the treated part of the breast at 2 years and later time points was around 90%. Cosmesis improved over time in several patients: excellent to good cosmetic score as rated by the physician was 68% at 6 months and 92% at 5 years. Seventy-seven percent (6 months) to 82% (5 years) of patients were "satisfied" or "very satisfied" with their cosmetic outcome. Three recurrences were detected in the biopsy track and 1 recurrence in the ipsilateral breast.

CONCLUSIONS

PAPBI is a feasible method with a low postoperative complication rate, limited fibrosis, and good to excellent cosmetic outcome. The local recurrence rate was 3% at 5 years; however, no local recurrences were observed since removal of the needle biopsy track.

REQUITE: A prospective multicentre cohort study of patients undergoing radiotherapy for breast, lung or prostate cancer

PURPOSE

REQUITE aimed to establish a resource for multi-national validation of models and biomarkers that predict risk of late toxicity following radiotherapy. The purpose of this article is to provide summary descriptive data.

METHODS

An international, prospective cohort study recruited cancer patients in 26 hospitals in eight countries between April 2014 and March 2017. Target recruitment was 5300 patients. Eligible patients had breast, prostate or lung cancer and planned potentially curable radiotherapy. Radiotherapy was prescribed according to local regimens, but centres used standardised data collection forms. Pre-treatment blood samples were collected. Patients were followed for a minimum of 12 (lung) or 24 (breast/prostate) months and summary descriptive statistics were generated.

RESULTS

The study recruited 2069 breast (99% of target), 1808 prostate (86%) and 561 lung (51%) cancer patients. The centralised, accessible database includes: physician- (47,025 forms) and patient- (54,901) reported outcomes; 11,563 breast photos; 17,107 DICOMs and 12,684 DVHs. Imputed genotype data are available for 4223 patients with European ancestry (1948 breast, 1728 prostate, 547 lung). Radiation-induced lymphocyte apoptosis (RILA) assay data are available for 1319 patients. DNA (n = 4409) and PAXgene tubes (n = 3039) are stored in the centralised biobank. Example prevalences of 2-year (1-year for lung) grade ≥2 CTCAE toxicities are 13% atrophy (breast), 3% rectal bleeding (prostate) and 27% dyspnoea (lung).

CONCLUSION

The comprehensive centralised database and linked biobank is a valuable resource for the radiotherapy community for validating predictive models and biomarkers.

PATIENT SUMMARY

Up to half of cancer patients undergo radiation therapy and irradiation of surrounding healthy tissue is unavoidable. Damage to healthy tissue can affect short- and long-term quality-of-life. Not all patients are equally sensitive to radiation "damage" but it is not possible at the moment to identify those who are. REQUITE was established with the aim of trying to understand more about how we could predict radiation sensitivity. The purpose of this paper is to provide an overview and summary of the data and material available. In the REQUITE study 4400 breast, prostate and lung cancer patients filled out questionnaires and donated blood. A large amount of data was collected in the same way. With all these data and samples a database and biobank were created that showed it is possible to collect this kind of information in a standardised way across countries. In the future, our database and linked biobank will be a resource for research and validation of clinical predictors and models of radiation sensitivity. REQUITE will also enable a better understanding of how many people suffer with radiotherapy toxicity.

[Individual modification of the dose, volume and fractionation of breast radiotherapy]

Randomized trials demonstrated similar overall survival between mastectomy and breast-conservative surgery followed by adjuvant radiation therapy. Breast-conservative surgery, with adjuvant radiation therapy, with or without neoadjuvant systemic therapy has become the standard of care for women with early or locally advanced breast cancer. Nevertheless, certain cardiac, lung or cutaneous toxicities may alter the long-term body image and the quality of life of a limited number of patients who consider having had "overtreatment" or treatment outside the best knowledge of science. In case of low-risk breast cancer, several trials have evaluated the carcinologic outcome in absence of radiation therapy after breast-conservative surgery. Local recurrences increased in case of breast-conservative surgery alone but without impact on overall survival. Multiple debates have emerged in order to select the most appropriate evaluation criteria. Finally, a large consensus has considered that reducing local recurrences is important but with modern technologies and after identifying patients of individual radiosensitivity. Indeed, in case of a low absolute risk of local recurrence, radiation therapy techniques have been developed to allow a focal treatment especially for patients with high risk of developing late effects. This kind of compromise takes into account the reduction risk of local recurrences but also the probability of developing radiation-induced cutaneous sequelae. In the same way, for patients considered at high risk of recurrence, the huge volumes need specific techniques to better cover the targets while protecting the surrounding critic organs such as heart and lung. Intensity-modulated radiation therapy and the local high boost may help to decrease local recurrences of these more extended and aggressive diseases while considering the individual radiosensitivity that paves the way of long-term sequelae. In this article, we detail a personalized approach of breast radiation therapy considering the absolute risk of local recurrences and the probability of radiation-induced toxicity appearance.

ESTRO ACROP consensus guideline for target volume delineation in the setting of postmastectomy radiation therapy after implant-based immediate reconstruction for early stage breast cancer

Immediate breast reconstruction (IBR) rates after mastectomy are increasing. Postmastectomy radiation therapy (PMRT) contouring guidelines for target volumes in the setting of IBR are lacking. Therefore, many patients who have had IBR receive PMRT to target volumes similar to conventional simulator-based whole breast irradiation. The aim of this paper is to describe delineation guidelines for PMRT after implant-based IBR based on a thorough understanding of the surgical procedures, disease stage, patterns of recurrence and radiation techniques. They are based on a consensus endorsed by a global multidisciplinary group of breast cancer experts.

The Assisi Think Tank Meeting Survey of post-mastectomy radiation therapy in ductal carcinoma in situ: Suggestions for routine practice

BACKGROUND

Risk factors for local recurrence after mastectomy in ductal carcinoma in situ (DCIS) emerged as a grey area during the second "Assisi Think Tank Meeting" (ATTM) on Breast Cancer.

AIM

To review practice patterns of post-mastectomy radiation therapy (PMRT) in DCIS, identify risk factors for recurrence and select suitable candidates for PMRT.

METHODS

A questionnaire concerning DCIS management, focusing on PMRT, was distributed online via SurveyMonkey.

RESULTS

142 responses were received from 15 countries. The majority worked in academic institutions, had 5-20 years work-experience and irradiated <5 DCIS patients/year. PMRT was more given if: surgical margins <1 mm, high-grade, multicentricity, young age, tumour size >5 cm, skin- or nipple- sparing mastectomy. Moderate hypofractionation was the most common schedule, except after immediate breast reconstruction (57% conventional fractionation).

CONCLUSIONS

The present survey highlighted risk factors for PMRT administration, which should be further evaluated.

Partial versus whole breast irradiation: Side effects, patient satisfaction and costs

PURPOSE

Since accelerated partial breast irradiation has demonstrated non-inferiority to whole breast irradiation regarding recurrence rate in patients with early stage breast cancer, our objective was to compare its impact on short-term adverse events, patient satisfaction and costs.

MATERIALS AND METHODS

Patients with early stage breast cancer treated by breast-conserving surgery between 2007 and 2012 were included: 48 women who received three-dimensional conformal accelerated partial breast irradiation in a multicentre phase-II trial were paired with 48 patients prospectively treated with whole breast irradiation. Adverse events, and patients' opinions concerning cosmesis, satisfaction and pain, were gathered 1 month after treatment. Direct and indirect costs were collected from the French National Health Insurance System perspective until the end of radiotherapy.

RESULTS

When comparing its impact, skin reactions occurred in 37% of patients receiving three-dimensional conformal accelerated partial breast radiotherapy and 60% of patients receiving whole breast irradiation (P=0.07); 98% were very satisfied in the group three-dimensional conformal accelerated partial breast radiotherapy versus 46% in the group treated with whole breast irradiation (P<0.001); direct costs were significantly lower in the group treated with partial breast irradiation (mean cost: 2510€ versus 5479€/patient), due to less radiation sessions.

CONCLUSION

In patients with early-stage breast cancer, partial irradiation offered a good alternative to whole breast irradiation, as it was less expensive and satisfactory. These, and the clinical safety and tolerance results, need to be confirmed by long-term accelerated partial breast irradiation results in on-going phase III trials.

Pravastatin Reverses Established Radiation-Induced Cutaneous and Subcutaneous Fibrosis in Patients With Head and Neck Cancer: Results of the Biology-Driven Phase 2 Clinical Trial Pravacur

PURPOSE

The "PRAVACUR" phase 2 trial (NCT01268202) assessed the efficacy of pravastatin as an antifibrotic agent in patients with established cutaneous and subcutaneous radiation-induced fibrosis (RIF) after head and neck squamous cell carcinoma (HNSCC) radiation therapy and/or radiochemotherapy.

METHODS AND MATERIALS

The main inclusion criteria were: NSCC in remission, grade ≥2 cutaneous and subcutaneous neck RIF (National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0), and no current treatment with statins or fibrates. Patients received pravastatin 40 mg/d for 12 months. The primary endpoint was reduction of RIF thickness by more than 30% at 12 months, as measured by cutaneous high-frequency ultrasonography. Secondary endpoints included RIF severity reduction, pravastatin tolerance, and quality of life.

RESULTS

Sixty patients with grade 2 (n = 37), grade 3 (n = 22), or grade 4 (n = 1) RIF were enrolled from February 2011 to April 2016. The mean interval between RIF diagnosis and pravastatin initiation was 17.1 months. Pravastatin was stopped before 11 months of treatment in 18 patients (because of grade ≥2 adverse events related to pravastatin in 8 patients [13%]). In the 40 patients in whom pravastatin efficacy was assessed by high-frequency ultrasonography at baseline and at 12 months of treatment, a reduction of RIF thickness ≥30% was observed in 15 of 42 patients (35.7%; 95% confidence interval, 21.6%-52.0%). At the 12-month clinical evaluation, RIF severity was decreased in 50% of patients (n = 21; 95% confidence interval, 34.2%-65.8%), and the patients' self-perception, mood state, and social functioning were significantly improved. Pravastatin was well tolerated, with a very low occurrence of grade 3 toxicities (myalgia, n = 1) and grade 2 toxicities (myalgia/arthralgia or esophagitis, n = 3).

CONCLUSIONS

This phase 2 prospective study supports the notion of radioinduced fibrosis reversibility. It showed that pravastatin (40 mg/d for 12 months) is an efficient antifibrotic agent in patients with grade ≥2 cutaneous and subcutaneous fibrosis after HNSCC radiation therapy.

[The major debate: Micrometastases and breast cancer - To be for nodal irradiation]

Standard of care in breast cancer management is well-defined. However, some gray zones still exist, in particular adjuvant radiotherapy indications in case of pN1mi breast cancer. Here we propose to define their prognosis, to underpin the benefit of adjuvant treatments in such patients' management and to define lymphedema risk, which is the most common late side effect of locoregional treatments.

[Modalities and advantages of image guided radiation therapy of breast cancer in adjuvant setting]

In adjuvant setting, breast cancer radiotherapy volumes include whole mammary gland or chest wall, and when indicated, nodal area such as axilla, supraclavicular, and internal mammary chain. An accurate patients positioning is required due to some geometric complexity of target volumes closed to organs at risk as heart and lung. Image guided radiation therapy allows such accuracy. Here we propose a review on image guided radiotherapy for breast cancer.

Personalizing Breast Cancer Irradiation Using Biology: From Bench to the Accelerator

While adjuvant treatments of early breast cancers (BCs) had significantly improved patients’ overall survival, some of them will still develop locoregional relapses and/or severe late radio-induced toxicities. Here, we propose to review how to personalize locoregional treatment by identifying patients at high and low risk of locoregional relapse, patients at risk of late radio-induced side effects. We will, therefore, discuss how to enhance BC radiosensitivity. Finally, we will address how personalized radiotherapy could be implemented in prospective clinical trials.

Management of the Axilla in the Era of Breast Cancer Heterogeneity

Systemic cancer therapies take into account breast cancer (BC) heterogeneity by targeting pathways specifically involved in some BC subtypes. On the other hand, BC intrinsic radiosensitivity is poorly understood and studied. Hence, radiotherapy personalization in BC is still “work in progress”. In this review, we will summarize the existing data on the management of axillary lymph nodes in BC, the impact of BC radiotherapy on axillary management, the indications for axillary radiotherapy, and biomarkers to predict patients’ outcome (tumor control and late toxicities) after axillary irradiation.

Abstract P1-17-04: Clinical presentation and outcome of leptomeningeal metastasis in patients with breast cancer in relation to histology and tumor subtypes

Background: Among solid tumors, breast cancer (BC) is one of the most common cause of leptomeningeal metastases. Leptomeningeal disease (LMD) typically carries a devastating prognosis; however, disease presentation and prognostic factors are still uncertain. The aim of this study was to characterize clinical features of LMD in relation to BC histology and subtypes.

Patients and Methods:104 patients (pts) with LMD from BC diagnosed between 2002 and 2017 at two European institutions were included. LMD diagnosis was based on the presence of neoplastic cells on cerebrospinal fluid examination and/or radiological evidence of LMD. Patients' characteristics and their associations with time from LMD to death or last follow up were evaluated by the Kaplan-Meier method, log-rank tests, and Cox proportional hazard models.

Results: Median age at LMD diagnosis was 56 yrs (range 26-75). Tumor histology (n=102) was ductal in 72 pts (70.6%), lobular in 22 (21.6%) and other histology in 8 (7.8%, including mixed ductal and lobular tumors). Tumor phenotype distribution was as follows: hormone receptor (HR)+/HER2- 54.8%, triple-negative (TN) 14.4%, HR+/HER2+ 12.5%, HR-/HER2+ 6.7% and unknown 11.5%. LMD diagnosis was cytologically proven (n=64, 62.7%) and/or radiologically proven (n=88, 85.4%). At time of LMD diagnosis, 63 pts (58.9%) had an ECOG performance status (PS) ≤ 2. 91 pts (87.5%) had extra-CNS disease localizations and 20 (18.7%) had a history of known BC brain metastasis (BM) (predating LMD diagnosis of more than 30 days). In lobular BC, LMD diagnosis was more frequently made in the absence of a known history of BM compared with ductal BC (95.5% vs 73.3%, Fisher test p=0.036). A majority of pts was treated with intrathecal (n=59, 55.1%) or systemic treatment (n=73, 68.2%) after LMD diagnosis, while only a minority underwent radiotherapy (n=28, 26.2%) or surgical derivation procedures (n=14, 13%). Median overall survival (OS) from LMD diagnosis was 3.2 months (95% CI, 1.9-4.4 months). No significant difference was observed across tumor phenotypes, with HER2+ subgroups experiencing better outcomes (median OS: 2.9, 1.6, 6.6 and 12.9 months in HR+HER2-, TN, HR+HER2+ and HR-HER2+ subgroups; p=0.54). In univariate analysis, ECOG PS ≤ 2 at LMD diagnosis, intrathecal treatment and systemic treatment after LDM diagnosis were significantly associated with an improved OS (see table). Multivariate analysis showed that only ECOG PS ≤ 2 and systemic treatment after LMD diagnosis were independent factors associated with OS (see table). Updated results on an extended cohort of about 150 patients total will be presented at the meeting.

  UnivariateMultivariatePrognostic factorsMedian OS in months (95%CI)HR (95%CI)pHR (95%CI)pECOG PS     0-25.9 (2.1-9.7)0.43 (0.27-0.66)0.0010.64 (0.4-1.0)0.06≥31.7 (1.2-2.3)ref ref Intrathecal treatment     Yes5.3 (1.9-8.7)0.65 (0.43-0.98)0.0370.89 (0.57-1.38)0.6No1.9 (0.5-3.3)ref ref Systemic treatment     Yes7.3 (4.7-9.8)0.13 (0.08-0.22)&lt;0.0010.16 (0.09-0.29)&lt;0.001No1.0 (0.6-1.3)ref ref 

Conclusions: LMD carries a dismal prognosis. The results of this series highlight that patient-related features and treatments (in particular the use of systemic treatment) contribute to modulate the prognosis of BC pts with LMD.

Citation Format: Griguolo G, Pouderoux S, Dieci MV, Jacot W, Bourgier C, Miglietta F, Firmin N, Conte P, Viala M, Guarneri V, Darlix A. Clinical presentation and outcome of leptomeningeal metastasis in patients with breast cancer in relation to histology and tumor subtypes [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-17-04.

Abstract P3-05-06: Prognostic value of androgen receptor and FOXA1 co-expression in non-metastatic triple-negative breast cancer

Background

Androgen receptor (AR) is expressed in 8-53% of triple negative breast cancer (TNBC). Its prognostic value in this subgroup is controverted. FOXA1 is essential for expression of 50% of estrogen receptor (ER)–related genes. Microarray studies identified the subgroup of molecular apocrine or luminal androgen receptor tumors that express AR and luminal genes including FOXA1 but nor ER. Preclinical data suggested that FOXA1 may direct AR to sites normally occupied by ER in luminal tumors, inducing an estrogen-like gene program stimulating proliferation. We have already shown that TNBC with AR/FOXA1 co-expression seem to behave like luminal tumors.

We aimed at evaluating co-expression AR/FOXA1-associated profiles and its prognostic value in a large retrospective series of patients with non-metastatic TNBC with a long follow-up.

Patients and methods

AR and FOXA1 expression were evaluated by immunohistochemistry in tissue microarrays of 300 patients with non-metastatic TNBC treated in our center between 2002 and 2012. Positivity threshold was set at ≥10% staining.

Results

Median age was 57.7 years (range 28.5-98). 46.2% of tumors were classified T1 and 64% pN0. We found 83.2% of ductal carcinomas, 5% of lobular carcinomas and 11.8% of other histological types. SBR grade 1-2 represented 21.4%. A basal-like phenotype (cytokeratins 5/6 and/or EGFR+) was observed in 63.7% of cases. In 161 evaluable patients, a PIKCA mutation (exon 9 or 20) was observed in 16.2% of cases. In 124 evaluable patients, a deletion of PTEN was observed in 25% of cases. Adjuvant chemotherapy was delivered in 74.5% of patients.

37.7% of patients had AR+ tumors and 29.7% had AR+ and FOXA1+ tumors. AR+/FOXA1+ tumors were more frequently: found in older patients (p&lt;0.001), lobular (p&lt;0.001) and of lower nuclear grade (p&lt;0.001) than others TNBC. AR+/FOXA1+ tumors exhibited less frequently basal-like phenotype (45.8%) than AR+/FOXA1- (77.3%) and AR-/FOXA1- (70.1%) tumors (p&lt;0.001). AR+/FOXA1+ tumors exhibited more frequently PIK3CA mutations (35.8%) than AR+/FOXA1- (16.7%) and AR-/FOXA1- (5.9%) tumors (p&lt;0.001). AR+/FOXA1+ tumors exhibited less frequently PTEN deletion (6.8% vs 16.7% for AR+/FOXA1- vs 36.5% for AR-/FOXA1- tumors, respectively, p=0.001).

With a median follow-up of 5.5 years, recurrence-free survival (RFS) was significantly lower for patients with AR+/FOXA1+ tumors (p=0.046). 3-years RFS were 84.2% and 85.3% for AR+/FOXA1+ and the others TNBC, respectively. 5-years RFS were 67.4% and 79.4% for AR+/FOXA1+ and the others TNBC, respectively. Tumor size, nodal status and adjuvant chemotherapy were also statistically correlated to RFS. Tumor size, nodal status, histology and adjuvant chemotherapy were significantly associated with overall survival.

Conclusions

In this large series, almost 30% of TNBC had an AR/FOXA1 co-expression with distinct clinicopathological characteristics and a worse outcome than others TNBC with higher risk of late recurrences. These biomarkers could be useful to identify a subgroup of TNBC and could have therapeutic implications: anti-androgen are under investigation, FOXA1 could be another therapeutic target and PI3K inhibitors should be evaluated in this specific subgroup, alone or in association with anti-androgens.

Citation Format: Guiu S, Charon-Barra C, Mollevi C, Boissiere F, Crapez E, Chartron E, Lamy P-J, Gutowski M, Bourgier C, Romieu G, Simony-Lafontaine J, Jacot W. Prognostic value of androgen receptor and FOXA1 co-expression in non-metastatic triple-negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-05-06.

Helical tomotherapy and volumetric modulated arc therapy: New therapeutic arms in the breast cancer radiotherapy

AIM

To analyse clinical and dosimetric results of helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) in complex adjuvant breast and nodes irradiation.

METHODS

Seventy-three patients were included (31 HT and 42 VMAT). Dose were 63.8 Gy (HT) and 63.2 Gy (VMAT) in the tumour bed, 52.2 Gy in the breast, 50.4 Gy in supraclavicular nodes (SCN) and internal mammary chain (IMC) with HT and 52.2 Gy and 49.3 Gy in IMC and SCN with VMAT in 29 fractions. Margins to particle tracking velocimetry were greater in the VMAT cohort (7 mm vs 5 mm).

RESULTS

For the HT cohort, the coverage of clinical target volumes was as follows: Tumour bed: 99.4% ± 2.4%; breast: 98.4% ± 4.3%; SCN: 99.5% ± 1.2%; IMC: 96.5% ± 13.9%. For the VMAT cohort, the coverage was as follows: Tumour bed: 99.7% ± 0.5%, breast: 99.3% ± 0.7%; SCN: 99.6% ± 1.4%; IMC: 99.3% ± 3%. For ipsilateral lung, Dmean and V20 were 13.6 ± 1.2 Gy, 21.1% ± 5% (HT) and 13.6 ± 1.4 Gy, 20.1% ± 3.2% (VMAT). Dmean and V30 of the heart were 7.4 ± 1.4 Gy, 1% ± 1% (HT) and 10.3 ± 4.2 Gy, 2.5% ± 3.9% (VMAT). For controlateral breast Dmean was 3.6 ± 0.2 Gy (HT) and 4.6 ± 0.9 Gy (VMAT). Acute skin toxicity grade 3 was 5% in the two cohorts.

CONCLUSION

HT and VMAT in complex adjuvant breast irradiation allow a good coverage of target volumes with an acceptable acute tolerance. A longer follow-up is needed to assess the impact of low doses to healthy tissues.

Abstract P3-12-18: Radiation-induced CD8 T-lymphocyte apoptosis as a predictor of late toxicity after radiotherapy: Results of the prospective multicenter French trial

Purpose/Objective(s): We and others showed in retrospective and monocentric studies that radiation-induced CD8-lymphocyte apoptosis (RILA) can significantly predict differences in late toxicity between individuals and can be used as a rapid screening for potential hyper-reactive patients to radiation therapy (RT). We present here the clinical results of the prospective multicenter French trial (NCT00893035) evaluating the predictive role of RILA as a predictor of late effects after RT.

Materials/Methods: A total of 502 consenting breast-cancer patients (pts) treated by conservative surgery and adjuvant RT were included by 10 French centers. Lymphocytes apoptosis was assessed before RT by associated condensation of DNA. The incidence of late toxicities was obtained using CTCAEv3.0 grading scale. Complication-free survival (CFS) and complication-relapse-free survival (CRFS) curves were estimated by the Kaplan-Meier method. The log-rank test was used to identify significant categorical variables for each of the survival curves. Cox model was used for multivariate analysis.

Results: Four hundred and fifty-four pts (90.4%) were included in the final analysis (clinical, biological and dosimetric data available). One hundred and eight pts (24%) received both whole breast (WB) and nodal irradiation (NI). A boost dose of 10-16 Gy was given in 448 pts (99%). Adjuvant hormonotherapy (tamoxifen or aromatase inhibitor) was delivered to 346 pts (76%). Three categories of absolute change in the percent CD8 cells in apoptosis before and after exposure to 8-Gy in vitro RT were constructed around the 33 percent quantiles, &lt;12%, 12-20%, and &gt;20%. In a median follow-up period of 38.5 months, grade 2 and 3 late fibrosis was observed in 54 (12%) and 3 (0.7%) pts, respectively. A decreased percentage of grade 2 or more late toxicity was observed for increasing values of CD8 apoptosis (p=0.001). No grade 3 late toxicity was observed for patients with RILA ≥12%. The 3-year CFS rates were significantly lower for patients with low levels of CD8 radiation-induced apoptosis, 79% (95% confidence interval [CI]: 72–85%), 90% (95% CI: 84–94%), and 93% (95% CI: 87–96%) for CD8 &lt;12%, 12–20%, and &gt;20%, respectively (p=0.001). Similar results were observed for the CRFS rates (p&lt;0.001). In multivariate analyses, prognostic factors for CFS were RILA&lt;12% (p=0.001), smoking history (p&lt;0.001), and adjuvant hormonal treatment (p=0.008). Negative predictive value for grade 2 or more toxicity was equal to 83% for CD8 &gt;20% and positive predictive value was equal to 22% for CD8 &lt;12% where the overall prevalence of grade 2 or more late side effects was estimated at 14%.

Conclusion: RILA significantly predicts differences in radiation-induced late toxicity between individuals. This study validates the use of RILA as a rapid screening for potential hyper-reactive pts to radiotherapy.

Citation Format: Hennequin C, Azria D, Riou O, Castan F, Coelho M, Nguyen TD, Peignaux K, Lemanski C, Lagrange J-L, Kirova Y, Lartigau E, Belkacemi Y, Bourgier C, Noel G, Clippe S, Mornex F, Kramar A, Pèlegrin A, Ozsahin M. Radiation-induced CD8 T-lymphocyte apoptosis as a predictor of late toxicity after radiotherapy: Results of the prospective multicenter French trial. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-18.

Performance of a Knowledge-Based Model for Optimization of Volumetric Modulated Arc Therapy Plans for Single and Bilateral Breast Irradiation

Purpose

To evaluate the performance of a model-based optimisation process for volumetric modulated arc therapy, VMAT, applied to whole breast irradiation.

Methods and Materials

A set of 150 VMAT dose plans with simultaneous integrated boost were selected to train a model for the prediction of dose-volume constraints. The dosimetric validation was done on different groups of patients from three institutes for single (50 cases) and bilateral breast (20 cases).

Results

Quantitative improvements were observed between the model-based and the reference plans, particularly for heart dose. Of 460 analysed dose-volume objectives, 13% of the clinical plans failed to meet the constraints while the respective model-based plans succeeded. Only in 5 cases did the reference plans pass while the respective model-based failed the criteria. For the bilateral breast analysis, the model-based plans resulted in superior or equivalent dose distributions to the reference plans in 96% of the cases.

Conclusions

Plans optimised using a knowledge-based model to determine the dose-volume constraints showed dosimetric improvements when compared to earlier approved clinical plans. The model was applicable to patients from different centres for both single and bilateral breast irradiation. The data suggests that the dose-volume constraint optimisation can be effectively automated with the new engine and could encourage its application to clinical practice.

Concurrent or sequential letrozole with adjuvant breast radiotherapy: final results of the CO-HO-RT phase II randomized trial

BACKGROUND

We present here final clinical results of the COHORT trial and both translational sub-studies aiming at identifying patients at risk of radiation-induced subcutaneous fibrosis (RISF): (i) radiation-induced lymphocyte apoptosis (RILA) and (ii) candidates of certain single-nucleotide polymorphisms (SNPs).

PATIENTS AND METHODS

Post-menopausal patients with stage I-II breast cancer (n = 150) were enrolled and assigned to either concurrent (arm A) or sequential radiotherapy (RT)-letrozole (arm B). Among them, 121 were eligible for RILA and SNP assays. Grade ≥2 RISF were the primary end point. Secondary end points were lung and heart events and carcinologic outcome. RILA was performed to predict differences in RISF between individuals. A genome-wide association study was performed to identify SNPs associated with RILA and RISF. Analyses were done by intention to treat.

RESULTS

After a median follow-up of 74 months, 5 patients developed a grade ≥2 RISF. No significant difference was observed between arms A and B. Neither grade ≥2 lung nor symptomatic cardiac toxicity was observed. Median RILA value of the five patients who had grade ≥2 RISF was significantly lower compared with those who developed grade ≤1 RISF (6.9% versus 13%, P = 0.02). Two SNPs were identified as being significantly associated with RILA: rs1182531 (P = 4.2 × 10(-9)) and rs1182532 (P = 3.6 × 10(-8)); both located within the PHACTR3 gene on chromosome 20q13.33.

CONCLUSIONS

With long-term follow-up, letrozole can safely be delivered concomitantly with adjuvant breast RT. Translational sub-studies showed that high RILA values were correlated with patients who did not develop RISF.

REGISTERED CLINICAL TRIAL

NCT00208273.