Dose gradient impact on equivalent dose at 2 Gy for high dose rate interstitial brachytherapy

Radiobiology and modelling in Brachytherapy: A review inspired by the ESTRO Brachytherapy pre-meeting course

Brachytherapy (BT) plays a key role in cancer treatment by delivering a high dose to a small volume over a short time. The use of BT is currently validated in a wide range of cancers such as cervical, prostate and breast cancers while being a favourable choice for organ preservation, such as in penile or rectal cancer, or in the setting of reirradiation. Consideration of the radiobiology of BT is integral to the choices made around dose and fractionation and combination with other techniques such as external beam radiotherapy (EBRT). Much of the radiobiology of brachytherapy is based on historic data, but fortunately there is a drive to integrate translational research including radiobiologic parameters into modern BT research. In a changing therapeutic landscape moving to a high dose rate (HDR) based on high dose per fraction, it is important to ensure that the incorporation of new radiobiology knowledge helps to drive clinical practice. This manuscript takes the ESTRO Brachytherapy pre-meeting course (May 3, 2024 - Glasgow ESTRO meeting) as a base and develops the concepts to present an overview of radiobiology in brachytherapy. Presented are 3 different considerations: the fundamentals of BT radiobiology (BT radiobiology history, biology and BT, α/β and re-irradiation), the pre-clinical radiobiology approach (pulsed dose radiotherapy (PDR) vs HDR, BT vs best EBRT techniques, high dose regions and integrated boost) and clinical radiobiology approaches (optimal number of BT fractions, radiobiology in BR for cervical, prostate, breast, skin/H&N and gastro-intestinal cancers). Presented is an analysis of radiobiology and modelling in BT aiding the integration of scientific pre-clinical and clinical data to allow a better understanding of the use of radioactive sources for cancer treatment.

Best practice in brachytherapy

The 2020 recommendations for good brachytherapy procedures ("Recorad") are updated based on the 2016 article. This new brachytherapy article took into account recent data published in the literature as well as international recommendations. The different brachytherapy steps are successively described from the treatment preparation (brachytherapy technique prescription; procedure and material, dedicated images for planification, dose distribution analysis and validation) to the end of the procedure as well as post-treatment surveillance.

ndocrine therapy with accelerated artial breast irradiatin or exclusive ultra-accelerated artial breast irradiation for women aged ≥ 60 years with arly-stage breast cancer (EPOPE): The rationale for a GEC-ESTRO randomized phase III-controlled trial

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Epidemiologic data confirm the increase of breast cancer incidence in the elderly.

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The risk of recurrence of breast cancer is basically low.

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De-escalation breast cancer adjuvant therapy is justified in selected elderly patients.

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Ultra-accelerated breast irradiation with endocrine therapy omission is under debate.

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Prospective randomized trial is warranted.

Purpose

Breast cancer in the elderly has become a public health concern; there is a need to re-design its treatment with a view to de-escalation. Our paper sets out the rationale for a phase 3 randomized trial to evaluate less burdensome adjuvant procedures that remain effective and efficient.

Materials and methods

For low-risk breast cancer in the elderly, adjuvant treatment has been adjusted in order to make it more suitable and efficient. Hypofractionated radiation therapy based on accelerated or non-accelerated regimens as well as accelerated and ultra-accelerated partial breast irradiation (APBI) protocols were reviewed. Withdrawal of radiation (RT) or endocrine therapies (ET) from the adjuvant procedure were also investigated. Based on molecular and APBI classifications, inclusion criteria were discussed.

Results

Phase 3 randomized trials which compared standard vs. accelerated/non-accelerated hypofractionated regimens confirmed that the latter were non-inferior in terms of local control. Similarly, except for intraoperative-based techniques, APBI achieved non-inferior local control rates compared to whole breast irradiation for low-risk breast cancer. In phase 2 prospective trials using ultra APBI, encouraging results were observed regarding oncological outcome and toxicity profile. In phase 3 trials, adjuvant ET without RT significantly increased the rate of local relapse with no impact on overall survival while RT alone proved effective. Elderly patients aged 60 or more with low-risk, luminal A breast cancer were chosen as the target population in a phase 3 randomized trial comparing APBI + 5-year ET vs. uAPBI (16 Gy 1f) alone.

Conclusion

To investigate de-escalation adjuvant treatment for elderly breast cancer patients, we have defined a road map for testing more convenient strategies. This EPOPE phase 3 randomized trial is supported by the GEC-ESTRO breast cancer working group.

Accelerated partial breast irradiation in the elderly: 5-Year results of the single fraction elderly breast irradiation (SiFEBI) phase I/II trial

PURPOSE

To evaluate the clinical outcomes of a very-accelerated partial breast irradiation (vAPBI) in the elderly based on a single fraction of multicatheter interstitial high-dose rate brachytherapy (MIB). Mature results with a median follow-up of 5 years.

METHODS AND MATERIALS

From November 2012 to September 2014, 26 patients (pts) (≥70) with early breast cancer were enrolled in a prospective phase II trial (NCT01727011). After lumpectomy, intraoperative catheter implant was performed for postoperative APBI (single fraction 16 Gy). Surveillance was performed twice a year after APBI. Oncologic outcome (local [LRFS], metastasis-free survival, cancer-specific survival, and overall survival [OS]) as well as late toxicity and cosmetic outcome were investigated.

RESULTS

Median age was 77 years [69-89]. After a median follow-up of 63 months [60-68], 5-year LRFS, metastasis-free survival, cancer-specific survival, and overall survival rates were 100%, 95.5%, 100%, and 88.5%, respectively. Late toxicity was observed in 5 pts (19.2%) with a total of five events: 3 pts G1 (60%); and 2 pts G2 (40%). The observed late side effects were breast pain in 1 pt (G2 cytosteatonecrosis with occasional acetaminophen consumption), hypopigmentation (puncture site) in 2 pts (G1) and breast fibrosis in 2 pts (G1: 1 pt; G2: 1 pt). Cosmetic evaluation was excellent for 21 pts (81%) and good for 2 pts (19%).

CONCLUSION

For elderly with early breast cancer, a vAPBI using a single fraction of postoperative MIB (16 Gy) provides excellent oncologic results, mainly in terms of local control and cancer death. Late toxicity and cosmetic profile are acceptable.

Accelerated partial breast irradiation in a single 18 Gy fraction with high-dose-rate brachytherapy: preliminary results

Purpose

To evaluate the feasibility of acute and chronic toxicity in patients suitable for accelerated partial breast irradiation (APBI) in a single 18 Gy fraction with multicatheter high-dose-rate (HDR) brachytherapy, as well as cosmetic and oncological outcomes.

Material and methods

Between September 2014 and March 2016, twenty consecutive patients with low-risk invasive and ductal carcinoma in situ were treated with interstitial multicatheter HDR brachytherapy in a single 18 Gy fraction.

Results

Median age was 63.5 years (range, 51-79). Acute toxicity was observed in seven patients, while the pain during following days and hematoma were seen in four patients. With a median follow-up of 24 months, late toxicity was found in one patient with fat necrosis g2 and fibrosis g2 in another patient. The overall survival (OS) and locoregional control (LC) was 100%. Disease-free survival (DFS) and distant control was 95%. Good to excellent cosmetic outcomes were noted in 80% of patients and fair in 4 patients (20%).

Conclusions

This is the first report in the medical literature that focuses on feasibility and acute and chronic toxicity, with a median follow-up of 24 months (range, 20-40). The protocol is viable and convenient. However, a longer follow-up is needed to know chronic toxicity and oncologic outcomes.

GEC-ESTRO ACROP recommendations in skin brachytherapy

PURPOSE

The aim of this publication is to compile available literature data and expert experience regarding skin brachytherapy (BT) in order to produce general recommendations on behalf of the GEC-ESTRO Group.

METHODS

We have done an exhaustive review of published articles to look for general recommendations.

RESULTS

Randomized controlled trials, systemic reviews and meta-analysis are lacking in literature and there is wide variety of prescription techniques successfully used across the radiotherapy centers. BT can be delivered as superficial application (also called contact BT or plesiotherapy) or as interstitial for tumours thicker than 5 mm within any surface, including very irregular. In selected cases, particularly in tumours located within curved surfaces, BT can be advantageous modality from dosimetric and planning point of view when compared to external beam radiotherapy. The general rule in skin BT is that the smaller the target volume, the highest dose per fraction and the shortest overall length of treatment can be used.

CONCLUSION

Skin cancer incidence is rising worldwide. BT offers an effective non-invasive or minimally invasive and relative short treatment that particularly appeals to elder and frail population.

Advancements in brachytherapy

Brachytherapy is a radiotherapy modality associated with a highly focal dose distribution. Brachytherapy treats the cancer tissue from the inside, and the radiation does not travel through healthy tissue to reach the target as with external beam radiotherapy techniques. The nature of brachytherapy makes it attractive for boosting limited size target volumes to very high doses while sparing normal tissues. Significant developments over the last decades have increased the use of 3D image guided procedures with the utilization of CT, MRI, US and PET. This has taken brachytherapy to a new level in terms of controlling dose and demonstrating excellent clinical outcome. Interests in focal, hypofractionated and adaptive treatments are increasing, and brachytherapy has significant potential to develop further in these directions with current and new treatment indications.

MiR-593 mediates curcumin-induced radiosensitization of nasopharyngeal carcinoma cells via MDR1

Curcumin (Cur) exhibits radiosensitization effects to a variety of malignant tumors. The present study investigates the radiosensitizing effect of Cur on nasopharyngeal carcinoma (NPC) cells and whether its mechanism is associated with microRNA-593 (miR-593) and multidrug resistance gene 1 (MDR1). A clonogenic assay was performed to measure the radiosensitizing effect. The expression of miR-593 and MDR1 was analyzed by quantitative polymerase chain reaction (qPCR) or western blot assay. A transplanted tumor model was established to identify the radiosensitizing effect in vivo. A luciferase-based reporter was constructed to evaluate the effect of direct binding of miR-593 to the putative target site on the 3' UTR of MDR1. The clonogenic assay showed that Cur enhanced the radiosensitivity of cells. Cur (100 mg/kg) combined with 4 Gy irradiation inhibited the growth of a transplanted tumor model in vivo, resulting in the higher inhibition ratio compared with the radiotherapy-alone group. These results demonstrated that Cur had a radiosensitizing effect on NPC cells in vivo and in vitro; Cur-mediated upregulation of miR-593 resulted in reduced MDR1 expression, which may promote radiosensitivity of NPC cells.

Proton beams in cancer treatments: Clinical outcomes and dosimetric comparisons with photon therapy

PURPOSE

To review current evidence of the role of proton therapy (PT) in other tumors than skull base, sinusal/parasinusal, spinal and pediatric tumors; to determine medico-economic aspects raised by PT.

MATERIAL AND METHODS

A systematic review on Medline was performed with the following keywords: proton therapy, proton beam, protontherapy, cancer; publications with comparison between PT and photon-therapy were also selected.

RESULTS

In silico studies have shown superiority (better dose delivery to the target and/or to organs at risk) of PT toward photon-therapy in most of thoracic and abdominal malignant tumors. Potential benefits of PT could be: reduction of toxicities (including radiation-induced cancer), increase of tumor control through a dose-escalation approach, hypofractionation. Cost of treatment is always cited as an issue which actually can be managed by a precise patient selection making PT a cost-effective procedure. Comparison plan with photon therapy may be useful to determine the dosimetric and clinical advantages of PT (Normal Tissue Complications Probability).

CONCLUSION

PT may be associated with a great advantage compared to the best photon-therapies in various types of cancers. Accumulation of clinical data is on-going and will challenge the in silico data analysis. Some indications are associated with strong superiority of PT and may be discussed as a new standard within prospective observational studies.

[Prostate cancer boost using high-dose-rate brachytherapy: impact of the learning curve on the dosimetry]

PURPOSE

To analyse the influence of the learning curve on dosimetric data for high-dose-rate brachytherapy prostate cancer boost.

PATIENTS AND METHODS

From February 2009 to May 2012, after a first course of external beam radiation therapy (46Gy/23 fractions), 124 patients underwent high-dose-rate brachytherapy boost using Plato™ (Nucletron, an Elekta company, Elekta AB, Stockholm, Sweden). The impact of the learning curve on the dosimetric quality of the prostate implant was assessed. The dosimetric data have been analysed: clinical target volume (CTV), D90 (dose to 90 % of CTV), D100, V100 (part on the CTV receiving 100 % of the dose), V150, V200 and DHI (dose non-homogeneity index). The doses delivered to 0.1, 1 and 2 cm(3) of the rectum and urethra were calculated.

RESULTS

During the study period (39 months), a significant reduction of V150 (P<0.001), V200 (P<0.001), D0.1rectum (P<0.001), D1rectum (P<0.001), D2rectum (P<0.001), D0.1urethra (P<0.001), and D1urethra (P<0.002) was observed associated with a significant degradation of the D90 (P<0.001) but not significant for the V100 (P=0.29) and the D100 (P=0.3).

CONCLUSION

This study confirms that the dosimetric quality of high-dose-rate brachytherapy prostate implant is significantly improved during the learning curve period.

Curcumin enhances the radiosensitivity in nasopharyngeal carcinoma cells involving the reversal of differentially expressed long non-coding RNAs

Long non-coding RNAs (lncRNAs) are aberrantly expressed and have important functions in pathological processes. The present study investigated the lncRNA profiles and the effects of curcumin (Cur) on the radiosensitivity of nasopharyngeal carcinoma (NPC) cells. The lncRNA and mRNA profiles of each cell group were described by microarray analysis. Numerous differentially expressed genes were observed by microarrays in three cell groups. Cur significantly reversed the IR-induced lncRNA and mRNA expression signatures, shown by clustering analysis. Moreover, 116 of these IR-induced and Cur-reversed differentially expressed lncRNAs were obtained. Six lncRNAs (AF086415, AK095147, RP1-179N16.3, MUDENG, AK056098 and AK294004) were confirmed by qPCR. Furthermore, functional studies showed that lncRNA AK294004 exhibited a negative effect on cyclin D1 (CCND1), indicating that CCND1 might be a direct target of AK294004. IR-induced differentially expressed lncRNAs were reversed during Cur-enhanced radiosensitization in NPC cells, suggesting that lncRNAs have important functions in IR-induced radioresistance. Thus, Cur could serve as a good radiosensitizer.

Prostate cancer boost using high-dose-rate brachytherapy: early toxicity analysis of 3 different fractionation schemes

Purpose

To analyse early toxicity of high-dose-rate brachytherapy (HDRB) boost for prostate cancer using 3 fractionation schemes.

Material and methods

From February 2009 to May 2012, after the first course of external beam radiation therapy (EBRT 46 Gy/23 f), 124 patients underwent HDRB boost for low (7%), intermediate (19%), and high-risk (73%) prostate cancers. From February to December 2009, Group 1 (G1) = 18 Gy/3 f/2 d (24%); from January 2010 to April 2011, Group 2 (G2) = 18 Gy/2 f/2 d (42%), and from May to September 2011, Group 3 (G3) = 14 Gy/1 f/1 d (34%). Planning and CT-scan was performed before each fraction. Dose constraints for G1/G2 were V₁₀₀ rectum = 0 and V₁₂₅ urethra = 0, while for G3 V₉₀ rectum = 0 and V₁₁₅ urethra = 0. Genito-urinary (GU) and Gastro-intestinal (GI) acute toxicities were assessed at 1 month (for the 3 fractionation schemes) and 6 months (for 18 Gy/3 f and 18 Gy/2 f) after the boost (CTCv3.0).

Results

Median follow-up was 25 months (8-46.9), median age was 71 years (50-82), and median CTV was 31 cc (16-71). The grades of acute GI and GU toxicities at 1 and 6 months after HDRB were mainly Grade 1 with few Grade 2 (GU: 5% at 1 month; GI: 1% at 6 months). One patient developed G4 sepsis toxicity 2 days after HDRB and recovered without after-effects. No significant differences were observed at 1 and 6 months after the HDRB between treatment groups.

Conclusions

The right fractionation remains under discussion, but prostate cancer HDRB boost using a single fraction (providing similar results in terms of acute toxicity) is more comfortable for the patient, and less time consuming for the medical staff.

[How to prepare the brachytherapy of the future]

For more than a century, brachytherapy has been a treatment of choice for delivering a high dose in a small volume. However, over the past 15 years, this irradiation technique has stalled. Even so, brachytherapy allows the delivery of the right dose at the right place by dispensing with target volume motion and repositioning. The evolution of brachytherapy can be based on a road-map including at least the following three points: the acquisition of clinical evidence, teaching and valuation of the procedures. The evolution of brachytherapy will be also impacted by technological considerations (end of the production of low dose rate 192 iridium wires). Regarding the evolution toward a personalized treatment, brachytherapy of the future should take its place as a partner of other modern external beam radiation techniques, be performed by experimented actors (physicians, physicists, technicians, etc.) who received adequate training, and be valued in proportion to the delivered medical service.

Past, present, and future of radiotherapy for the benefit of patients

Radiotherapy has been driven by constant technological advances since the discovery of X-rays in 1895. Radiotherapy aims to sculpt the optimal isodose on the tumour volume while sparing normal tissues. The benefits are threefold: patient cure, organ preservation and cost-efficiency. The efficacy and tolerance of radiotherapy were demonstrated by randomized trials in many different types of cancer (including breast, prostate and rectum) with a high level of scientific evidence. Such achievements, of major importance for the quality of life of patients, have been fostered during the past decade by linear accelerators with computer-assisted technology. More recently, these developments were augmented by proton and particle beam radiotherapy, usually combined with surgery and medical treatment in a multidisciplinary and personalized strategy against cancer. This article reviews the timeline of 100 years of radiotherapy with a focus on breakthroughs in the physics of radiotherapy and technology during the past two decades, and the associated clinical benefits.