Radical radiotherapy for invasive bladder cancer: What dose and fractionation schedule to choose?

Bladder Tumor-Focused Adaptive Radiation Therapy: Clinical Outcomes of a Phase I Dose Escalation Study

PURPOSE

We determine the maximum tolerated tumor-focused dose (MTD) for the radical treatment of muscle invasive bladder cancer enabled by image guided adaptive radiation therapy and long-term clinical outcomes.

METHODS AND MATERIALS

Fifty-nine patients with T2 to T4aN0M0 unifocal urothelial muscle invasive bladder cancer suitable for daily radical radiation therapy were recruited prospectively to an ethics-approved protocol (NCT01124682). The uninvolved bladder (PTVbladder) was planned to 52 Gy in 32 fractions. The bladder tumor (PTVtumor) was planned to an assigned dose level of 68, 70, 72, or 74 Gy. If organ at risk dose constraints were violated, then PTVtumor was planned to 64 Gy. Dose level allocation was determined by concurrent toxicity assessment of all previous patients recruited. Acute toxicity was evaluated using Common Terminology Criteria for Adverse Events v3.0; late toxicity was evaluated using Radiation Therapy Oncology Group criteria. The MTD was predefined as the highest dose level with an estimated probability of ≤ 15% ≥ G3 late toxicity and an observed rate of <50% acute G3 and <10% acute G4 toxicity.

RESULTS

Twenty-six patients were assigned to 68 Gy, of whom 6 were planned to 64 Gy; 29 patients were assigned to 70 Gy of whom 1 was planned to 68 Gy, 2 patients were assigned and planned to 72 Gy; no patients were assigned to 74 Gy. Three patients did not complete the treatment as planned, of whom only 1 patient stopped treatment because dose-limiting toxicity occurred. The MTD was 70 Gy. Acute genito-urinary and gastro-intestinal G3 acute toxicity was seen in 19% and 7% of patients, respectively. No acute G4 genito-urinary or gastro-intestinal toxicity was seen. Late toxicity (any) G3 and G4 was seen in 14% and 2% of patients, respectively. The 5-year overall survival was 58% (95% CI, 44%-71%). The bladder preservation rate was 89% (95% CI, 88%-96%) with 6 patients not retaining native bladder function.

CONCLUSIONS

Bladder tumor-focused dose escalation to 70 Gy using image guided adaptive radiation therapy is feasible with acceptable toxicity. This dose level has been evaluated in a phase II randomized control trial (RAIDER NCT02447549).

News and prospects on radiotherapy for bladder cancer: Is trimodal therapy becoming the gold standard?

Trimodal therapy consisting of transurethral resection of bladder tumors followed by radiotherapy and chemotherapy, has emerged as a valuable therapeutic alternative to radical cystectomy in patients with muscle invasive bladder cancer. Concomitant radiosensitising chemotherapy is a component of trimodality increasing locoregional control compared to radiotherapy alone. The combinations 5-fluorouracil with mitomycin or cisplatin are the best supported in the literature. Gemcitabine appears to be a feasible and promising alternative. There is considerable international heterogeneity in terms of dose, volumes and fractionation. The most commonly used regimens are moderately hypofractionated (55Gy in 20 fractions over 4 weeks) and normofractionated (64Gy in 32 fractions) regimens. Radiotherapy for bladder cancer is an effective and evolving treatment, with current technical developments, and studies of new combinations with systemic treatments underway.

Fractionation versus Adaptation for Compensation of Target Volume Changes during Online Adaptive Radiotherapy for Bladder Cancer: Answers from a Prospective Registry

Online adaptive radiotherapy (ART) allows adaptation of the dose distribution to the anatomy captured by with pre-adaptation imaging. ART is time-consuming, and thus intra-fractional deformations can occur. This prospective registry study analyzed the effects of intra-fraction deformations of clinical target volume (CTV) on the equivalent uniform dose (EUDCTV) of focal bladder cancer radiotherapy. Using margins of 5-10 mm around CTV on pre-adaptation imaging, intra-fraction CTV-deformations found in a second imaging study reduced the 10th percentile of EUDCTV values per fraction from 101.1% to 63.2% of the prescribed dose. Dose accumulation across fractions of a series was determined with deformable-image registration and worst-case dose accumulation that maximizes the correlation of cold spots. A strong fractionation effect was demonstrated-the EUDCTV was above 95% and 92.5% as determined by the two abovementioned accumulation methods, respectively, for all series of dose fractions. A comparison of both methods showed that the fractionation effect caused the EUDCTV of a series to be insensitive to EUDCTV-declines per dose fraction, and this could be explained by the small size and spatial variations of cold spots. Therefore, ART for each dose fraction is unnecessary, and selective ART for fractions with large inter-fractional deformations alone is sufficient for maintaining a high EUDCTV for a radiotherapy series.

Consolidative Radiotherapy for Metastatic Urothelial Bladder Cancer Patients with No Progression and with No More than Five Residual Metastatic Lesions Following First-Line Systemic Therapy: A Retrospective Analysis

Local consolidative radiotherapy in the treatment of metastatic malignancies has shown promising results in several types of tumors. The objective of this study was to assess consolidative radiotherapy to the bladder and to residual metastases in metastatic urothelial bladder cancer with no progression following first-line systemic therapy.

MATERIALS/METHODS

Patients who received first-line therapy for the treatment of metastatic urothelial bladder cancer (mUBC) and who were progression-free following treatment with no more than five residual metastases were retrospectively identified through the database of four Comprehensive Cancer Centers, between January 2005 and December 2018. Among them, patients who received subsequent definitive radiotherapy (of EQD2Gy > 45Gy) to the bladder and residual metastases were included in the consolidative group (irradiated (IR) group), and the other patients were included in the observation group (NIR group). Progression-free survival (PFS) and overall survival (OS) were determined from the start of the first-line chemotherapy using the Kaplan-Meier method. To prevent immortal time bias, a Cox model with time-dependent covariates and 6-month landmark analyses were performed to examine OS and PFS.

RESULTS

A total of 91 patients with at least stable disease following first-line therapy and with no more than five residual metastases were analyzed: 51 in the IR group and 40 in the NIR group. Metachronous metastatic disease was more frequent in the NIR group (19% vs. 5%, p = 0.02); the median number of metastases in the IR group vs. in the NIR group was 2 (1-9) vs. 3 (1-5) (p = 0.04) at metastatic presentation, and 1 (0-5) vs. 2 (0-5) (p = 0.18) after completion of chemotherapy (residual lesions), respectively. Two grade 3 toxicities (3.9%) and no grade 4 toxicity were reported in the IR group related to radiotherapy. With a median follow up of 85.9 months (95% IC (36.7; 101.6)), median OS and PFS were 21.7 months (95% IC (17.1; 29.7)) and 11.1 months (95% IC (9.9; 14.1)) for the whole cohort, respectively. In multivariable analysis, consolidative radiotherapy conferred a benefit in both PFS (HR = 0.49, p = 0.007) and OS (HR = 0.47, p = 0.015) in the whole population; in the landmark analysis at 6 months, radiotherapy was associated with improved OS (HR = 0.48, p = 0.026), with a trend for PFS (HR = 0.57, p = 0.082).

CONCLUSION

Consolidative radiotherapy for mUBC patients who have not progressed after first-line therapy and with limited residual disease seems to confer both OS and PFS benefits. The role of consolidative radiotherapy in the context of avelumab maintenance should be addressed prospectively.

Radiation Treatment Timing and Dose Delivery: Effects on Bladder Cancer Cells in 3D in Vitro Culture

While radical cystectomy remains the primary treatment of choice for bladder cancer, increased evidence supports the use of bladder-preservation strategies based on adjuvant radiotherapy. This highlights the need for a better understanding of bladder cancer radiosensitivity to different types of treatment deliveries. The purpose of this study is to analyze the effect of treatment time, dose and fractionation on the number and sizes of grown three-dimensional (3D) bladder cancer spheres, and to assess the capacity of the linear-quadratic model in describing the response of cells cultured in 3D. 3D MatrigelTM-based cultures were employed to enrich for cancer stem cells (CSCs) from three human bladder cancer cell lines, RT4, T24 and UM-UC-3. Three single dose radiation treatments were performed at different time points after plating, and sphere number and sizes were assessed. Anti-CD44 immunofluorescence, clonogenic assay and anti-γH2AX staining were also performed to analyze the cell lines’ radiosensitivity. The radiosensitivity of spheres was dependent on the treatment timing after plating. Current linear quadratic dose fractionation models were shown to over-estimate radiosensitivity in 3D models. Our results showed the importance of treatment timing on the radio-response of bladder cancer spheres. We also demonstrated that bladder cancer spheres are more resistant to dose-fractionation than the estimation from the theoretical linear-quadratic model.

Oncologic Impact and Safety of Pre-Operative Radiotherapy in Localized Prostate and Bladder Cancer: A Comprehensive Review from the Cancerology Committee of the Association Française d'Urologie

Preoperative radiotherapy (RT) is commonly used for the treatment of various malignancies, including sarcomas, rectal, and gynaecological cancers, but it is preferentially used as a competitive treatment to radical surgery in uro-oncology or as a salvage procedure in cases of local recurrence. Nevertheless, preoperative RT represents an attractive strategy to prevent from intraoperative tumor seeding in the operative field, to sterilize microscopic extension outside the organ, and to enhance the pathological and/or imaging tumor response rate. Several clinical works support this research field in uro-oncology. In this review article, we summarized the oncologic impact and safety of preoperative RT in localized prostate and muscle-invasive bladder cancer. Preliminary studies suggest that both modalities can be complementary as initial primary tumor treatments and that a pre-operative radiotherapy strategy could be beneficial in a well-defined population of patients who are at a very high-risk of local relapse. Future prospective trials are warranted to evaluate the oncologic benefit of such a combination of local treatments in addition to new life-prolonging systemic therapies, such as immunotherapy, and new generation hormone therapies. Moreover, the safety and the feasibility of salvage surgical procedures due to non-response or local recurrence after pelvic RT remain poorly evaluated in that context.

Recommendations for planning and delivery of radical radiotherapy for localized urothelial carcinoma of the bladder

PURPOSE

Curative radio-chemotherapy is recognized as a standard treatment option for muscle-invasive bladder cancer (MIBC). Nevertheless, the technical aspects for MIBC radiotherapy are heterogeneous with a lack of practical recommendations.

METHODS AND MATERIALS

In 2018, a workshop identified the need for two cooperative groups to develop consistent, evidence-based guidelines for irradiation technique in the delivery of curative radiotherapy. Two radiation oncologists performed a review of the literature addressing several topics relative to radical bladder radiotherapy: planning computed tomography acquisition, target volume delineation, radiation schedules (total dose and fractionation) and dose delivery (including radiotherapy techniques, image-guided radiotherapy (IGRT) and adaptive treatment modalities). Searches for original and review articles in the PubMed and Google Scholar databases were conducted from January 1990 until March 2020. During a meeting conducted in October 2020, results on 32 topics were presented and discussed with a working group involving 15 radiation oncologists, 3 urologists and one medical oncologist. We applied the American Urological Association guideline development's method to define a consensus strategy.

RESULTS

A consensus was obtained for all 34 except 4 items. The group did not obtain an agreement on CT enhancement added value for planning, PTV margins definition for empty bladder and full bladder protocols, and for pelvic lymph-nodes irradiation. High quality evidence was shown in 6 items; 8 items were considered as low quality of evidence.

CONCLUSION

The current recommendations propose a homogenized modality of treatment both for routine clinical practice and for future clinical trials, following the best evidence to date, analyzed with a robust methodology. The XXX group formulates practical guidelines for the implementation of innovative techniques such as adaptive radiotherapy.

What is the Optimal Dose, Fractionation and Volume for Bladder Radiotherapy?

External beam radiotherapy (EBRT), as part of a trimodality approach, is an attractive bladder-preserving alternative to radical cystectomy. Several EBRT regimens with different treatment volumes have been described with similar tumour control and, so far, clear recommendations on the optimal radiotherapy regimen and treatment volume are lacking. The current review summarises EBRT literature on dose prescription, fractionation as well as treatment volume in order to guide clinicians in their daily practice when treating patients with muscle-invasive bladder cancer. Taking into account literature on repopulation, continuous-course radiotherapy can be used safely in daily practice where a split-course should only be reserved for those patients who are fit enough to undergo a radical cystectomy in case of a poor early response. A recent meta-analysis has proven that hypofractionated radiotherapy is superior to conventional radiotherapy with regards to invasive locoregional control with similar toxicity profiles. In the absence of node-positive disease, the target volume can be restricted to the bladder. In order to compensate for organ motion, very large margins need to be applied in the absence of image-guided radiotherapy (IGRT). Therefore, the use of IGRT or an adaptive approach is recommended. Based on the available literature, one can conclude that moderate hypofractionated radiotherapy to a dose of 55 Gy in 20 fractions to the bladder only, delivered with IGRT, can be considered standard of care for patients with node-negative invasive bladder cancer.

Muscle-invasive Bladder Cancer in the Elderly Patient With a Focus on Hypofractionated Radiotherapy

Muscle-invasive bladder cancer is most frequently diagnosed in older patients and the presence of multimorbidity and frailty is common. This means that many patients are unsuitable for definitive treatment with radical cystectomy/(chemo)radiotherapy and are at risk of poor survival outcomes and considerable disease-related morbidity. Screening tools for functional status may be useful to determine the most appropriate treatment for an older person and to identify patients most likely to benefit from comprehensive geriatric assessment and its targeted prehabilitation interventions. For patients unsuitable for definitive treatment, ultrahypofractionated radiotherapy schedules may provide good local control with acceptable toxicity. Short fractionated palliative radiotherapy schedules can provide effective symptom control for patients unsuitable for longer courses of treatment.

[A review of adaptive radiotherapy for bladder cancer]

PURPOSE

Radiation therapy (RT) for muscle invasive bladder cancer (MIBC) is challenging, with observed variations in bladder shape and size resulting in inappropriate coverage of the target volumes (CTV). Large margins were historically applied around the CTV, increasing the dose delivered to organs at risk (OAR). With repositioning imaging and visualization of soft tissues during image guided RT, an opportunity to consider these movements and deformations appeared possible with an adaptive RT approach (ART).

MATERIALS AND METHODS

A bibliographic search on the PubMed database has been done in January 2019. Studies focusing on patients with MIBC, treating on ART, with the objectives of feasibility, clinical and/or dosimetric evaluation and comparison with a standard irradiation technique were eligible. The purpose of this review was to define the different ART techniques used in clinical practice, to discuss their advantages compared to conventional RT in terms of target volume's coverage and OAR dose and to describe their feasibility in clinical practice.

RESULTS

A total of 30 studies were selected. The strategies known as "composite offline", "plan of the day" not individualized or individualized, and "re-optimization" have been identified. All the studies have shown a significant benefit of ART in target coverage and dose of OAR, especially the rectum and small bowel. All ART plans produced are not used during RT sessions. Inter-observer variability for the selection of these plans can be observed. The practical implementation within a department required staff education and training, and increases the duration of treatment preparation. The "A-POLO" approach seems to be the most suitable for practice.

CONCLUSION

ART is the technique of choice for bladder cancer RT. The "plan of the day" approach, individualized according to the A-POLO methodology, seems to be the most effective. The emergence of daily re-optimization, especially using MRI-Linac, is promising. The correlation between dosimetric benefits and clinical efficacy and safety results should be demonstrated into future trials.

Protocol for tumour-focused dose-escalated adaptive radiotherapy for the radical treatment of bladder cancer in a multicentre phase II randomised controlled trial (RAIDER): radiotherapy planning and delivery guidance

INTRODUCTION

Daily radiotherapy delivered with radiosensitisation offers patients with muscle invasive bladder cancer (MIBC) comparable outcomes to cystectomy with functional organ preservation. Most recurrences following radiotherapy occur within the bladder. Increasing the delivered radiotherapy dose to the tumour may further improve local control. Developments in image-guided radiotherapy have allowed bladder tumour-focused 'plan of the day' radiotherapy delivery. We aim to test within a randomised multicentre phase II trial whether this technique will enable dose escalation with acceptable rates of toxicity.

METHODS AND ANALYSIS

Patients with T2-T4aN0M0 unifocal MIBC will be randomised (1:1:2) between standard/control whole bladder single plan radiotherapy, standard dose adaptive tumour-focused radiotherapy or dose-escalated adaptive tumour-focused radiotherapy (DART). Adaptive tumour-focused radiotherapy will use a library of three plans (small, medium and large) for treatment. A cone beam CT taken prior to each treatment will be used to visualise the anatomy and inform selection of the most appropriate plan for treatment.Two radiotherapy fractionation schedules (32f and 20f) are permitted. A minimum of 120 participants will be randomised in each fractionation cohort (to ensure 57 evaluable DART patients per cohort).A comprehensive radiotherapy quality assurance programme including pretrial and on-trial components is instituted to ensure standardisation of radiotherapy planning and delivery.The trial has a two-stage non-comparative design. The primary end point of stage I is the proportion of patients meeting predefined normal tissue constraints in the DART group. The primary end point of stage II is late Common Terminology Criteria for Adverse Events grade 3 or worse toxicity aiming to exclude a rate of >20% (80% power and 5% alpha, one sided) in each DART fractionation cohort. Secondary end points include locoregional MIBC control, progression-free survival overall survival and patient-reported outcomes.

ETHICS AND DISSEMINATION

This clinical trial is approved by the London-Surrey Borders Research Ethics Committee (15/LO/0539). The results when available will be disseminated via peer-reviewed scientific journals, conference presentations and submission to regulatory authorities.

TRIAL REGISTRATION NUMBER

NCT02447549; Pre-results.

Optimizing Sequence of PD-L1 Immune-Checkpoint Inhibitors and Radiation Therapy in Bladder Cancer

BACKGROUND: New bladder preserving strategies are needed for muscle invasive bladder cancer (MIBC). Combined therapy of immune-checkpoint inhibitors and radiation was shown to have synergistic antitumoral effects in preclinical studies. OBJECTIVES: We aim to evaluate whether the sequence of administration of this combined therapy impacts antitumoral response. METHODS: We developed an in-vivo syngeneic MIBC mouse model where murine bladder cancer cells (MB49) were injected subcutaneously in the right flank of C57BL/6 mice. Mice were then randomized to the following treatments: control, anti-programmed cell death ligand 1 (PD-L1) alone, radiation alone (XRT) consisting of 6.25 Gy x2 fractions, concurrent anti-PD-L1 with XRT, neoadjuvant anti-PD-L1 followed by XRT, or XRT followed by adjuvant anti-PD-L1 therapy. Tumor growth, survival, and rate of response were analyzed. RESULTS: Total of 60 mice were randomized. One-way analysis of variance showed statistically significant difference in tumor growth rate across the treatment arms (p = 0.029). Importantly, timing of immunotherapy (neoadjuvant, concurrent, or adjuvant) did not alter either tumor growth or survival (p > 0.05). The rate of response was also similar in each combination arm (p > 0.05). CONCLUSION: Combining anti-PD-L1 immunotherapy and radiation therapy offers optimal antitumoral responses. Timing of immunotherapy (neoadjuvant, concurrent, or adjuvant) does not appear to affect outcomes. Whether the toxicity profile differs across various sequential deliveries of combination therapy requires further evaluation.

Protocol for hypofractionated adaptive radiotherapy to the bladder within a multicentre phase II randomised trial: radiotherapy planning and delivery guidance

INTRODUCTION

Patients with muscle invasive bladder cancer (MIBC) who are unfit and unsuitable for standard radical treatment with cystectomy or daily radiotherapy present a large unmet clinical need. Untreated, they suffer high cancer specific mortality and risk significant disease-related local symptoms. Hypofractionated radiotherapy (delivering higher doses in fewer fractions/visits) is a potential treatment solution but could be compromised by the mobile nature of the bladder, resulting in target misses in a significant proportion of fractions. Adaptive 'plan of the day' image-guided radiotherapy delivery may improve the precision and accuracy of treatment. We aim to demonstrate within a randomised multicentre phase II trial feasibility of plan of the day hypofractionated bladder radiotherapy delivery with acceptable rates of toxicity.

METHODS AND ANALYSIS

Patients with T2-T4aN0M0 MIBC receiving 36 Gy in 6-weekly fractions are randomised (1:1) between treatment delivered using a single-standard plan or adaptive radiotherapy using a library of three plans (small, medium and large). A cone beam CT taken prior to each treatment is used to visualise the anatomy and select the most appropriate plan depending on the bladder shape and size. A comprehensive radiotherapy quality assurance programme has been instituted to ensure standardisation of radiotherapy planning and delivery. The primary endpoint is to exclude >30% acute grade >3 non-genitourinary toxicity at 3 months for adaptive radiotherapy in patients who received >1 fraction (p0=0.7, p1=0.9, α=0.05, β=0.2). Secondary endpoints include local disease control, symptom control, late toxicity, overall survival, patient-reported outcomes and proportion of fractions benefiting from adaptive planning. Target recruitment is 62 patients.

ETHICS AND DISSEMINATION

The trial is approved by the London-Surrey Borders Research Ethics Committee (13/LO/1350). The results will be disseminated via peer-reviewed scientific journals, conference presentations and submission to regulatory authorities.

TRIAL REGISTRATION NUMBER

NCT01810757.

Adaptive Radiotherapy for Carcinoma of the Urinary Bladder: Long-term Outcomes With Dose Escalation

AIMS

To report long-term outcomes with dose-escalated, image-guided adaptive radiotherapy (ART) for bladder preservation in muscle-invasive bladder cancer (MIBC).

MATERIALS AND METHODS

All MIBC patients receiving bladder-preserving ART at our institute from 2009 to 2018 were analysed. For ART, three anisotropic planning target volumes (PTV) were concentrically grown around the simulation bladder volume. A library of intensity-modulated radiotherapy plans was created for each patient. A total dose of 64 Gy in 32 fractions to the entire bladder and 55 Gy to pelvic nodes was planned, with 68 Gy to the tumour bed (2 Gy equivalent dose = 68.7 Gy, α/β = 10) as simultaneous integrated boost for solitary tumours. The most appropriate PTV encompassing the bladder ('plan-of-the-day') was chosen daily using on-board megavoltage imaging. Neoadjuvant and concurrent chemotherapy was prescribed for medically fit patients.

RESULTS

Of a total of 106 patients, most had T2 (68%) or T3 (19%) disease. Ninety-two patients (87%) completed 64 Gy to the whole bladder. Sixty-three patients (59%) received 68 Gy as tumour bed boost. Seventy-six per cent received concurrent weekly chemotherapy. At a median follow-up of 26 months, 3-year locoregional control, disease-free survival and overall survival were 74.3, 62.9 and 67.7%, respectively. Eighty-two per cent of patients retained disease-free bladder. Radiation Therapy Oncology Group grade III/IV acute genitourinary and gastrointestinal toxicities were 7.5% and 0%, respectively, and late genitourinary/gastrointestinal toxicities were 6.5% and 3.8%, respectively. Overall survival, disease-free survival, locoregional control and grade III/IV genitourinary/gastrointestinal toxicities did not differ significantly with dose escalation.

CONCLUSION

Plan-of-the-day ART is clinically safe and effective for bladder preservation and can be implemented in routine clinical practice. A high bladder preservation rate is achievable without compromising on survival or toxicities. Dose escalation does not seem to affect outcomes.

The alfa and beta of tumours: a review of parameters of the linear-quadratic model, derived from clinical radiotherapy studies

BACKGROUND

Prediction of radiobiological response is a major challenge in radiotherapy. Of several radiobiological models, the linear-quadratic (LQ) model has been best validated by experimental and clinical data. Clinically, the LQ model is mainly used to estimate equivalent radiotherapy schedules (e.g. calculate the equivalent dose in 2 Gy fractions, EQD₂), but increasingly also to predict tumour control probability (TCP) and normal tissue complication probability (NTCP) using logistic models. The selection of accurate LQ parameters α, β and α/β is pivotal for a reliable estimate of radiation response. The aim of this review is to provide an overview of published values for the LQ parameters of human tumours as a guideline for radiation oncologists and radiation researchers to select appropriate radiobiological parameter values for LQ modelling in clinical radiotherapy.

METHODS AND MATERIALS

We performed a systematic literature search and found sixty-four clinical studies reporting α, β and α/β for tumours. Tumour site, histology, stage, number of patients, type of LQ model, radiation type, TCP model, clinical endpoint and radiobiological parameter estimates were extracted. Next, we stratified by tumour site and by tumour histology. Study heterogeneity was expressed by the I² statistic, i.e. the percentage of variance in reported values not explained by chance.

RESULTS

A large heterogeneity in LQ parameters was found within and between studies (I² > 75%). For the same tumour site, differences in histology partially explain differences in the LQ parameters: epithelial tumours have higher α/β values than adenocarcinomas. For tumour sites with different histologies, such as in oesophageal cancer, the α/β estimates correlate well with histology. However, many other factors contribute to the study heterogeneity of LQ parameters, e.g. tumour stage, type of LQ model, TCP model and clinical endpoint (i.e. survival, tumour control and biochemical control).

CONCLUSIONS

The value of LQ parameters for tumours as published in clinical radiotherapy studies depends on many clinical and methodological factors. Therefore, for clinical use of the LQ model, LQ parameters for tumour should be selected carefully, based on tumour site, histology and the applied LQ model. To account for uncertainties in LQ parameter estimates, exploring a range of values is recommended.

The alfa and beta of tumours: a review of parameters of the linear-quadratic model, derived from clinical radiotherapy studies

Background

Prediction of radiobiological response is a major challenge in radiotherapy. Of several radiobiological models, the linear-quadratic (LQ) model has been best validated by experimental and clinical data. Clinically, the LQ model is mainly used to estimate equivalent radiotherapy schedules (e.g. calculate the equivalent dose in 2 Gy fractions, EQD₂), but increasingly also to predict tumour control probability (TCP) and normal tissue complication probability (NTCP) using logistic models. The selection of accurate LQ parameters α, β and α/β is pivotal for a reliable estimate of radiation response. The aim of this review is to provide an overview of published values for the LQ parameters of human tumours as a guideline for radiation oncologists and radiation researchers to select appropriate radiobiological parameter values for LQ modelling in clinical radiotherapy.

Methods and materials

We performed a systematic literature search and found sixty-four clinical studies reporting α, β and α/β for tumours. Tumour site, histology, stage, number of patients, type of LQ model, radiation type, TCP model, clinical endpoint and radiobiological parameter estimates were extracted. Next, we stratified by tumour site and by tumour histology. Study heterogeneity was expressed by the I² statistic, i.e. the percentage of variance in reported values not explained by chance.

Results

A large heterogeneity in LQ parameters was found within and between studies (I² > 75%). For the same tumour site, differences in histology partially explain differences in the LQ parameters: epithelial tumours have higher α/β values than adenocarcinomas. For tumour sites with different histologies, such as in oesophageal cancer, the α/β estimates correlate well with histology. However, many other factors contribute to the study heterogeneity of LQ parameters, e.g. tumour stage, type of LQ model, TCP model and clinical endpoint (i.e. survival, tumour control and biochemical control).

Conclusions

The value of LQ parameters for tumours as published in clinical radiotherapy studies depends on many clinical and methodological factors. Therefore, for clinical use of the LQ model, LQ parameters for tumour should be selected carefully, based on tumour site, histology and the applied LQ model. To account for uncertainties in LQ parameter estimates, exploring a range of values is recommended.

Electronic supplementary material

The online version of this article (10.1186/s13014-018-1040-z) contains supplementary material, which is available to authorized users.

A review of plan library approaches in adaptive radiotherapy of bladder cancer

BACKGROUND

Large variations in the shape and size of the bladder volume are commonly observed in bladder cancer radiotherapy (RT). The clinical target volume (CTV) is therefore frequently inadequately treated and large isotropic margins are inappropriate in terms of dose to organs at risk (OAR); thereby making adaptive radiotherapy (ART) attractive for this tumour site. There are various methods of ART delivery, however, for bladder cancer, plan libraries are frequently used.

MATERIAL AND METHODS

A review of published studies on plan libraries for bladder cancer using four databases (Pubmed, Science Direct, Embase and Cochrane Library) was conducted. The endpoints selected were accuracy and feasibility of initiation of a plan library strategy into a RT department.

RESULTS

Twenty-four articles were included in this review. The majority of studies reported improvement in accuracy with 10 studies showing an improvement in planning target volume (PTV) and CTV coverage with plan libraries, some by up to 24%. Seventeen studies showed a dose reduction to OARs, particularly the small bowel V45Gy, V40Gy, V30Gy and V10Gy, and the rectal V30Gy. However, the occurrence of no suitable plan was reported in six studies, with three studies showing no significant difference between adaptive and non-adaptive strategies in terms of target coverage. In addition, inter-observer variability in plan selection appears to remain problematic. The additional resources, education and technology required for the initiation of plan library selection for bladder cancer may hinder its routine clinical implementation, with eight studies illustrating increased treatment time required.

CONCLUSIONS

While there is a growing body of evidence in support of plan libraries for bladder RT, many studies differed in their delivery approach. The advent of the clinical use of the MRI-linear accelerator will provide RT departments with the opportunity to consider daily online adaption for bladder cancer as an alternate to plan library approaches.

Adjuvant radiotherapy after radical cystectomy for patients with muscle invasive bladder cancer: a phase II trial

Background

Neo-adjuvant chemotherapy followed by radical cystectomy with extended pelvic lymph node dissection is considered to be the treatment of choice for patients with muscle invasive bladder cancer (MIBC). Despite this aggressive treatment the outcome is poor and ultimately, 30% of the patients with ≥pT3 tumors develop a pelvic recurrence. We hypothesize that postoperative adjuvant external beam radiotherapy (EBRT) might prevent local and lymph node recurrence and improve disease free- and overall survival as loco-regional recurrence is linked to the development of distant metastasis.

Methods

We plan to perform a multicentric prospective phase two study including 76 patients. Eligible patients are patients with MIBC, treated with radical cystectomy and presenting with ≥1 of the following characteristics:

Pathological (p)T3 stage + presence of lymphovascular invasion on pathological examination

pT4 stage

<10 lymph nodes removed

positive lymph nodes

positive surgical margins

Patients will have a ¹⁸F–FDG PET-CT to rule out the presence of distant metastasis prior to EBRT. A median dose of 50 Gy in 25 fractions is prescribed to the pelvic lymph node regions with inclusion of the operative bladder bed in case of a positive surgical margin. Patients with suspected lymph nodes on PET- CT can still be included in the trial, but a simultaneous integrated boost to 74Gy to the positive lymph nodes will be delivered. Blood and urine samples will be collected on day-1 and last day of EBRT for evaluation of biomarkers. The primary endpoint is evaluation of acute ≥Grade 3 intestinal or grade 4 urinary toxicity, in case of a neo-bladder reconstruction, within 12 weeks after EBRT. Secondary endpoints are: assessment of QOL, late RTOG toxicity, local control, disease free survival and overall survival. Biomarkers in urine and blood will be correlated with secondary survival endpoints.

Discussion

This is a prospective phase 2 trial re-assessing the feasibility of adjuvant radiotherapy in high-risk MIBC.

Trial registration

The Ethics committee of the Ghent University Hospital (EC2014/0630) approved this study on 31/07/2014.

Trial registration on Clinicaltrials.gov (NCT02397434) on November 19, 2014.

Clinical Outcomes of Image Guided Adaptive Hypofractionated Weekly Radiation Therapy for Bladder Cancer in Patients Unsuitable for Radical Treatment

PURPOSE AND OBJECTIVES

We report on the clinical outcomes of a phase 2 study assessing image guided hypofractionated weekly radiation therapy in bladder cancer patients unsuitable for radical treatment.

METHODS AND MATERIALS

Fifty-five patients with T2-T4aNx-2M0-1 bladder cancer not suitable for cystectomy or daily radiation therapy treatment were recruited. A "plan of the day" radiation therapy approach was used, treating the whole (empty) bladder to 36 Gy in 6 weekly fractions. Acute toxicity was assessed weekly during radiation therapy, at 6 and 12 weeks using the Common Terminology Criteria for Adverse Events version 3.0. Late toxicity was assessed at 6 months and 12 months using Radiation Therapy Oncology Group grading. Cystoscopy was used to assess local control at 3 months. Cumulative incidence function was used to determine local progression at 1 at 2 years. Death without local progression was treated as a competing risk. Overall survival was estimated using the Kaplan-Meier method.

RESULTS

Median age was 86 years (range, 68-97 years). Eighty-seven percent of patients completed their prescribed course of radiation therapy. Genitourinary and gastrointestinal grade 3 acute toxicity was seen in 18% (10/55) and 4% (2/55) of patients, respectively. No grade 4 genitourinary or gastrointestinal toxicity was seen. Grade ≥3 late toxicity (any) at 6 and 12 months was seen in 6.5% (2/31) and 4.3% (1/23) of patients, respectively. Local control after radiation therapy was 92% of assessed patients (60% total population). Cumulative incidence of local progression at 1 year and 2 years for all patients was 7% (95% confidence interval [CI] 2%-17%) and 17% (95% CI 8%-29%), respectively. Overall survival at 1 year was 63% (95% CI 48%-74%).

CONCLUSION

Hypofractionated radiation therapy delivered weekly with a plan of the day approach offers good local control with acceptable toxicity in a patient population not suitable for radical bladder treatment.

Where are we with bladder preservation for muscle-invasive bladder cancer in 2017?

INTRODUCTION

In 2017, neoadjuvant, cisplatin-based chemotherapy followed by radical cystectomy (RC) is considered the gold standard therapy for muscle-invasive bladder based on randomized controlled trials. Across all tumor stages, this approach has been associated with the highest rates of disease-specific survival. However, RC is one of the most challenging procedures performed by urologic surgeons and carries with it significant risks of complications, hospital readmission, and even a small risk of mortality, in addition to lifestyle changes that can have long-term effects on well-being. For these reasons, bladder-sparing approaches are utilized in some highly selected patients. We reviewed the most recent evidence for bladder-sparing modalities for muscle-invasive urothelial bladder cancer and summarize those findings in this review article.

METHODS

We performed a PubMed literature review utilizing the key words "bladder preservation," "trimodal therapy," "muscle-invasive bladder cancer," and "partial cystectomy" written in English, dating back to 1990. We excluded case reports.

RESULTS

Our search yielded more than 2000 articles which we screened. Some articles were then rejected due to inappropriate topic. In addition, we reviewed the most recent American Urological Association, National Comprehensive Cancer Network (NCCN), and European guidelines on muscle-invasive bladder cancer. We identified fifty relevant articles which are summarized in this text. In some rare instances, recommendations are based on expert opinion.

CONCLUSIONS

Bladder preservation is often considered for quality of life considerations or in the setting of multiple medical comorbidities, and this remains oncologically appropriate even in 2016 in highly selected patients with muscle-invasive urothelial carcinoma of the bladder.

Analysis of inter- and intra fractional partial bladder wall movement using implanted fiducial markers

Background

Current adaptive and dose escalating radiotherapy for muscle invasive bladder cancer requires knowledge of both inter-fractional and intra-fractional motion of the bladder wall involved. The purpose of this study is to characterize inter- and intra-fractional movement of the partial bladder wall using implanted fiducial markers and a real-time tumor-tracking radiotherapy system.

Methods

Two hundred fifty one sessions with 29 patients were analysed. After maximal transurethral bladder tumor resection and 40 Gy of whole bladder irradiation, up to six gold markers were implanted transurethrally into the bladder wall around the tumor bed and used for positional registration. We compared the systematic and random uncertainty of positions between cranial vs. caudal, left vs. right, and anterior vs. posterior tumor groups. The variance in intrafractional movement and the percentage of sessions where 3 mm and 5 mm or more of intrafractional wall movement occurring at 2, 4, 6, 8, 10, and at more than 10 min until the end of a session were determined.

Results

The cranial and anterior tumor group showed larger interfractional uncertainties in the position than the opposite side tumor group in the CC and AP directions respectively, but these differences did not reach significance. Among the intrafractional uncertainty of position, the cranial and anterior tumor group showed significantly larger systematic uncertainty of position than the groups on the opposite side in the CC direction. The variance of intrafractional movement increased over time; the percentage of sessions where intrafractional wall movement was larger than 3 mm within 2 min of the start of a radiation session or larger than 5 mm within 10 min was less than 5%, but this percentage was increasing further during the session, especially in the cranial and anterior tumor group.

Conclusions

More attention for intrafractional uncertainty of position is required in the treatment of cranial and anterior bladder tumors especially in the CC direction. The optimal internal margins in each direction should be chosen or a precise intrafractional target localization system is required depending on the tumor location and treatment delivery time in the setting of partial bladder radiotherapy.

Chemoradiotherapy in octogenarians as primary treatment for muscle-invasive bladder cancer

INTRODUCTION

While radical cystectomy is the gold standard for muscle-invasive bladder cancer (MIBC), in octogenarians cystectomy results in a higher perioperative mortality rate (6.8-11.1%) than in younger patients (2.2%). Trimodality therapy is a bladder-sparing regimen composed of transurethral resection of bladder tumour (TURBT) and chemoradiotherapy, with intent for salvage cystectomy, and has a 62.5-90% initial complete response rate. In this study, we evaluate TURBT and chemoradiotherapy without salvage cystectomy in medically inoperable octogenarian patients.

METHODS

We identified a retrospective cohort of patients aged 80-89 years with invasive urothelial carcinoma who received combination chemoradiotherapy between 2008 and June 2014. Outcomes were evaluated by Kaplan-Meier (KM) and Cox regression.

RESULTS

In 40 patients, the mean age was 84.5 years (interquartile range [IQR] 83-86). Seventeen patients received hypofractionated, low-dose radiotherapy (LD) (37.5-40 Gy), while 23 received conventionally fractionated radiotherapy (high-dose [HD]) (50-65 Gy). Mean overall survival (OS) was 20.7 months (IQR 12.75-23.25), while mean recurrence-free survival (RFS) was 13.75 months (IQR 3.75-16.5). Patients receiving HD radiotherapy showed improved OS and local RFS (LRFS) without significant differences in Grade 3-4 toxicities. Univariate Cox regression identified hydronephrosis as a predictor of worse OS and local recurrence and HD radiotherapy as a predictor of improved OS and local recurrence rates. Multivariate Cox regression identified hydronephrosis to be a significant predictor of LRFS.

CONCLUSIONS

Primary chemoradiotherapy for inoperable patients with MIBC resulted in a three-year OS of 54.9% (comparable to cystectomy) and three-year RFS of 42.3%. Superior outcomes were associated with more aggressive chemoradiotherapy treatment. The results of the local control subanalyses in this study are hypothesis-generating due to the limited patient numbers in the cohort.

Prospective Study Delivering Simultaneous Integrated High-dose Tumor Boost (≤70 Gy) With Image Guided Adaptive Radiation Therapy for Radical Treatment of Localized Muscle-Invasive Bladder Cancer

PURPOSE

Image guided adaptive radiation therapy offers individualized solutions to improve target coverage and reduce normal tissue irradiation, allowing the opportunity to increase the radiation tumor dose and spare normal bladder tissue.

METHODS AND MATERIALS

A library of 3 intensity modulated radiation therapy plans were created (small, medium, and large) from planning computed tomography (CT) scans performed at 30 and 60 minutes; treating the whole bladder to 52 Gy and the tumor to 70 Gy in 32 fractions. A "plan of the day" approach was used for treatment delivery. A post-treatment cone beam CT (CBCT) scan was acquired weekly to assess intrafraction filling and coverage.

RESULTS

A total of 18 patients completed treatment to 70 Gy. The plan and treatment for 1 patient was to 68 Gy. Also, 1 patient's plan was to 70 Gy but the patient was treated to a total dose of 65.6 Gy because dose-limiting toxicity occurred before dose escalation. A total of 734 CBCT scans were evaluated. Small, medium, and large plans were used in 36%, 48%, and 16% of cases, respectively. The mean ± standard deviation rate of intrafraction filling at the start of treatment (ie, week 1) was 4.0 ± 4.8 mL/min (range 0.1-19.4) and at end of radiation therapy (ie, week 5 or 6) was 1.1 ± 1.6 mL/min (range 0.01-7.5; P=.002). The mean D98 (dose received by 98% volume) of the tumor boost and bladder as assessed on the post-treatment CBCT scan was 97.07% ± 2.10% (range 89.0%-104%) and 99.97% ± 2.62% (range 96.4%-112.0%). At a median follow-up period of 19 months (range 4-33), no muscle-invasive recurrences had developed. Two patients experienced late toxicity (both grade 3 cystitis) at 5.3 months (now resolved) and 18 months after radiation therapy.

CONCLUSIONS

Image guided adaptive radiation therapy using intensity modulated radiation therapy to deliver a simultaneous integrated tumor boost to 70 Gy is feasible, with acceptable toxicity, and will be evaluated in a randomized trial.

Muscle-invasive bladder cancer treated with TURB followed by concomitant boost with small reduction of radiotherapy field with or without of chemotherapy

AIM

To evaluate the clinical outcome and toxicity of the treatment of muscle-invasive bladder cancer (MIBC) that combined transurethral resection of bladder tumor (TURB) with "concomitant boost" radiotherapy delivered over a shortened overall treatment time of 5 weeks, with or without concurrent chemotherapy.

BACKGROUND

Local control of MIBC by bladder-sparing approach is unsatisfactory. In order to improve the effectiveness of radiotherapy, we have designed a protocol that combines TURB with a non-conventionally fractionated radiotherapy "concomitant boost".

MATERIALS AND METHODS

Between 2004 and 2010, 73 patients with MIBC cT2-4aN0M0, were treated with "concomitant boost" radiotherapy. The whole bladder with a 2-3 cm margin was irradiated with fractions of 1.8 Gy to a dose of 45 Gy, with a "concomitant boost" to the bladder with 1-1.5 cm margin, during the last two weeks of treatment, as a second fraction of 1.5 Gy, to a total dose of 60 Gy. Radiochemotherapy using mostly cisplatin was delivered in 42/73(58%) patients, 31/73(42%) patients received radiotherapy alone.

RESULTS

Acute genitourinary toxicity of G3 was scored in 3/73(4%) patients. Late gastrointestinal toxicity higher than G2 and genitourinary higher than G3 were not reported. Complete remission was achieved in 48/73(66%), partial remission in 17/73(23%), and stabilization disease in 8/73(11%) patients. Three- and five-year overall, disease specific and invasive locoregional disease-free survival rates were 65% and 52%, 70% and 59%, 52% and 43%, respectively.

CONCLUSIONS

An organ-sparing approach using TURB followed by radio(chemo)therapy with "concomitant boost" in patients with MIBC allows to obtain long-term survival with acceptable toxicity.

Hypofractionated palliative radiotherapy for bladder cancer

PURPOSE

The aim of this study was to evaluate hematuria-free survival as well as acute and late toxicity after hypofractionated palliative radiotherapy for bladder cancer.

METHODS AND MATERIALS

Between September 2004 and January 2013, 44 patients with biopsy-proven urothelial carcinoma of the bladder were irradiated according to a palliative schedule to a total dose of 34.5 Gy in six fractions of 5.75 Gy given once a week.

RESULTS

After a mean follow-up of 10 months, 91% of patients were still hematuria free, with a mean hematuria-free survival of 13 months. Severe (≥ grade 3) acute and late urinary toxicity was observed in 9 and 19% of patients, respectively.

CONCLUSION

This hypofractionated radiotherapy schedule appears to result in acceptable toxicity and manages successful and long-term palliation of hematuria in most patients.

Defining bowel dose volume constraints for bladder radiotherapy treatment planning

AIMS

Increases to radiotherapy dose are constrained by normal tissue effects. The relationship between bowel dose volume data and late bowel toxicity in patients with muscle-invasive bladder cancer treated with radical radiotherapy was assessed.

MATERIALS AND METHODS

The bowel was contoured retrospectively on radiotherapy plans of 47 patients recruited to the BC2001 trial (CRUK/01/004). The relationship between bowel volume at various dose levels and prospectively collected late bowel toxicity was explored.

RESULTS

Fifteen per cent and 6% of patients experienced grade 1 and grade 2 or more late bowel toxicity, respectively. The mean bowel volume was significantly less at doses ≥50 Gy in those treated with reduced high dose volume radiotherapy compared with standard radiotherapy. The probability of late bowel toxicity increased as bowel volume increased (P ≤ 0.05 for dose levels 30-50 Gy). No grade 2 or more late bowel toxicity was observed in patients with bowel volumes under the thresholds given in the model that predict for 25% probability of late bowel toxicity.

CONCLUSIONS

There is a dose volume effect for late bowel toxicity in radical bladder radiotherapy. We have modelled the probability of late bowel toxicity from absolute bowel volumes to guide clinicians in assessing radical bladder radiotherapy plans. Thresholds predicting for a 25% probability of late bowel toxicity are proposed as dose volume constraints.

[Concomitant chemoradiotherapy for muscle-invasive bladder cancer: current knowledge, controversies and future directions]

Radical cystectomy with lymphadenectomy is currently the standard of care for muscle-invasive urothelial bladder cancer; however and because of its morbidity and its impact on quality of life, there is a growing tendency for bladder-sparing strategies. Initially reserved for elderly or unfit patients unable to undergo radical cystectomy, chemoradiotherapy became a true alternative to surgery for highly selected patients. Although there are no randomized trials comparing radical cystectomy with bladder preserving approaches, surgery remains the preferred treatment for many clinicians. Furthermore, comparison is even more difficult as modalities of radiotherapy are not consensual and differ between centers with a variability of protocols, volume of irradiation and type of chemotherapy. Several ongoing trials are attempting to optimize chemoradiotherapy and limit its toxicity, especially through techniques of adaptive radiotherapy or targeted therapies.

Trimodality bladder-sparing approach without neoadjuvant chemotherapy for node-negative localized muscle-invasive urinary bladder cancer resulted in comparable cystectomy-free survival

BACKGROUND

To retrospectively review the efficacy and organ preservation experience for muscle-invasive bladder cancer by trimodality therapy at our institution.

METHODS

Between July 2004 and February 2012, seventy patients (M/F = 55/15; median age = 69 years) of lymph node negative localized muscle-invasive bladder cancer were treated primarily with trimodality approach including transurethral resection of bladder tumor (TURBT) prior to combined chemotherapy and radiotherapy (CCRT). Radiotherapy consisted of initial large field size irradiation with 3D conformal technique (3D-CRT), followed by cone-down tumor bed boost with intensity modulated radiotherapy (IMRT) technique. The median total doses delivered to bladder tumor bed and whole bladder were 59.4Gy and 40.0Gy, respectively. No patient received neoadjuvant chemotherapy (NAC). Weekly cisplatin was administered during radiotherapy. Toxicity was scored according to the RTOG criteria. Tumor response was evaluated both cystoscopically and radiographically 3 months after treatment.

RESULTS

The numbers of patients with T2, T3 and T4 lesions were 41, 16 and 13, respectively. Overall survival (OS) and progression-free survival (PFS) at 2 and 5 year were 65.7%, 51.9% and 50.8%, 39.9%, respectively, after a median follow-up time of 24 months. Local-regional control and distant metastasis free survival at 2 year were 69.8% and 73.5%, respectively. Complete response (CR) rate assessed three month after CCRT was 78.1%. Ten patients (20%) had local recurrence after initial CR (n = 50), 3 of them were superficial recurrence. One patient underwent radical cystectomy after recurrence. The overall 5-year bladder intact survival was 49.0% (95% CI, 35.5% to 62.5%). Acute toxicities were limited to grade 1-2. One patient developed late grade 3 GU toxicity.

CONCLUSIONS

Our result suggested that trimodality bladder-sparing approach without NAC or dose-intensification could be well-tolerated with a high CR rate and bladder preserving rate for muscle-invasive bladder cancer.

Current clinical practice guidelines on chemotherapy and radiotherapy for the treatment of non-metastatic muscle-invasive urothelial cancer: a systematic review and critical evaluation by the Hellenic Genito-Urinary Cancer Group (HGUCG)

Radical cystectomy is the treatment of choice in localized muscle-invasive urothelial cancer. Nevertheless, relapses are frequent and systemic chemotherapy has been employed in order to reduce this risk. In addition, bladder preservation strategies are appealing. During the last decade, there has been a difficulty in conducting and completing large-scale trials in urothelial cancer. This has resulted in relatively few changes in the existing guidelines. Recent studies have created renewed interest in certain fields, such as the role of chemo-radiotherapy and management of unfit patients. In addition, application of certain guidelines has been limited in everyday practice. We conducted a systematic review of the existing guidelines and recent randomized trials not included in these guidelines, and developed a treatment algorithm, regarding non-surgical therapies for non-metastatic, muscle-invasive urothelial cancer based predominantly on patients' fitness for the available therapeutic modalities.

The role of radiotherapy in bladder cancer

In this article we report on the current role of radiotherapy in the management of non-muscle invasive as well as in muscle invasive bladder cancer.
Radiotherapy seems to have no role in non-muscle invasive bladder cancer.
In muscle invasive bladder tumors, the role of radiotherapy is under investigation in view of new radiotherapy techniques and novel cytotoxic and biological agents.

Assessment of the radiation-equivalent of chemotherapy contributions in 1-phase radio-chemotherapy treatment of muscle-invasive bladder cancer

PURPOSE

To estimate the radiation equivalent of the chemotherapy contribution to observed complete response rates in published results of 1-phase radio-chemotherapy of muscle-invasive bladder cancer.

METHODS AND MATERIALS

A standard logistic dose-response curve was fitted to data from radiation therapy-alone trials and then used as the platform from which to quantify the chemotherapy contribution in 1-phase radio-chemotherapy trials. Two possible mechanisms of chemotherapy effect were assumed (1) a fixed radiation-independent contribution to local control; or (2) a fixed degree of chemotherapy-induced radiosensitization. A combination of both mechanisms was also considered.

RESULTS

The respective best-fit values of the independent chemotherapy-induced complete response (CCR) and radiosensitization (s) coefficients were 0.40 (95% confidence interval -0.07 to 0.87) and 1.30 (95% confidence interval 0.86-1.70). Independent chemotherapy effect was slightly favored by the analysis, and the derived CCR value was consistent with reports of pathologic complete response rates seen in neoadjuvant chemotherapy-alone treatments of muscle-invasive bladder cancer. The radiation equivalent of the CCR was 36.3 Gy.

CONCLUSION

Although the data points in the analyzed radio-chemotherapy studies are widely dispersed (largely on account of the diverse range of chemotherapy schedules used), it is nonetheless possible to fit plausible-looking response curves. The methodology used here is based on a standard technique for analyzing dose-response in radiation therapy-alone studies and is capable of application to other mixed-modality treatment combinations involving radiation therapy.

Prospective phase II study of image-guided local boost using a real-time tumor-tracking radiotherapy (RTRT) system for locally advanced bladder cancer

OBJECTIVE

The real-time tumor-tracking radiotherapy system with fiducial markers has the advantage that it can be used to verify the localization of the markers during radiation delivery in real-time. We conducted a prospective Phase II study of image-guided local-boost radiotherapy for locally advanced bladder cancer using a real-time tumor-tracking radiotherapy system for positioning, and here we report the results regarding the safety and efficacy of the technique.

METHODS

Twenty patients with a T2-T4N0M0 urothelial carcinoma of the bladder who were clinically inoperable or refused surgery were enrolled. Transurethral tumor resection and 40 Gy irradiation to the whole bladder was followed by the transurethral endoscopic implantation of gold markers in the bladder wall around the primary tumor. A boost of 25 Gy in 10 fractions was made to the primary tumor while maintaining the displacement from the planned position at less than ±2 mm during radiation delivery using a real-time tumor-tracking radiotherapy system. The toxicity, local control and survival were evaluated.

RESULTS

Among the 20 patients, 14 were treated with concurrent chemoradiotherapy. The median follow-up period was 55.5 months. Urethral and bowel late toxicity (Grade 3) were each observed in one patient. The local-control rate, overall survival and cause-specific survival with the native bladder after 5 years were 64, 61 and 65%.

CONCLUSIONS

Image-guided local-boost radiotherapy using a real-time tumor-tracking radiotherapy system can be safely accomplished, and the clinical outcome is encouraging. A larger prospective multi-institutional study is warranted for more precise evaluations of the technological efficacy and patients' quality of life.

Radio-chemotherapy for bladder cancer: Contribution of chemotherapy on local control

The purpose of this study was to review the magnitude of contribution of chemotherapy (CT) in the local control of muscle invasive bladder carcinoma in the studies where a combined radio-chemotherapy (RCT) was used (how much higher local control rates are obtained with RCT compared to RT alone). Studies on radiotherapy (RT) and combined RCT, neo-adjuvant, concurrent, adjuvant or combinations, reported after 1990 were reviewed. The mean complete response (CR) rates were significantly higher for the RCT studies compared to RT-alone studies: 75.9% vs 64.4% (Wilcoxon rank-sum test, P = 0.001). Eleven of the included RCT studies involved 2-3 cycles of neo-adjuvant CT, in addition to concurrent RCT. The RCT studies included the one-phase type (where a full dose of RCT was given and then assessment of response and cystectomy for non-responders followed) and the two-phase types (where an assessment of response was undertaken after an initial RCT course, followed 6 wk later by a consolidation RCT for those patients with a CR). CR rates between the two subgroups of RCT studies were 79.6% (one phase) vs 71.6% (two-phase) (P = 0.015). The average achievable tumour control rates, with an acceptable rate of side effects have been around 70%, which may represent a plateau. Further increase in CR response rates demands for new chemotherapeutic agents, targeted therapies, or modified fractionation in various combinations. Quantification of RT and CT contribution to local control using radiobiological modelling in trial designs would enhance the potential for both improved outcomes and the estimation of the potential gain.

The role of radiotherapy in urinary bladder cancer: current status

The role of radiotherapy (RT) in the treatment of urinary bladder cancer has undergone several modifications along the last decades. In the beginning, definitive RT was used as treatment in an attempt to preserve the urinary bladder; however, the results were poor compared to those of radical surgery. Recently, many protocols have been developed supporting the use of multi-modality therapy, and the concept of organ preservation began to be reconsidered. Although phase III randomized clinical studies comparing radical cystectomy with bladder preservation therapies do not exist, the conservative treatment may present low toxicity and high indexes of complete response for selected patients. The aim of this study was to review the literature on the subject in order to situate RT in the current treatment of urinary bladder cancer.

Transurethral resection, neoadjuvant chemotherapy and accelerated hyperfractionated radiotherapy (concomitant boost), with or without concurrent cisplatin, for patients with invasive bladder cancer - clinical outcome

AIM OF THE STUDY

To evaluate the toxicity, clinical effectiveness and survival rate of transurethral resection, neoadjuvant chemotherapy and accelerated hyperfractionated radiotherapy (concomitant boost), with or without concurrent cisplatin in patients with muscle invasive bladder cancer.

MATERIAL AND METHODS

Between March 2004 and December 2009, 35 patients with histologically proven invasive carcinoma of the bladder (T2-4a, N0-1, M0), who were fit for combined radiochemotherapy and refused radical surgery or were medically or surgically inoperable, were selected for the bladder-sparing protocol.

RESULTS

In this study, twenty-five patients (25/35; 72%) received two cycles of neoadjuvant chemotherapy, and ten of them (10/35; 28%) only one, because of treatment-related toxicity. In twenty-one patients (21/35; 60%) chemotherapy consisting of gemcitabine with cisplatin and in fourteen patients (14/35; 40%) gemcitabine with carboplatin were applied. Only 13 patients (13/35; 37%) received combined irradiation with cisplatin. All patients completed their planned course of radiation therapy. Complete response (CR) occurred in 26/35 (74%) patients, partial response (PR) in 2/35(6%), and stable disease (SD) in 7/35 (20%). The overall actuarial survival rates at 3 and 5 years were 75% and 66%, respectively. Disease-specific actuarial survival rates at 3 and 5 years were 81% and 71%, respectively.

CONCLUSIONS

Conservative treatment of patients with muscle-invasive bladder cancer by transurethral resection, neoadjuvant chemotherapy, and accelerated hyperfractionated radiotherapy with concomitant boost, with or without concurrent cisplatin, provides a high probability of local and distal response with acceptable toxicity in properly selected patients.

Trimodality treatment in the conservative management of infiltrating bladder cancer: a critical review of the literature

Although radical cystectomy is still the treatment of choice for patients with infiltrating bladder cancer, there is growing evidence of the effectiveness of a conservative approach. Developed as a treatment of need for elderly or unfit patients unable to undergo radical cystectomy, conservative therapy is becoming a true alternative to surgery for highly selected patients. Although transurethral bladder resection, external radiotherapy and systemic chemotherapy can control the disease as single treatments, the best results have been observed when they are combined. Moreover, new irradiation techniques and new-generation drugs are now being tested in an attempt to improve disease control further. Conservative management requires the multidisciplinary involvement of different specialties in order to give patients a real alternative to surgical treatment.

Australian & New Zealand Faculty of Radiation Oncology Genito-Urinary Group: 2011 consensus guidelines for curative radiotherapy for urothelial carcinoma of the bladder

Curative radiotherapy, with or without concurrent chemotherapy, is recognized as a standard treatment option for muscle-invasive bladder cancer. It is commonly used for two distinct groups of patients: either for those medically unfit for surgery, or as part of a 'bladder preserving' management plan incorporating the possibility of salvage cystectomy. However, in both situations, the approach to radiotherapy varies widely around the world. The Australian and New Zealand Faculty of Radiation Oncology Genito-Urinary Group recognised a need to develop consistent, evidence-based guidelines for patient selection and radiotherapy technique in the delivery of curative radiotherapy. Following a workshop convened in May 2009, a working party collated opinions and conducted a wide literature appraisal linking each recommendation with the best available evidence. This process was subject to ongoing re-presentation to the Faculty of Radiation Oncology Genito-Urinary Group members prior to final endorsement. These Guidelines include patient selection, radiation target delineation, dose and fractionation schedules, normal tissue constraints and investigational techniques. Particular emphasis is given to the rationale for the target volumes described. These Guidelines provide a consensus-based framework for the delivery of curative radiotherapy for muscle-invasive bladder cancer. Widespread input from radiation oncologists treating bladder cancer ensures that these techniques are feasible in practice. We recommend these Guidelines be adopted widely in order to encourage a uniformly high standard of radiotherapy in this setting, and to allow for better comparison of outcomes.