Hypofractionated conformal radiotherapy in carcinoma of the prostate: five-year outcome analysis

Early Results of Extreme Hypofractionation Using Stereotactic Body Radiation Therapy for High-risk, Very High-risk and Node-positive Prostate Cancer

AIMS

Stereotactic body radiotherapy (SBRT) in low- and intermediate-risk prostate cancer has shown encouraging results. However, its use in high-risk patients is limited due to lack of data regarding adequate radiotherapy dose, need for pelvic nodal treatment and androgen deprivation therapy. Herein we report our experience of SBRT in this subgroup.

MATERIALS AND METHODS

Analysis of a prospectively maintained database of 68 consecutive patients of the National Comprehensive Cancer Network (NCCN) high-risk, very high-risk and node-positive adenocarcinoma prostate treated with SBRT was undertaken. All patients were treated with rotational intensity-modulated radiotherapy with daily image guidance. The dose delivered to the prostate and gross node was 35-37.5 Gy in 5 alternate day fractions. Node-positive patients received 25 Gy to pelvic nodal regions until the common iliac nodes. Treatment was delivered in 7-10 days. All patients received long-term androgen deprivation therapy (79% medical and 21% surgical).

RESULTS

Most patients (65%) had a Gleason score ≥ 8. The median prostate-specific antigen was 42. Twenty patients were high risk (30%), 11 (16%) very high risk and 37 (54%) node positive. No acute Radiation Therapy Oncology Group grade ≥ 3 genitourinary or gastrointestinal toxicity was noted. Acute grade 2 genitourinary and gastrointestinal toxicity were 12% and 3%, respectively. Late grade 3 genitourinary and gastrointestinal toxicity was 3% and 0%, respectively. There was no increase in acute or late gastrointestinal toxicity with prophylactic pelvic nodal radiotherapy. Prior transurethral resection of prostate (n = 11) did not increase toxicity. At a median follow-up of 18 months, 97% patients were alive and 94% were biochemically controlled.

CONCLUSION

SBRT is safe in the treatment of high-risk, very high-risk and node-positive prostate cancer, even with prophylactic pelvic radiotherapy or prior transurethral resection of prostate. Longer follow-up is required to determine efficacy.

Stereotactic Body Radiation Therapy for Localized Prostate Cancer

Stereotactic body radiation therapy (SBRT) has become a viable treatment option for the many patients who receive a diagnosis of localized prostate cancer each year. Technological advancements have led to tight target conformality, allowing for high-dose-per-fraction delivery without untoward normal tissue toxicity. Biochemical control, now reported up to 5 years, appears to compare favorably with dose-escalated conventionally fractionated radiotherapy. Moreover, toxicity and quality of life follow-up data indicate genitourinary and gastrointestinal toxicities are likewise comparable to conventional radiation therapy. Nevertheless, because of the long natural history of prostate cancer, extended follow-up will be necessary to confirm these impressive initial results. Within this prostate SBRT review, we explore the detailed rationale for SBRT treatment, the diverse SBRT techniques utilized and their unique technical considerations, and finally data for SBRT clinical efficacy and treatment-related toxicity.

Moderate Hypofractionation with Simultaneous Integrated Boost in Prostate Cancer: Long-term Results of a Phase I-II Study

AIMS

To report 5 year outcome and late toxicity in prostate cancer patients treated with image-guided tomotherapy with a moderate hypofractionated simultaneous integrated boost approach.

MATERIALS AND METHODS

In total, 211 prostate cancer patients, 78 low risk, 53 intermediate risk and 80 high risk were treated between 2005 and 2011. Intermediate- and high-risk patients received 51.8 Gy to pelvic lymph nodes and concomitant simultaneous integrated boost to prostate up to 74.2 Gy/28 fractions, whereas low-risk patients were treated to the prostate only with 71.4 Gy/28 fractions. Daily megavoltage computed tomography (MVCT) image guidance was applied. Androgen deprivation was prescribed for a median duration of 6 months for low-risk patients (for downsizing), 12 months for intermediate-risk and 36 months for high-risk patients. The 5 year biochemical relapse-free survival (bRFS), cancer-specific survival (CSS), overall survival and late gastrointestinal and genitourinary CTCAE.v3 toxicity were assessed. The effect of several clinical variables on both outcome and gastrointestinal/genitourinary toxicity was tested by uni- and multivariate Cox regression analyses.

RESULTS

After a median follow-up of 5 years, the late toxicity actuarial incidence was: genitourinary ≥ grade 2: 20.2%; genitourinary ≥ grade 3: 5.9%; gastrointestinal ≥ grade 2: 17%; gastrointestinal ≥ grade 3: 6.3% with lower prevalence at the last follow-up visit (≥ grade 3: genitourinary: 1.9%; gastrointestinal: 1.9%). Major predictors of ≥ grade 3 genitourinary and gastrointestinal late toxicity were genitourinary acute toxicity ≥ grade 2 (hazard ratio: 4.9) and previous surgery (hazard ratio: 3.4). The overall 5 year bRFS was 93.7% (low risk: 94.6%; intermediate risk: 96.2%; high risk: 91.1%), overall survival and CSS were 88.6% (low risk: 90.5%; intermediate risk: 87.4%; high risk: 87%) and 97.5% (low risk: 98.7%; intermediate risk: 95%; high risk: 94.3%), respectively. Risk classes and androgen deprivation were not significantly correlated with either bRFS, overall survival or CSS. Twelve patients experienced a biochemical relapse but none experienced clinically proven local and/or pelvic recurrence.

CONCLUSION

A satisfactory 5 year outcome with an acceptable toxicity profile was observed. The combination of image-guided radiotherapy-intensity-modulated radiotherapy, high equivalent 2 Gy dose (EQD2) with a moderate hypofractionated approach and extensive prophylactic lymph node irradiation also leads to very good outcome in high-risk patients.

Sexual, irritative, and voiding outcomes, following stereotactic body radiation therapy for prostate cancer

BACKGROUND

Urinary symptoms and sexual dysfunction are the two most common complaints following prostate radiotherapy. The impact of hypofractionated treatment on sexual function, irritative symptoms, and voiding symptoms has not been determined within the same patient population. Here we present our institutional data on sexual function, voiding function, irritative symptoms, and treatment response following SBRT.

METHODS

This retrospective analysis includes 102 non-metastatic patients treated with SBRT at a single institution between May 2008 and September 2014. The course of radiotherapy consisted of 36.25 Gy (range 35-40) over five daily fractions. International Prostate Symptom Score (IPSS), Sexual Health Inventory for Men (SHIM), and PSA were recorded at baseline, 1, 3, 6, 9, 12, 18, 24, and 36 months after treatment.

RESULTS

Median patient age was 72 years old with a median follow-up of 4.3 years. Pretreatment IPSS-I score was 5.21, increasing to 6.97 (p < .001) after 1 month. The mean IPSS-I score returned close to baseline after 3 months to 5.86 and decreased to below baseline after 2 years to 5.09. At 3 months, 9 months, and 2 years, 47.5, 76.2, and 91.1% of patients had reached IPSS-I resolution. The mean IPSS-O score prior to treatment was 5.31 and there was an increase in the score to 6.45 (p = 0.344) at 1 month. The score remained close to baseline and decreased to 4.00 at 2 years and significantly decreased to 3.74 (p = 0.035) at 3 years. 64.4, 82.1, and 96.0% of patients had IPSS-O resolution by 3 months, 9 months, and 2 years. The mean SHIM score prior to treatment was 13.52 and continually decreased to below baseline a year after treatment to 10.56 (p < .001). SHIM score began to improve at 18 months, but was still significantly less than baseline at 12.12 (p = .01).

CONCLUSIONS

While an increase in AUA/IPSS score initially occurred, all patients resume normal activities immediately following treatment and the AUA/IPSS symptoms improved from baseline. Irittative symptoms take longer to resolve when compared to obstructive voiding symptoms in patients treated with SBRT. Three year PSA response, reported toxicity, erectile function preservation, and urinary function improvement, shows favorable results.

Efficacy of dose escalation on TCP, recurrence and second cancer risks: a mathematical study

OBJECTIVE

We investigated the effects of conventional and hypofractionation protocols by modelling tumour control probability (TCP) and tumour recurrence time, and examined their impact on second cancer risks. The main objectives of this study include the following: (a) incorporate tumour recurrence time and second cancer risks into the TCP framework and analyse the effects of variable doses and (b) investigate an efficient protocol to reduce the risk of a secondary malignancy while maximizing disease-free survival and tumour control.

METHODS

A generalized mathematical formalism was developed that incorporated recurrence and second cancer risk models into the TCP dynamics.

RESULTS

Our results suggest that TCP and relapse time are almost identical for conventional and hypofractionated regimens; however, second cancer risks resulting from hypofractionation were reduced by 22% when compared with the second cancer risk associated with a conventional protocol. The hypofractionated regimen appears to be sensitive to dose escalation and the corresponding impact on tumour recurrence time and reduction in second cancer risks. The reduction in second cancer risks is approximately 20% when the dose is increased from 60 to 72 Gy in a hypofractionated protocol.

CONCLUSION

Our results suggest that hypofractionation may be a more efficient regimen in the context of TCP, relapse time and second cancer risks. Overall, our study demonstrates the importance of including a second cancer risk model in designing an efficient radiation regimen.

ADVANCES IN KNOWLEDGE

The impact of various fractionation protocols on TCP and relapse in conjunction with second cancer risks is an important clinical question that is as yet unexplored.

Outcome and patient-reported toxicity in localised prostate cancer treated with dose-escalated hypofractionated intensity-modulated radiotherapy

Objective

To report outcomes and late toxicity for a hypofractionated dose-escalated radiotherapy schedule in patients treated using intensity-modulated radiotherapy (IMRT) for localised prostate cancer.

Materials and methods

Eighty-eight men with localised prostate cancer were treated with 57 Gy in 19 daily fractions over 4 weeks. A total of 70 out of 88 had high-risk disease. Overall survival, cause-specific survival and biochemical progression-free survival (bPFS, Phoenix definition) were reported. Toxicity was measured retrospectively using Radiation Therapy Oncology Group (RTOG) criteria and assessed prospectively with a validated Late Effects in Normal Tissues Subjective, Objective, Management and Analytic (LENT/SOMA) patient questionnaire.

Results

At 5 years, overall survival was 84%, cause-specific survival 88% and bPFS 65%. In patients with high-risk disease, 5-year bPFS was 62%. There was no RTOG toxicity above grade III. LENT/SOMA questionnaires were returned by 74% patients. Median scores for bowel and urinary function were <1. Maximum bowel and urinary toxicity scores ≥2 were reported by 64% and 59% of patients, respectively. The median score for sexual function was 1·5, but nearly all (96%) patients recorded a toxicity score ≥2 for at least one question.

Conclusions

Dose-escalated hypofractionated radiotherapy delivered using IMRT has promising outcomes and acceptable late toxicity. This fractionation schedule is being compared with conventional treatment within an on-going multicentre phase III clinical trial.

Stereotactic body radiotherapy for localized prostate cancer: pooled analysis from a multi-institutional consortium of prospective phase II trials

PURPOSE

The effectiveness of stereotactic body radiotherapy (SBRT) for localized prostate cancer is tested.

METHODS AND MATERIALS

A total of 1100 patients with clinically localized prostate cancer were enrolled in separate prospective phase 2 clinical trials of SBRT from 8 institutions during 2003-11 and pooled for analysis. SBRT using the CyberKnife delivered a median dose of 36.25Gy in 4-5 fractions. Patients were low-risk (58%), intermediate-risk (30%) and high-risk (11%). A short-course of androgen deprivation therapy (ADT) was given to 14%. PSA relapse defined as a rise >2ng/ml above nadir was analyzed with the Kaplan Meier method.

RESULTS

With a median follow-up of 36months there were 49 patients with PSA failure (4.5%), 9 of whom were subsequently determined to be benign PSA bounces. The 5-year biochemical relapse free survival (bRFS) rate was 93% for all patients; 95%, 83% and 78% for GS ⩽6, 7 and ⩾8, respectively (p=0.001), and 95%, 84% and 81% for low-, intermediate- and high-risk patients, respectively (p<0.001). No differences were observed with ADT (p=0.71) or as a function of total dose (p=0.17). A PSA bounce of >0.2ng/ml was noted among 16% of patients. For 135 patients possessing a minimum of 5years follow-up, the 5-year bRFS rate for low- and intermediate-risk patients was 99% and 93%, respectively.

CONCLUSION

PSA relapse-free survival rates after SBRT compare favorably with other definitive treatments for low and intermediate risk patients. The current evidence supports consideration of SBRT among the therapeutic options for these patients.

[Hypofractionated radiotherapy in prostate cancer]

Radiotherapy plays a central role in the management of localized prostate cancer, but the total duration of treatment of nearly 2 months poses not only problems of fatigue related to repetitive transports, especially for older patients, but also increases the overall cost of treatment including linear accelerators occupancy and patient transportation. To address this problem, various teams have developed hypofractionated radiotherapy protocols seeking to maintain the same efficacy and toxicity while reducing the total duration of treatment. These hypofractionated protocols require recent techniques such as image-guided radiation therapy (IGRT) and intensity-modulated radiation therapy (IMRT). Single centre series have validated the feasibility of "light" hypofractionation schemes at doses per fraction less than 6 Gy Similarly, different teams have shown the possibility of stereotactic irradiation for delivering "severe" hypofractionation schemes at doses greater than 6 Gy per fraction. Whatever the dose per fraction, the current clinical data support the conclusion that hypofractionated radiotherapy does not increase mid-term toxicity and could even improve biochemical control. Studies with the objective of demonstrating non-inferiority are expected to definitively validate the role of hypofractionated irradiation in the treatment of prostate cancer.

How to select the optimal therapy for early-stage prostate cancer

Selecting the "optimal therapy" for the patient with localized prostate cancer may be one of the most challenging medical decisions facing the oncologist. Most patients will have a number of appropriate therapeutic options available to them. Before determining which therapy is most appropriate for a patient, a critical question which needs to be asked is whether any therapy is necessary, especially for those who present with early-stage, low-grade, low-volume disease. Furthermore, given the lack of randomized trials available to guide physicians regarding the superiority of one therapy over another, it is important to consider the different side-effect profiles relevant for each treatment modality. The potential toxicities of therapy impact quality-of-life outcomes and play an important role for most patients in their individual selection of a particular therapy. In addition, there are other important issues that need to be considered, which include the medical condition of the patient and emotional and psychological considerations, as well as family/peer viewpoints or perceived notions of a particular therapy. This review will discuss the relevant issues in the decision making and treatment selection for the patient.

Stereotactic body radiotherapy for localized prostate cancer: disease control and quality of life at 6 years

Background

Stereotactic body radiotherapy (SBRT) may yield disease control for prostate cancer in a brief, hypofractionated treatment regimen without increasing treatment toxicity. Our report presents a 6-year update from 304 low- (n = 211), intermediate- (n = 81), and high-risk (n = 12) prostate cancer patients who received CyberKnife SBRT.

Methods

The median PSA at presentation was 5.8 ng/ml. Fifty-seven patients received neoadjuvant hormonal therapy for up to one year. The first 50 patients received a total dose of 35 Gy in 5 fractions of 7 Gy. The subsequent 254 patients received a total dose of 36.25 Gy in 5 fractions of 7.25 Gy. Toxicity was assessed with the Expanded Prostate Cancer Index Composite questionnaire and the Radiation Therapy Oncology Group urinary and rectal toxicity scale. Biochemical failure was assessed using the nadir + 2 definition.

Results

No patients experienced Grade III or IV acute complications. Fewer than 5% of patients experienced any acute Grade II urinary or rectal toxicities. Late urinary Grade II complications were observed in 4% of patients treated to 35 Gy and 9% of patients treated to 36.25 Gy. Five (2%) late Grade III urinary toxicities occurred in patients who were treated with 36.25 Gy. Late Grade II rectal complications were observed in 2% of patients treated to 35 Gy and 5% of patients treated to 36.25 Gy. Bowel and urinary quality of life (QOL) scores initially decreased, but later returned to baseline values. An overall decrease of 20% in the sexual QOL score was observed. QOL in each domain was not differentially affected by dose. For patients that were potent prior to treatment, 75% stated that they remained sexually potent. Actuarial 5-year biochemical recurrence-free survival was 97% for low-risk, 90.7% for intermediate-risk, and 74.1% for high-risk patients. PSA fell to a median of 0.12 ng/ml at 5 years; dose did not influence median PSA levels.

Conclusions

In this large series with long-term follow-up, we found excellent biochemical control rates and low and acceptable toxicity, outcomes consistent with those reported for from high dose rate brachytherapy (HDR BT). Provided that measures are taken to account for prostate motion, SBRT’s distinct advantages over HDR BT include its noninvasiveness and delivery to patients without anesthesia or hospitalization.

Acute toxicity profile in prostate cancer with conventional and hypofractionated treatment

Purpose

To compare the acute toxicities in radical treatment of prostate cancer between conventional schedule (C-ARM) with 78 Gy/39 fractions and hypofractionation conformal treatment (H-ARM) with 69 Gy/23 fractions.

Methods and material

This prospective double arm study consisted of 217 patients with prostate cancer, 112 in H-ARM and 105 in C-ARM arm. C-ARM received conventional six- field conformal radiotherapy with 78 Gy in 39 fractions while H-ARM received hypofractionation with 69 Gy in 23 fractions. Weekly assessment of acute reactions was done during treatment and with one, and 3 months using RTOG scale. Univariated analysis was performed to evaluate differences between the incidences of acute reaction in the treatment arms. Variables with p value less than 0.1 were included in the multivariated logistic regression.

Results

There was no difference between H-ARM versus C-ARM for severity and incidence in genitourinary (GU) and gastrointestinal (GI) acute toxicity. During the treatment comparing H-ARM with C-ARM no differences was observed for GI toxicity (grade 0–3; H-ARM = 45.5%, 34%, 18.7% and 1.8% versus C-ARM = 47.6%, 35.2%, 17.2% and 0). For acute GU toxicity no difference was detected between H-ARM (grade 0–3; 22.3%, 54.5%, 18.7% and 4.5%) and C-ARM (grade 0–3; 25.8%, 53.3%, 17.1% and 3.8%).

At the 3- months follow-up, persistent Grade > =2 acute GU and GI toxicity were 2.5% and 1.8% in H-ARM versus 5.7% and 3% in C-ARM (p > 0.05). In univariated and multivariated analyses, there was not any dosimetric predictor for GI and GU toxicity.

Conclusions

Our data demonstrate that hypofractionated radiotherapy achieving high biological effective dose using conformal radiotherapy is feasible for prostate cancer, being well tolerated with minimal severe acute toxicity.

Prognostic factors for acute toxicity in prostate cancer patients treated with high-dose hypofractionated radiotherapy

PURPOSE

To prospectively study acute genitourinary (GU) and gastrointestinal (GI) toxicity during hypofractionated radiotherapy.

PATIENTS AND MATERIALS

One-hundred and seventy-one consecutive men with cT1-T3cN0cM0 prostate cancer were treated at 2.6 Gy/fraction to a total dose of 67.6 for low risk (EQD2 = 79 Gy) and 70.2 Gy for intermediate-high risk (EQD2 = 82 Gy) over 5.2-5.4 weeks (α/β 1.5). Acute toxicity was scored according to RTOG/EORTC toxicity extended criteria after completing a 22-item questionnaire (basal, weekly, at 6 months).

RESULTS

Minimum and median follow-up were 36 and 54.2 months, respectively. GU toxicity grades 0, 1, 2 and 3 were found in 30.4, 37, 32 and 0.6 % of patients, respectively. The figures for grades 0, 1, 2 and 3 GI toxicity were 66, 24, 10 and 0 %. The highest degree of acute reactions was reached at 4-5 weeks. At 6 months, 15 % of patients had GU toxicity (11 % grade 1, 4 % grade 2) and 5.8 % GI toxicity (5.3 % grade 1, 0.5 % grade 2). Multivariate analysis shows that bladder volume receiving ≥65 Gy (V 65) is associated with an increased risk of GU complications (p = 0.017, HR = 1.143, 95 % CI = 1.025-1.276), while history of TURP is linked to lower risk (p = 0.002, HR = 0.310, 95 % CI 0.004-0.370). Mean rectal dose (p = 0.013, HR = 1.089, 95 % CI 1.018-1.116) and total dose (p = 0.019, HR = 0.734, 95 % CI 0.567-0.950) are significantly related to GI toxicity.

CONCLUSIONS

This 5-week dose-escalation hypofractionated radiotherapy schedule that uses 3D-conformal radiotherapy without IGRT has resulted in <1 % grade 3 acute complications. Our study suggests that reducing the mean rectal dose and the bladder V 65 helps prevent acute toxicity. TURP before radiotherapy was associated with lower acute GU toxicity.

Prostate alpha/beta revisited -- an analysis of clinical results from 14 168 patients

PURPOSE

To determine the dose response parameters and the fractionation sensitivity of prostate tumours from clinical results of patients treated with external beam radiotherapy.

MATERIAL AND METHODS

The study was based on five-year biochemical results from 14 168 patients treated with external beam radiotherapy. Treatment data from 11 330 patients treated with conventional fractionation have been corrected for overall treatment time and fitted with a logit equation. The results have been used to determine the optimum α/β values that minimise differences in predictions from 2838 patients treated with hypofractionated schedules.

RESULTS

Conventional fractionation data yielded logit dose response parameters for all risk groups and for all definitions of biochemical failures. The analysis of hypofractionation data led to very low α/β values (1-1.7 Gy) in all mentioned cases. Neglecting the correction for overall treatment time has little impact on the derivation of α/β values for prostate cancers.

CONCLUSIONS

These results indicate that the high fractionation sensitivity is an intrinsic property of prostate carcinomas and they support the use of hypofractionation to increase the therapeutic gain for these tumours.

Review of hypofractionated radiotherapy for prostate cancer

Hypofractionated radiotherapy for prostate cancer has become of increasing interest with the recognition of a potential improvement in therapeutic outcome with treatments delivered in large-sized daily fractions. In addition, hypofractionation offers a reduction in fraction number and produces attractive cost and increased convenience for patients. There is convincing evidence, by several clinical trials, that biochemical control is significantly improved with higher administered radiation doses to the prostate gland. Furthermore, the improved radiation delivery techniques such as 3D conformal radiotherapy (3DCRT) or, better, intensity modulated radiation therapy (IMRT) allow high administered doses to the prostate while sparing the normal surrounding tissues. Several studies of the radiobiology of prostate cancer suggest that it may be more susceptible to large fraction sizes compared with conventional fractionation of external beam radiation.

Hypofractionated radiotherapy in prostate cancer

In regards to prostate cancer, the classic radiotherapy dose ranges from 70-80 Gy, administered in daily 2-Gy fractions. However, when taking into account the particular radiobiological model of prostate cancer cells, one realizes that there is a potential theoretical advantage to delivering a greater biological effective dose per treatment in a lower number of fractions. Both recent and older publications have attempted to explore this treatment option. This critical review comprehensively examines the current state of knowledge concerning hypofractionated radiotherapy in prostate cancer.

Dose-escalated hypofractionated intensity-modulated radiotherapy in high-risk carcinoma of the prostate: outcome and late toxicity

Background. The benefit of dose-escalated hypofractionated radiotherapy using intensity-modulated radiotherapy (IMRT) in prostate cancer is not established. We report 5-year outcome and long-term toxicity data within a phase II clinical trial. Materials and Methods. 60 men with predominantly high-risk prostate cancer were treated. All patients received neoadjuvant hormone therapy, completing up to 6 months in total. Thirty patients were treated with 57 Gy in 19 fractions and 30 patients with 60 Gy in 20 fractions. Acute and 2-year toxicities were reported and patients followed longitudinally to assess 5 year outcomes and long-term toxicity. Toxicity was measured using RTOG criteria and LENT/SOMA questionnaire. Results. Median followup was 84 months. Five-year overall survival (OS) was 83% and biochemical progression-free survival (bPFS) was 50% for 57 Gy. Five-year OS was 75% and bPFS 58% for 60 Gy. At 7 years, toxicity by RTOG criteria was acceptable with no grade 3 or above toxicity. Compared with baseline, there was no significant change in urinary symptoms at 2 or 7 years. Bowel symptoms were stable between 2 and 7 years. All patients continued to have significant sexual dysfunction. Conclusion. In high-risk prostate cancer, dose-escalated hypofractionated radiotherapy using IMRT results in encouraging outcomes and acceptable late toxicity.

Carbon-ion radiation therapy for prostate cancer

In 1994, carbon-ion radiotherapy was started at the National Institute of Radiological Sciences using the Heavy-Ion Medical Accelerator in Chiba. Between June 1995 and March 2000, two phase I/II dose escalation studies (protocols 9402 and 9703) of hypofractionated carbon-ion radiotherapy for both early- and advance-stage prostate cancer patients had been carried out to establish radiotherapy technique and to determine the optimal radiation dose. To validate the feasibility and efficacy of hypofractionated carbon-ion radiotherapy, a phase II study (9904) was initiated in April 2000 using the shrinking field technique and the recommended dose fractionation (66 gray equivalents in 20 fractions over 5 weeks) obtained from the phase I/II studies, and was successfully completed in October 2003. The data from 175 patients in the phase II study showed the importance of an appropriate use of androgen deprivation therapy according to tumor risk group. Since November 2003, carbon-ion radiotherapy for prostate cancer was approved as "Highly Advanced Medical Technology" from the Ministry of Health, Labor, and Welfare, and since then approximately 1100 patients have received carbon-ion radiotherapy as of July 2011. In this review, we introduce our steps thorough three clinical trials carried out at National Institute of Radiological Sciences, and show the updated data of carbon-ion radiotherapy obtained from approximately 1000 prostate cancer patients. In addition, our recent challenge and future direction will be also described.

Conventional versus hypofractionated high-dose intensity-modulated radiotherapy for prostate cancer: preliminary safety results from the CHHiP randomised controlled trial

BACKGROUND

Prostate cancer might have high radiation-fraction sensitivity, implying a therapeutic advantage of hypofractionated treatment. We present a pre-planned preliminary safety analysis of side-effects in stages 1 and 2 of a randomised trial comparing standard and hypofractionated radiotherapy.

METHODS

We did a multicentre, randomised study and recruited men with localised prostate cancer between Oct 18, 2002, and Aug 12, 2006, at 11 UK centres. Patients were randomly assigned in a 1:1:1 ratio to receive conventional or hypofractionated high-dose intensity-modulated radiotherapy, and all were given with 3-6 months of neoadjuvant androgen suppression. Computer-generated random permuted blocks were used, with risk of seminal vesicle involvement and radiotherapy-treatment centre as stratification factors. The conventional schedule was 37 fractions of 2 Gy to a total of 74 Gy. The two hypofractionated schedules involved 3 Gy treatments given in either 20 fractions to a total of 60 Gy, or 19 fractions to a total of 57 Gy. The primary endpoint was proportion of patients with grade 2 or worse toxicity at 2 years on the Radiation Therapy Oncology Group (RTOG) scale. The primary analysis included all patients who had received at least one fraction of radiotherapy and completed a 2 year assessment. Treatment allocation was not masked and clinicians were not blinded. Stage 3 of this trial completed the planned recruitment in June, 2011. This study is registered, number ISRCTN97182923.

FINDINGS

153 men recruited to stages 1 and 2 were randomly assigned to receive conventional treatment of 74 Gy, 153 to receive 60 Gy, and 151 to receive 57 Gy. With 50·5 months median follow-up (IQR 43·5-61·3), six (4·3%; 95% CI 1·6-9·2) of 138 men in the 74 Gy group had bowel toxicity of grade 2 or worse on the RTOG scale at 2 years, as did five (3·6%; 1·2-8·3) of 137 men in the 60 Gy group, and two (1·4%; 0·2-5·0) of 143 men in the 57 Gy group. For bladder toxicities, three (2·2%; 0·5-6·2) of 138 men, three (2·2%; 0·5-6·3) of 137, and none (0·0%; 97·5% CI 0·0-2·6) of 143 had scores of grade 2 or worse on the RTOG scale at 2 years.

INTERPRETATION

Hypofractionated high-dose radiotherapy seems equally well tolerated as conventionally fractionated treatment at 2 years.

FUNDING

Stage 1 was funded by the Academic Radiotherapy Unit, Cancer Research UK programme grant; stage 2 was funded by the Department of Health and Cancer Research UK.

Stereotactic body radiation therapy for prostate cancer

Stereotactic body radiation therapy (SBRT) is a promising treatment option for prostate cancer. Hypofractionation regimens, such as SBRT, may be more advantageous compared with conventional regimens because low α:β ratio of prostate cancer has high sensitivity to dose per fraction. In addition, a smaller and tighter margin with SBRT is expected to provide a low toxicity rate without reducing tumor control. The purpose of this article is to examine radiobiological, technical and clinical aspects of SBRT for prostate cancer.

Dose-fractionation sensitivity of prostate cancer deduced from radiotherapy outcomes of 5,969 patients in seven international institutional datasets: α/β = 1.4 (0.9-2.2) Gy

PURPOSE

There are reports of a high sensitivity of prostate cancer to radiotherapy dose fractionation, and this has prompted several trials of hypofractionation schedules. It remains unclear whether hypofractionation will provide a significant therapeutic benefit in the treatment of prostate cancer, and whether there are different fractionation sensitivities for different stages of disease. In order to address this, multiple primary datasets have been collected for analysis.

METHODS AND MATERIALS

Seven datasets were assembled from institutions worldwide. A total of 5969 patients were treated using external beams with or without androgen deprivation (AD). Standard fractionation (1.8-2.0 Gy per fraction) was used for 40% of the patients, and hypofractionation (2.5-6.7 Gy per fraction) for the remainder. The overall treatment time ranged from 1 to 8 weeks. Low-risk patients comprised 23% of the total, intermediate-risk 44%, and high-risk 33%. Direct analysis of the primary data for tumor control at 5 years was undertaken, using the Phoenix criterion of biochemical relapse-free survival, in order to calculate values in the linear-quadratic equation of k (natural log of the effective target cell number), α (dose-response slope using very low doses per fraction), and the ratio α/β that characterizes dose-fractionation sensitivity.

RESULTS

There was no significant difference between the α/β value for the three risk groups, and the value of α/β for the pooled data was 1.4 (95% CI = 0.9-2.2) Gy. Androgen deprivation improved the bNED outcome index by about 5% for all risk groups, but did not affect the α/β value.

CONCLUSIONS

The overall α/β value was consistently low, unaffected by AD deprivation, and lower than the appropriate values for late normal-tissue morbidity. Hence the fractionation sensitivity differential (tumor/normal tissue) favors the use of hypofractionated radiotherapy schedules for all risk groups, which is also very beneficial logistically in limited-resource settings.

Long-term outcomes from a prospective trial of stereotactic body radiotherapy for low-risk prostate cancer

PURPOSE

Hypofractionated radiotherapy has an intrinsically different normal tissue and tumor radiobiology. The results of a prospective trial of stereotactic body radiotherapy (SBRT) for prostate cancer with long-term patient-reported toxicity and tumor control rates are presented.

METHODS AND MATERIALS

From 2003 through 2009, 67 patients with clinically localized low-risk prostate cancer were enrolled. Treatment consisted of 36.25 Gy in 5 fractions using SBRT with the CyberKnife as the delivery technology. No patient received hormone therapy. Patient self-reported bladder and rectal toxicities were graded on the Radiation Therapy Oncology Group scale (RTOG).

RESULTS

Median follow-up was 2.7 years. There were no grade 4 toxicities. Radiation Therapy Oncology Group Grade 3, 2, and 1 bladder toxicities were seen in 3% (2 patients), 5% (3 patients), and 23% (13 patients) respectively. Dysuria exacerbated by urologic instrumentation accounted for both patients with Grade 3 toxicity. Urinary incontinence, complete obstruction, or persistent hematuria was not observed. Rectal Grade 3, 2, and 1 toxicities were seen in 0, 2% (1 patient), and 12.5% (7 patients), respectively. Persistent rectal bleeding was not observed. Low-grade toxicities were substantially less frequent with QOD vs. QD dose regimen (p = 0.001 for gastrointestinal and p = 0.007 for genitourinary). There were two prostate-specific antigen (PSA), biopsy-proven failures with negative metastatic workup. Median PSA at follow-up was 0.5 ± 0.72 ng/mL. The 4-year Kaplan-Meier PSA relapse-free survival was 94% (95% confidence interval, 85%-102%).

CONCLUSION

Significant late bladder and rectal toxicities from SBRT for prostate cancer are infrequent. PSA relapse-free survival compares favorably with other definitive treatments. The current evidence supports consideration of stereotactic body radiotherapy among the therapeutic options for localized prostate cancer.

Late morbidity and oncological outcome after radical hypofractionated radiotherapy in men with prostate cancer

OBJECTIVE

To test the hypothesis that three-dimensional hypofractionated radiotherapy (3D-HFRT) is well tolerated and not worse than 3-D conventional RT (3D-CRT) for oncological outcome.

PATIENTS AND METHODS

In all, 162 men with hystologically confirmed prostate adenocarcinoma were included in the analysis. In all, 82 men were treated with 3D-HFRT (15 fractions of 3.62 Gy delivered 3 times/week; a total dose of 54.3 Gy). This group was retrospectively compared with 80 men who met the same inclusion criteria and who were treated with 3D-CRT (39 fractions of 2 Gy delivered daily; a total dose of 78 Gy). A short course of hormone therapy was administered concomitantly with the RT.

RESULTS

Only one (1.7%) patient in the 3D-CRT group and two (4.0%) in the 3D-HFRT group had Grade 3 genitourinary toxicity. There was late gastrointestinal morbidity of ≥ grade 3 in only 5.1% of men treated with 3D-HFRT and in 4.0% of men treated with 3D-CRT. In both groups there was no Grade 4 toxicity. At the median (range) follow-up of 45 (39.4-51) months for the 3D-HFRT group and 57.5 (54.9-59.1) months for 3D-CRT group the progression rate was 18/82 (21.9%) and 20/80 (25.0%), respectively, with no significant worsening in the risk of biochemical failure (BCF; log-rank test, P= 0.222).

CONCLUSIONS

In the present study, men with clinically localized prostate cancer had similar levels of morbidity irrespective of whether they received HFRT or CRT without any worsening in the early risk of BCF. Thus, the present data provide some clinical evidence to justify trends already emerging toward HF regimens for treating clinically localised prostate cancer.

Assessment of normal tissue complications following prostate cancer irradiation: comparison of radiation treatment modalities using NTCP models

PURPOSE

Normal tissue complication probability (NTCP) of the rectum, bladder, urethra, and femoral heads following several techniques for radiation treatment of prostate cancer were evaluated applying the relative seriality and Lyman models.

METHODS

Model parameters from literature were used in this evaluation. The treatment techniques included external (standard fractionated, hypofractionated, and dose-escalated) three-dimensional conformal radiotherapy (3D-CRT), low-dose-rate (LDR) brachytherapy (I-125 seeds), and high-dose-rate (HDR) brachytherapy (Ir-192 source). Dose-volume histograms (DVHs) of the rectum, bladder, and urethra retrieved from corresponding treatment planning systems were converted to biological effective dose-based and equivalent dose-based DVHs, respectively, in order to account for differences in radiation treatment modality and fractionation schedule.

RESULTS

Results indicated that with hypofractionated 3D-CRT (20 fractions of 2.75 Gy/fraction delivered five times/week to total dose of 55 Gy), NTCP of the rectum, bladder, and urethra were less than those for standard fractionated 3D-CRT using a four-field technique (32 fractions of 2 Gy/fraction delivered five times/week to total dose of 64 Gy) and dose-escalated 3D-CRT. Rectal and bladder NTCPs (5.2% and 6.6%, respectively) following the dose-escalated four-field 3D-CRT (2 Gy/fraction to total dose of 74 Gy) were the highest among analyzed treatment techniques. The average NTCP for the rectum and urethra were 0.6% and 24.7% for LDR-BT and 0.5% and 11.2% for HDR-BT.

CONCLUSIONS

Although brachytherapy techniques resulted in delivering larger equivalent doses to normal tissues, the corresponding NTCPs were lower than those of external beam techniques other than the urethra because of much smaller volumes irradiated to higher doses. Among analyzed normal tissues, the femoral heads were found to have the lowest probability of complications as most of their volume was irradiated to lower equivalent doses compared to other tissues.

Dose Escalation Study with Two Different Hypofractionated Intensity Modulated Radiotherapy Techniques for Localized Prostate Cancer: Acute Toxicity

To assess acute gastrointestinal (GI) and genitourinary (GU) toxicities in patients with localized prostate cancer treated with a sequential dose escalation hypofractionated intensity-modulated radiotherapy (IMRT) study using two different delivery methods. Since 2003, 88 and 48 patients were sequentially treated to 56 Gy and to 60 Gy (4 Gy/fraction twice weekly), respectively. IMRT with 6 MV beams was delivered with five fields in Geneva and with nine in Barcelona. Acute GI and GU side effects were scored weekly during treatment and 6 weeks after treatment completion using the Radiation Therapy Oncology Group (RTOG) toxicity scale. Clinical, technical, and dosimetric parameters were analyzed in order to assess for a potential correlation with toxicity.

Grade 1–2, GU and GI toxicities during and 6 weeks after treatment completion were 64%, and 24%, and 35% and 12%, respectively. Only one Grade 4 GU toxicity, consisting of transitory urinary obstruction, was observed. Patients treated to 60 Gy in Geneva presented a higher rate of Grade 1–2 GU toxicity ( p = 0.01), while patients treated to both 56 and 60 Gy in Barcelona presented a higher Grade 1–2 GI toxicity ( p = 0.02). A lower rate of rectal toxicity was observed in the subgroup of 22 patients treated with a rectal balloon ( p = 0.02). The use of androgen deprivation therapy was associated with a higher rate of Grade 1–2 GU toxicity after the end of the treatment ( p = 0.02). Dose escalation with either 14 × 4 Gy or 15 × 4 Gy delivered with two different IMRT techniques is feasible and is associated with a tolerable acute toxicity.

Altered fractionation in radiotherapy: from radiobiological rationale to therapeutic gain

The implementation of altered fractionation schedules in clinical practice came as a need to improve loco-regional control and survival in those cancer patient groups which did not respond satisfactorily to conventionally fractionated radiotherapy. The current review aims to present the radiobiological rationale behind various non-conventional treatment schedules including the encountered challenges, through a compilation of clinical studies/trials and their contribution towards therapeutic gain.

Acute and late toxicity in a randomized trial of conventional versus hypofractionated three-dimensional conformal radiotherapy for prostate cancer

PURPOSE

To compare the toxicity between hypofractionation vs. conventional fractionation schedules in patients with high-risk prostate cancer.

METHODS AND MATERIALS

Between January 2003 and December 2007, 168 patients were randomized to receive either hypofractionated (62 Gy in 20 fractions within 5 weeks, 4 fractions/wk) or conventionally fractionated (80 Gy in 40 fractions within 8 weeks) three-dimensional conformal radiotherapy to the prostate and seminal vesicles. All patients had undergone a 9-month course of total androgen deprivation, with radiotherapy starting 2 months after initiation of the total androgen deprivation.

RESULTS

The median follow-up was 32 and 35 months in the hypofractionation and conventional fractionation arms, respectively. For the patients developing acute toxicity, no difference between the two fractionation groups was found in either severity or duration of gastrointestinal or genitourinary toxicity. Also, no difference was found in the incidence and severity of late gastrointestinal and genitourinary toxicity between the two treatment schedules, with a 3-year rate of Grade 2 or greater toxicity of 17% and 16% for the hypofractionation arm and 14% and 11% for the conventional fractionation arm, respectively. A statistically significant correlation between acute and late gastrointestinal toxicity was found only in the conventional fractionation group.

CONCLUSION

Our findings suggest that the hypofractionation regimen used in our study is safe, with only a slight, nonsignificant increase in tolerable and temporary acute toxicity compared with the conventional fractionation schedule. The severity and frequency of late complications was equivalent between the two treatment groups.

Confirmation of a low α/β ratio for prostate cancer treated by external beam radiation therapy alone using a post-treatment repeated-measures model for PSA dynamics

PURPOSE

To estimate the α/β ratio of prostate cancer treated with external beam radiation only by use of a model of long-term prostate-specific antigen (PSA) dynamics.

METHODS AND MATERIALS

Repeated measures of PSA from 5,093 patients from 6 institutions treated for localized prostate cancer by external beam radiation therapy (EBRT) without planned androgen deprivation were analyzed. A biphasic linear mixed model described the post-treatment evolution of PSA, rather than a conventional model of time to biochemical recurrence. The model was adjusted for standard prognostic factors (T stage, initial PSA level, and Gleason score) and cohort-specific effects. The radiation dose fractionation effect was estimated from the long-term rate of rise of PSA level.

RESULTS

Adjusted for other factors, total dose of EBRT and sum of squared doses per fraction were associated with long-term rate of change of PSA level (p = 0.0017 and p = 0.0003, respectively), an increase of each being associated with a lower rate of rise. The α/β ratio was estimated at 1.55 Gy (95% confidence band, 0.46-4.52 Gy). This estimate was robust to adjustment of the linear mixed model.

CONCLUSIONS

By analysis of a large EBRT-only cohort along with a method that uses all the repeated measures of PSA after the end of treatment, a low and precise α/β was estimated. These data support the use of hypofractionation at fractional doses up to 2.8 Gy but cannot presently be assumed to accurately represent higher doses per fraction.

Stereotactic body radiotherapy for organ-confined prostate cancer

BACKGROUND

Improved understanding of prostate cancer radiobiology combined with advances in delivery of radiation to the moving prostate offer the potential to reduce treatment-related morbidity and maintain quality of life (QOL) following prostate cancer treatment. We present preliminary results following stereotactic body radiotherapy (SBRT) treatment for organ-confined prostate cancer.

METHODS

SBRT was performed on 304 patients with clinically localized prostate cancer: 50 received 5 fractions of 7 Gy (total dose 35 Gy) and 254 received 5 fractions of 7.25 Gy (total dose 36.25 Gy). Acute and late toxicity was assessed using the Radiation Therapy Oncology Group scale. The Expanded Prostate Cancer Index Composite questionnaire was used to assess QOL. Prostate-specific antigen response was monitored.

RESULTS

At a median 30-month (26 - 37 month, range) follow-up there were no biochemical failures for the 35-Gy dose level. Acute Grade II urinary and rectal toxicities occurred in 4% of patients with no higher Grade acute toxicities. One Grade II late urinary toxicity occurred with no other Grade II or higher late toxicities. At a median 17-month (8 - 27 month, range) follow-up the 36.25 Gy dose level had 2 low- and 2 high-risk patients fail biochemically (biopsy showed 2 low- and 1 high-risk patients were disease-free in the gland). Acute Grade II urinary and rectal toxicities occurred in 4.7% (12/253) and 3.6% (9/253) of patients, respectively. For those patients with a minimum of 12 months follow-up, 5.8% (12/206) had late Grade II urinary toxicity and 2.9% (6/206) had late Grade II rectal toxicities. One late Grade III urinary toxicity occurred; no Grade IV toxicities occurred. For both dose levels at 17 months, bowel and urinary QOL returned to baseline values; sexual QOL decreased by 10%.

CONCLUSIONS

The low toxicity and maintained QOL are highly encouraging. Additional follow-up is needed to determine long-term biochemical control and maintenance of low toxicity and QOL.

Positional reproducibility and effects of a rectal balloon in prostate cancer radiotherapy

Despite the increasing use of the rectal balloon in prostate cancer radiotherapy, many issues still remain to be verified objectively including its positional reproducibility and relevance to treatment morbidity. We have developed a custom rectal balloon that has a scale indicating the depth of insertion and dilates symmetrically ensuring positional reproducibility. Fifty patients with prostate cancer treated by definitive 3D-conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) with rectal balloon were analyzed. Each of first five patients undergone computed tomography (CT) three times with a rectal balloon. The positional reproducibility was tested by Intraclass Correlation Coefficient (ICC) from the CT-to-CT fusion images. Planning variables and clinical acute toxicities were compared between when or not applying balloon. An ICC of greater than 0.9 in all directions revealed an excellent reproducibility of the balloon. Rectal balloon improved considerably the mean dose and V(45Gy)-V(65Gy) in plan comparison, and especially in 3D-CRT the rectal volume exposed to more than 60 Gy dropped from 41.3% to 19.5%. Clinically, the balloon lowered acute toxicity, which was lowest when both the balloon and IMRT were applied simultaneously. The rectal balloon carries excellent reproducibility and reduces acute toxicity in 3D-CRT and IMRT for prostate cancer.

Modeling of alpha/beta for late rectal toxicity from a randomized phase II study: conventional versus hypofractionated scheme for localized prostate cancer

BACKGROUND

Recently, the use of hypo-fractionated treatment schemes for the prostate cancer has been encouraged due to the fact that alpha/beta ratio for prostate cancer should be low. However a major concern on the use of hypofractionation is the late rectal toxicity, it is important to be able to predict the risk of toxicity for alternative treatment schemes, with the best accuracy. The main purpose of this study is to evaluate the response of rectum wall to changes in fractionation and to quantify the alpha/beta ratio for late rectal toxicity

METHODS

162 patients with localized prostate cancer, treated with conformal radiotherapy, were enrolled in a phase II randomized trial. The patients were randomly assigned to 80 Gy in 40 fractions over 8 weeks (arm A) or 62 Gy in 20 fractions over 5 weeks (arm B). The median follow-up was 30 months. The late rectal toxicity was evaluated using the Radiation Therapy Oncology Group (RTOG) scale. It was assumed >or= Grade 2 (G2) toxicity incidence as primary end point. Fit of toxicity incidence by the Lyman-Burman-Kutcher (LKB) model was performed.

RESULTS

The crude incidence of late rectal toxicity >or= G2 was 14% and 12% for the standard arm and the hypofractionated arm, respectively. The crude incidence of late rectal toxicity >or= G2 was 14.0% and 12.3% for the arm A and B, respectively. For the arm A, volumes receiving >or= 50 Gy (V50) and 70 Gy (V70) were 38.3 +/- 7.5% and 23.4 +/- 5.5%; for arm B, V38 and V54 were 40.9 +/- 6.8% and 24.5 +/- 4.4%. An alpha/beta ratio for late rectal toxicity very close to 3 Gy was found.

CONCLUSION

The >or= G2 late toxicities in both arms were comparable, indicating the feasibility of hypofractionated regimes in prostate cancer. An alpha/beta ratio for late rectal toxicity very close to 3 Gy was found.

Radiobiological model comparison of 3D conformal radiotherapy and IMRT plans for the treatment of prostate cancer

The main aim of radiotherapy is to deliver a dose of radiation that is high enough to destroy the tumour cells while at the same time minimising the damage to normal healthy tissues. Clinically, this has been achieved by assigning a prescription dose to the tumour volume and a set of dose constraints on critical structures. Once an optimal treatment plan has been achieved the dosimetry is assessed using the physical parameters of dose and volume. There has been an interest in using radiobiological parameters to evaluate and predict the outcome of a treatment plan in terms of both a tumour control probability (TCP) and a normal tissue complication probability (NTCP). In this study, simple radiobiological models that are available in a commercial treatment planning system were used to compare three dimensional conformal radiotherapy treatments (3D-CRT) and intensity modulated radiotherapy (IMRT) treatments of the prostate. Initially both 3D-CRT and IMRT were planned for 2 Gy/fraction to a total dose of 60 Gy to the prostate. The sensitivity of the TCP and the NTCP to both conventional dose escalation and hypo-fractionation was investigated. The biological responses were calculated using the Källman S-model. The complication free tumour control probability (P+) is generated from the combined NTCP and TCP response values. It has been suggested that the alpha/beta ratio for prostate carcinoma cells may be lower than for most other tumour cell types. The effect of this on the modelled biological response for the different fractionation schedules was also investigated.