Adjuvant androgen deprivation impacts late rectal toxicity after conformal radiotherapy of prostate carcinoma

Risk factors for rectal bleeding after volumetric-modulated arc radiotherapy of prostate cancer

Background

It is crucially important to understand the risk factors for rectal bleeding after volumetric-modulated arc radiotherapy (VMAT) for prostate cancer to prevent subsequent rectal bleeding. We assayed clinical and dosimetric data to investigate the risk factors for rectal bleeding after VMAT of prostate cancer.

Materials and methods

This study included 149 patients with prostate cancer who received VMAT from February, 2012 to June, 2020. Irradiated total doses were 78 Gy/39 fractions in 33 patients (22.1%), 76 Gy/38 fractions in 89 (59.7%), 74 Gy/37 fractions in 4 (2.7%), and 72 Gy/36 fractions in 23 (15.4%). We investigated multiple clinical and dosimetric factors with reference to rectal bleeding.

Results

The median observation period was 38 months. Fourteen patients (9.4%) experienced rectal bleeding: five (3.4%) were classified as Grade 2, and nine (6.0%) as Grade 1. There were significant differences between Grade ≥ 1 and Grade 0 patients in the overlap region of the planning target volume (PTV) and the rectum, the rectal V30-75, and the mean rectal dose (p < 0.05). There were significant differences between Grade 2 and Grade 0-1 patients in rectal V30-65 and mean rectal dose (p < 0.05).

Conclusions

Rectal bleeding occurred, but its grades and rate of occurrence were permissible. Higher rectal doses were shown to be related to rectal bleeding, and reduction of low/intermediate and mean rectal doses will be important for preventing rectal bleeding.

Comparative evaluation of hypofractionated radiotherapy versus conventionally fractionated radiotherapy for patients with intermediate and high risk prostate cancer

Background

The purpose of this study was to comparatively evaluate an efficacy and toxicity profile of hypofractionated radiotherapy (67.5 Gy in 25 fractions) to conventionally fractionated radiotherapy (78 Gy in 39 fractions) in prostate cancer patients with intermediate and high-risk disease.

Materials and methods

From January 2015 to December 2018, 168 patients were randomized to hypofractionated radiation treatment and conventional fractionated radiation treatment schedules of volumetric modulated arc therapy (VMAT) to the prostate and seminal vesicles. All the patients also received androgen deprivation therapy (ADT) and radiation therapy started after ADT.

Results

The median (range) follow-up was 51 (31-63) and 53 (33-64) months in the hypofractionated and conventionally fractionated regimes, respectively. The 3-year biochemical no evidence of disease (bNED) rates were 86.9% and 73.8% in the hypofractionated and conventionally fractionated groups, respectively (p = 0.032, significant). The 3-year bNED rates in patients at a high risk [i.e., pretreatment prostate-specific antigen (PSA) > 20 ng/mL, Gleason score ≥ 8, or T ≥ 2 c], were 87.9% and 73.5% (p = 0.007, significant) in the hypofractionated and conventionally fractionated radiotherapy groups, respectively. No statistically significant difference was found for late toxicity between the two groups, with 3-year grade 2 gastrointestinal toxicity rates of 19% and 16.7% and 3-year grade 2 genitourinary toxicity rates of 15.5% and 11.9% in the hypofractionated and conventionally fractionated radiotherapy groups, respectively.

Conclusion

Hypofractionated schedule is superior to the conventional fractionation schedule of radiation treatment in terms of bNED in intermediate and high grade prostate cancer patients. Also, the late toxicity is found to be equivalent between the two treatment groups.

Late toxicity after post-prostatectomy intensity modulated radiation therapy: Evaluating normal-tissue sparing guidelines

Purpose

Dose-volume histogram (DVH) toxicity relationships are poorly defined in men who receive radiation after radical prostatectomy (RP). We evaluated Radiation Therapy Oncology Group (RTOG) study 0534 and institutional intact normal-tissue sparing guidelines, as well as dose to bladder trigone, for ability to minimize late toxicity.

Methods and materials

164 men received intensity modulated radiation therapy (RT) to a median prostate bed dose of 66.6 Gy at a median of 22 months after RP. 46% of men were prescribed androgen deprivation therapy and pelvic lymph node irradiation to a median dose of 50.4 Gy. DVH relationships for the rectum, bladder, trigone, and bladder excluding the clinical target volume (bladder-CTV) were analyzed against the Common Terminology Criteria for Adverse Events late grade 2 + (G2+) gastrointestinal (GI) and genitourinary (GU) toxicity by log-rank test. RTOG 0534 (rectum V65, 40 Gy ≤35, 55%, and bladder-CTV V65, 40 ≤50, 70%) and intact prostate RT institutional guidelines (rectum V70, 65, 40 ≤20, 40, 80% and bladder V70, 65, 40 ≤30, 60, 80%, respectively) guidelines were evaluated.

Results

With a median follow-up time of of 33 months, the 4-year freedom from G2 + GI and GU toxicity were both 91%. G2 + GI (n = 12) and GU (n = 15) toxicity included 4% diarrhea (n = 6), 4% hemorrhage (n = 6), 1% proctitis (n = 1), and 4% urinary frequency (n = 7), 1% obstructive (n = 2), 2% cystitis (n = 3), and 3% incontinence (n = 5), respectively. RTOG 0534 rectum and bladder goals were not achieved in 65% and 41% of cases, while the institutional intact prostate goals were not achieved in 21% and 25% of cases, respectively. Neither dose to the bladder trigone nor any of the proposed normal tissue goals were associated with late toxicity (P > .1). In the univariate analysis, age, pelvic RT, RT dose, anticoagulation use, androgen deprivation therapy, time from RP to RT, and tobacco history were not associated with toxicity.

Conclusions

More than 90% of men were free from late G2 + toxicity 4 years after post-RP intensity modulated RT. No tested parameters were associated with late toxicity. In the absence of established normal-tissue DVH guidelines in the postoperative setting, the use of intact guidelines is reasonable.

Androgen Ablation Therapy Does not Increase the Risk of Late Morbidity following 3D-conformal Radiotherapy of Organ-confined Prostate Cancer: The Experience of the European Institute of Oncology

Aims and Background

Androgen ablation therapy in conjunction with radiotherapy-neoadjuvant and adjuvant – has consistently been shown to be associated with improved biochemical and local control, whereas controversy still remains as regards its benefit in terms of overall survival. The objective of this study is to determine the impact of androgen ablation in combination to 3D-conformal radiotherapy on late treatment-related toxicity.

Methods

236 patients were treated with 3D-conformal radiotherapy to a total dose ranging from 70 and 78.6 Gy. Fifty-six patients did not receive any form of androgen ablation whereas 176 were given at least 3 months of neoadjuvant androgen ablation. Of these, 64 stayed on androgen ablation for a median time of 6 months post-radiotherapy. Acute toxicity was evaluated weekly during the course of treatment. Late toxicity was assessed at 3-months intervals during the follow-up. Toxicity was scored according to the RTOG criteria.

Results

The median follow-up was 24.6 months (range, 12-62). The incidence of late genitourinary toxicity was: 3% G2, 3.5% G3, 0.5% G4. The incidence of late gastrointestinal toxicity was: 12% G2, 2% G3, 1% G4. No association was observed between the use of androgen ablation and late treatment-related toxicity. High-risk patients who continued on androgen ablation long-term were not found to have an increased risk of developing late toxicity with respect to those who never had any form of androgen ablation or those only treated neoadjuvantly.

Conclusions

In our experience, the use of androgen ablation does not impact on late toxicity following high dose 3D-conformal radiotherapy for prostate cancer.

Does the Presence of a Major Psychiatric Disorder Affect Tolerance and Outcomes in Men With Prostate Cancer Receiving Radiation Therapy?

Prior studies have suggested that men with prostate cancer and psychiatric disorders (+Psy) have worse outcomes compared with those without (-Psy), particularly due to delayed diagnosis or reduced access to definitive treatment. In the current study, the toxicity and outcomes of men who were primarily diagnosed through prostate-specific antigen screening and who underwent definitive treatment with external beam radiation was investigated. The charts of 469 men diagnosed with prostate cancer from 2003 to 2010 were reviewed. The presence of +Psy was based on a Diagnostic and Statistical Manual of Mental Disorders-Fourth edition diagnosis of posttraumatic stress disorder, depression, schizophrenia, bipolar disorder, and/or generalized anxiety disorder. Kaplan-Meier analysis was used to analyze biochemical control, distant control, prostate cancer-specific survival, and overall survival. One hundred patients (21.3%) were identified as +Psy. At a median follow-up of 73 months, there were no differences regarding 6-year biochemical control (79.8% -Psy vs. 80.4% +Psy, p = .50) or 6-year distant metastatic-free survival (96.4% -Psy vs. 98.0% +Psy, p = .36). There were also no differences regarding the 6-year prostate cancer-specific survival (98.4% -Psy vs. 99.0% +Psy, p = .45) or 6-year overall survival (80.2% -Psy vs. 82.2% +Psy, p = .35). Short- and long-term genitourinary and gastrointestinal toxicities were similar between the groups. On multivariate analyses with propensity score adjustment, +Psy was not a significant predictor for toxicity, biochemical recurrence, or survival. The presence of +Psy was not associated with higher toxicity or worse clinical outcomes, suggesting that effective removal of screening and treatment barriers may reduce the survival disparities of these patients.

Late Radiation and Cardiovascular Adverse Effects After Androgen Deprivation and High-Dose Radiation Therapy in Prostate Cancer: Results From the DART 01/05 Randomized Phase 3 Trial

PURPOSE

To present data on the late toxicity endpoints of a randomized trial (DART 01/05) conducted to determine whether long-term androgen deprivation (LTAD) was superior to short-term AD (STAD) when combined with high-dose radiation therapy (HDRT) in patients with prostate cancer (PCa).

PATIENTS AND METHODS

Between November 2005 and December 2010, 355 eligible men with cT1c-T3aN0M0 PCa and intermediate-risk and high-risk factors (2005 National Comprehensive Cancer Network criteria) were randomized to 4 months of AD combined with HDRT (median dose, 78 Gy) (STAD) or the same treatment followed by 24 months of AD (LTAD). Treatment-related complications were assessed using European Organization for Research and Treatment of Cancer-Radiation Therapy Oncology Group and Common Terminology Criteria for Adverse Events v3.0 scoring schemes. Multivariate analyses for late toxicity were done using the Fine-Gray method.

RESULTS

The 5-year incidence of grade ≥2 rectal and urinary toxicity was 11.1% and 8.2% for LTAD and 7.6% and 7.3% for STAD, respectively. Compared with STAD, LTAD was not significantly associated with a higher risk of late grade ≥2 rectal toxicity (hazard ratio [HR] 1.360, 95% confidence interval [CI] 0.660-2.790, P=.410) or urinary toxicity (HR 1.028, 95% CI 0.495-2.130, P=.940). The multivariate analysis showed that a baseline history of intestinal comorbidity (HR 3.510, 95% CI 1.560-7.930, P=.025) and the rectal volume receiving >60 Gy (Vr60) (HR 1.030, 95% CI 1.001-1.060, P=.043) were the only factors significantly correlated with the risk of late grade ≥2 rectal complications. A history of previous surgical prostate manipulations was significantly associated with a higher risk of grade ≥2 urinary complications (HR 2.427, 95% CI 1.051-5.600, P=.038). Long-term AD (HR 2.090; 95% CI 1.170-3.720, P=.012) and a history of myocardial infarction (HR 2.080; 95% CI 1.130-3.810, P=.018) were significantly correlated with a higher probability of cardiovascular events.

CONCLUSION

Long-term AD did not significantly impact urinary or rectal radiation-induced toxicity, although it was associated with a higher risk of cardiovascular events. Longer follow-up is needed to measure the impact of AD on late morbidity and non-PCa mortality.

Transitioning from conventional radiotherapy to intensity-modulated radiotherapy for localized prostate cancer: changing focus from rectal bleeding to detailed quality of life analysis

With the advent of modern radiation techniques, we have been able to deliver a higher prescribed radiotherapy dose for localized prostate cancer without severe adverse reactions. We reviewed and analyzed the change of toxicity profiles of external beam radiation therapy (EBRT) from the literature. Late rectal bleeding is the main adverse effect, and an incidence of >20% of Grade ≥2 adverse events was reported for 2D conventional radiotherapy of up to 70 Gy. 3D conformal radiation therapy (3D-CRT) was found to reduce the incidence to ∼10%. Furthermore, intensity-modulated radiation therapy (IMRT) reduced it further to a few percentage points. However, simultaneously, urological toxicities were enhanced by dose escalation using highly precise external radiotherapy. We should pay more attention to detailed quality of life (QOL) analysis, not only with respect to rectal bleeding but also other specific symptoms (such as urinary incontinence and impotence), for two reasons: (i) because of the increasing number of patients aged >80 years, and (ii) because of improved survival with elevated doses of radiotherapy and/or hormonal therapy; age is an important prognostic factor not only for prostate-specific antigen (PSA) control but also for adverse reactions. Those factors shift the main focus of treatment purpose from survival and avoidance of PSA failure to maintaining good QOL, particularly in older patients. In conclusion, the focus of toxicity analysis after radiotherapy for prostate cancer patients is changing from rectal bleeding to total elaborate quality of life assessment.

Different rectal toxicity tolerance with and without simultaneous conventionally-fractionated pelvic lymph node treatment in patients receiving hypofractionated prostate radiotherapy

PURPOSE

To investigate added morbidity associated with the addition of pelvic elective nodal irradiation (ENI) to hypofractionated radiotherapy to the prostate.

METHODS AND MATERIALS

Two-hundred twelve patients, treated with hypofractionated radiotherapy to the prostate between 2004 and 2011, met the inclusion criteria for the analysis. All patients received 70 Gy to the prostate delivered over 28 fractions and 103 (49%) received ENI consisting of 50.4 Gy to the pelvic lymphatics delivered simultaneously in 1.8 Gy fractions. The mean dose-volume histograms were compared between the two subgroups defined by use of ENI, and various dose-volume parameters were analyzed for effect on late lower gastrointestinal (GI) and genitourinary (GU) toxicity.

RESULTS

Acute grade 2 lower GI toxicity occurred in 38 (37%) patients receiving ENI versus 19 (17%) in those who did not (p = 0.001). The Kaplan-Meier estimate of grade ≥ 2 lower GI toxicity at 3 years was 15.3% for patients receiving ENI versus 5.3% for those who did not (p = 0.026). Each rectal isodose volume was increased for patients receiving ENI up to 50 Gy (p ≤ 0.021 for each 5 Gy increment). Across all patients, the absolute V70 of the rectum was the only predictor of late GI toxicity. When subgroups, defined by the use of ENI, were analyzed separately, rectal V70 was only predictive of late GI toxicity for patients who received ENI. For patients receiving ENI, V70 > 3 cc was associated with an increased risk of late GI events.

CONCLUSIONS

Elective nodal irradiation increases the rates of acute and late GI toxicity when delivered simultaneously with hypofractioanted prostate radiotherapy. The use of ENI appears to sensitize the rectum to hot spots, therefore we recommend added caution to minimize the volume of rectum receiving 100% of the prescription dose in these patients.

Dose escalation using ultra-high dose IMRT in intermediate risk prostate cancer without androgen deprivation therapy: preliminary results of toxicity and biochemical control

Background

To investigate the feasibility of dose escalation (86 Gy at 2 Gy/fraction) with intensity modulated radiation therapy (IMRT) in intermediate-risk prostate cancer without androgen deprivation therapy.

Methods

Patients with histologically proven adenocarcinoma of the prostate, intermediate prognostic category, were enrolled in this study. Early and late toxicity were scored according to the Cancer Therapy Evaluation Program, Common Terminology Criteria for Adverse Events, Version 3.0. Treatment outcome was stated in terms of biochemical failure, biopsy result and clinical failure.

Results

39 patients with a median follow-up of 71 months were analyzed. No patient experienced G3 or G4 acute gastrointestinal (GI) or genitourinary (GU) toxicity. G2 acute GI and GU toxicity were observed in 17 (44%) and 20 (51%) patients, respectively. Fourteen patients (36%) did not experience acute GI toxicity and 4 patients (10%) did not experience acute GU toxicity. G2 late GI bleeding occurred in 7 of 39 patients (18%). Both G3 and G4 late GI toxicity were seen only in one patient (2.5%). Two patients (5%) experienced G2 late GU toxicity, while G3 late GU toxicity occurred in 3 patients (8%). The 5-year actuarial freedom from biochemical failure (FFBF) was 87%. Thirty-four patients (87%) did not show biochemical relapse. Seventeen patients (44%) underwent biopsy two year after radiotherapy; of these only two were non-negative and both did not show evidence of biochemical disease.

Conclusions

IMRT treatment of patients with localized intermediate-risk prostate cancer at high dose levels without using androgen deprivation therapy (ADT) seems to give good disease control. Nevertheless, future trials should aim at further decreasing toxicity by exploiting image guidance techniques and by reducing the dose delivered at the interface between organs at risk and prostate.

Predictive factors and management of rectal bleeding side effects following prostate cancer brachytherapy

PURPOSE

To report on the incidence, nature, and management of rectal toxicities following individual or combination brachytherapy following treatment for prostate cancer over a 17-year period. We also report the patient and treatment factors predisposing to acute ≥ grade 2 proctitis.

METHODS AND MATERIALS

A total of 2752 patients were treated for prostate cancer between October 1990 and April 2007 with either low-dose-rate brachytherapy alone or in combination with androgen depletion therapy (ADT) or external beam radiation therapy (EBRT) and were followed for a median of 5.86 years (minimum 1.0 years; maximum 19.19 years). We investigated the 10-year incidence, nature, and treatment of acute and chronic rectal toxicities following BT. Using univariate, and multivariate analyses, we determined the treatment and comorbidity factors predisposing to rectal toxicities. We also outline the most common and effective management for these toxicities.

RESULTS

Actuarial risk of ≥ grade 2 rectal bleeding was 6.4%, though notably only 0.9% of all patients required medical intervention to manage this toxicity. The majority of rectal bleeding episodes (72%) occurred within the first 3 years following placement of BT seeds. Of the 27 patients requiring management for their rectal bleeding, 18 underwent formalin treatment and nine underwent cauterization. Post-hoc univariate statistical analysis revealed that coronary artery disease (CAD), biologically effective dose, rectal volume receiving 100% of the prescription dose (RV100), and treatment modality predict the likelihood of grade ≥2 rectal bleeding. Only CAD, treatment type, and RV100 fit a Cox regression multivariate model.

CONCLUSIONS

Low-dose-rate prostate brachytherapy is very well tolerated and rectal bleeding toxicities are either self-resolving or effectively managed by medical intervention. Treatment planning incorporating adjuvant ADT while minimizing RV100 has yielded the best toxicity-free survival following BT.

Late rectal and bladder toxicity following radiation therapy for prostate cancer: Predictive factors and treatment results

AIM

This study aimed at investigating factors associated to late rectal and bladder toxicity following radiation therapy and the effectiveness of Hyperbaric Oxygen Therapy (HBOT) when toxicity is grade ≥2.

BACKGROUND

Radiation is frequently used for prostate cancer, but a 5-20% incidence of late radiation proctitis and cystitis exists. Some clinical and dosimetric factors have been defined without a full agreement. For patients diagnosed of late chronic proctitis and/or cystitis grade ≥2 treatment is not well defined. Hyperbaric Oxygen Therapy (HBOT) has been used, but its effectiveness is not well known.

MATERIALS AND METHODS

257 patients were treated with radiation therapy for prostate cancer. Clinical, pharmacological and dosimetric parameters were collected. Patients having a grade ≥2 toxicity were treated with HBOT. Results of the intervention were measured by monitoring toxicity by Common Toxicity Criteria v3 (CTCv3).

RESULTS

Late rectal toxicity was related to the volume irradiated, i.e. V50 > 53.64 (p = 0.013); V60 > 38.59% (p = 0.005); V65 > 31.09% (p = 0.002) and V70 > 22.81% (p = 0.012). We could not correlate the volume for bladder. A total of 24 (9.3%) patients experienced a grade ≥2. Only the use of dicumarinic treatment was significant for late rectal toxicity (p = 0.014). A total of 14 patients needed HBOT. Final percentage of patients with a persistent toxicity grade ≥2 was 4.5%.

CONCLUSION

Rectal volume irradiated and dicumarinic treatment were associated to late rectal/bladder toxicity. When toxicity grade ≥2 is diagnosed, HBOT significantly ameliorate symptoms.

ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

Rectal dose constraints for intensity modulated radiation therapy of the prostate

Prostate dose escalation appears to have resulted in increased cancer control. Such escalation has been made possible by the ability to deliver more conformal treatment that spares normal tissue from the higher radiation doses. The supposition is that this has enabled higher doses, but without an increase in toxicity. The most disabling toxicity in prostate cancer radiotherapy is rectal. We evaluated the current status of conformal radiation and late rectal toxicity with the goal of determining whether reasonable rectal dose and volume constraints can be determined. Although the literature is inexact, we believe that some generalized constraints can be recommended and show that those recommendations are consistent with what is being used at experienced centers.

Is it time to tailor the prediction of radio-induced toxicity in prostate cancer patients? Building the first set of nomograms for late rectal syndrome

PURPOSE

Development of user-friendly tools for the prediction of single-patient probability of late rectal toxicity after conformal radiotherapy for prostate cancer.

METHODS AND MATERIALS

This multicenter protocol was characterized by the prospective evaluation of rectal toxicity through self-assessed questionnaires (minimum follow-up, 36 months) by 718 adult men in the AIROPROS 0102 trial. Doses were between 70 and 80 Gy. Nomograms were created based on multivariable logistic regression analysis. Three endpoints were considered: G2 to G3 late rectal bleeding (52/718 events), G3 late rectal bleeding (24/718 events), and G2 to G3 late fecal incontinence (LINC, 19/718 events).

RESULTS

Inputs for the nomogram for G2 to G3 late rectal bleeding estimation were as follows: presence of abdominal surgery before RT, percentage volume of rectum receiving >75 Gy (V75Gy), and nomogram-based estimation of the probability of G2 to G3 acute gastrointestinal toxicity (continuous variable, which was estimated using a previously published nomogram). G3 late rectal bleeding estimation was based on abdominal surgery before RT, V75Gy, and NOMACU. Prediction of G2 to G3 late fecal incontinence was based on abdominal surgery before RT, presence of hemorrhoids, use of antihypertensive medications (protective factor), and percentage volume of rectum receiving >40 Gy.

CONCLUSIONS

We developed and internally validated the first set of nomograms available in the literature for the prediction of radio-induced toxicity in prostate cancer patients. Calculations included dosimetric as well as clinical variables to help radiation oncologists predict late rectal morbidity, thus introducing the possibility of RT plan corrections to better tailor treatment to the patient's characteristics, to avoid unnecessary worsening of quality of life, and to provide support to the patient in selecting the best therapeutic approach.

Modeling late rectal toxicities based on a parameterized representation of the 3D dose distribution

Many models exist for predicting toxicities based on dose-volume histograms (DVHs) or dose-surface histograms (DSHs). This approach has several drawbacks as firstly the reduction of the dose distribution to a histogram results in the loss of spatial information and secondly the bins of the histograms are highly correlated with each other. Furthermore, some of the complex nonlinear models proposed in the past lack a direct physical interpretation and the ability to predict probabilities rather than binary outcomes. We propose a parameterized representation of the 3D distribution of the dose to the rectal wall which explicitly includes geometrical information in the form of the eccentricity of the dose distribution as well as its lateral and longitudinal extent. We use a nonlinear kernel-based probabilistic model to predict late rectal toxicity based on the parameterized dose distribution and assessed its predictive power using data from the MRC RT01 trial (ISCTRN 47772397). The endpoints under consideration were rectal bleeding, loose stools, and a global toxicity score. We extract simple rules identifying 3D dose patterns related to a specifically low risk of complication. Normal tissue complication probability (NTCP) models based on parameterized representations of geometrical and volumetric measures resulted in areas under the curve (AUCs) of 0.66, 0.63 and 0.67 for predicting rectal bleeding, loose stools and global toxicity, respectively. In comparison, NTCP models based on standard DVHs performed worse and resulted in AUCs of 0.59 for all three endpoints. In conclusion, we have presented low-dimensional, interpretable and nonlinear NTCP models based on the parameterized representation of the dose to the rectal wall. These models had a higher predictive power than models based on standard DVHs and their low dimensionality allowed for the identification of 3D dose patterns related to a low risk of complication.

Using Bayesian logistic regression to evaluate a new type of dosimetric constraint for prostate radiotherapy treatment planning

PURPOSE

Modern radiotherapy treatments can be optimized using dose-volume constraints which specify the volume of tumor and organs-at-risk receiving a given threshold dose. Careful derivation and evaluation of rectal constraints is essential to allow safe dose escalation in radiotherapy of prostate cancer. The authors present a new type of hybrid dosimetric constraint which comprises both volumetric and spatial factors of the dose-distribution. The authors also propose a framework to evaluate these constraints.

METHODS

The authors used data from the RT01 prostate radiotherapy trial (ISRCTN 47772397) to derive this set of hybrid constraints for the rectum based on measures extracted from dose-surface maps. For comparison, the authors also derive a set of dose-volume constraints. In order to evaluate these dosimetric constraints, the authors propose a new framework for predicting radiation-induced toxicities using Bayesian logistic regression with high-order interactions. The predictive power of the new RT01-based constraints, as well as of two sets of rectal dose-volume constraints proposed in the recent literature-The constraints proposed by other researchers [C. Fiorino, G. Fellin, T. Rancati, V. Vavassori, C. Bianchi, V. C. Borca, G. Girelli, M. Mapelli, L. Menegotti, S. Nava, and R. Valdagni, "Clinical and dosimetric predictors of late rectal syndrome after 3D-CRT for localized prostate cancer: Preliminary results of a multicenter prospective study," Int. J. Radiat. Oncol., Biol., Phys. 70, 1130-1137 (2008)] and the constraints used in the conventional or hypofractionated high dose intensity modulated radiotherapy for prostate cancer (CHHiP) trial [C. P. South, V. S. Khoo, O. Naismith, A. Norman, and D. P. Dearnaley, "A comparison of treatment planning techniques used in two randomised UK external beam radiotherapy trials for localised prostate cancer," Clin. Oncol. (R Coll. Radiol) 20, 15-21 (2008)]--were evaluated using a tenfold cross-validation with follow-up data from the RT01 trial. The predictive power was quantified using receiver-operator characteristic (ROC) curves. Toxicities considered were rectal bleeding, loose stools, and a global toxicity score.

RESULTS

Dose-volume constraints had less predictive power than the new type of hybrid constraints. A probabilistic model for predicting rectal bleeding based on the dose-volume constraints proposed by other researchers [C. Fiorino, G. Fellin, T. Rancati, V. Vavassori, C. Bianchi, V. C. Borca, G. Girelli, M. Mapelli, L. Menegotti, S. Nava, and R. Valdagni, "Clinical and dosimetric predictors of late rectal syndrome after 3D-CRT for localized prostate cancer: Preliminary results of a multicenter prospective study," Int. J. Radiat. Oncol., Biol., Phys. 70, 1130-1137 (2008)], the CHHiP dose-volume constraints, the RT01-based dose-volume constraints, and the hybrid constraints resulted in average areas under the ROC curves of 0.56, 0.58, 0.62, and 0.67, respectively. For predicting loose stools, the corresponding values were 0.57, 0.53, 0.66, and 0.71, respectively. The areas under the respective ROC curves for predicting the global toxicity score were 0.58, 0.55, 0.61, and 0.63.

CONCLUSIONS

Thus, imposing the new type of hybrid constraints when generating a treatment plan should result in a reduction in the incidence of radiation-induced late rectal toxicity.

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.

A prospective phase III randomized trial of hypofractionation versus conventional fractionation in patients with high-risk prostate cancer

PURPOSE

To compare the toxicity and efficacy of hypofractionated (62 Gy/20 fractions/5 weeks, 4 fractions per week) vs. conventional fractionation radiotherapy (80 Gy/40 fractions/8 weeks) in patients with high-risk prostate cancer.

METHODS AND MATERIALS

From January 2003 to December 2007, 168 patients were randomized to receive either hypofractionated or conventional fractionated schedules of three-dimensional conformal radiotherapy to the prostate and seminal vesicles. All patients received a 9-month course of total androgen deprivation (TAD), and radiotherapy started 2 months thereafter.

RESULTS

The median (range) follow-up was 32 (8-66) and 35 (7-64) months in the hypofractionation and conventional fractionation arms, respectively. No difference was found for late toxicity between the two treatment groups, with 3-year Grade 2 rates of 17% and 16% for gastrointestinal and 14% and 11% for genitourinary in the hypofractionation and conventional fractionation groups, respectively. The 3-year freedom from biochemical failure (FFBF) rates were 87% and 79% in the hypofractionation and conventional fractionation groups, respectively (p = 0.035). The 3-year FFBF rates in patients at a very high risk (i.e., pretreatment prostate-specific antigen (iPSA) >20 ng/mL, Gleason score >or=8, or T >or=2c), were 88% and 76% (p = 0.014) in the former and latter arm, respectively. The multivariate Cox analysis confirmed fractionation, iPSA, and Gleason score as significant prognostic factors.

CONCLUSIONS

Our findings suggest that late toxicity is equivalent between the two treatment groups and that the hypofractionated schedule used in this trial is superior to the conventional fractionation in terms of FFBF.

Assessing correlations between the spatial distribution of the dose to the rectal wall and late rectal toxicity after prostate radiotherapy: an analysis of data from the MRC RT01 trial (ISRCTN 47772397)

Many studies have been performed to assess correlations between measures derived from dose-volume histograms and late rectal toxicities for radiotherapy of prostate cancer. The purpose of this study was to quantify correlations between measures describing the shape and location of the dose distribution and different outcomes. The dose to the rectal wall was projected on a two-dimensional map. In order to characterize the dose distribution, its centre of mass, longitudinal and lateral extent, and eccentricity were calculated at different dose levels. Furthermore, the dose-surface histogram (DSH) was determined. Correlations between these measures and seven clinically relevant rectal-toxicity endpoints were quantified by maximally selected standardized Wilcoxon rank statistics. The analysis was performed using data from the RT01 prostate radiotherapy trial. For some endpoints, the shape of the dose distribution is more strongly correlated with the outcome than simple DSHs. Rectal bleeding was most strongly correlated with the lateral extent of the dose distribution. For loose stools, the strongest correlations were found for longitudinal extent; proctitis was most strongly correlated with DSH. For the other endpoints no statistically significant correlations could be found. The strengths of the correlations between the shape of the dose distribution and outcome differed considerably between the different endpoints. Due to these significant correlations, it is desirable to use shape-based tools in order to assess the quality of a dose distribution.

Helical Tomotherapy with Simultaneous Integrated Boost for High-Risk and Lymph Node-Positive Prostate Cancer: Early Report on Acute and Late Toxicity

The use of whole pelvic radiotherapy (WPRT) for high-risk and lymph node-positive prostate cancer (PC) remains controversial. The purpose of this study was to evaluate the acute toxicity associated with helical tomotherapy in the treatment of high-risk and lymph node-positive prostate cancer. To do so, twenty-eight patients were treated to a dose of 54 Gy in daily fractions of 1.8 Gy to the pelvic lymph node area, while the prostate and the seminal vesicles received a simultaneous integrated boost (SIB) to a dose of 70.5 Gy. A SIB to a dose of 60 Gy was delivered to the involved lymph node region(s) in 8 patients with pelvic lymph node metastases. All patients received concurrent hormonal treatment. The incidence of grade 2 and 3 acute gastrointestinal (GI) toxicity was 7% and 0% respectively. Grade 2 and 3 acute genito-urinary (GU) side effects were observed in 14% and 4% of the patients respectively. No grade 4 side effects occurred. No increased toxicity was observed in the 8 lymph node-positive patients receiving a simultaneous pelvic nodal dose escalation. In conclusion, WPRT with a SIB to the prostate and seminal vesicles by helical tomotherapy resulted in a favourable toxicity profile. Pelvic nodal dose escalation in node-positive patients is feasible without increasing toxicity.

Is hormone therapy a protective factor for late hematuria after high-dose radiotherapy in prostate cancer?

OBJECTIVES

To identify potential clinical and dosimetric factors predictive of a higher risk of grade 2 or higher late hematuria in patients with prostate cancer treated with high-dose radiotherapy.

METHODS

For this purpose, we have analyzed 229 T1c-T3b prostate cancer patients treated with 3-dimensional conformal radiotherapy (3DCRT) in a prospective dose escalation study and with a minimum follow-up of 1 year. The mean radiation dose was 79 Gy (range 72.1 to 84.14 Gy) and the mean follow-up was 47 months (range 14 to 95). One hundred eighteen patients also received androgen deprivation (AD) for high-risk disease. Univariate and multivariate analysis (MVA) were performed to identify variables significantly associated with late hematuria.

RESULTS

Of the 31 (14%) patients with grade 2 or higher genitourinary toxicity, hematuria was the main symptom in 24 (10.5%) with only 1 patient (0.5%) experiencing grade 3 hematuria. On statistical analysis, all the dosimetric parameters failed to show a significant correlation with grade 2 or higher hematuria. On MVA, prior transurethral resection of the prostate (TURP) was significantly associated with a higher risk of late hematuria (relative risk [RR] = 2.8; P = 0.026), whereas long-term AD was correlated with a significantly decreased risk (RR = 0.21; P = 0.019).

CONCLUSIONS

TURP was a relevant factor increasing 3 times the risk of late hematuria in prostate cancer patients treated with 3DCRT. Conversely, long-term AD resulted in a protective factor decreasing 5 times the risk of late hematuria. To our knowledge, this is the first study reporting a protecting effect of long-term hormones in late toxicity after radiotherapy.

Long-term treatment sequelae after external beam irradiation with or without hormonal manipulation for adenocarcinoma of the prostate: analysis of radiation therapy oncology group studies 85-31, 86-10, and 92-02

PURPOSE

Late gastrointestinal (GI) and genitourinary (GU) morbidity from external beam irradiation used to treat adenocarcinoma of the prostate continue to be a concern of physicians and patients alike. In addition, for locally advanced/high-risk cancer, the appropriate use of hormonal manipulation in addition to radiation therapy (RT) may increase toxicity. We analyzed three large Radiation Therapy Oncology Group (RTOG) studies (85-31, 86-10, and 92-02) to try to address these issues.

METHODS AND MATERIALS

A total of 2,922 patients were accrued with a median follow-up of 10.3 years for surviving patients. The RTOG scoring scheme was used to assess GI, GU, and other toxicities. Toxicity reported was Grade 3 or higher late toxicity. Patient toxicity level was assessed by study and by treatment type combining RT only vs. RT + short-course hormone therapy (STH) vs. RT + long-term hormone therapy (LTH).

RESULTS

Multivariate analysis reveals that age >70 was statistically significantly associated with a decrease in late any Grade 3+ toxicity (hazard ratio [HR] = 0.78, p = 0.0476) adjusted for treatment type. Comparing treatment type, patients treated with RT+STH had a statistically significant lower probability of Grade 3+ GI, GU, and other toxicity compared with RT alone (p = .00006; p = 0.0037; p = 0.0127, respectively). Patients treated with RT+LTH had a statistically significant lower probability of Grade 3+ GU toxicity compared with RT alone (p = 0.023).

CONCLUSIONS

These data show that external beam radiation therapy remains a safe option for locally advanced/high-risk prostate cancer, and the use of hormonal manipulation does appear to be protective for GU and GI toxicity depending upon length of treatment.

Hypofractionated intensity modulated irradiation for localized prostate cancer, results from a phase I/II feasibility study

BACKGROUND

To assess acute (primary endpoint) and late toxicity, quality of life (QOL), biochemical or clinical failure (secondary endpoints) of a hypofractionated IMRT schedule for prostate cancer (PC).

METHODS

38 men with localized PC received 66 Gy (2.64 Gy) to prostate,2 Gy to seminal vesicles (50 Gy total) using IMRT.Acute toxicity was evaluated weekly during radiotherapy (RT), at 1-3 months afterwards using RTOG acute scoring system. Late side effects were scored at 6, 9, 12, 16, 20, 24 and 36 months after RT using RTOG/EORTC criteria.Quality of life was assessed by EORTC-C30 questionnaire and PR25 prostate module. Biochemical failure was defined using ASTRO consensus and nadir+2 definition, clinical failure as local, regional or distant relapse.

RESULTS

None experienced grade III-IV toxicity. 10% had no acute genito-urinary (GU) toxicity, 63% grade I; 26% grade II. Maximum acute gastrointestinal (GI) scores 0, I, II were 37%, 47% and 16%. Maximal acute toxicity was reached weeks 4-5 and resolved within 4 weeks after RT in 82%.Grade II rectal bleeding needing coagulation had a peak incidence of 18% at 16 months after RT but is 0% at 24-36 months. One developed a urethral stricture at 2 years (grade II late GU toxicity) successfully dilated until now. QOL urinary symptom scores reached a peak incidence 1 month after RT but normalized 6 months later. Bowel symptom scores before, at 1-6 months showed similar values but rose slowly 2-3 years after RT. Nadir of sexual symptom scores was reached 1-6 months after RT but improved 2-3 years later as well as physical, cognitive and role functional scales.Emotional, social functional scales were lowest before RT when diagnosis was given but improved later. Two years after RT global health status normalized.

CONCLUSION

This hypofractionated IMRT schedule for PC using 25 fractions of 2.64 Gy did not result in severe acute side effects. Until now late urethral, rectal toxicities seemed acceptable as well as failure rates. Detailed analysis of QOL questionnaires resulted in the same conclusion.

Evidence-based radiation oncology: Definitive, adjuvant and salvage radiotherapy for non-metastatic prostate cancer

The standard treatment options based on the risk category (stage, Gleason score, PSA) for localized prostate cancer include surgery, radiotherapy and watchful waiting. The literature does not provide clear-cut evidence for the superiority of surgery over radiotherapy, whereas both approaches differ in their side effects. The definitive external beam irradiation is frequently employed in stage T1b-T1c, T2 and T3 tumors. There is a pretty strong evidence that intermediate- and high-risk patients benefit from dose escalation. The latter requires reduction of the irradiated normal tissue (using 3-dimensional conformal approach, intensity modulated radiotherapy, image-guided radiotherapy, etc.). Recent data suggest that prostate cancer may benefit from hypofractionation due to relatively low alpha/beta ratio; these findings warrant confirmation though. The role of whole pelvis irradiation is still controversial. Numerous randomized trials demonstrated a clinical benefit in terms of biochemical control, local and distant control, and overall survival from the addition of androgen suppression to external beam radiotherapy in intermediate- and high-risk patients. These studies typically included locally advanced (T3-T4) and poor-prognosis (Gleason score >7 and/or PSA >20 ng/mL) tumors and employed neoadjuvant/concomitant/adjuvant androgen suppression rather than only adjuvant setting. The ongoing trials will hopefully further define the role of endocrine treatment in more favorable risk patients and in the setting of the dose escalated radiotherapy. Brachytherapy (BRT) with permanent implants may be offered to low-risk patients (cT1-T2a, Gleason score <7, or 3+4, PSA <or=10 ng/mL), with prostate volume of <or=50 ml, no previous transurethral prostate resection and a good urinary function. Some recent data suggest a benefit from combining external beam irradiation and BRT for intermediate-risk patients. EBRT after radical prostatectomy improves disease-free survival and biochemical and local control rates in patients with positive surgical margins or pT3 tumors. Salvage radiotherapy may be considered at the time of biochemical failure in previously non-irradiated patients.

Intensity-modulated radiation therapy for prostate cancer: Late morbidity and results on biochemical control

PURPOSE

To report on late morbidity and biochemical relapse-free survival (bRFS) after intensity-modulated radiation therapy (IMRT) for prostate cancer.

METHODS

Between 1998 and 2005 133 patients were treated with IMRT for T(1-4) N0 M0 prostate cancer. The median follow-up time was 36 months. In a first cohort, patients received a median planning target volume (PTV) dose of 74 Gy with a hard constraint on maximum rectum dose of 72 Gy (74R72, n=51). Later, median PTV and maximum rectum dose were increased to 76 and 74 Gy, respectively (76R74; n=82). We defined low-risk (n=20), intermediate-risk (n=70) and high-risk (n=43) groups. Androgen deprivation was given to patients in the intermediate- and high-risk group. Late gastro-intestinal (GI) and genito-urinary (GU) morbidity and biochemical relapse, in accordance with the ASTRO consensus, were recorded.

RESULTS

We observed grade 2 GI (17%) and GU (19%), grade 3 GI (1%) and GU (3%) late toxicities. Except for hematuria, the median duration of side-effects was 6 months. Biochemical relapse-free survival (bRFS) at 3 and 5 years was 88% and 83%, respectively, with a significantly better 3-year bRSF for the 76R74 than for the 74R72 group (p=0.01). Five-year bRFS for patients in the low-risk, intermediate-risk and high-risk group was 100%, 94% and 74%, respectively (p<0.01).

CONCLUSION

IMRT for localized or locally advanced prostate cancer combines low morbidity with excellent biochemical control.

Results of radiation therapy combined with neoadjuvant hormonal therapy for stage III prostate cancer: comparison of two different definitions of PSA failure

BACKGROUND

We herein report the clinical outcome of radical radiation therapy combined with neoadjuvant hormonal therapy (NHT) for stage III (International Union Against Cancer [UICC] 1997: UICC 97) prostate cancer. Prostate-specific antigen (PSA) failure-free survival was assessed according to two different definitions, and the appropriateness of each definition is discussed.

METHODS

Between October 1997 and December 2000, 27 patients with stage III prostate cancer were enrolled in this study. The median pretreatment PSA level was 29 ng/ml (range, 7.4-430 ng/ml). The Gleason score (GS) was 7 or more in 22 patients (81%). All patients received 3 months of NHT with a luteinizing hormone-releasing hormone (LH-RH) analogue, in combination with an antiandrogen (flutamide), given during the first 2 weeks, followed by 70-Gy external-beam radiation therapy (EBRT) in 35 fractions. The initial 46 Gy was given with a four-field technique, while the remainder was given with a dynamic conformal technique. No adjuvant hormonal therapy (AHT) was given.

RESULTS

The median follow-up time was 63 months. PSA levels decreased to the normal range (<4 ng/ml) after irradiation in all but one patient. The 5-year PSA failure-free survival was 34.8% according to the American Society for Therapeutic Radiology and Oncology (ASTRO) definition and it was 43.0% according to the "nadir plus 2" definition. Discordance of the results between the two definitions was seen in two patients. The 5-year overall and cause-specific survivals were 83.0% and 93.3%, respectively. No severe acute or late adverse effects were observed.

CONCLUSION

Seventy Gy of EBRT following 3 months of NHT produced therapeutic results comparable to those reported in other studies which used long-term AHT. The value of long-term AHT for Japanese men should be tested in a clinical trial.

Risk factors of late rectal bleeding after carbon ion therapy for prostate cancer

PURPOSE

The aim of this study was to determine the risk factors for late gastrointestinal (GI) morbidity after hypofractionated carbon ion radiotherapy (C-ion RT) for prostate cancer.

METHODS AND MATERIALS

Between April 2000 and November 2003, a Phase II clinical trial of C-ion RT with a total dose of 66 GyE in 20 fractions was performed on 175 patients with prostate cancer, and the correlations of clinical and dosimetric parameters with the incidence of late GI toxicity in 172 patients who survived for more than 18 months were investigated.

RESULTS

Although no Grade 3-4 late morbidities of the rectum were observed, Grade 1 and 2 morbidities developed in 23 (13%) and 4 (2%) patients, respectively. Dose-volume histogram analysis revealed that the percentage of rectal volume receiving 50% of the prescribed dose (V50) was significantly higher in patients with rectal toxicity than without toxicity (13.2 +/- 5.6% with toxicity; 11.4 +/- 4.0% without toxicity, p = 0.046). Multivariate analysis demonstrated that the use of anticoagulation therapy (p = 0.010) and rectal V50 (p = 0.012) were significant risk factors for the occurrence of Grade 1-2 late GI toxicity.

CONCLUSIONS

Although C-ion RT with hypofractionation yielded favorable results regarding late GI complication, dosimetric parameter was a very important factor in the occurrence of rectal bleeding after C-ion RT as well as photon beam RT. Our results provide useful information for physicians applying charged particle RT in the treatment of prostate cancer.

Impact of neoadjuvant hormonal therapy on dose-volume histograms in patients with localized prostate cancer under radical radiation therapy

INTRODUCTION

Prostate volume involves a defined toxicity predictor in the radiation therapy of localized prostate cancer. Neoadjuvant hormone therapy (nHT) can reduce prostate volume and, therefore, the planned volume. The objective of this study was to establish if the value of nHT reduces the planned volume and if this reduction correlates with a reduction of the dose received in the target organs.

MATERIAL AND METHODS

28 patients diagnosed of localized prostate cancer and referred to our departments for radiation therapy with radical intention, in the period ranging between April 2002 and October 2003, were included prospectively. The patients received nHT (triptorelin + flutamide) for 2 months and adjuvant HT until completing 2 years in the high-risk cases. A transrectal ultrasound study was performed in all patients, simulation CT and planning before the start of HT and after 2 months of treatment. The radiation therapy was carried out with 6 or 18 MV LINAC photons, with a dose fractioning scheme of 5 x 180-200 cGy, a total dosage of 66-72 Gy to prostate, 56 Gy to seminal vesicles and, in the high-risk cases, 46 Gy to pelvic lymph nodes.

RESULTS

The distribution according to risk group was: low risk 3.6%, intermediate risk 28.6% and high risk 67.9%. By transrectal ultrasound, prostate volume on diagnosis was 50.65 cc pre HT and 38.97 cc post HT (p < 0.001), which means a volume reduction of 24%. The comparative analysis of the dose-volume histograms of the first versus the second CT shows a reduction in the planned volume GTV1 (prostate) (81.33 cc vs 63.96 cc, p < 0.05), PTV1 (prostate and margin) (197.51 cc vs 168.38 cc, p < 0.001) and PTV2 (prostate, vesicles and margin) (340.5 cc vs 307.26 cc, p < 0.05), a reduction of the maximum dose in the seminal vesicles (70.2 versus 68.75 Gy, p < 0.05), a reduction of the mean dose in the seminal vesicles (65.07 Gy versus 63.07 Gy, p < 0.05), PTV2 (67.72 Gy versus 66.9 Gy, p < 0.01) and PTV3 (prostate, vesicles, pelvic lymph nodes and margin) (58.86 Gy versus 57.21 Gy, p < 0.01), a reduction of the D90 in the seminal vesicles (61.83 Gy versus 60.06 Gy, p < 0.05) and PTV2 (61.04 Gy versus 59.45 Gy, p < 0.05) and a reduction of V60 of the rectum (32.45% versus 28.22%, p < 0.05) and V60 of the bladder (41.78% versus 31.67%, p < 0.005).

CONCLUSIONS

Neoadjuvant hormone therapy reduces significantly prostate volume and as a result the planned volume and consequently the rectal and bladder V60 can be significantly reduced.

Long-term hormone therapy and radiation is cost-effective for patients with locally advanced prostate carcinoma

BACKGROUND

In Radiation Therapy Oncology Group (RTOG) trial 92-02, after men received neoadjuvant hormone cytoreduction and radiotherapy for locally advanced prostate carcinoma, they were randomized to receive either 2 years of long-term androgen-deprivation (LTAD) or no further treatment (short-term androgen-deprivation [STAD]). The specific objective of the current study was to determine whether LTAD was a cost-effective treatment for patients with locally advanced prostate carcinoma.

METHODS

The cost-effectiveness of LTAD was tested using a Markov model that was designed using proprietary software. The analysis took a payor's perspective. Unit costs were obtained by estimation using a global Medicare fee schedule. Costs and outcomes were discounted by 3%. Distributions were sampled at random from the treatment utilities, transition probabilities, and costs using a second-order Monte Carlo simulation technique.

RESULTS

The expected mean cost was 32,564 dollars for LTAD compared with 33,039 dollars for STAD after accounting for the additional cost of salvage treatment for men who were treated with STAD. The mean number of quality-adjusted life years (QALYs) for men who received LTAD was 4.13 QALYs compared with a mean of 3.68 QALYs for men who received STAD. The cost-effectiveness acceptability curve analysis showed a 91% probability that LTAD was cost-effective compared with STAD. Although overall survival was similar in the LTAD and STAD groups, the patients who received LTAD experienced gains in QALYs and had lower costs, because LTAD prevented biochemical failure and the necessitating salvage hormone therapy.

CONCLUSIONS

The current analysis showed that LTAD was cost-effective for the entire population studied in RTOG trial 92-02.

Rectal toxicity profile after transperineal interstitial permanent prostate brachytherapy: Use of a comprehensive toxicity scoring system and identification of rectal dosimetric toxicity predictors

PURPOSE

To better understand rectal toxicity after prostate brachytherapy, we employed the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE version 3.0), a comprehensive system with distinct and separately reported gastrointestinal adverse event items (unlike Radiation Therapy Oncology Group morbidity scoring), to evaluate item-specific postimplant rectal toxicities.

METHODS AND MATERIALS

We analyzed 135 patients treated with brachytherapy +/- hormonal therapy, using CTCAE v3.0 to score acute/late rectal toxicities (median follow-up, 41 months). Dosimetric parameters were evaluated for ability to predict toxicities.

RESULTS

Use of CTCAE yielded a novel rectal toxicity profile consisting of diarrhea, incontinence, urgency, proctitis, pain, spasms, and hemorrhage event rates. No item had a < 5% Grade 1-2 acute toxicity rate (except spasms). Rectal dosimetry predicted late toxicities: for diarrhea, 5% Grade 1 toxicity rate for %V25 (percent of rectal volume receiving 25% of prescribed prostate dose) < or = 25% vs. 60% for %V25 > 25% (p < 0.001); for maximum toxicity, 10% Grade 1 toxicity rate for %V10 < or = 40% vs. 44% for %V10 > 40% (p = 0.007).

CONCLUSIONS

A comprehensive understanding of item-specific postimplant rectal toxicities was obtained using CTCAE. Rectal %V25 > 25% and %V10 > 40% predicted worse late diarrhea and maximum toxicity, respectively.

Treatment- and disease-related complications of prostate cancer

One of the highlights of the 16th International Prostate Cancer Update was a session on treatment- and disease-related complications of prostate disease. It began with presentation of a challenging case of rising prostate-specific antigen levels after radical prostatectomy, followed by an overview of the use of zoledronic acid in prostate cancer, a review of side effects of complementary medicines, an overview of complications of cryotherapy, an assessment of complications of brachytherapy and external beam radiation therapy, and a comparison of laparoscopy versus open prostatectomy.

Systematic review of the effect of radiation dose on tumor control and morbidity in the treatment of prostate cancer by 3D-CRT

PURPOSE

A higher radiation dose is believed to result in a larger probability of tumor control and a higher risk of side effects. To make an evidence-based choice of dose, the relation between dose and outcome needs to be known. This study focuses on the dose-response relation for prostate cancer.

METHODS AND MATERIALS

A systematic review was carried out on the literature from 1990 to 2003. From the selected studies, the radiation dose, the associated 5-year survival, 5-year bNED (biochemical no evidence of disease), acute and late gastrointestinal (GI) and genitourinary (GU) morbidity Grade 2 or more, and sexual dysfunction were extracted. With logistic regression models, the relation between dose and outcome was described.

RESULTS

Thirty-eight studies met our criteria, describing 87 subgroups and involving up to 3000 patients per outcome measure. Between the (equivalent) dose of 70 and 80 Gy, various models estimated an increase in 5-year survival (ranging from 10% to 11%), 5-year bNED for low-risk patients (5-7%), late GI complications (12-16%), late GU complications (8-10%), and erectile dysfunction (19-24%). Only for the overall 5-year bNED, results were inconclusive (range, 0-18%).

CONCLUSIONS

The data suggest a relationship between dose and outcome measures, including survival. However, the strength of these conclusions is limited by the sometimes small number of studies, the incompleteness of the data, and above all, the correlational nature of the data. Unambiguous proof for the dose-response relationships can, therefore, only be obtained by conducting randomized trials.

Dose-volume analysis of predictors for chronic rectal toxicity after treatment of prostate cancer with adaptive image-guided radiotherapy

PURPOSE

We analyzed our experience treating localized prostate cancer with image-guided off-line correction with adaptive high-dose radiotherapy (ART) in our Phase II dose escalation study to identify factors predictive of chronic rectal toxicity.

MATERIALS AND METHODS

From 1999-2002, 331 patients with clinical stage T1-T3N0M0 prostate cancer were prospectively treated in our Phase II 3D conformal dose escalation ART study to a median dose of 75.6 Gy (range, 63.0-79.2 Gy), minimum dose to confidence limited-planning target volume (cl-PTV) in 1.8 Gy fractions (median isocenter dose = 79.7 Gy). Seventy-four patients (22%) also received neoadjuvant/adjuvant androgen deprivation therapy. A patient-specific cl-PTV was constructed using 5 computed tomography scans and 4 sets of electronic portal images by applying an adaptive process to assure target accuracy and minimize PTV margin. For each case, the rectum (rectal solid) was contoured from the sacroiliac joints or rectosigmoid junction (whichever was higher) to the anal verge or ischial tuberosities (whichever was lower), with a median volume of 81.2 cc. The rectal wall was defined using the rectal solid with an individualized 3-mm wall thickness (median volume = 29.8 cc). Rectal wall dose-volume histogram was used to determine the prescribed dose. Toxicity was quantified using the National Cancer Institute Common Toxicity Criteria 2.0. Multiple dose-volume endpoints were evaluated for their association with chronic rectal toxicity.

RESULTS

Median follow-up was 1.6 years. Thirty-four patients (crude rate = 10.3%) experienced Grade 2 chronic rectal toxicity at a median interval of 1.1 years. Nine patients (crude rate = 2.7%) experienced Grade > or =3 chronic rectal toxicity (1 was Grade 4) at a median interval of 1.2 years. The 3-year rates of Grade > or =2 and Grade > or =3 chronic rectal toxicity were 20% and 4%, respectively. Acute toxicity predicted for chronic: Acute Grade 2-3 rectal toxicity (p < 0.001) including any acute rectal Grade 2-3 tenesmus (p = 0.02) and pain (p = 0.008) were significant predictors of chronic Grade > or =2 rectal toxicity. Any acute rectal toxicity (p = 0.001), any acute tenesmus (p = 0.03), and any acute diarrhea (p < 0.001) were also found to be predictive for chronic toxicity, as continuous variables. Dose-volume histogram predicted for chronic toxicity: Rectal wall absolute and relative V50, V60, V66.6, V70, and V72 and rectal solid relative V60-V72 were significantly associated with chronic Grade > or =2 rectal toxicity both as categorical and continuous variables (t test, linear regression) and when divided into subgroups (chi-square table). The chronic rectal toxicity Grade > or =2 risk was 9%, 18%, and 25% for the rectal wall relative V70 <15%, 25%-40%, and >40% respectively. The volume of rectum or rectal wall radiated to > or =50 Gy was a strong predictor for chronic rectal toxicity. Nonpredictive factors: Rectal solid/wall absolute or relative volumes irradiated to < or =40 Gy, dose level, and use of androgen deprivation were not found predictive.

CONCLUSIONS

In our ART dose escalation study, rectal wall or rectum relative > or =V50 are closely predictive for chronic rectal toxicity. If rectal dose-volume histogram constraints are used to select the dose level, the risk of chronic rectal toxicity will reflect the risk of toxicity of the selected constraint rather than the dose selected as found in our study using an adaptive process. To select the prescribed dose, different dose-volume histogram constraints may be used including the rectal wall V70. Patients experiencing acute rectal toxicity are more likely to experience chronic toxicity.

Late radiotherapy toxicity after prostate cancer treatment: Influence of hormonal therapy

OBJECTIVES

To analyze the impact of hormonal therapy (HT) on late gastrointestinal (GI) and genitourinary (GU) toxicity from external beam radiotherapy (RT).

METHODS

The records of 445 consecutive patients with prostate cancer undergoing RT with or without HT were reviewed. Late toxicity rates, using established toxicity scoring guidelines, were tabulated in the two groups and compared using the chi-square test. Ordered logit regression analyses were performed that included the major demographic, disease, and treatment factors.

RESULTS

The chi-square analyses demonstrated lower rates of GI toxicity (P = 0.013) and GU toxicity (P = 0.041) in the cohort receiving HT; this reduction in toxicity appeared to be consistent across different toxicity grades. However, on regression analysis, the only factor reaching statistical significance in predicting late GI and late GU toxicity was the radiation dose (P = 0.004 and P = 0.047, respectively). In particular, on regression analysis, HT did not reach statistical significance in predicting late GI toxicity (P = 0.229) or late GU toxicity (P = 0.910).

CONCLUSIONS

Observed late RT toxicity rates were generally similar in patients who did and did not receive HT. Thus, increased late RT toxicity should not be a major concern when deciding to add HT to RT for treatment of localized prostate cancer.

Impact of hormone therapy on acute radiotherapy toxicity in the treatment of prostate cancer

PURPOSE

To analyze the impact of neoadjuvant hormone therapy (HT) on acute gastrointestinal (GI) and genitourinary (GU) toxicity from radiotherapy (RT).

SCOPE

The toxicity rates of 480 consecutive prostate cancer patients were reviewed and compared using the chi2 test. Ordered logit regression analyses were performed including the major demographic, disease, and treatment factors. Although no reduction in acute GI toxicity from HT use was observed (P=0.067), a lower rate of acute GU toxicity was observed (P=0.002). No factor reached statistical significance on regression analysis.

CONCLUSIONS

Observed toxicity rates were similar or lower in patients receiving HT. Thus, increased RT toxicity should not be a concern when deciding to add neoadjuvant HT to RT for prostate cancer.

Long-term androgen deprivation increases Grade 2 and higher late morbidity in prostate cancer patients treated with three-dimensional conformal radiation therapy

PURPOSE

To determine whether the use of androgen deprivation (AD) increases late morbidity when combined with high-dose three-dimensional conformal radiation therapy (3D-CRT).

METHODS AND MATERIALS

Between May 1989 and November 1998, 1,204 patients were treated for prostate cancer with 3D-CRT to a median dose of 74 Gy. Patients were evaluated every 3-6 months. No AD was given to 945 patients, whereas 140 and 119 patients, respectively, received short-term AD (STAD; < or =6 months) and long-term AD (LTAD; > 6 months). Radiation morbidity was graded according to the Fox Chase modification of the Late Effects Normal Tissue Task Force late morbidity scale. Covariates in the multivariate analysis (MVA) included age, history of diabetes mellitus, prostate-specific antigen (PSA) level, Gleason score, T category, RT field size, total RT dose, use of rectal shielding, and AD status (no AD vs. STAD vs. LTAD).

RESULTS

The only independent predictor for Grade 2 or higher genitourinary (GU) morbidity in the MVA was the use of AD (p = 0.0065). The 5-year risk of Grade 2 or higher GU morbidity was 8% for no AD, 8% for STAD, and 14% for LTAD (p = 0.02). Independent predictors of Grade 2 or higher gastrointestinal (GI) morbidity in the MVA were the use of AD (p = 0.0079), higher total radiation dose (p < 0.0001), the lack of a rectal shield (p = 0.0003), and older age (p = 0.0009). The 5-year actuarial risk of Grade 2 or higher GI morbidity was 17% for no AD vs. 18% for STAD and 26% for LTAD (p = 0.017).

CONCLUSIONS

The use of LTAD seems to significantly increase the risk of both GU and GI morbidity for patients treated with 3D-CRT.

Acute and late complications after radiotherapy for prostate cancer: results of a multicenter randomized trial comparing 68 Gy to 78 Gy

PURPOSE

To compare acute and late gastrointestinal (GI) and genitourinary (GU) side effects in prostate cancer patients randomized to receive 68 Gy or 78 Gy.

METHODS AND MATERIALS

Between June 1997 and February 2003, 669 prostate cancer patients were randomized between radiotherapy with a dose of 68 Gy and 78 Gy, in 2 Gy per fraction and using three-dimensional conformal radiotherapy. All T stages with prostate-specific antigen (PSA) <60 ng/mL were included, except any T1a and well-differentiated T1b-c tumors with PSA < or =4 ng/mL. Stratification was done for four dose-volume groups (according to the risk of seminal vesicles [SV] involvement), age, hormonal treatment (HT), and hospital. The clinical target volume (CTV) consisted of the prostate with or without the SV, depending on the estimated risk of SV invasion. The CTV-planning target volume (PTV) margin was 1 cm for the first 68 Gy and was reduced to 0.5 cm (0 cm toward the rectum) for the last 10 Gy in the 78 Gy arm. Four Dutch hospitals participated in this Phase III trial. Evaluation of acute and late toxicity was based on 658 and 643 patients, respectively. For acute toxicity (<120 days), the Radiation Therapy Oncology Group (RTOG) scoring system was used and the maximum score was reported. Late toxicity (>120 days) was scored according to the slightly adapted RTOG/European Organization for Research and Treatment of Cancer (EORTC) criteria.

RESULTS

The median follow-up time was 31 months. For acute toxicity no significant differences were seen between the two randomization arms. GI toxicity Grade 2 and 3 was reported as the maximum acute toxicity in 44% and 5% of the patients, respectively. For acute GU toxicity, these figures were 41% and 13%. No significant differences between both randomization arms were seen for late GI and GU toxicity, except for rectal bleeding requiring laser treatment or transfusion (p = 0.007) and nocturia (p = 0.05). The 3-year cumulative risk of late RTOG/EORTC GI toxicity grade > or =2 was 23.2% for 68 Gy, and 26.5% for 78 Gy (p = 0.3). The 3-year risks of late RTOG/EORTC GU toxicity grade > or =2 were 28.5% and 30.2% for 68 Gy and 78 Gy, respectively (p = 0.3). Factors related to acute GI toxicity were HT (p < 0.001), a higher dose-volume group (p = 0.01), and pretreatment GI symptoms (p = 0.04). For acute GU toxicity, prognostic factors were: pretreatment GU symptoms (p < 0.001), HT (p = 0.003), and prior transurethral resection of the prostate (TURP) (p = 0.02). A history of abdominal surgery (p < 0.001) and pretreatment GI symptoms (p = 0.001) were associated with a higher incidence of late GI grade > or =2 toxicity, whereas HT (p < 0.001), pretreatment GU symptoms (p < 0.001), and prior TURP (p = 0.006) were prognostic factors for late GU grade > or =2.

CONCLUSIONS

Raising the dose to the prostate from 68 Gy to 78 Gy resulted in higher incidences of acute and late GI and GU toxicity, but these differences were not significant, except for late rectal bleeding requiring treatment and late nocturia. Other factors than the studied dose levels appeared to be important in predicting toxicity after radiotherapy, especially previous surgical interventions (abdominal surgery or TURP), hormonal therapy, and the presence of pretreatment symptoms.

What pretreatment prostate-specific antigen level warrants long-term androgen deprivation?

PURPOSE

Several large randomized prospective studies have demonstrated a survival benefit with the addition of long-term androgen deprivation to definitive radiotherapy for patients with Gleason score 8-10 or T3-T4 prostate cancer. However, these studies were performed before the routine use of prostate-specific antigen (PSA) measurement. The purpose of this study was to determine what pretreatment (initial) PSA (iPSA) level, if any, warrants the addition of long-term androgen deprivation in the PSA era.

METHODS AND MATERIALS

The data set evaluated consisted of 1003 prostate cancer patients treated definitively with three-dimensional conformal radiotherapy between May 1, 1989 and November 30, 1999 (median follow-up, 61 months). Specifically excluded were patients with T3-T4 disease or Gleason score greater than 7 or those who had undergone androgen deprivation as a part of their initial therapy. The median radiation dose was 76 Gy. Patients were randomly split into two data sets, with the first (n = 487) used to evaluate the optimal iPSA cutpoint for which a statistically significant difference in outcome was noted. The second data set (n = 516) served as a validation data set for the initial modeling. The analysis of the optimal iPSA cutpoint was based on a recursive partitioning approach for censored data using the log-rank test for nodal separation of freedom from biochemical failure (FFBF) as defined by the American Society for Therapeutic Radiology and Oncology definition. Cox multivariate regression analysis was used to confirm independent predictors of outcome among the clinical and treatment-related factors: iPSA (grouped as defined by the recursive partitioning analysis), Gleason score (2-6 vs. 7), T stage (T1c-T2a vs. T2b-T2c), and total radiation dose (continuous).

RESULTS

The recursive partitioning analysis data set resulted in an optimal iPSA cutpoint of 35 ng/mL, such that the 5-year Kaplan-Meier estimate of FFBF was 80%, 69%, and 19% for iPSA groups of 0-9.9, 10-35, and >35 ng/mL, respectively. The validation data set demonstrated the optimal iPSA cutpoint to be 30 ng/mL. Conservatively choosing 30 ng/mL as the optimal cutpoint, the 5-year FFBF estimate for the entire 1003 patients was 82%, 69%, and 20% for iPSA groups 0-9.9 (n = 630), 10-30 (n = 329), and >30 (n = 44) ng/mL, respectively. On multivariate regression analysis, with the iPSA grouped as above, the Gleason score and radiation dose were independent predictors of outcome in this patient group (all p < 0.001). On univariate analysis, a higher radiation dose improved FFBF when the iPSA level was between 10 and 30 ng/mL (p = 0.001) but not when the iPSA level was >30 or <10 ng/mL.

CONCLUSION

Recursive partitioning techniques defined an iPSA cutpoint of 30 ng/mL for delineating intermediate vs. high risk. Patients with a PSA level >30 ng/mL in the absence of Gleason score >7 or T3 disease do poorly when treated with radiotherapy alone and should be considered for long-term androgen deprivation or other aggressive systemic therapy.