Normal tissue complication probability (NTCP) models for late rectal bleeding, stool frequency and fecal incontinence after radiotherapy in prostate cancer patients

BACKGROUND AND PURPOSE

Curative radiotherapy for prostate cancer may lead to anorectal side effects, including rectal bleeding, fecal incontinence, increased stool frequency and rectal pain. The main objective of this study was to develop multivariable NTCP models for these side effects.

MATERIAL AND METHODS

The study sample was composed of 262 patients with localized or locally advanced prostate cancer (stage T1-3). Anorectal toxicity was prospectively assessed using a standardized follow-up program. Different anatomical subregions within and around the anorectum were delineated. A LASSO logistic regression analysis was used to analyze dose volume effects on toxicity.

RESULTS

In the univariable analysis, rectal bleeding, increase in stool frequency and fecal incontinence were significantly associated with a large number of dosimetric parameters. The collinearity between these predictors was high (VIF>5). In the multivariable model, rectal bleeding was associated with the anorectum (V70) and anticoagulant use, fecal incontinence was associated with the external sphincter (V15) and the iliococcygeal muscle (V55). Finally, increase in stool frequency was associated with the iliococcygeal muscle (V45) and the levator ani (V40). No significant associations were found for rectal pain.

CONCLUSIONS

Different anorectal side effects are associated with different anatomical substructures within and around the anorectum. The dosimetric variables associated with these side effects can be used to optimize radiotherapy treatment planning aiming at prevention of specific side effects and to estimate the benefit of new radiation technologies.

Relationships between dose to the gastro-intestinal tract and patient-reported symptom domains after radiotherapy for localized prostate cancer

BACKGROUND

Gastrointestinal (GI) morbidity after radiotherapy (RT) for prostate cancer is typically addressed by studying specific single symptoms. The aim of this study was to explore the interplay between domains of patient- reported outcomes (PROs) on GI morbidity, and to what extent these are explained by RT dose to the GI tract.

MATERIAL AND METHODS

The study included men from two Scandinavian studies (N = 211/277) who had undergone primary external beam radiotherapy (EBRT) for localized prostate cancer to 70-78 Gy (2 Gy/fraction). Factor analysis was applied to previously identified PRO-based symptom domains from two study-specific questionnaires. Number of questions: 43; median time to follow-up: 3.6-6.4 years) and dose-response outcome variables were defined from these domains. Dose/volume parameters of the anal sphincter (AS) or the rectum were tested as predictors for each outcome variable using logistic regression with 10-fold cross-validation. Performance was assessed using area under the receiver operating characteristic curve (Az) and model frequency.

RESULTS

Outcome variables from Defecation urgency (number of symptoms: 2-3), Fecal leakage (4-6), Mucous (4), and Pain (3-6) were defined. In both cohorts, intermediate rectal doses predicted Defecation urgency (mean Az: 0.53-0.54; Frequency: 70-75%), and near minimum and low AS doses predicted Fecal leakage (mean Az: 0.63-0.67; Frequency: 83-99%). In one cohort, high AS doses predicted Mucous (mean Az: 0.54; Frequency: 96%), whereas in the other, low AS doses and intermediate rectal doses predicted Pain (mean Az: 0.69; Frequency: 28-82%).

CONCLUSION

We have demonstrated that Defecation urgency, Fecal leakage, Mucous, and Pain following primary EBRT for localized prostate cancer primarily are predicted by intermediate rectal doses, low AS doses, high AS doses, or a combination of low AS and intermediate rectal doses, respectively. This suggests that there is a domain-specific dose-response for the GI tract. To reduce risk of GI morbidity, dose distributions of both the AS region and the rectum should, therefore, be considered when prescribing prostate cancer RT.

Gastrointestinal dose-histogram effects in the context of dose-volume-constrained prostate radiation therapy: analysis of data from the RADAR prostate radiation therapy trial

PURPOSE

To use a high-quality multicenter trial dataset to determine dose-volume effects for gastrointestinal (GI) toxicity following radiation therapy for prostate carcinoma. Influential dose-volume histogram regions were to be determined as functions of dose, anatomical location, toxicity, and clinical endpoint.

METHODS AND MATERIALS

Planning datasets for 754 participants in the TROG 03.04 RADAR trial were available, with Late Effects of Normal Tissues (LENT) Subjective, Objective, Management, and Analytic (SOMA) toxicity assessment to a median of 72 months. A rank sum method was used to define dose-volume cut-points as near-continuous functions of dose to 3 GI anatomical regions, together with a comprehensive assessment of significance. Univariate and multivariate ordinal regression was used to assess the importance of cut-points at each dose.

RESULTS

Dose ranges providing significant cut-points tended to be consistent with those showing significant univariate regression odds-ratios (representing the probability of a unitary increase in toxicity grade per percent relative volume). Ranges of significant cut-points for rectal bleeding validated previously published results. Separation of the lower GI anatomy into complete anorectum, rectum, and anal canal showed the impact of mid-low doses to the anal canal on urgency and tenesmus, completeness of evacuation and stool frequency, and mid-high doses to the anorectum on bleeding and stool frequency. Derived multivariate models emphasized the importance of the high-dose region of the anorectum and rectum for rectal bleeding and mid- to low-dose regions for diarrhea and urgency and tenesmus, and low-to-mid doses to the anal canal for stool frequency, diarrhea, evacuation, and bleeding.

CONCLUSIONS

Results confirm anatomical dependence of specific GI toxicities. They provide an atlas summarizing dose-histogram effects and derived constraints as functions of anatomical region, dose, toxicity, and endpoint for informing future radiation therapy planning.

Identification of motor neurons and a mechanosensitive sensory neuron in the defecation circuitry of Drosophila larvae

Defecation allows the body to eliminate waste, an essential step in food processing for animal survival. In contrast to the extensive studies of feeding, its obligate counterpart, defecation, has received much less attention until recently. In this study, we report our characterizations of the defecation behavior of Drosophila larvae and its neural basis. Drosophila larvae display defecation cycles of stereotypic frequency, involving sequential contraction of hindgut and anal sphincter. The defecation behavior requires two groups of motor neurons that innervate hindgut and anal sphincter, respectively, and can excite gut muscles directly. These two groups of motor neurons fire sequentially with the same periodicity as the defecation behavior, as revealed by in vivo Ca(2+) imaging. Moreover, we identified a single mechanosensitive sensory neuron that innervates the anal slit and senses the opening of the intestine terminus. This anus sensory neuron relies on the TRP channel NOMPC but not on INACTIVE, NANCHUNG, or PIEZO for mechanotransduction.

Cross validation of the prostate cancer radiotherapy late toxicity (PCRT) questionnaire with the expanded prostate cancer index composite (EPIC) instrument

INTRODUCTION

A 29-item prostate cancer radiotherapy (PCRT) questionnaire with genitourinary (GU), gastrointestinal (GI), and sexual (S) domains has been previously validated for the assessment of late toxicity health-related quality of life (HRQoL) effects. The study objective was to cross-validate the PCRT domains versus the expanded prostate cancer index composite (EPIC) questionnaire urinary (U), bowel (B), hormonal (H), and S subscales.

METHODS AND MATERIALS

A single-institution cross-sectional PCRT patient cohort was surveyed. Descriptive and intra- and inter-class correlation coefficient statistics for the various EPIC and PCRT HRQoL domain scores were generated. Univariable and multivariable Cox and logistic regressions were performed depending on the HRQoL endpoint being assessed.

RESULTS

A total of 189/276 patients (68%) completed questionnaires with EPIC and PCRT missing data rates of 9% and 4%, respectively. Mean age was 75.8 years (SD 5.5) and the mean time of questionnaire completion after radiotherapy was 852 days (range 212-1454 days). Mean EPIC urinary (85.1 SD 12.9), bowel (84.1 SD 15.8), sexual (21.8 SD 20.7), and hormonal (85.3 SD 13.7) as well as PCRT genitourinary (66.1 SD 15.3), gastrointestinal (83.6 SD 14.3), and sexual (39.4 SD 21.6) domain scores were calculated. Intraclass correlation coefficients comparing corresponding EPIC/PCRT domains ranged from 0.50-0.88. Interclass correlation coefficients for non-corresponding EPIC/PCRT domains ranged from 0.16-0.43 and 0.23-0.30, respectively. EPIC B/U, PCRT GI/GU and PCRT S required arcsin square root transformation and EPIC S/H domains required dichotomous transformations prior to univariable/multivariable analyses. Multivariable analysis demonstrated novel associations between predictive variables and HRQoL domains including between the PTV-bladder overlap volume and PCRT GU score.

CONCLUSIONS

The PCRT is a compact, valid, and HRQoL instrument with very high questionnaire compliance rates and similar statistical properties to the EPIC instrument. However, dichotomization of the PRCT S data was not required which suggests some potential statistical advantage to the PCRT.

Patient assessment of bowel function during and after pelvic radiotherapy: results of a prospective phase III North Central Cancer Treatment Group clinical trial

PURPOSE

To evaluate patient assessment of long-term effect of pelvic radiotherapy on bowel function.

PATIENTS AND METHODS

As part of a prospective randomized trial evaluating the impact of sucralfate on bowel function in patients receiving pelvic radiotherapy, patient-assessed bowel function data were collected during radiotherapy and again at 4 weeks and 1 year after completion of radiotherapy.

RESULTS

The number of bowel movements per day increased up to week 4 and then slowly decreased. At 1 year, the mean number of bowel movements per day had increased from 1.75 to 2.09 and the median from 1 to 2. All measures of adverse bowel function worsened during radiotherapy. Frequency of bowel movements and symptoms of frequency, nocturnal bowel movements, cramping, and bleeding returned close to baseline values by 1 year. Symptoms of urgency, clustering, and measures of incontinence were all persistent at 1 year. The mean increase in bowel function score at 1 year was 0.74 (range, -5 to 7).

CONCLUSION

Pelvic radiotherapy is associated with a slight increase in bowel movement frequency and decrease in several patient-reported measures of adverse bowel function. Several measures of adverse function persisted at 1 year.

Long-Term Rectal Function After Permanent Prostate Brachytherapy

PURPOSE

To evaluate the effect of prostate brachytherapy with or without supplemental therapies on long-term rectal function by means of a patient-administered quality-of-life instrument.

MATERIALS AND METHODS

As part of an ongoing prospective evaluation, 164 of an initial 209 patients who remain alive were mailed the Rectal Function Assessment Score (R-FAS) with a prestamped return envelope. R-FAS range from 0 to 27 with lower scores being indicative of better bowel function. Of the 162 eligible patients, 161 (99.4%) returned the survey. Median follow-up was 9.0 years (range 8.2-11.2 years). Clinical, treatment, and dosimetric parameters evaluated for bowel function included patient age, diabetes, hypertension, tobacco consumption, clinical T stage, elapsed time since brachytherapy, ultrasound volume, planning target volume, androgen deprivation therapy, supplemental external beam radiation, isotope, rectal dose, prostate D100/D150/D200, and prostate D90.

RESULTS

For the entire cohort, the current R-FAS was 3.59, which represented a nonstatistical improvement from prior surveys in 1999 (4.29) and 2002 (3.92) (P=0.134). Only 16 patients (9.9%) reported bowel function to be worse after brachytherapy. Of the clinical, treatment, and dosimetric parameters evaluated, only the number of preimplant bowel movements, tobacco use, and diabetes correlated with R-FAS. Despite lower rectal doses with Pd, isotope did not predict for bowel function. Consistent with prior surveys, patient perception of overall rectal quality of life was inversely related to supplemental external beam radiation (P=0.027).

CONCLUSION

Prostate brachytherapy adversely affects bowel function. However, in most patients the changes are minimal and slowly resolve with time. Overall rectal quality of life is inversely related to supplemental external beam radiation.

Patient and Treatment Factors Associated With Complications After Prostate Brachytherapy

Purpose

To assess the prevalence and predictors of complications after prostate brachytherapy in a population-based sample of older men.

Patients and Methods

We analyzed claims for Medicare-enrolled men older than age 65 years living in Surveillance, Epidemiology, and End Results (SEER) surveillance areas diagnosed with prostate cancer from 1991 to 1999 who underwent brachytherapy as initial treatment.

Results

There were 5,621 men who had brachytherapy with at least 2 years of follow-up. A complication diagnosis or invasive procedure occurred in 54.5% of men within 2 years, with 14.1% undergoing an invasive procedure. Urinary, bowel, and erectile morbidity rates were 33.8%, 21.0%, and 16.7%, respectively, and invasive procedure rates were 10.3%, 0.8%, and 4.0%, respectively. On multivariable analysis, combined urinary diagnoses and invasive procedures (obstruction, incontinence, bleeding, fistula) were associated with older age (P < .01), nonwhite race (odds ratio [OR], 1.30; P = .01), low income (OR, 1.74; P < .01), external-beam radiotherapy (EBRT; OR, 0.85; P = .01), androgen deprivation (OR, 1.31; P < .01), later year of brachytherapy (OR, 1.03/yr; P = .02), higher Charlson comorbidity score (P < .01), and prior transurethral resection of the prostate (OR, 1.65; P < .01). Bowel morbidity (bleeding/proctitis, injury) was associated with older age (P = .04), EBRT (OR, 1.46; P < .01), later year (OR, 1.04/yr; P < .01), higher Charlson score (P = .01), and inflammatory bowel disease (OR, 2.60; P < .01). Erectile morbidity was associated with younger age (P < .01), nonwhite race (OR, 1.37; P < .01), AD (OR, 1.18; P = .04), and later year (OR, 1.08/yr; P < .01). Invasive procedure rates declined with later year of brachytherapy (OR, 0.93/yr; P < .01).

Conclusion

Morbidity after prostate brachytherapy was common, though invasive procedures were required infrequently. Invasive procedures for complications declined during the 1990s, suggesting technical improvement with experience.

Rectal bleeding, fecal incontinence, and high stool frequency after conformal radiotherapy for prostate cancer: normal tissue complication probability modeling

PURPOSE

To analyze whether inclusion of predisposing clinical features in the Lyman-Kutcher-Burman (LKB) normal tissue complication probability (NTCP) model improves the estimation of late gastrointestinal toxicity.

METHODS AND MATERIALS

This study includes 468 prostate cancer patients participating in a randomized trial comparing 68 with 78 Gy. We fitted the probability of developing late toxicity within 3 years (rectal bleeding, high stool frequency, and fecal incontinence) with the original, and a modified LKB model, in which a clinical feature (e.g., history of abdominal surgery) was taken into account by fitting subset specific TD50s. The ratio of these TD50s is the dose-modifying factor for that clinical feature. Dose distributions of anorectal (bleeding and frequency) and anal wall (fecal incontinence) were used.

RESULTS

The modified LKB model gave significantly better fits than the original LKB model. Patients with a history of abdominal surgery had a lower tolerance to radiation than did patients without previous surgery, with a dose-modifying factor of 1.1 for bleeding and of 2.5 for fecal incontinence. The dose-response curve for bleeding was approximately two times steeper than that for frequency and three times steeper than that for fecal incontinence.

CONCLUSIONS

Inclusion of predisposing clinical features significantly improved the estimation of the NTCP. For patients with a history of abdominal surgery, more severe dose constraints should therefore be used during treatment plan optimization.

Electro-acupuncture attenuates stress-induced defecation in rats with chronic visceral hypersensitivity via serotonergic pathway

Acupuncture has long been used for patients with irritable bowel syndrome. However, it has remained unclear. The aim of this study was to testify the effect of electro-acupuncture(EA) on (1) visceral hypersensitivity induced by the mechanical colorectal irritation during postnatal development of rats, and (2) stress-induced colonic motility changes on rats with chronic visceral hypersensitivity. The abdominal withdrawal reflex (pain threshold and score) for visceral hypersensitivity and fecal pellet output for motor dysfunction were selected as two indexes for measurement. In addition, the effect of EA on 5-HT(4a) receptor and serotonin transporter (SERT) expression in the colon mucosa was analyzed semi-quantitatively through immunohistochemistry and 5-HT concentration in the colon tissue was observed through spectro-photo-fluorimeter detection, respectively. Our results showed that EA significantly elevated pain threshold, decreased the scores and also decreased fecal pellet output during water avoid stress. Furthermore, EA decreased 5-HT concentration in colon in rats with CVH and CVH rats with water avoidance stress, and increased the 5-HT(4a) and SERT expression in rats with CVH. Thus, it can be concluded that EA attenuates behavioral hyperalgesia and stress-induced colonic motor dysfunction in CVH rats via serotonergic pathway.

Acute gastrointestinal, genitourinary, and dermatological toxicity during dose-escalated 3D-conformal radiation therapy (3DCRT) using an intrarectal balloon for prostate gland localization and immobilization

PURPOSE

We determined the acute gastrointestinal (GI), genitourinary (GU), and dermatologic (D) toxicity during dose-escalated three-dimensional conformal radiation therapy (3DCRT). A modified intrarectal balloon (Medrad) was used for prostate gland localization and immobilization.

METHODS

Forty-six men with clinical category T1c to T3a, and at least one high-risk feature (PSA >10, Gleason > or =7, or MRI evidence of extracapsular extension or seminal vesical invasion) comprised the study cohort. Treatment consisted of hormonal therapy and 4-field 3DCRT using an intrarectal balloon for the initial 15 of 40 treatments. Planning treatment volume dose was 72 Gy (95% normalization). A Mantel-Haenzel Chi-square test compared the distribution of GU, GI, and D symptoms at baseline and at end of treatment (EOT).

RESULTS

There was no significant difference between the 2 time points in the proportion of patients with bowel symptoms (p = 0.73), tenesmus (p = 0.27), nocturia (p = 1.00), or GU urgency (p = 0.40). However, there was a significant decrease in GU frequency (70% vs. 50%, p = 0.46) as a result of medical interventions and a significant increase in hemorrhoidal irritation (4% vs. 20%, p = 0.02) and anal cutaneous skin reaction (0% vs. 70%, p < 0.001). By 3 months after EOT compared to baseline, there was no significant difference in the proportion of patients experiencing hemorrhoidal bleeding (4% vs. 8%, p = 0.52), requiring intervention for hemorrhoidal symptoms (7% vs. 5%, p = 0.8), or experiencing persistent anal cutaneous skin reaction (0% vs. 3%, p = 0.31).

CONCLUSION

Dose-escalated 3DCRT using an intrarectal balloon for prostate localization and immobilization was well tolerated. Acute GU, GI, and D symptoms resolved with standard dietary or medical interventions by the EOT or shortly thereafter.

Gastrointestinal toxicity and its relation to dose distributions in the anorectal region of prostate cancer patients treated with radiotherapy

PURPOSE

To study the correlations between the dose distributions in the anorectal region and late GI symptoms in patients treated for localized prostate carcinoma.

METHODS AND MATERIALS

Data from a randomized study were analyzed. In this trial, patients were treated with either rectangular or conformal fields with a dose of 66 Gy. Data concerning GI symptoms were collected from questionnaires of 197 patients. The distributions of the anorectal region were projected on maps, and the dose parameters were calculated. The incidences of complaints were studied as a function of the dose-area parameters and clinical parameters, using a proportional hazard regression model. Finally, we tested a series of dose parameters originating from different parts of the anorectal region.

RESULTS

Analyzing the total region, only a statistically significant dose-area effect relation for bleeding was found (p < 0.01). Defining subareas, we found effect relations for bleeding, soiling, fecal incontinence, and mucus loss. For bleeding and mucus loss, the strongest correlation was found for the dose received by the upper 70-80% of the anorectal region (p < 0.01). For soiling and fecal incontinence, we found the strongest association with the dose to the lower 40-50% (p < 0.05).

CONCLUSION

We found evidence that complaints originate from specific regions of the irradiated lower GI tract. Bleeding and mucus loss are probably related to irradiation of the upper part of the rectum. Soiling and fecal incontinence are more likely related to the dose to the anal canal and the lower part of the rectum.

The impact of radiation on functional outcomes in patients with rectal cancer and sphincter preservation

Radiation therapy (RT) plays an important role in the management of patients with rectal cancer. However, there is mounting evidence that RT results in functional changes. The purpose of this study was to review the published data on bowel and sexual functional changes associated with RT and to determine the optimal strategy. The data suggest that studies are generally small, retrospective studies, use various RT regimens, and assess function with various nonstandardized parameters. In general, bowel function as measured by frequency, urgency, evacuation, sensation, and/or continence is impaired after RT when compared with patients not treated with RT. Although limited, preoperative RT tends to cause less impairment than postoperative RT. Sexual function is poorly studied, but data suggest that RT has a negative impact in both men and women. Further study is necessary to understand the extent of impairment, optimize radiation strategies, and select patients who will gain the most with RT.

Evaluation of preoperative and postoperative radiotherapy on long-term functional results of straight coloanal anastomosis

PURPOSE

Preoperative radiotherapy for rectal cancer avoids radiation to the reconstructed rectum and may circumvent the detrimental effects on bowel function associated with postoperative radiotherapy. We compared the long-term functional results of patients who received preoperative radiotherapy, postoperative radiotherapy, or no radiotherapy in conjunction with low anterior resection and coloanal anastomosis to assess the impact of pelvic radiation on anorectal function.

METHODS

One hundred nine patients treated by low anterior resection and straight coloanal anastomosis for rectal cancer between 1986 and 1997 were assessed with a standardized questionnaire at two to eight years after resection. All radiotherapy was given to a total dose of 4,500 to 5,400 cGy with conventional doses and techniques. Most patients received concurrent 5-fluorouracil-based chemotherapy.

RESULTS

There were 39 patients in the preoperative radiotherapy group, 11 patients in the postoperative radiotherapy group, and 59 patients in the no radiotherapy group. The postoperative radiotherapy group reported a significantly greater number of bowel movements per 24-hour period (P < 0.01) and significantly more episodes of clustered bowel movements (P < 0.02) than either the preoperative radiotherapy group or the no radiotherapy group. No significant difference in anal continence or satisfaction with bowel function was found among the three groups.

CONCLUSION

In this study of straight (nonreservoir) coloanal anastomoses, postoperative pelvic radiotherapy had significant adverse effects on anorectal function, with higher rates of clustering and frequency of defecation than with preoperative radiotherapy. No differences in continence rates were demonstrated, perhaps because of the sample size of the compared groups. We attribute the adverse effects of postoperative radiotherapy to irradiation of the neorectum, which is spared when treatment is given preoperatively. The deleterious effects of adjuvant radiation on long-term anorectal function can be reduced by preoperative treatment.

Evidence for efficacy without increased toxicity of hypofractionated radiotherapy for prostate carcinoma: early results of a Phase III randomized trial

PURPOSE

We performed a randomized trial to compare the GI and urogenital toxicity of radiotherapy (RT) for localized (confined to the organ), early-stage (T1-T2N0M0, TNM classification) carcinoma of the prostate, using a conventional (64 Gy in 32 fractions within 6.5 weeks) vs. a hypofractionated (55 Gy in 20 fractions within 4 weeks) schedule and to determine the efficacy of the respective treatment schedules.

METHODS AND MATERIALS

This report is based on an interim analysis of the first 120 consecutive patients in this Phase III trial after a median follow-up of 43.5 months (range 23-62). RT planning was based on two-dimensional CT data, and the treatment was delivered using a three- or four-field 6-23-MV photon technique. GI and urogenital toxicity (symptom questionnaires incorporating the subjective elements of the late effects of normal tissues-subjective, objective, management, analytic classification of late effects and the European Organization for Research and Treatment of Cancer sexual function questionnaire) were evaluated before RT and 1 month, 1 year, and 2 years after RT completion. The efficacy of RT was assessed clinically (digital rectal examination and radiologic imaging) and biochemically (prostate-specific antigen assay) at baseline, and every 3 months for 2 years after RT and every 6 months subsequently.

RESULTS

RT, whether conventional or hypofractionated, resulted in an increase in all six symptom categories used to characterize GI toxicity and in four of five symptom categories used to document urinary morbidity 1 month after therapy completion. Sexual dysfunction (based on limited data), which existed in more than one-third of patients before RT, also increased to just more than one-half of patients 1 month after RT. The increase in urinary toxicity after RT was not sustained (diurnal urinary frequency had decreased significantly at 2 years). In contrast, all six symptom categories of GI toxicity remained increased 1 year after RT. Four of the six GI symptom categories (rectal pain, mucous discharge, urgency of defecation, and rectal bleeding) were still increased at 2 years compared with baseline. Except for a slightly greater percentage of patients experiencing mild rectal bleeding at 2 years among those who received hypofractionated RT, no differences were noted in toxicity between the conventional and hypofractionated RT schedule. The mean prostate-specific antigen level was 14.0 +/- 1.0 ng/mL at baseline and declined to a nadir of 1.3 +/- 0.2 ng/mL at a median of 16.8 months (range 0.8-28.3) after RT completion. However, it then rose in 17 patients (8 in the hypofractionated and 9 in the conventional treatment group). Only 8 of these 17 patients were found to have signs of clinical relapse (5 local, 1 regional lymph node, and 2 systemic [bony metastases]) after histopathologic and radiologic reassessment). The remaining 9 patients had biochemical relapse only (defined as three consecutive rises in prostate-specific antigen after nadir). The 4-year biochemical relapse-free survival rate was 85.8% for all patients and did not differ significantly between the two radiation dose schedules (86.2% for the hypofractionated and 85.5% for the conventional fractionation group).

CONCLUSION

RT for prostate carcinoma, using a three- or four-field 6-23-MV photon technique without posterior shielding of the lateral fields, is an underestimated cause of persistent GI morbidity. The incidence of clinically significant GI and urogenital toxicity after conventional and hypofractionated RT appears to be similar. Hypofractionated RT for carcinoma of the prostate seems just as effective as conventional RT after a median follow-up approaching 4 years.

Dose distribution and morbidity after high dose rate brachytherapy for prostate cancer: influence of V150 and V200 parameters

The purpose of this study is to identify factors predicting morbidity in patients undergoing high dose rate (HDR) brachytherapy boost with external beam irradiation for prostate cancer. Acute and late morbidity data were collected for 104 prostate cancer patients treated with an HDR boost together with external beam radiotherapy. Significant urinary and rectal morbidity were correlated with urethral and rectal point doses, and the proportions of the target volume receiving 100%, 150% and 200% (V200) or more of the prescribed dose. Rectal or urethral point doses did not predict morbidity. By contrast, the V200 was significantly higher for patients experiencing either acute or late urinary morbidity. The cut-off V200 was 15% of the target volume. Although theoretically beneficial for tumour cell kill, the treatment of significant proportions of the prostate to high dose might be associated with increased morbidity, and should preferably be avoided.

Anorectal function after modern conformal radiation therapy for prostate cancer: a pilot study

We evaluated whether, and if so to what extent, radiotherapy applied on a series of patients with prostate cancer influenced the patient's bowel habits and anorectal function. Ten consecutive patients participated in the study. The median age of the patients was 74 years (range, 61-71) and the average follow-up period was 22 (range, 15-28) months. Four patients were irradiated using external beam radiotherapy (2 Gy/day for a total of 70 Gy); 6 patients were irradiated with a combination of external beam radiotherapy (50 Gy, 2 Gy/day) and high dose rate brachytherapy (two 10-Gy fractions). Upon interview, patients disclosed characteristic functional disturbances such as urgency with occasional accidents, faecal soiling and spotting of underwear. Involuntary release of gas was another embarrassing problem. One or more of these problems were present in half of the patients. Endoscopy disclosed signs of mild proctitis. Sphincter pressure, rectal capacity and the volume threshold for appreciation of defecation urge were all significantly lower in patients than in 10 age-matched controls. In conclusion, disturbances of anorectal function with imperfection of incontinence still occur so some extent despite improved precision, and reduced margins offered by the modern conformal radiation therapy of prostate cancer. Anal sphincter function, the reservoir capacity of the rectum and its sensory function are adversely affected and radiation proctitis with rectal fibrosis and damage of the extrinsic innervations of the anal sphincters appear to be the principal causative factors. Although conformal radiotherapy together with better positioning may be two substantial improvements of modern radiotherapy, further improvements are needed.

Chronic effects of therapeutic irradiation for localized prostatic carcinoma on anorectal function

PURPOSE

To evaluate prospectively the prevalence and pathophysiology of anorectal dysfunction following radiation therapy (RTH) for localized carcinoma of the prostate.

METHODS AND MATERIALS

The following parameters of anorectal function were evaluated in each of 35 patients (aged 55-82 years) with localized prostatic carcinoma treated with RTH either to a dose of 55 Gy/20 fractions/4 weeks (18 patients) or 64 Gy/32 fractions/6.5 weeks (17 patients), before RTH and 4-6 weeks and at a mean (+/- SD) of 1.4 (+/- 0.2) years after its completion: (1) anorectal symptoms (questionnaire), (2) anorectal pressures at rest and in response to voluntary squeeze and increases in intra-abdominal pressure (multiport anorectal manometry), (3) rectal sensation (balloon distension) and (4) anal sphincteric morphology (endoanal ultrasound).

RESULTS

All but 1 patient completed three series of measurements. RTH had no effect on anal sphincteric morphology. The increase in frequency of defecation and fecal urgency and incontinence scores previously reported in the patients 4-6 weeks after RTH were sustained 1 year later (p < 0.001, p < 0.001, and p < 0.05, cf. baseline, respectively). At this time, 56% (19 of 34), 50% (17 of 34) and 26% (9 of 34) of the patients had increased frequency of defecation, fecal urgency, and incontinence, respectively. Decreases in anal sphincteric pressures at rest and in response to voluntary squeeze recorded in the patients 4-6 weeks after RTH were not sustained 1 year later but the volumes of rectal distension associated with perception of the stimulus and desire to defecate were lower compared with baseline volumes (p < 0.01 and p < 0.05, respectively), reflecting heightened rectal sensitivity in the patients. There was no difference in measurements between the two radiation dose regimens. Univariate logistical regression analysis was performed on patients who had experienced increased symptom scores or decreases in recorded motor and sensory manometric parameters at 1 year, cf. baseline. The predictor variables used included individual patient tumor and treatment characteristics as well as individual patient symptom scores and parameters of anorectal motor and sensory function at baseline and 4-6 weeks after RTH. The results of the univariate logistical regression analysis showed that (1) frequency of defecation at 4-6 weeks and (2) rectal volumes at baseline both for (a) perception (p < 0.001) and (b) desire to defecate (p < 0.001), predicted significantly for the patients who had symptoms and signs of anorectal dysfunction at 1 year. Individual patient tumor and treatment-related variables tested, in contrast, had no predictive significance.

CONCLUSIONS

Anorectal symptoms following RTH for prostatic carcinoma are common and persist at least until 1 year after its completion and are associated with objective evidence of heightened rectal sensitivity.

Daily-diary evaluated side-effects of conformal versus conventional prostatic cancer radiotherapy technique

Conventional 4-field box radiotherapy technique induces high morbidity for patients with localized prostatic cancer. Using a patient daily diary, the present study compared side-effects after conventional radiotherapy with conformal radiotherapy for prostate cancer. Fifty-eight patients treated with the conventional technique (with or without sucralfate) were compared with 72 patients treated with conformal technique. The patient groups were compared with an age-matched control population. Patients treated with conformal technique were also evaluated regarding acute and late urinary problems. Results showed that patients treated with conformal technique reported significantly fewer side-effects as compared with conventional technique. Patients treated with sucralfate also showed slightly decreased intestinal morbidity in comparison to non-sucralfate group. Acute and late morbidity evaluated by the patients was decreased after conformal radiotherapy as compared with the conventional technique. Sucralfate may be of value if conformal radiotherapy is used for dose escalation in prostatic cancer patients.

Effect of radiotherapy on anorectal function in patients with cervical cancer

PURPOSE

The acute and long-term effects of pelvic radiation on defecation were studied.

METHOD

Anorectal function was assessed based on manometry and subjective symptoms in 31 patients with cervical cancer treated by radiotherapy alone. Sixteen of 31 patients were examined periodically before, during, and after radiotherapy (early group). Fifteen others were examined more than six months after completion of radiotherapy (late group).

RESULTS

One-third of patients in both groups had symptoms, mainly diarrhea and increased stool frequency. Patients in the late group also suffered from disturbed gas-stool discrimination, urgency, a sense of residual stool, and soiling. Anal canal resting pressure was significantly higher after radiotherapy (47 +/- 15.5 mmHg) than before radiotherapy (36.3 +/- 12.5 mmHg; P < 0.05). The maximum tolerable volume decreased with radiation, from 163.3 +/- 45 before to 119.2 +/- 41.4 ml during, 112.7 +/- 36.6 ml immediately after, and 94.6 +/- 34.4 ml in the late group (P < 0.01). Rectal compliance also decreased over time and was lower in the early group (before, 5.7 +/- 1.3 ml/mmHg; P < 0.01; during, 4.6 +/- 2.2 ml/mmHg, P < 0.01; after, 3.7 +/- 1.4 ml/mmHg; P < 0.05) than the late group (2.1 +/- 1.5 ml/mmHg) and lower before than after in the early group (P < 0.01). Although rectal pressure initiating continuous desire to defecate did not change, the maximum tolerable pressure was significantly higher in the late group (81 +/- 19.5 mmHg) than during (59 +/- 16.8 mmHg) or after (59.9 +/- 16.9 mmHg) radiotherapy in the early group (P < 0.05).

CONCLUSION

Radiation reduces the capacity of the rectal reservoir, even in asymptomatic patients. These changes develop during radiotherapy and progress over time.

Acute toxicity in pelvic radiotherapy; a randomised trial of conformal versus conventional treatment

BACKGROUND

A prospective, randomized clinical trial to assess the effect of reducing the volume of irradiated normal tissue on acute reactions in pelvic radiotherapy accured 266 evaluable patients between 1988 and 1993.

PURPOSE

This is the definitive analysis to assess the differences between the conformal and conventional arms of the trial.

MATERIALS AND METHODS

In both arms, patients were treated with 6 MV X-rays using a 3-field technique (in all but 5 cases) consisting of an anterior and two wedged lateral or posterior oblique fields; in the conventional arm, rectangular fields were employed, whereas in the conformal arm, the fields were shaped with customized blocks drawn according to the beam's-eye-view of the target volume. The most common dosage was 64 Gy in 2-Gy fractions 5 times a week, although a subgroup (of ca. bladder patients) were treated with 30-36 Gy in once-a-week 6 Gy fractions. Each patients completed a comprehensive acute toxicity scoring questionnaire concentrating on bowel and bladder problems, tiredness and nausea, before the start of treatment, weekly during and for 3 weeks after the end of treatment and then monthly for a further 2 months. compliance was excellent.

RESULTS

There were no differences between the patients in the two arms with respect to age, gender, tumour type (52% prostate, 41% bladder, 5% rectum, 2% other) fractionation/dosage, anterior field size, weight, or baseline symptoms. Substantial differences in normal-tissue volumes (rectum, bladder, etc.) were achieved: median high-dose volume (HDV) of 689 cm3 for the conformal technique versus 792 cm3 for the conventional. A clear pattern of an increase in symptoms during RT, followed by a decrease after RT, was observed for the patient group as a whole. However, a very extensive analysis has not revealed any (statistically) significant differences between the two arms in level of symptoms, nor in medication prescribed. The disparity between our findings and those of other, non-randomized studies is discussed.

CONCLUSIONS

The data on late effects must be collected and analyzed before any definite conclusions can be drawn on the benefits of conformal therapy in the pelvis.

The effects of gamma-radiation on intestinal motor activity and faecal pellet expulsion in the guinea pig

The effects of whole-body gamma-radiation (10 Gy) on intestinal motor activity was examined in the small and large intestine of the guinea pig 18 hr post irradiation. Neurally mediated relaxations of isolated gut bath preparations were generally unaffected. However, the contractile responses to direct smooth muscle stimulation with the cholinergic muscarinic agonist carbachol or ganglionic stimulation of intrinsic cholinergic motor neurones were significantly increased in the duodenum and colon but not the jejunum. This increased sensitivity to cholinergic stimulation was reflected in an increased contractility and a shift in the concentration-response curves for carbachol. The specificity of radiation actions for cholinergic mediated contractions was further supported by the observation that histamine-evoked contractions were unaffected. In a second series of experiments we examined the effects of gamma-radiation on the rate of pellet expulsion from freshly excised colons. Both colons from irradiated animals and nonirradiated colons exposed to carbachol showed significantly faster rates of pellet expulsion, indicative of increased propulsive motility. Pretreatment of animals with 0.5 mg/kg sc of the 5HT3 receptor antagonist Granisetron prevented the effect of radiation and reduced the pellet expulsion rate to below normal. These results indicate that gastrointestinal motility disturbances seen in organ-bath preparations of the intestine from rats exposed to whole-body gamma-radiation may be related to an increased sensitivity of the cholinergic muscarinic system.

A retrospective study of the effects of pelvic irradiation for gynecological cancer on anorectal function

PURPOSE

To evaluate the prevalence of anorectal dysfunction following therapeutic pelvic irradiation.

METHODS AND MATERIALS

Anorectal function was evaluated in 15 randomly selected patients (aged 47-84 years) who had received pelvic irradiation for treatment of carcinoma of the uterine body and cervix 5 and 10 years earlier. The following parameters were assessed in each patient: (a) anorectal symptoms (questionnaire), (b) anorectal pressures at rest and in response to rectal distension, voluntary squeeze, and increases in intraabdominal pressure (multiport anorectal manometry with concurrent electromyography of the anal sphincters), (c) rectal sensation (rectal balloon distension) and, (d) anal sphincteric morphology (ultrasound). Results were compared with those obtained in nine female control subjects.

RESULTS

Ten of the 15 patients had urgency of defecation and 4 also suffered fecal incontinence. Basal anorectal pressures measured just proximal to the anal canal (p = 0.05) and anorectal pressures generated in response to voluntary squeeze measured at the anal canal were less (p < 0.01) in the patients. The fall in anal pressures in response to rectal distension was greater in the patients (p < 0.05) and the desire to defecate occurred at lower rectal volumes (p < 0.05). The slope of the pressure/volume relationship in response to rectal distension was greater (p < 0.05) in the patients, suggestive of a reduction in rectal compliance. In 14 of the 15 patients at least one parameter of anorectal motor function was outside the control range. There was no difference in the thickness of the anal sphincters between the two groups.

CONCLUSION

Abnormal anorectal function occurs frequently following pelvic irradiation for gynecological malignant diseases and is characterized by multiple dysfunctions including weakness of the external anal sphincter, stiffness of the rectal wall, and a consequent increase in rectal sensitivity.

Anorectal function after preoperative intraluminal brachytherapy and colonic J pouch-anal anastomosis for rectal carcinoma

The effects of preoperative intraluminal brachytherapy on bowel function after anoabdominal rectal resection and colonic J pouch-anal anastomosis were studied. The patients included eight not receiving irradiation (group 1), eight who received 30 Gy (group 2) and eight who received 80 Gy (group 3). Stool frequency and the incidence of soiling were significantly greater in group 3 than in the other groups. Anal resting pressure was lower in group 3 during the study period but J pouch distensibility was not reduced. The maximum tolerated volume, threshold volume and squeeze pressure were significantly lower in group 3 than in the other groups in the early postoperative period. These results suggest that high-dose brachytherapy affects the anal sphincters and colonic J pouch. A moderate dose of 30 Gy may be more suitable before restorative anorectal surgery.

Early effect of external beam radiation therapy on the anal sphincter: a study using anal manometry and transrectal ultrasound

The early of pelvic irradiation on the anal sphincter has not been previously investigated. This study prospectively evaluated the acute effect of preoperative radiation on anal function. Twenty patients with rectal carcinoma received 4,500 cGy of preoperative external beam radiation. The field of radiation included the sphincter in 10 patients and was delivered above the anorectal ring in 10 patients. Anal manometry and transrectal ultrasound were performed before and four weeks after radiotherapy. No significant difference in mean maximal squeeze or resting pressure was found after radiation therapy. An increase in mean minimal sensory threshold was significant. Histologic examination revealed minimal radiation changes at the distal margin in 8 of 10 patients who underwent low anterior resection and in 1 of 3 patients who underwent abdominoperineal resection. We conclude that preoperative radiation therapy has minimal immediate effect on the anal sphincter and is not a major contributing factor to postoperative incontinence in patients after sphincter-saving operations for rectal cancer.

The response of the caecotrophy rhythm of the rabbit to single light signals

The direction of temporary phase shifts depends on the timing of the light signal in the dark period (1800-0600). Delays predominated following signals between 2100 and 2400, while advances tended, even more uniformly, to follow signals given between 0100 and 0400. In one animal the caecotrophy rhythm split into 2 components after a light signal at 0400, while in another it was so disturbed that the signal was followed by a coprostasis of 10 days. The phase responses to light stimuli of the rabbit caecotrophy rhythm correspond well with those obtained in nocturnal rodents.

Open-field behavior of prenatally irradiated and/or postnatally handled C57BL/6 mice

Mice (C57BL/6) were prenatally irradiated with 60Co and/or handled on postnatal Days 1-10, and subsequently tested in an open field on Days 21, 42, and 63, and in a shuttle box on Days 30 and 60. Another group of mice was treated and tested similarly, but the shuttle box testing was omitted. All animals were cross-fostered at birth. Handling increased open-field activity and decreased defecation whereas irradiation decreased activity and had inconsistent effects on defecation. A comparison of the data from both groups of mice indicated that the shuttle box experience decreased open-field activity, particularly for the irradiated and unhandled animals. Direct and indirect irradiation effects--revealed by the cross-fostering procedure--were both significant and about equal in magnitude, underlining the importance of attending to irradiation effects on maternal as well as on offspring behavior.