Acute toxicity during external-beam radiotherapy for localized prostate cancer: comparison of different techniques

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.

Late GI and GU complications in the treatment of prostate cancer

PURPOSE

To assess the factors that predict late GI and GU morbidity in radiation treatment of the prostate.

METHODS AND MATERIALS

Seven hundred twelve consecutive prostate cancer patients treated at this institution between 1986 and 1994 (inclusive) with conformal or conventional techniques were included in the analysis. Patients had at least 3 months follow-up and received at least 65 Gy. Late GI Grade 3 morbidity was rectal bleeding (requiring three or more procedures) or proctitis. Late Grade 3 GU morbidity was cystitis or stricture. Multivariate analysis (MVA) was used to assess factors related to the complication-free survival. The factors assessed were age, occurrence of side effects > or = Grade 2 during treatment, irradiated volume parameters (use of pelvic fields, treatment of seminal vesicles to full dose or 57 Gy, and use of additional rectal shielding), dose, comorbidities, and other treatments (hormonal manipulation, TURP).

RESULTS

Acute GI and GU side effects (Grade 2 or higher) were noted in 246 and 201 patients, respectively; 67 of these patients exhibited both. GI side effects were not correlated with GU side effects acutely. Late and acute morbidities were correlated (both GI and GU). Fifteen of the 712 patients expressed Grade 3 or 4 GI injuries 3 to 32 months after the end of treatment, with a mean of 14.3 months. One hundred fifteen patients expressed Grade 2 or higher GI morbidity (mean: 13.7 months). The 43 Grade 2 or higher GU morbidities occurred significantly later (mean: 22.7 months). Central axis dose was the only independent variable significantly related to the incidence of late GI morbidity on MVA. No treatment volume parameters were significant for Grade 3. The following parameters were significantly related (by MVA) to Grade 2 GI morbidity: central axis dose, use of the increased rectal shielding, androgen deprivation therapy starting before RT. Acute and late GI morbidities were highly correlated. History of diabetes, treatment of pelvic nodes, and age less than 60 years were significantly related to acute GI side effects. The parameters significantly related to late Grade 2 or higher GU morbidity were central axis dose, androgen deprivation therapy (Zoladex or Lupron) prior to radiation therapy (RT), history of obstructive symptoms, and acute GU side effects. There were too few late Grade 3 GU morbidities to perform multivariate analysis. Acute GU side effects were highly correlated with late GU injury. The following were correlated with acute GU side effects: history of diabetes (+), treatment with conformal fields (-), TURP before RT (-), presentation with urinary obstructive symptoms.

CONCLUSION

Both late GI and GU morbidity demonstrate a dose dependence, but only the volume dependence observed is a reduction in late Grade 2-4 GI morbidity by increasing the rectal shielding in the lateral fields for the final 10 Gy. Moreover, both late GI and GU morbidity was increased in patients treated with hormone manipulation prior to RT. GI and GU injuries were correlated with their corresponding acute side effects. GI and GU complications must not be combined for analysis to determine the factors related to their occurrence.

Three dimensional comparison of blocked arcs vs. four and six field conformal treatment of the prostate

PURPOSE

The purpose of this study is to compare five different techniques for treatment the prostate without seminal vesicles. Dose volume histograms and a time survey are the tools that were used for this analysis.

METHODS AND MATERIALS

For this study we compared 3D techniques using four and six field conformal treatments, to open and blocked 8 x 8 cm2 120 degrees bilateral arcs. All the plans were normalized to deliver 100% to the central axis, and full 3D calculations were performed. Blocked arcs were created using the 'average beam's eye view' (A-BEV) technique.

RESULTS

Analysis of the dose volume histograms revealed: (1) Arcs with blocks result in an improved dose distribution compared to standard arcs and four field 3DCRT techniques, (2) The DVH associated with blocked arcs, using block margins of 1.3 cm, resulted in a somewhat lower dose to the rectum but a 'tighter' margin around the prostate compared to the DVH generated using the six field 3DCRT technique.

CONCLUSION

This technique is for treatment of the prostate only, when treatment of the seminal vesicle is not required. The use of blocked arcs significantly improved the dose distribution compared to using standard arcs and 4-field conformal techniques. The DVHs associated with using blocked arcs is comparable to the SFC technique. It is likely to be less expensive, faster to set-up and may allow for safe dose escalation when only the prostate is receiving treatment.

Localization of the prostatic apex for radiotherapy planning: a comparison of two techniques

Autopsy and pathology studies have shown that the caudal portion of the prostate gland harbors tumour in 64-75% of specimens examined. Accurate localization of the prostatic apex may be important in improving local control with external beam radiation therapy. We compared the location of the apex obtained with CT based treatment planning versus localization using retrograde urethrography in 32 consecutive patients. The prostatic apex, localized by CT and retrograde urethrography, was compared relative to the ischial tuberosities and the symphysis pubis. Discordance between the location of the prostatic apex as defined on CT scan and retrograde urethrography was found in 50% of patients evaluated. There was 31% discordance between the location of the prostatic apex as defined on CT and retrograde urethrography when data were analysed with the location of the prostatic apex 1 cm above the narrowing on urethrography, a definition others have suggested. The urethrogram defined prostatic apex, as compared with the CT definition, necessitated the treatment of more of the surrounding normal tissues in 31% of our cases, with four-field techniques. Comparison of dose-volume histograms of the bladder, rectum and penis irradiated for target volumes defined by CT versus retrograde urethrography showed that more penis was irradiated in some patients with the urethrogram defined prostatic apex; irradiation of the base of the penis could be relatively avoided by using a six-field treatment plan instead of the standard four-field box. There is discordance between the CT and urethrogram defined prostatic apex. Dose-volume histogram information suggests that differences in apex localization can significantly affect doses to normal adjacent prostatic tissues. Combining CT localization with the urethrogram localization of the prostatic apex optimizes radiotherapy planning and dose delivery.

Prostate volumes defined by magnetic resonance imaging and computerized tomographic scans for three-dimensional conformal radiotherapy

PURPOSE

To compare the prostate volumes defined on magnetic resonance imaging (MRI), and noncontrast computerized tomographic (CT) scans used for three-dimensional (3D) treatment planning.

METHODS AND MATERIALS

Ten patients were simulated for treatment using immobilization and a retrograde urethrogram. 3D images were used to compare prostate volumes defined by MRI (4-6 mm thick slices) and CT images (5 mm thick slices). Prostate volumes were calculated in cm(3) using the Scanditronix 3D planning system. MRI/CT images were merged using bony anatomy to define the regions of discrepancy in prostate volumes.

RESULTS

The mean prostate volume was 32% larger (range-5-63%) when defined by noncontrast CT compared to MRI. The areas of nonagreement tended to occur in four distinct regions of discrepancy: (a) the posterior portion of the prostate, (b) the posterior-inferior-apical portion of the prostate, (c) the apex due to disagreement between a urethrogram based definition and the location defined by MRI, (d) regions corresponding to the neurovascular bundle.

CONCLUSION

There is a tendency to overestimate the prostate volume by noncontrast CT compared to MRI. Awareness of this tendency should allow us to be to more accurately define the prostate during 3-D treatment planning.

Prostate cancer. Who is best benefited by external beam radiation therapy?

The major indications for radical radiation therapy of prostate cancer for both early-stage and locally advanced disease are discussed. Important issues in the interpretation of long-term treatment series are reviewed. The outcomes of therapy are analyzed for both early-stage and locally advanced disease, including alternative therapeutic strategies. On the basis of this review of the literature, current treatment recommendations delineate patients most likely to benefit from radiation therapy as opposed to alternative therapeutic modalities.

The impact of isocenter placement errors associated with dose distributions used in irradiating prostate cancer

Historically, four perpendicular treatment fields or bilateral arcs have been used in the treatment of prostate cancer. "New techniques" including four conformal fields, seven conformal fields, 120 degrees bilateral conformal coplanar, and non-coplanar arc'ed beam arrangements, are replacing the "older" approaches. These techniques result in a reduction in doses to adjacent critical structures while covering the clinical target volume (CTV). This study, analyzes the impact of random or systematic isocenter displacement errors (IDE) associated with the delivery of radiotherapy, using the best of these "newer techniques". Dose Volume Histograms (DVH) were used to evaluate the dose to the prostate and surrounding normal tissues with 0.3 cm, 0.5 cm and 0.8 cm IDE. It was determined that IDE associated with fixed coplanar treatment techniques could reduced the prescribed dose to the prostate by 0-8%, the coplanar are technique reduced the prescribed prostate dose by 3-10%, and the noncoplanar conformal arc technique could lower the prescribed prostate dose by 0-5%. Predictably, 0.3 cm IDE found in the posterior and inferior direction increase the dose to the rectum by 5-12% and lowered the dose to the bladder by 4-8%. Errors in the superior and anterior direction increased the dose to the bladder by 4-8% and decreased the dose to the rectum by 8-10%. Errors in the right to left direction slightly increased the dose to the ipsilateral femoral head. Doses to the rectum and bladder associated with 0.5 cm and 0.8 cm IDE are significantly larger. The frequency and magnitude of IDE must be accounted for before higher doses can be delivered safety. Recognizing the impact of IDE on our ability to deliver the prescribed dose to the planning target volumes (PTV) could incorporate the impact of IDE during the planning process.

Acute morbidity of radiation therapy for prostate carcinoma

The acute morbidity of high dose radiation therapy for carcinoma of the prostate in a group of 169 patients treated between February 1993 and April 1994 was examined. Morbidity was determined at the start of therapy, then weekly during therapy and at 1, 2, 3, 6 and 12 months after therapy. Morbidity was examined from the view of the treating doctor and the patients. Morbidity was found to peak at the end of the treatment. From the radiation oncologist's perspective, 80-85% of patients experienced significant bladder and bowel morbidity. The level of acute morbidity was acceptable and there was only one patient that was admitted to hospital for symptomatic control of his acute reaction. Recovery was practically complete after 3 months for both bladder and bowel morbidity. Fifty per cent of patients experienced dysuria, 75% perianal discomfort and 87% frequency at the end of the treatment. Most of the individual factors recovered following radiation but urinary frequency and perianal discomfort were the most persistent problems.

Accuracy of pelvic radiotherapy: prospective analysis of 90 patients in a randomised trial of blocked versus standard radiotherapy

The aim of this study was to assess the accuracy of pelvic radiotherapy during a trial of blocked radiotherapy at the Royal Marsden Hospital, UK. Prospective evaluation was performed on 90 patients receiving CT planned pelvic radiotherapy using weekly anterior-posterior and lateral portal films. Field placement errors (FPEs) were calculated by comparing field centres of each film with a designated point of interest. Data was evaluated to calculate the overall treatment simulator differences, the number of error free treatments, and mean treatment-simulator position and to evaluate the role of systematic versus random errors. Age, weight, disease site, position of treatment, fractionation, blocked versus conventional techniques were assessed for their effect on treatment accuracy. The mean absolute error between treatment and simulator films was anterior right-left (ARL) 0.25 cm, anterior superior-inferior (ASI) 0.32 cm, lateral anterior-posterior (LAP) 0.42 cm, and lateral superior-inferior (LSI) 0.28 cm. On average the field centre was displaced by 0.66 cm (standard deviation, S.D. = 0.34) from that intended. On each treatment day 29% of anterior films and 45% of lateral films had at least one 0.5 cm error. Overall 59% of treatments had at least one 0.5 cm error and 9% a 1.0 cm error. The field centre was more than 0.5 cm from the position intended in 66% of treatments and over 1 cm for 14% of treatments. Analysis of variance showed that both random and systematic errors occurred in all directions. Though random errors were of similar magnitude in all direction (variance sigma 2 = 0.06-0.09 cm2); systematic errors showed a 4-fold variation being greatest in the LAP direction (sigma 2 = 0.19 cm2) and least the ARL direction (sigma 2 = 0.048 cm2). No factor consistently predicted for worse outcome in all directions. Hypofractionated treatments were less accurate in the LSI direction (P > 0.05). Systematic errors were associated in the ARL direction with hypofractionation (P < 0.01) and, in the LSI direction with weight (P < 0.03) and age (P < 0.05). We conclude that significant random and systematic errors can occur during pelvic radiotherapy especially in the LAP direction. These results suggest that in the absence of a customised immobilisation device, to cover 95% of errors, margins of 0.6 cm for RL and SI directions and 0.9 cm for AP direction should be allowed between the planning and clinical target volumes. However, ideally, each centre should determine their own margin requirements according to local clinical practice.

Management of prostate and bladder cancer in the elderly

The management of prostate and bladder cancer in the elderly will increasingly require clinicians to judge the impact on comorbidity and toxicity of the proposed therapy in order to make sound management decisions. As PSA-based screening has rapidly increased, physicians are increasingly challenged to decide the upper age limits for such screening and therapy. Bladder cancer management in the elderly differs little from that offered to the younger patient and the new therapeutic developments may improve the risk-to-benefit ratio of treating advanced disease. It is clear that as the US population ages, management of prostate and bladder cancer will become an increasingly common dilemma for the urologic practitioner.

Conventional vs. conformal radiotherapy for prostate cancer: preliminary results of dosimetry and acute toxicity

PURPOSE

To compare conformal radiotherapy using three dimensional treatment planning (3D-CRT) to conventional radiotherapy (Conven-RT) for patients with Stages T2-T4 adenocarcinoma of the prostate.

METHODS AND MATERIALS

A Phase III randomized study was activated in May 1993, to compare treatment toxicity and patient outcome after 78 Gy in 39 fractions using 3D-CRT to that after 70 Gy in 35 fractions using Conven-RT. The first 46 Gy were administered using the same nonconformal field arrangement (four field) in both arms. The boost was given nonconformally using four fields in the Conven-RT arm and conformally using six fields in the 3D-CRT arm. The dose was specific to the isocenter. The first 60 patients, 29 in the 3D-CRT arm and 31 in the Conven-RT arm, are the subject of this preliminary analysis.

RESULTS

The two treatment arms were first compared in terms of dosimetry by dose-volume histogram analysis. Using a subgroup of patients in the 3D-CRT arm (n=15), both Conven-RT and 3D-CRT plans were generated and the dose-volume histogram data compared. The mean volumes treated to doses above 60 Gy for the bladder and rectum were 28 and 36% for the 3D-CRT plans, and 43 and 38% for the Conven-RT plans, respectively (p < 0.05 for the bladder volumes). The mean clinical target volume (prostate and seminal vesicles) treated to 95% of the prescribed dose was 97.5% for the 3D-CRT arm, and 95.6% for the Conven-RT arm (p < 0.05). There were no significant differences in the acute reactions between the two arms, with the majority experiencing Grade 2 or less toxicity (92%). Moreover, no relationship was seen between acute toxicity and the volume of bladder and rectum receiving in excess of 60 Gy for those in the 3D-CRT arm. There was also no difference between the groups in terms of early biochemical response. Prostate-specific antigen levels at 3 and 6 months after completion of radiotherapy were similar in the two treatment arms. There was only one biochemical failure in the study population at the time of the analysis.

CONCLUSIONS

Comparison of the Conven-RT and 3D-RT treatment plans revealed that significantly less bladder was in the high dose volume in the 3D-CRT plans, while the volume of rectum receiving doses over 60 Gy was equivalent. There were no differences between the two treatment arms in terms of acute toxicity or early biochemical response. Longer follow-up is needed to determine the impact of 3D-CRT on long-term patient outcome and late reactions.

A comparison of four patient immobilization devices in the treatment of prostate cancer patients with three dimensional conformal radiotherapy

PURPOSE

To determine the variability of patient positioning during three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer treated with no immobilization or one of four immunobilization devices, and to determine the effects of patient body habitus and pelvic circumference on patient movement with each individual inmobilization technique.

METHODS AND MATERIALS

To see whether our immobilization techniques have improved day-to-day patient movement, a retrospective analysis was carried out. A total of 62 patients treated at one facility on a single machine with 3D-CRT via a four-field box technique (anterior-posterior and opposed laterals) in the supine position with either no immobilization or one of four immobilization devices. Five groups of patients were compared: (a) group 1-no immobilization; (b) group 2-alpha cradle from the waist to upper thigh; (c) group 3-alpha cradle from waist to below the knees; (d) group 4-styrofoam leg immobilizer (below knees); and (e) group 5-aquaplast cast encompassing the entire abdomen and pelvis to midthigh with alpha cradle immobilization to their lower legs and feet. Prior to starting radiotherapy, portal films of all four treatment fields were obtained 1 day before treatment. Subsequently, portal films were then obtained at least once a week. Portal films were compared with the simulation films and appropriate changes were made and verified on the next day prior to treatment. A deviation of greater than 0.5 cm or greater was considered to be clincally significant in our analysis. We studied the difference among the types of immobilization and no immobilization by looking at the frequency of movements (overall, and on each of the three axes) that a patient had during the course of his treatment. Using a logistic regression model, the probability of overall and individual directional movement for each group was obtained. In addition, the effects of patient body habitus and pelvic circumference on movement were analyzed.

RESULTS

The maximum deviation was 2 cm and the median deviation was 1.2 cm. For each patient, the probability of movement ranged from 0 to 76%, with a mean of 39%. There was no significant difference seen in overall movement with any of the immobilzation devices compared to no immobilization, but there was less vertical (9 vs. 18%; p = 0.03) and AP (6 vs. 15%; p = 0.14) movement with the aquaplast than any other group. However, when examining the lateral direction, the aquaplast had significantly more movement (32 vs. 9%; p < 0.001). When accounting for body habitus and pelvic circumference, no immobilization device was effective in reducing movement in obese patients or in patients with pelvic circumference greater than 105 cm. The aquaplast group had a significantly increased amount of lateral movement with obesity (42 vs. 23%; p < 0.05), and with pelvic circumference >105 cm (33 vs. 29%; p < 0.05).

CONCLUSIONS

There was no significant reduction in overall patient movement noted with any of the immobilization devices compared to no immobilization. The aquaplast group had reduced vertical and AP movement of greater than 0.5 cm. There was significantly more lateral movement with aquaplast appreciated in obese patients or patients with pelvic circumferences greater than 105 cm. The aquaplast immobilization appears to be useful in reducing movement in two very clinicaly important dimensions (AP and vertical). Despite our findings, other immobilization may still be useful especially in the treatment of nonobese patients. It is clear that the optimal immobilization technique and patient positioning are yet to be determined.

The potential for normal tissue dose reduction with neoadjuvant hormonal therapy in conformal treatment planning for stage C prostate cancer

PURPOSE

Preirradiation hormonal cytoreduction of prostate cancer has been proven to reduce exposure of normal structures by decreasing the size of the target volume. Dose-volume histogram (DVH) analysis, however, does not always appear to demonstrate a strong positive benefit with the use of neoadjuvant hormone therapy. This study analyzes various other factors influencing dose to normal organs, which may determine the success or failure of neoadjuvant hormonal therapy in achieving its goals.

METHODS AND MATERIALS

Patients with bulky clinical Stage C adenocarcinoma of the prostate were given 3 months of hormone treatment consisting of oral Flutamide and monthly Zoladex injections prior to irradiation. Computerized tomography (CT) scans of the pelvis were obtained both prior to and following hormonal treatment. Treatment plans were generated by three-dimensional (3D) conformal treatment planning. The change in the volume of the prostate was assessed along with the percentage of prescribed dose delivered to the rectum and bladder. Various factors such as prostate size, bladder/rectum size, and organ shape were studied. Both dose-volume histograms (DVH) and dose-surface area histograms (DSH) were used for analysis.

RESULTS

Six of seven patients had reduction in the size of their prostates. The mean volumes of the prostate before and after hormonal manipulation were 129.1 +/- 32.9 standard deviation (SD) cm3 and 73.0 +/- 29.5 SD cm3, respectively (p = 0.0059). The volume of rectum receiving 80% of the prescribed dose was reduced in five of seven patients from a mean of 83.2 to 59.9 cm3 (p = 0.045). The volume of bladder receiving 80% of the prescribed dose was also reduced in five out of seven patients from a mean of 74.5 to 40.2 cm3 (p = 0.098). Correlation between the size of the prostate and volume of rectum and bladder treated was not always consistent: greater reduction in prostate size did not necessarily result in large decreases in dose to bladder or rectum. The total size of the bladder and rectum were found to be important factors in normal tissue radiation exposure; the benefits of hormone therapy may be lost if the bladder and rectum are allowed to decrease in size. Also, the bladder may be prone to sagging into the pelvis of some patients following hormone therapy, resulting in a less optimal therapeutic ratio.

CONCLUSION

Reduction in prostate size by neoadjuvant hormonal manipulation does decrease the amount of normal tissue irradiated in most patients. However, the correlation between the reduction in prostate size and amount of rectum or bladder treated is not linear if other variables are not controlled. Factors such as the shape of the organs, as well as the distensible nature of the bladder and rectum, play major roles in dose to normal tissues. These facts may mask the benefits of cytoreduction and could be obstacles in realizing consistent benefits from preirradiation hormonal treatment in the clinical setting if they are ignored.

Ultrasound-guided high dose rate conformal brachytherapy boost in prostate cancer: treatment description and preliminary results of a phase I/II clinical trial

PURPOSE

To improve results for locally advanced prostate cancer, a prospective clinical trial of concurrent external beam irradiation and fractionated iridium-192 (Ir-192) high dose rate (HDR) conformal boost brachytherapy was initiated.

METHODS AND MATERIALS

Between November 1991 and February 1994, 99 implants were performed on 33 patients with prostatic adenocarcinoma at William Beaumont Hospital. Using AJCC staging criteria, 9 patients had T2b tumors, 17 patients had T2c tumors, and 7 patients had T3 disease. Patients were treated with (a) 45.6 Gy whole pelvis external irradiation and (b) three HDR fractions of 5.5 Gy each (18 patients) or 6 Gy each (15 patients) to the prostate. Transperineal needle implants using real-time ultrasound guidance with interactive on-line isodose distributions were performed on an outpatient basis during weeks 1, 2, and 3 of external irradiation. Acute toxicity was scored using the Radiation Therapy Oncology Group (RTOG) morbidity grading system.

RESULTS

This technique of concurrent external pelvic irradiation and conformal HDR brachytherapy was well tolerated. No significant intraoperative or perioperative complications occurred. Three patients (9%) experienced Grade 3 acute toxicity (two dysuria and one diarrhea). All toxicities were otherwise Grades 1 or 2 and were primarily as expected from pelvic external irradiation. Persistent implant-related toxicities included Grades 1-2 perineal pain (12%) and hematospermia (15%). Median follow-up time was 13 months. Serum prostatic-specific antigen (PSA) levels normalized in 91% of patients (29 out of 32) within 1-14 months (median 2.8 months) after irradiation. PSA levels were progressively decreasing in the other three patients at last measurement. Prospectively planned prostatic rebiopsies done at 18 months in the first 10 patients were negative in 9 out of 10 (90%).

CONCLUSIONS

Acute toxicity has been acceptable with this unique approach using conformal high dose rate Ir-192 boost brachytherapy with concurrent external irradiation. The initial tumor response as assessed by serial PSA measurement and rebiopsy is extremely encouraging. Dose escalation will proceed in accordance with the protocol guidelines. Further patient accrual and longer follow-up will allow comparison to other techniques.

Incidence of and factors related to late complications in conformal and conventional radiation treatment of cancer of the prostate

PURPOSE

The fundament hypothesis of conformal radiation therapy is that tumor control can be increased by using conformal treatment techniques that allow a higher tumor dose while maintaining an acceptable level of complications. To test this hypothesis, it is necessary first to estimate the incidence of morbidity for both standard and conformal fields. In this study, we examine factors that influence the incidence of late Grade 3 and 4 morbidity in patients treated with conformal and standard radiation treatment for prostate cancer.

METHODS AND MATERIALS

Six hundred sixteen consecutive patients treated with conformal or standard techniques between 1986 and 1994 to doses greater than 65 Gy and with more than 3 months follow-up were analyzed. No patients treated with prostatectomies were included in the analysis. The conformal technique includes special immobilization by a cast, careful identification of the target volume in three dimensions, localization of the inferior border of the prostate using a retrograde urethrogram, and individually shaped portals that conform to the Planning Target Volume (PTV). Multivariate analysis using a proportional hazards model compares differences in the incidence of Radiation Therapy Oncology Group/European Organization for Research and Center Treatment (RTOG/EORTC) Grade 3 and 4 late gastrointestinal (GI) and genitourinary (GU) morbidity by technique, T-stage, grade, age, hormonal treatment, irradiated volume, dose, and comorbid conditions. Grade 3 rectal bleeding was defined as requiring three or more cautery procedures.

RESULTS

The overall actuarial incidence of genitourinary (GU) toxicities at 5 years was 3.4%, with the crude incidence being six cases in 616 patients satisfying the selection criteria; for gastrointestinal (GI) toxicities, the overall actuarial incidence was 2.7%, with the crude incidence being 13 cases out of 616 patients. The average time to complication for our patients was 12.8 months for GI toxicity and 32.9 months for GU toxicity (p < 0.001). No factors were found that were predictive for GU morbidity. The only factors significantly related to incidence of late GI morbidity on multivariate analysis of our data were dose and age. The central axis dose was a more significant variable than the dose prescribed to the Treated Volume. Age was negatively correlated with late GI morbidity, with older patients having a reduced incidence of toxicity. The median tolerance dose for GI complications was estimated to be 92.8 Gy, and the dose for 10% incidence was estimated to be 80.2 Gy. Treating the pelvis to 45 Gy did not increase the incidence of late morbidity. Late GI and GU toxicities were not correlated.

CONCLUSION

The conformal technique has been associated with fewer acute Grade 2 toxicities (6). The use of conformal fields did not decrease the incidence of late GI morbidity; however, patients with this technique invariably had higher doses. Because of the dose response for this complication and the correlation between the dose and the use of conformal fields, one would not expect to demonstrate an advantage to conformal fields in this data set. On the other hand, no dose effect was observed for late GU morbidity. In this case, there appears to be an advantage for conformal treatment that has not reached statistical significance because the follow-up time is shorter than for the patients treated with conventional fields and the latency for GU morbidity is long.

Conformal treatment of prostate cancer with improved targeting: superior prostate-specific antigen response compared to standard treatment

PURPOSE

Conformal radiation therapy (CRT) decreases the morbidity of prostate cancer treatment, but no published data attest to the improved ability of CRT to control disease. Therefore, we compared Prostate-Specific Antigen (PSA) response at 1 year among similarly staged patients treated by conformal techniques to those treated with conventional approaches, looking for an early indicator of tumor response.

METHOD AND MATERIALS

Patients with locally advanced disease were treated by pelvic field followed by prostate field conedowns; those with early stage/low grade disease received only prostate field irradiation. Between October, 1987 and November, 1991, conventional treatments used rectangular beams with or without corner blocks. Neither urethrography nor immobilization casts were used for conventionally treated patients. Between April, 1989 and December, 1992, conformal treatments have used rigid immobilization and Computed Tomography-based, beams-eye-view field design. As such, our conformal approach allowed improved targeting. Median prescribed doses (minimal doses to the Planning Target Volume) were 70 Gy (66-73 Gy) and 70.2 Gy (64.8-75 Gy) for conventionally and conformally treated patients, respectively. Median daily fraction size was 1.8 Gy for conventional treatment and 2.0 Gy for conformal therapy. Baseline PSA data were available on 170 consecutive patients treated conformally and 90 consecutive patients treated conventionally.

RESULTS

Among those receiving only prostatic field irradiation, 12-month PSA values returned to normal in 96% and 85% of conformally and conventionally treated patients, respectively, when normalization was defined as < or = 4 ng/ml (p < 0.03) and in 76% vs. 55% of patients when PSA normalization was defined as < or = 1.5 ng/ml (p < 0.02). Among those receiving pelvic irradiation prior to prostatic conedown, PSA normalization (< or = 4 ng/ml) occurred in 82% and 61% (p < 0.01) of conformally and conventionally treated patients, respectively, and in 56% vs. 38% of patients when normalization was defined as < or = 1.5 ng/ml (p < 0.05). In a multivariate analysis, pretreatment PSA level (< or = 15 vs. > 15), and the use of conformal irradiation were statistically significant prognostic discriminants of PSA normalization at 1 year while total irradiation dose, clinical stage, and the addition of pelvic fields were not significant.

CONCLUSIONS

As measured by PSA normalization, conformal techniques with improved targeting produced responses that were significantly better than conventional techniques among patients treated with definitive irradiation. These results, coupled with our previously documented reduction of acute and chronic sequelae, support the continued use of CRT as a more effective method of treatment for prostate cancer.

The effectiveness of immobilization during prostate irradiation

PURPOSE

To evaluate the effect of a hemibody foam cradle on the reproducibility of patient setup during external beam radiation treatment of prostate cancer.

METHODS AND MATERIALS

Between January 1992 and April 1993, 74 patients received external beam radiation treatment to the prostate +/- nodes, generally with a four-field box technique. Forty-four of the 74 patients had a custom-made hemibody foam cast used in an attempt to improve setup accuracy. A review of the routine weekly port films was performed following the completion of therapy to determine the reproducibility of patient setup in all 74 patients. The physician's request of an isocenter shift was used as an indicator of reproducibility. Neither the treating technologists nor the physicians knew at the time the films were taken that the port films would be reviewed for setup reproducibility at a later date. The results were compared between the patients treated with (44) and without (30) an immobilization device.

RESULTS

In the 44 immobilized patients, 213 routine checks of the isocenter were performed during the 7-week course of radiation therapy. In 17.4% of these instances (37 out of 213), an isocenter shift was requested. This rate is compared to 23.1% (30 out of 130) in the 30 patients who did not have the immobilization device (p < 0.2). There was a statistically significant reduction in isocenter shifts requested in the anterior to posterior direction in the patients who were immobilized, 5.1% (9 out of 175) vs. 12.6% (13 out of 103) (p < 0.05, two tailed chi-square test). There was no significant improvement in the reproducibility of isocenter placement in the cephalad to caudal or right to left directions.

CONCLUSIONS

This custom-made hemibody foam cradle appears to improve the reproducibility of patient setup during the 7-week course of fractionated external beam irradiation for patients with adenocarcinoma of the prostate. This type of immobilization device is now routinely used in our clinic and is recommended for all patients receiving pelvic radiotherapy. These devices are likely to be particularly useful when contemplating dose escalation to minimize the volume of bladder and rectum included in the treatment fields.

Factors influencing incidence of acute grade 2 morbidity in conformal and standard radiation treatment of prostate cancer

PURPOSE

The fundament hypothesis of conformal radiation therapy is that tumor control can be increased by using conformal treatment techniques that allow a higher tumor dose while maintaining an acceptable level of complications. To test this hypothesis, it is necessary first to estimate the incidence of morbidity for both standard and conformal fields. In this study, we examine factors that influence the incidence of acute grade 2 morbidity in patients treated with conformal and standard radiation treatment for prostate cancer.

METHODS AND MATERIALS

Two hundred and forty-seven consecutive patients treated with conformal technique are combined with and compared to 162 consecutive patients treated with standard techniques. The conformal technique includes special immobilization by a cast, careful identification of the target volume in three dimensions, localization of the inferior border of the prostate using the retrograde urethrogram, and individually shaped portals that conform to the Planning Target Volume (PTV). Univariate analysis compares differences in the incidence of RTOG-EORTC grade two acute morbidity by technique, T stage, age, irradiated volume, and dose. Multivariate logistic regression includes these same variables.

RESULTS

In nearly all categories, the conformal treatment group experienced significantly fewer acute grade 2 complications than the standard treatment group. Only volume (prostate +/- whole pelvis) and technique (conformal vs. standard) were significantly related to incidence of morbidity on multivariate analysis. When dose is treated as a continuous variable (rather than being dichotomized into two levels), a trend is observed on multivariate analysis, but it does not reach significant levels. The incidence of acute grade 2 morbidity in patients 65 years or older is significantly reduced by use of the conformal technique.

CONCLUSION

The conformal technique is associated with fewer grade 2 acute toxicities for all patients. This conclusion is valid irrespective of selection criteria except in a few cases. Older age is associated with increased toxicity only with the standard technique and not then at a statistically significant level. Elderly patients should not be excluded from external beam radiation because of increased morbidity especially if conformal treatment is available. Volume is not significantly related to morbidity in patients with standard treatment, but it is for conformal treatment. Furthermore, it remains significant in a multivariate analysis that also shows the advantage of conformal treatment. Grade 2 acute toxicities are more volume dependent than dose dependent.

Self-assessment questionnaire for evaluating urinary and intestinal late side effects after pelvic radiotherapy in patients with prostate cancer compared with an age-matched control population

BACKGROUND

Pelvic irradiation to patients with prostate cancer is accompanied by urinary and intestinal reactions. In men older than 60 years, treatment-induced problems should be evaluated in relation to problems in an age-matched nonirradiated population.

METHODS

In the present study, problems in the urinary tract and intestine were evaluated with a self-assessment questionnaire using the linear-analogue scale. The questionnaire was mailed out to 200 patients and to an age-matched population 24-56 months after irradiation.

RESULTS

Twenty-five percent of the control group and 50% of the patient group reported some kind of problem in the urinary tract. The most common urinary problems in the control group and in the patient group, respectively, were urgency (19 and 42%), starting problems (22 and 33%), and leakage (11 and 32%). In the control and patient groups, 14 and 59%, respectively, reported some kind of gastrointestinal problems. The most common intestinal problems in the control and patient groups were respectively, mucus (4 and 38%), cramp (5 and 14%), leakage (2 and 27%), and blood (2 and 36%). Ninety percent of the patients' problems were minor.

CONCLUSION

Pelvic irradiation induced a relatively large number of minor problems, evaluated with a self-assessment questionnaire and compared with an age-matched population of men, of approximately similar magnitude as with a physician's systematic evaluation. The most important urinary factors were urgency and leakage. The most important intestinal factors were blood, mucus, and leakage. The results support the ongoing efforts to use 3-D computed tomography-based conformal therapy to decrease irradiation dose to the rectum and bladder.

Treatment related sequelae following external beam radiation for prostate cancer: a review with an update in patients with stages T1 and T2 tumor

The primary goal of radical radiation therapy in men with localized prostate carcinoma is cure and a secondary but important goal is to achieve cure without treatment related sequelae, such as loss of continence, rectal injury, loss of potency and the need for castration. A literature review of 2,611 men undergoing irradiation for all stages of localized prostatic carcinoma documented a 0.2% incidence of treatment related mortality, 1.9% severe complications, 0.9% incontinence and 33 to 60% maintenance of full potency 5 or more years after treatment. A separate analysis was made of 331 patients with only early tumors (stages T1 and T2) treated with conventional external beam radiation therapy to doses of 63 to 74 Gy. from 2 individual centers (Massachusetts General Hospital and M.D. Anderson Hospital) and 1 multi-institutional group (Radiation Therapy Oncology Group). Median followup was 6.1 years; however, in 2 series followup ranged to 14 years. This analysis revealed frequencies of treatment associated sequelae of 0% for mortality, 0% severe complications, 0.4% urinary incontinence, 5.4% genitourinary structures (1.2% persisting), 5.1% hematuria (0.9% persisting) and 5.4% rectal bleeding (0.6% persisting). This composite analysis of men undergoing irradiation for stages T1 and T2 tumors with conventional fractionation and doses indicates that acute morbidity is minor and usually transient, severe injury is rare, most late gastrointestinal and genitourinary symptoms of radiation injury are neither permanent nor debilitating, and few symptoms of radiation injury develop beyond 5 years from treatment. These data, combined with the low progression rates (using prostate specific antigen criteria) following irradiation of men with early tumors, further substantiate the primary role of radical radiotherapy in the treatment of surgical risk adversive patients.

Comparison of a conformal nonaxial boost with a four-field boost technique in the treatment of adenocarcinoma of the prostate

PURPOSE

A comparative study of a standard four-field boost technique and a customized nonaxial external beam technique for the treatment of adenocarcinoma of the prostate was performed to quantify rectal and bladder sparing.

METHODS AND MATERIALS

Sixteen patients with localized carcinoma of the prostate who underwent simulation and treatment planning computed tomography formed the basis of this study. The prostate, seminal vesicles, lymph node, pelvic bones, rectum, bladder, and skin volumes were contoured from the CT slices to the three-dimensional treatment planning system. Each patient was planned for both standard four-field and nonaxial techniques to a boost treatment dose of 24 Gy to the prostate. Isodose plans were chosen on the basis of adequate tumor coverage and normal tissue sparing.

RESULTS

The volumes of the prostate, rectum, and bladder ranged from 46-148 cc, 25-196 cc, and 50-378 cc, respectively. Data analysis demonstrated a statistically significant reduction (p < 0.01) in normal tissue irradiation with the nonaxial external beam technique at dose levels of 15 and 20 Gy.

CONCLUSION

The nonaxial four-field external beam technique appears to be superior to the standard four-field approach in reducing the volume of high dose irradiation to the adjacent rectum and bladder.

Technical factors affecting morbidity in definitive irradiation for localized carcinoma of the prostate

PURPOSE

The impact of some technical factors on morbidity was analyzed in 738 patients with histologically confirmed carcinoma of the prostate treated with definitive irradiation.

METHODS AND MATERIALS

The records of all patients were reviewed, and morbidity of irradiation was evaluated according to severity. All patients were followed up for a minimum of 3 years (median observation, 6.5 years).

RESULTS

The most frequent Grade 2 (moderate) intestinal complication was proctitis, which was observed in 5% of the patients, followed by enteritis (1%) and anal-rectal fibrosis or stricture (about 1%). Incidence of Grade 3 (severe) proctitis was less than 1% and small bowel obstruction, 0.2%. One patient developed radiation-induced ileitis complicated with peritonitis, which was fatal. The most frequent Grade 2 urinary complication was urethral stricture (5%) and cystitis with significant symptoms or hematuria (2%). A vesicosigmoid and a rectovesical fistula (.4%) were noted, which required colostomy. One patient with hemorrhagic cystitis (.2%) required an ileal bladder, and two cases of ureteral stricture (.3%) required surgical correction. Most cases of Grade 2-3 intestinal or urinary morbidity appeared within 2-5 years after therapy (8% moderate and 3% severe cumulative intestinal morbidity at 10 years, and 9% and 3%, urinary). The actuarial incidence of rectosigmoid Grade 2 and 3 morbidity was 10% for patients treated to the pelvic lymph nodes and the prostate and 3% for those treated to the prostate only (p = 0.04). The difference in urinary morbidity in these two groups of patients was not statistically significant. There was also no significant correlation of morbidity with boost portal size for prostate irradiation. Patients treated with a stationary portal technique that delivered higher doses to the urinary bladder had a significantly greater incidence of urinary morbidity (18% cumulative) compared with patients treated with rotational techniques (5%) (p < 0.1). However, patients treated with pelvic fields and rotational techniques had a higher intestinal and rectosigmoid morbidity (11%) than patients treated to the prostate only (< or = 5%) (p = 0.05). No statistically significant difference in intestinal or urinary morbidity was related to doses of irradiation (60-70 Gy).

CONCLUSION

Volume treated and, to a lesser extent, dose of irradiation at tolerance levels are important factors influencing significant morbidity in patients with carcinoma of the prostate treated with definitive irradiation. With recent advances in three-dimensional (3-D) treatment planning and conformal radiation therapy techniques, it is imperative to precisely determine optimal volumes and doses of irradiation required to achieve the highest local-pelvic tumor control while minimizing morbidity to enhance the role of irradiation in the management of localized carcinoma of the prostate.

Bilateral arcs using "averaged beam's eye views": a simplified technique for delivering 3-D based conformal radiotherapy

The purpose of this study is to describe a conformal radiotherapy technique for treating only the prostate with bilateral 120 degrees arcs using "averaged beams-eye-views" (A-BEV). For this study a CT scan from a patient with a large prostate but with a low risk for seminal vesicle involvement was chosen for comparing several different treatment techniques. Dose volume histograms (DVHs) of the prostate, femoral heads, bladder, and rectum were compared for plans using "standard" bilateral 120 degree unblocked arcs (8 x 8 and 9 x 9 cm), similar sized arcs with "generic" (small corner) blocks applied, arcs using hand drawn "semi-conformal" blocks added, and arcs using the A-BEV. The A-BEV was generated by averaging the shapes of fixed lateral and oblique BEVs from a six-field plan. These arc techniques were compared to four-field conformal (4-FC) and six-field conformal (6-FC) techniques. The addition of generic corner blocks to a 9 x 9 field resulted in a more favorable dose distribution than using open unblocked 9 x 9 arcs. The technique employing the A-BEV resulted in an improvement in the DVHs compared to other arc techniques and to 4-FC techniques. The dose volume histograms associated with using this technique approached those associated with using a 6-FC technique. Treating only the prostate with blocked arcs generated using an A-BEV results in an improved dose distribution compared to unblocked arcs and 4-FC techniques. This blocked arc technique also results in a DVH that is comparable to using a more complex 6-FC technique. Blocks that are drawn on manually reduce the dose to the surrounding normal tissues but are associated with a greater risk of underdosing the target volume. This problem is diminished when computer generated conformal blocks are used.

Comparison of CT-based treatment planning and retrograde urethrography in determining the prostatic apex at simulation

In 20 consecutive patients who underwent treatment planning, localization of the prostatic apex with CT-based techniques at simulation was compared to location of the apex as defined by retrograde urethrography. In addition, the location of the urethrogram-defined prostatic apex was compared with the bottom of the ischial tuberosities, which is often recommended as the inferior margin of the field. In 15% of the patients there was agreement between the CT-defined apex and the urethrogram-defined apex; in 85% there was discordance. In a majority of patients with discordance, the urethrogram apex was located caudad to the CT-defined apex (71%) with a median difference of .65 cm. In 29% of the patients the urethrogram apex was located superior to the CT-defined apex. Overall, 75% of the patients had discordance between the urethrogram apex and the CT apex of 0.5 cm or greater; 30% had an absolute difference of 1.0 cm or greater. Comparing the location of the prostatic apex with the bottom of the ischial tuberosities revealed that in 15% of the patients the apex was 1.0 cm or less from the bottom of the tuberosities and in 45% it was less than 1.5 cm. This would place the apex of the prostate in the penumbra region of the field and risk undertreatment of the prostate if the bottom of the ischial tuberosities was the inferior margin of the field. Measuring the location of the prostatic apex from the top of the symphysis pubis revealed that a distance of 4.9 cm encompassed the apex in all 20 patients.(ABSTRACT TRUNCATED AT 250 WORDS)