Radiation dose response in patients with favorable localized prostate cancer (Stage T1-T2, biopsy Gleason < or = 6, and pretreatment prostate-specific antigen < or = 10)

Comparison of Moderate Hypofractionated Volumetric-Modulated Arc Therapy Plans With and Without Flattening Filter for Localized Prostate Cancer

Background/Aim The aim of this study was to compare volumetric-modulated arc therapy (VMAT) radiation plans between conventional VMAT with flattening filter (cFF-VMAT) and flattening filter-free VMAT (FFF-VMAT) for localized prostate cancer. Materials and methods Ten patients with localized prostate cancer who underwent cFF-VMAT at Yokosuka General Hospital Uwamachi, Yokosuka, Japan, from July 2020 to October 2020 were enrolled. Dose-volume histogram (DVH) parameters of the target volume, normal organs, monitor units (MU), and beam-on time (BOT) were compared between cFF-VMAT and FFF-VMAT plans. Results No significant difference was observed for DVH parameters for the target volume. No significant difference was observed in all parameters for the bladder and rectum between the cFF-VMAT and FFF-VMAT groups. The mean values of MU were 686 ± 52 and 784 ± 80 in cFF-VMAT and FFF-VMAT, respectively (p < 0.001). The mean BOT was 97.0 ± 6.6 s and 72.9 ± 1.4 s for cFF-VMAT and FFF-VMAT, respectively (p < 0.001). Conclusion DVH parameters of the target volume and normal organs were not significantly different between the cFF-VMAT and FFF-VMAT plans. In FFF-VMAT, MU was significantly higher, and the BOT was significantly shorter than those in cFF-VMAT.

Preliminary result of carbon-ion radiotherapy using the spot scanning method for prostate cancer

BACKGROUND

Carbon-ion radiotherapy (CIRT) for prostate cancer was initiated at Kanagawa Cancer Center in 2015. The present study analyzed the preliminary clinical outcomes of CIRT for prostate cancer.

METHODS

The clinical outcomes of 253 patients with prostate cancer who were treated with CIRT delivered using the spot scanning method between December 2015 and December 2017 were retrospectively analyzed. The irradiation dose was set at 51.6 Gy (relative biological effectiveness) delivered in 12 fractions over 3 weeks. Biochemical relapse was defined using the Phoenix definition. Toxicities were assessed according to CTCAE version 4.0.

RESULTS

The median patient age was 70 (47-86) years. The median follow-up duration was 35.3 (4.1-52.9) months. According to the D'Amico classification system, 8, 88, and 157 patients were classified as having low, intermediate, and high risks, respectively. Androgen deprivation therapy was administered in 244 patients. The biochemical relapse-free rate in the low-, intermediate-, and high-risk groups at 3 years was 87.5, 88.0, and 97.5%, respectively (P = 0.036). Grade 2 acute urinary toxicity was observed in 12 (4.7%) patients. Grade 2 acute rectal toxicity was not observed. Grade 2 late urinary toxicity and grade 2 late rectal toxicity were observed in 17 (6.7%) and 3 patients (1.2%), respectively. Previous transurethral resection of the prostate was significantly associated with late grade 2 toxicity in univariate analysis. The predictive factor for late rectal toxicity was not detected.

CONCLUSION

The present study demonstrated that CIRT using the spot scanning method for prostate cancer produces favorable outcomes.

Dose escalation (81 Gy) with image-guided radiation therapy and volumetric-modulated arc therapy for localized prostate cancer: A retrospective preliminary result

Objectives:

The objective of the study is to report the acute and late toxicity and preliminary results of localized prostate cancer treated with high-dose radiation therapy (RT).

Materials and Methods:

Between March 2010 and October 2018, a total of 53 patients with clinically localized prostate cancer were treated with definitive RT at our institution. All patients were planned to receive a total dose of 81 Gy with the volumetric-modulated arc therapy technique. Patients were stratified by prognostic risk groups based on the National Comprehensive Cancer Network risk classification criteria. Acute and late toxicities were scored by the Radiation Therapy Oncology Group morbidity grading scales. The definition of biochemical failure was using the 2005 ASTRO Phoenix consensus definition. Median follow-up time was 46.5 months (range: 4.7–81.0 months).

Results:

The 3-year biochemical failure-free survival rates for low-, intermediate-, and high-risk group patients were 100%, 87.5%, and 84%, respectively. The 3- and 5-year overall survival rates were 83% and 62%, respectively. Three (5.6%) patients developed Grade II acute gastrointestinal (GI) toxicity. Four (7.5%) patients developed Grade II acute genitourinary (GU) toxicity, and none experienced Grade III or higher acute GI or GU symptoms. One (1.8%) patient developed Grade II or higher late GI toxicity. Six (11.3%) patients experienced Grade II late GU toxicity. No Grade III or higher late GI and GU complications have been observed.

Conclusions:

Data from the current study demonstrated the feasibility of dose escalation with image-guided and volumetric-modulated arc therapy techniques for the treatment of localized prostate cancer. Minimal acute and late toxicities were observed from patients in this study. Long-term prostate-specific antigen controls are comparable to previously published results of high-dose intensity-modulated RT for localized prostate cancer. Based on this favorable outcome, dose escalation (81 Gy) has become the standard treatment for localized prostate cancer at our institution.

Long-term outcome of hypofractionated intensity-modulated radiotherapy using TomoTherapy for localized prostate cancer: A retrospective study

BACKGROUND

Recently, the clinical outcome of prostate cancer treated by hypofractionated radiation therapy has been reported. However, there are few reports from Japan. In Hidaka Hospital, hypofractionated intensity-modulated radiotherapy (HIMRT) for prostate cancer was initiated in 2007. The purpose of this study is to analyze the long-term outcome.

METHODS

Ninety-two patients with localized prostate cancer treated with HIMRT at Hidaka Hospital between 2007 and 2009 were retrospectively analyzed. HIMRT was delivered using TomoTherapy. The prescription dose was 66 Gy at 95% of the PTV in 22 fractions performed 3 days a week over 7 weeks in all patients. The overall survival rate, biochemical relapse-free rate, and acute and late toxicities were evaluated.

RESULTS

The median follow-up duration was 78 (range 14-100) months. The median age at the start of the HIMRT was 72 (range 46-84) years. The disease characteristics were as follows: stage T1c, 45; T2a, 20; T2b, 5; T2c, 1; T3a, 13; T3b, 6; T4, 2; Gleason score 6, 13; 7, 44; 8, 20; 9, 15; 10, 0; pretreatment PSA ≤10 ng/mL, 42; 10 to ≤20, 27; and >20, 23. According to the D'Amico classification system, 10, 37, and 45 patients were classified as low-risk, intermediate-risk, and high-risk. The overall survival rate, the cause-specific survival rate, and the biochemical relapse-free rate at 5 years was 94.7%, 100% and 98.9%, respectively. Severe acute toxicity (grade 3 or more) was not observed. The late urinary toxicity was 52.2% in grade 0, 28.3% in grade 1, 19.6% in grade 2, and 2.2% in grade 3. The late rectal toxicity was 78.3% in grade 0, 7.6% in grade 1, 9.8% in grade 2, and 4.3% in grade 3.

CONCLUSIONS

The present study demonstrated that HIMRT using TomoTherapy for prostate cancer has a favorable outcome with tolerable toxicity.

Hypofractionated helical tomotherapy (75 Gy at 2.5 Gy per fraction) for localized prostate cancer: long-term analysis of gastrointestinal and genitourinary toxicity

Background

This study is a report on the long-term analysis of acute and late toxicities for patients with localized prostate cancer treated with hypofractionated helical tomotherapy.

Methods

From January 2008 through August 2013, 70 patients with localized prostate cancer were treated definitively with hypofractionated helical tomotherapy. The helical tomotherapy was designed to deliver 75 Gy in 2.5 Gy per fraction to the prostate gland, 63 Gy in 2.1 Gy per fraction to the seminal vesicles, and 54 Gy in 1.8 Gy per fraction to the pelvic lymph nodes. Incidence rates and predictive factors for radiation toxicities were analyzed retrospectively.

Results

The incidences of grades 0, 1, and 2 acute gastrointestinal (GI) toxicity were 51.4%, 42.9%, and 5.7%, and those of acute genitourinary (GU) toxicity were 7.1%, 64.3%, and 28.6%, respectively. The maximum dose of rectum and bladder V40 and V50 were significant predictive factors for acute GI and GU toxicity. The cutoff value of rectum maximum dose and bladder V40 and V50 by receiver-operating characteristic curves analysis were 76.5 Gy, 17.3%, and 10.2%, respectively. The incidences of grades 0, 1, and 2 late GI toxicity were 82.0%, 14.0%, and 4.0%, and those of late GU toxicity were 18.0%, 56.0%, and 26.0%, respectively. Rectum V70 and bladder V70 and V75 were significant predictive factors for late GI and GU toxicity. The cutoff value of rectum V70 and bladder V70 and V75 by receiver-operating characteristic curves analysis was 2.8%, 2.8%, and 1.0%, respectively.

Conclusion

Hypofractionated helical tomotherapy using a schedule of 75 Gy at 2.5 Gy per fraction had favorable acute and late toxicity rates and no serious complication, such as grade 3 or worse toxicity. To minimize radiation toxicities, constraining the rectum maximum dose to less than 76.5 Gy, rectum V70 to less than 2.8%, bladder V40 to less than 17.3%, bladder V50 to less than 10.2%, bladder V70 to less than 2.8%, and bladder V75 to less than 1.0% would be necessary.

[Radiotherapy of prostate cancer]

With the development of modern radiation techniques, such as intensity-modulated radiotherapy (IMRT), a dose escalation in the definitive radiotherapy of prostate cancer and a consecutive improvement in biochemical recurrence-free survival (BFS) could be achieved. Among others, investigators at the Memorial Sloan-Kettering Cancer Center (MSKCC) saw 5-year BFS rates of up to 98%. A further gain in effectiveness and safety is expected of hypofractionation schedules, as suggested by data published by Kupelian et al., who saw a low 5-year rate of grade ≥2 rectal side-effects of 4.5%. However, randomized studies are just beginning to mature. Patients with intermediate or high-risk tumors should receive neoadjuvant (NHT) and adjuvant (AHT) androgen deprivation. Bolla et al. could show an increase in 5-year overall survival from 62-78%. The inclusion of the whole pelvis in the treatment field (WPRT) is still controversial. The RTOG 94-13 study showed a significant advantage in disease-free survival after 60 months but long-term data did not yield significant differences between WPRT and irradiation of the prostate alone.The German Society of Urology strongly recommends adjuvant radiotherapy of the prostate bed for pT3 N0 tumors with positive margins. In a pT3 N0 R0 or pT2 N0 R+ situation, adjuvant radiotherapy should at least be considered. So far, no randomized data on NHT and AHT have been published, so androgen deprivation remains an individual decision in the postoperative setting. In a retrospective analysis Spiotto et al. reported a positive effect for adjuvant WPRT and biochemical control.This article summarizes the essential publications on definitive and adjuvant radiotherapy and discusses the additional use of androgen deprivation and WPRT.

Parameters favorable to intraprostatic radiation dose escalation in men with localized prostate cancer

PURPOSE

To identify , within the framework of a current Phase I trial, whether factors related to intraprostatic cancer lesions (IPLs) or individual patients predict the feasibility of high-dose intraprostatic irradiation.

METHODS AND MATERIALS

Endorectal coil MRI scans of the prostate from 42 men were evaluated for dominant IPLs. The IPLs, prostate, and critical normal tissues were contoured. Intensity-modulated radiotherapy plans were generated with the goal of delivering 75.6 Gy in 1.8-Gy fractions to the prostate, with IPLs receiving a simultaneous integrated boost of 3.6 Gy per fraction to a total dose of 151.2 Gy, 200% of the prescribed dose and the highest dose cohort in our trial. Rectal and bladder dose constraints were consistent with those outlined in current Radiation Therapy Oncology Group protocols.

RESULTS

Dominant IPLs were identified in 24 patients (57.1%). Simultaneous integrated boosts (SIB) to 200% of the prescribed dose were achieved in 12 of the 24 patients without violating dose constraints. Both the distance between the IPL and rectum and the hip-to-hip patient width on planning CT scans were associated with the feasibility to plan an SIB (p = 0.002 and p = 0.0137, respectively).

CONCLUSIONS

On the basis of this small cohort, the distance between an intraprostatic lesion and the rectum most strongly predicted the ability to plan high-dose radiation to a dominant intraprostatic lesion. High-dose SIB planning seems possible for select intraprostatic lesions.

Higher-than-conventional radiation doses in localized prostate cancer treatment: a meta-analysis of randomized, controlled trials

PURPOSE

To determine in a meta-analysis whether the outcomes in men with localized prostate cancer treated with high-dose radiotherapy (HDRT) are better than those in men treated with conventional-dose radiotherapy (CDRT), by quantifying the effect of the total dose of radiotherapy on biochemical control (BC).

METHODS AND MATERIALS

The MEDLINE, EMBASE, CANCERLIT, and Cochrane Library databases, as well as the proceedings of annual meetings, were systematically searched to identify randomized, controlled studies comparing HDRT with CDRT for localized prostate cancer. To evaluate the dose-response relationship, we conducted a meta-regression analysis of BC ratios by means of weighted linear regression.

RESULTS

Seven RCTs with a total patient population of 2812 were identified that met the study criteria. Pooled results from these RCTs showed a significant reduction in the incidence of biochemical failure in those patients with prostate cancer treated with HDRT (p < 0.0001). However, there was no difference in the mortality rate (p = 0.38) and specific prostate cancer mortality rates (p = 0.45) between the groups receiving HDRT and CDRT. However, there were more cases of late Grade >2 gastrointestinal toxicity after HDRT than after CDRT. In the subgroup analysis, patients classified as being at low (p = 0.007), intermediate (p < 0.0001), and high risk (p < 0.0001) of biochemical failure all showed a benefit from HDRT. The meta-regression analysis also detected a linear correlation between the total dose of radiotherapy and biochemical failure (BC = -67.3 + [1.8 x radiotherapy total dose in Gy]; p = 0.04).

CONCLUSIONS

Our meta-analysis showed that HDRT is superior to CDRT in preventing biochemical failure in low-, intermediate-, and high-risk prostate cancer patients, suggesting that this should be offered as a treatment for all patients, regardless of their risk status.

What dose of external-beam radiation is high enough for prostate cancer?

PURPOSE

To quantify the radiotherapy dose-response of prostate cancer, adjusted for prognostic factors in a mature cohort of men treated relatively uniformly at a single institution.

PATIENTS AND METHODS

The study cohort consisted of 1,530 men treated with three-dimensional conformal external-beam radiotherapy between 1989 and 2002. Patients were divided into four isocenter dose groups: <70 Gy (n = 43), 70-74.9 Gy (n = 552), 75-79.9 Gy (n = 568), and > or =80 Gy (n = 367). The primary endpoints were freedom from biochemical failure (FFBF), defined by American Society for Therapeutic Radiology and Oncology (ASTRO) and Phoenix (nadir + 2.0 ng/mL) criteria, and freedom from distant metastases (FFDM). Multivariate analyses were performed and adjusted Kaplan-Meier estimates were calculated. Logit regression dose-response functions were determined at 5 and 8 years for FFBF and at 5 and 10 years for FFDM.

RESULTS

Radiotherapy dose was significant in multivariate analyses for FFBF (ASTRO and Phoenix) and FFDM. Adjusted 5-year estimates of ASTRO FFBF for the four dose groups were 60%, 68%, 76%, and 84%. Adjusted 5-year Phoenix FFBFs for the four dose groups were 70%, 81%, 83%, and 89%. Adjusted 5-year and 10-year estimates of FFDM for the four dose groups were 96% and 93%, 97% and 93%, 99% and 95%, and 98% and 96%. Dose-response functions showed an increasing benefit for doses > or =80 Gy.

CONCLUSIONS

Doses of > or =80 Gy are recommended for most men with prostate cancer. The ASTRO definition of biochemical failure does not accurately estimate the effects of radiotherapy at 5 years because of backdating, compared to the Phoenix definition, which is less sensitive to follow-up and more reproducible over time.

Update on Radiation Therapy in Prostate Cancer

Higher doses of radiation result in improved clinical control of prostate cancer,and the recent advances in prostate cancer radiotherapy are designed to escalate dose while minimizing toxicity. To achieve this goal, tighter treatment margins are needed, which require more accurate delineation of the prostate target and normal tissue at the time of treatment planning and before actual daily treatments. Modem radiation therapy techniques can deposit conformal dose virtually anywhere in the body; however, this precise therapy is of no value if it is not accurately hitting the target. Whether dose escalation is achieved by external beam techniques (eg, IMRT, protons) or brachytherapy, these ba-sic planning and delivery considerations are essentially the same. Future directions in prostate radiation therapy will use even higher radiation doses,alternative fractionation patterns, intraprostatic targets (eg, prostate tumor seen on MRI), and improved patient selection regarding which patients will benefit the most from these advanced techniques.

Clinicopathologic analysis of extracapsular extension in prostate cancer: Should the clinical target volume be expanded posterolaterally to account for microscopic extension?

PURPOSE

We performed a complete pathologic analysis examining extracapsular extension (ECE) and microscopic spread of malignant cells beyond the prostate capsule to determine whether and when clinical target volume (CTV) expansion should be performed.

METHODS AND MATERIALS

A detailed pathologic analysis was performed for 371 prostatectomy specimens. All slides from each case were reviewed by a single pathologist (N.S.G.). The ECE status and ECE distance, defined as the maximal linear radial distance of malignant cells beyond the capsule, were recorded.

RESULTS

A total of 121 patients (33%) were found to have ECE (68 unilateral, 53 bilateral). Median ECE distance=2.4 mm [range: 0.05-7.0 mm]. The 90th-percentile distance = 5.0 mm. Of the 121 cases with ECE, 55% had ECE distance>or=2 mm, 19%>or=4 mm, and 6%>or=6 mm. ECE occurred primarily posterolaterally along the neurovascular bundle in all cases. Pretreatment prostrate-specific antigen (PSA), biopsy Gleason, pathologic Gleason, clinical stage, bilateral involvement, positive margins, percentage of gland involved, and maximal tumor dimension were associated with presence of ECE. Both PSA and Gleason score were associated with ECE distance. In all 371 patients, for those with either pretreatment PSA>or=10 or biopsy Gleason score>or=7, 21% had ECE>or=2 mm and 5%>or=4 mm beyond the capsule. For patients with both of these risk factors, 49% had ECE>or=2 mm and 21%>or=4 mm.

CONCLUSIONS

For prostate cancer with ECE, the median linear distance of ECE was 2.4 mm and occurred primarily posterolaterally. Although only 5% of patients demonstrate ECE>4 to 5 mm beyond the capsule, this risk may exceed 20% in patients with PSA>or=10 ng/ml and biopsy Gleason score>or=7. As imaging techniques improve for prostate capsule delineation and as radiotherapy delivery techniques increase in accuracy, a posterolateral CTV expansion should be considered for patients at high risk.

Outcome analysis of 300 prostate cancer patients treated with neoadjuvant androgen deprivation and hypofractionated radiotherapy

PURPOSE

Neoadjuvant androgen deprivation and radical radiotherapy is an established treatment for localized prostate carcinoma. This study sought to analyze the outcomes of patients treated with relatively low-dose hypofractionated radiotherapy.

METHODS AND MATERIALS

Three hundred patients with T1-T3 prostate cancer were treated between 1996 and 2001. Patients were prescribed 3 months of neoadjuvant androgen deprivation before receiving 5250 cGy in 20 fractions. Patients' case notes and the oncology database were used to retrospectively assess outcomes. Median follow-up was 58 months.

RESULTS

Patients presented with prostate cancer with poorer prognostic indicators than that reported in other series. At 5 years, the actuarial cause-specific survival rate was 83.2% and the prostate-specific antigen (PSA) relapse rate was 57.3%. Metastatic disease had developed in 23.4% of patients. PSA relapse continued to occur 5 years from treatment in all prognostic groups. Independent prognostic factors for relapse included treatment near the start of the study period, neoadjuvant oral anti-androgen monotherapy rather than neoadjuvant luteinizing hormone releasing hormone therapy, and diagnosis through transurethral resection of the prostate rather than transrectal ultrasound.

CONCLUSION

This is the largest reported series of patients treated with neoadjuvant androgen deprivation and hypofractionated radiotherapy in the United Kingdom. Neoadjuvant hormonal therapy did not appear to adequately compensate for the relatively low effective radiation dose used.

Dose-Response in Radiotherapy for Localized Prostate Cancer: Results of the Dutch Multicenter Randomized Phase III Trial Comparing 68 Gy of Radiotherapy With 78 Gy

Purpose

To determine whether a dose of 78 Gy improves outcome compared with a conventional dose of 68 Gy for prostate cancer patients treated with three-dimensional conformal radiotherapy.

Patients and Methods

Between June 1997 and February 2003, stage T1b-4 prostate cancer patients were enrolled onto a multicenter randomized trial comparing 68 Gy with 78 Gy. Patients were stratified by institution, age, (neo)adjuvant hormonal therapy (HT), and treatment group. Four treatment groups (with specific radiation volumes) were defined based on the probability of seminal vesicle involvement. The primary end point was freedom from failure (FFF). Failure was defined as clinical failure or biochemical failure, according to the American Society of Therapeutic Radiation Oncology definition. Other end points were freedom from clinical failure (FFCF), overall survival (OS), and toxicity.

Results

Median follow-up time was 51 months. Of the 669 enrolled patients, 664 were included in the analysis. HT was prescribed for 143 patients. FFF was significantly better in the 78-Gy arm compared with the 68-Gy arm (5-year FFF rate, 64% v 54%, respectively), with an adjusted hazard ratio of 0.74 (P = .02). No significant differences in FFCF or OS were seen between the treatment arms. There was no difference in late genitourinary toxicity of Radiation Therapy Oncology Group and European Organisation for Research and Treatment of Cancer grade 2 or more and a slightly higher nonsignificant incidence of late gastrointestinal toxicity of grade 2 or more.

Conclusion

This multicenter randomized trial shows a significantly improved FFF in prostate cancer patients treated with a higher dose of radiotherapy.

Combination of celecoxib with percutaneous radiotherapy in patients with localised prostate cancer - a phase I study

BACKGROUND

Current approaches for the improvement of bNED for prostate cancer patients treated with radiotherapy mainly focus on dose escalation. However molecularly targeted approaches may also turn out to be of value. In this regard cyclooxygenase (COX)-2 inhibitors have been shown to exert some anti-tumour activities in human prostate cancer in vivo and in vitro. Although in vitro data indicated that the combination of COX-2 inhibition and radiation was not associated with an increased toxicity, we performed a phase I trial using high dose celecoxib together with percutaneous radiation therapy.

METHODS

In order to rule out any increases of more than 20% incidence for a given side effect level 22 patients were included in the trial. Celecoxib was given 400 mg twice daily with onset of the radiation treatment. Risk adapted radiation doses were between 70 and 74 Gy standard fractionation. RTOG based gastrointestinal (GI) and genitourinary (GU) acute toxicity scoring was performed weekly during radiation therapy, at six weeks after therapy and three month after completing radiation treatment.

RESULTS

Generally no major increase in the level and incidence of side effects potentially caused by the combined treatment was observed. In two cases a generalised skin rash occurred which immediately resolved upon discontinuation of the drug. No grade 3 and 4 toxicity was seen. Maximal GI toxicity grade 1 and 2 was observed in 85% and 10%, respectively. In terms of GU toxicity 80% of the patients experienced a grade 1 toxicity and 10 % had grade 2 symptoms.

CONCLUSION

The combination of irradiation to the prostate with concurrent high dose celecoxib was not associated with an increased level of side effects.

PSA nadir predicts biochemical and distant failures after external beam radiotherapy for prostate cancer: a multi-institutional analysis

PURPOSE

To determine the significance of prostate-specific antigen (PSA) nadir (nPSA) and the time to nPSA (T(nPSA)) in predicting biochemical or clinical disease-free survival (PSA-DFS) and distant metastasis-free survival (DMFS) in patients treated with definitive external beam radiotherapy (RT) for clinical Stage T1b-T2 prostate cancer.

METHODS AND MATERIALS

Nine participating institutions submitted data on 4839 patients treated between 1986 and 1995 for Stage T1b-T2cN0-NxM0 prostate cancer. All patients were treated definitively with RT alone to doses > or =60 Gy, without neoadjuvant or planned adjuvant androgen suppression. A total of 4833 patients with a median follow-up of 6.3 years met the criteria for analysis. Two endpoints were considered: (1) PSA-DFS, defined as freedom from PSA failure (American Society for Therapeutic Radiology and Oncology definition), initiation of androgen suppression after completion of RT, or documented local or distant failure; and (2) DMFS, defined as freedom from clinically apparent distant failure. In patients with failure, nPSA was defined as the lowest PSA measurement before any failure. In patients without failure, nPSA was the lowest PSA measurement during the entire follow-up period. T(nPSA) was calculated from the completion of RT to the nPSA date.

RESULTS

A greater nPSA level and shorter T(nPSA) were associated with decreased PSA-DFS and DMFS in all patients and in all risk categories (low [Stage T1b, T1c, or T2a, Gleason score < or =6, and PSA level < or =10 ng/mL], intermediate [Stage T1b, T1c, or T2a, Gleason score < or =6, and PSA level >10 but < or =20 ng/mL, or Stage T2b or T2c, Gleason score < or =6, and PSA level < or =20 ng/mL, or Gleason score 7 and PSA level < or =20 ng/mL], and high [Gleason score 8-10 or PSA level >20 ng/mL]), regardless of RT dose. The 8-year PSA-DFS and DMFS rate for patients with nPSA <0.5 ng/mL was 75% and 97%; nPSA > or =0.5 but <1.0 ng/mL, 52% and 96%; nPSA > or =1.0 but <2.0 ng/mL, 40% and 91%; and nPSA > or =2.0 ng/mL, 17% and 73%, respectively. The 8-year PSA-DFS and DMFS rate for patients with T(nPSA) <6 months was 27% and 66%; T(nPSA) > or =6 but <12 months, 31% and 85%; T(nPSA) > or =12 but <24 months, 42% and 94%; and T(nPSA) > or =24 months, 75% and 99%, respectively. A shorter T(nPSA) was associated with decreased PSA-DFS and DMFS, regardless of the nPSA. Both nPSA and T(nPSA) were significant predictors of PSA-DFS and DMFS in multivariate models incorporating clinical stage, Gleason score, initial PSA level, and RT dose. The significance of nPSA and T(nPSA) was supported by landmark analysis, as well as by analysis of nPSA and T(nPSA) as time-dependent covariates. A dose > or =70 Gy was associated with a lower nPSA level and longer T(nPSA) in all risk categories, and a greater dose was significantly associated with greater PSA-DFS and DMFS in multivariate analysis. Regression analysis confirmed that higher clinical stage, Gleason score, and initial PSA were associated with a greater nPSA level.

CONCLUSION

The results of this large, multi-institutional analysis of 4833 patients have provided important evidence that nPSA and T(nPSA) after definitive external beam RT are not only predictive of a predominantly PSA endpoint (PSA-DFS), but are also predictive of distant metastasis in all clinical risk categories. Greater RT doses were associated with lower nPSA, longer T(nPSA), and improved PSA-DFS and DMFS.

Intensity modulated radiotherapy for high risk prostate cancer based on sentinel node SPECT imaging for target volume definition

Background

The RTOG 94-13 trial has provided evidence that patients with high risk prostate cancer benefit from an additional radiotherapy to the pelvic nodes combined with concomitant hormonal ablation. Since lymphatic drainage of the prostate is highly variable, the optimal target volume definition for the pelvic lymph nodes is problematic. To overcome this limitation, we tested the feasibility of an intensity modulated radiation therapy (IMRT) protocol, taking under consideration the individual pelvic sentinel node drainage pattern by SPECT functional imaging.

Methods

Patients with high risk prostate cancer were included. Sentinel nodes (SN) were localised 1.5–3 hours after injection of 250 MBq ^99mTc-Nanocoll using a double-headed gamma camera with an integrated X-Ray device. All sentinel node localisations were included into the pelvic clinical target volume (CTV). Dose prescriptions were 50.4 Gy (5 × 1.8 Gy / week) to the pelvis and 70.0 Gy (5 × 2.0 Gy / week) to the prostate including the base of seminal vesicles or whole seminal vesicles. Patients were treated with IMRT. Furthermore a theoretical comparison between IMRT and a three-dimensional conformal technique was performed.

Results

Since 08/2003 6 patients were treated with this protocol. All patients had detectable sentinel lymph nodes (total 29). 4 of 6 patients showed sentinel node localisations (total 10), that would not have been treated adequately with CT-based planning ('geographical miss') only. The most common localisation for a probable geographical miss was the perirectal area. The comparison between dose-volume-histograms of IMRT- and conventional CT-planning demonstrated clear superiority of IMRT when all sentinel lymph nodes were included. IMRT allowed a significantly better sparing of normal tissue and reduced volumes of small bowel, large bowel and rectum irradiated with critical doses. No gastrointestinal or genitourinary acute toxicity Grade 3 or 4 (RTOG) occurred.

Conclusion

IMRT based on sentinel lymph node identification is feasible and reduces the probability of a geographical miss. Furthermore, IMRT allows a pronounced sparing of normal tissue irradiation. Thus, the chosen approach will help to increase the curative potential of radiotherapy in high risk prostate cancer patients.

IMRT versus conventional 3DCRT on prostate and normal tissue dosimetry using an endorectal balloon for prostate immobilization

This study was undertaken to compare prostate and normal tissue dosimetry in prostate cancer patients treated with intensity-modulated radiation therapy (IMRT) and conventional 3-dimensional conformal radiotherapy (3DCRT) using an endorectal balloon for prostate immobilization. Ten prostate cancer patients were studied using both IMRT and conventional 3DCRT at Houston Veterans Affairs Medical Center. For IMRT, the prescription was 70 Gy at 2 Gy/fraction at the 83.4% isodose line, allowing no more than 15% of the rectum and 33% of the bladder to receive above 68 and 65 Gy, respectively. For conventional 3DCRT, a 6-field arrangement with lateral and oblique fields was used to deliver 76 Gy at 2Gy/fraction, ensuring complete tumor coverage by the 72-Gy isodose line. Mean doses for prostate and seminal vesicles were 75.10 and 75.11 Gy, respectively, for IMRT and 75.40 and 75.02 Gy, respectively, for 3DCRT (p > 0.218). 3DCRT delivered significantly higher doses to 33%, 50%, and 66% volumes of rectum by 3.55, 6.64, and 10.18 Gy, respectively (p < 0.002), and upper rectum by 7.26, 9.86, and 9.16 Gy, respectively (p < 0.007). 3DCRT also delivered higher doses to femur volumes of 33% and 50% by 9.38 and 10.19 Gy, respectively, (p < 0.001). Insignificant differences in tumor control probability (TCP) values between IMRT and 3DCRT were calculated for prostate (p = 0.320) and seminal vesicles (p = 0.289). Compared to 3DCRT, IMRT resulted in significantly reduced normal tissue complication probability (NTCP) only for upper rectum (p = 0.025) and femurs (p = 0.021). This study demonstrates that IMRT achieves superior normal tissue avoidance, especially for rectum and femurs compared to 3DCRT, with comparable target dose escalation.

70 Gy or more: which dose for which prostate cancer?

INTRODUCTION

Radical prostatectomy and radiotherapy are currently accepted treatment modalities for localized prostate cancer. Regarding radiotherapy, current evidence suggests that favorable treatment outcome critically depends on adequate radiation doses. However, the exact role of dose in relation to the individual risk profile is complex. In order to evaluate available data on radiation dose response relationships, in prostate cancer, a thorough and critical literature analysis was performed.

MATERIAL AND METHODS

Studies on dose response relationships from randomized trials, dose escalation trials, retrospective subgroup analyses and pooled data were identified by Pubmed and ISI web of sciences searches and were critically reviewed.

RESULTS AND CONCLUSION

All available data suggest a clear dose response relationship for radiotherapy for localized prostate cancer. In low risk cases, most studies suggest that doses of 70-72 Gy are adequate. Dose escalations up to 78-80 Gy seem to be beneficial for intermediate risk patients. Due to confounding variables, the dose response curves for high-risk patients are less steep. The integration of dose escalation into a more comprehensive treatment protocol is difficult, since trials on the relative impact of either hormonal ablation or inclusion of adjuvant nodal regions on dose escalation are missing.

Evidence-based review of three-dimensional conformal radiotherapy for localized prostate cancer: An ASTRO outcomes initiative

PURPOSE

To perform a systematic review of the evidence to determine the efficacy and effectiveness of three-dimensional conformal radiotherapy (3D-CRT) for localized prostate cancer; provide a clear presentation of the key clinical outcome questions related to the use of 3D-CRT in the treatment of localized prostate cancer that may be answered by a formal literature review; and provide concise information on whether 3D-CRT improves the clinical outcomes in the treatment of localized prostate cancer compared with conventional RT.

METHODS AND MATERIALS

We performed a systematic review of the literature through a structured process developed by the American Society for Therapeutic Radiology and Oncology's Outcomes Committee that involved the creation of a multidisciplinary task force, development of clinical outcome questions, a formal literature review and data abstraction, data review, and outside peer review.

RESULTS

Seven key clinical questions were identified. The results and task force conclusions of the literature review for each question are reported.

CONCLUSION

The technological goals of reducing morbidity with 3D-CRT have been achieved. Randomized trials and follow-up of completed trials remain necessary to address these clinical outcomes specifically with regard to patient subsets and the use of hormonal therapy.

Australian and New Zealand three-dimensional conformal radiation therapy consensus guidelines for prostate cancer

Three-dimensional conformal radiation therapy (3DCRT) has been shown to reduce normal tissue toxicity and allow dose escalation in the curative treatment of prostate cancer. The Faculty of Radiation Oncology Genito-Urinary Group initiated a consensus process to generate evidence-based guidelines for the safe and effective implementation of 3DCRT. All radiation oncology departments in Australia and New Zealand were invited to complete a survey of their prostate practice and to send representatives to a consensus workshop. After a review of the evidence, key issues were identified and debated. If agreement was not reached, working parties were formed to make recommendations. Draft guidelines were circulated to workshop participants for approval prior to publication. Where possible, evidence-based recommendations have been made with regard to patient selection, risk stratification, simulation, planning, treatment delivery and toxicity reporting. This is the first time a group of radiation therapists, physicists and oncologists representing professional radiotherapy practice across Australia and New Zealand have worked together to develop best-practice guidelines. These guidelines should serve as a baseline for prospective clinical trials, outcome research and quality assurance.

The GETUG 70 Gy vs. 80 Gy randomized trial for localized prostate cancer: feasibility and acute toxicity

PURPOSE

To describe treatments and acute tolerance in a randomized trial comparing 70 Gy and 80 Gy to the prostate in patients with localized prostate cancer.

METHODS AND MATERIALS

Between September 1999 and February 2002, 306 patients were randomized to receive 70 Gy (153 patients) or 80 Gy (153 patients) in 17 institutions. Patients exhibited intermediate-prognosis tumors. If the risk of node involvement was greater than 10%, surgical staging was required. Previous prostatectomy was excluded, and androgen deprivation was not admitted. The treatment was delivered in two steps. PTV1-including seminal vesicles, prostate, and a 1-0.5-cm margin-received 46 Gy given with a 4-field conformal technique. PTV2, reduced to prostate with the same margins, irradiated with at least 5 fields. Dose was prescribed according to ICRU recommendations in the 70 Gy group, but adapted at the 80 Gy level.

RESULTS

All patients but one in the 80 Gy arm completed the treatment. In the 70 Gy arm, the mean dose to the PTV2 was 69.5 Gy. In the 80 Gy arm, the mean dose in the PTV2 was 78.5 Gy. Acute toxicity according to Radiation Therapy Oncology Group scale during treatment was reported in 306 patients. There was no statistically significant difference between the two arms: 12% had no toxicity, 80% complained of bladder toxicity, and 70% complained of rectal symptoms. Two months after the end of treatment, 43% of the 70 Gy level and 48% of the 80 Gy level complained of side effects, including 24% and 20% of sexual disorders. There was 6% and 2% of Grade 3 urinary and rectal toxicity. Five patients required a 10-29-day suspension of the treatment. Acute Grade 2 and 3 side effects were related to PTV and CTV1 size, which was the only independent predictive factor in multivariate analysis. Toxicity was not related to the center, age, arm of treatment, or selected data from dose-volume histogram of organ at risk.

CONCLUSION

Treatments were completed in respect to constraints. Acute toxicity was acceptable. Intensity of toxicity depended on target volumes.

Impact of Elapsed Treatment Time on Outcome of External-Beam Radiation Therapy for Localized Carcinoma of the Prostate

PURPOSE

The purpose of this study was to evaluate the impact of elapsed treatment time in external-beam radiation therapy for localized prostate carcinoma.

MATERIALS AND METHODS

The medical records of 1083 patients with localized prostate carcinoma treated between 1970 and December 1999 with external irradiation alone were reviewed. Median follow-up was 6 years (range, 4-24 years). Since 1987, prostate-specific antigen levels were obtained in 687 patients before the initiation of radiation therapy, and all patients seen in follow-up had prostate-specific antigen determinations. There were 344 patients with T1c, 496 with T2, and 243 with T3 tumors. The elapsed treatment time was divided into < or = 7, 7.1-9, or > 9 weeks. Local tumor control was determined by rectal examination and cause-specific survival or prostate-specific antigen failure according to American Society of Therapeutic Radiology and Oncology consensus criteria. Because of dose-escalation studies, tumor dose levels ranged from 66-73.8 Gy, given in 1.8- to 2-Gy fractions.

RESULTS

In patients with stage T1c, local failure ranged from 0% to 10% with doses < or = 72 Gy with; elapsed treatment time had no impact. No pelvic failures were detected in 88 patients receiving doses > 72 Gy. In patients with T2 who received < or = 70 Gy, overall pelvic failure rate was 4% (12/306) in those with an elapsed treatment time of < or = 9 weeks, in contrast to 27% (12/44) for those with an elapsed treatment time > 9 weeks; at 10 years, patients with T2 tumors treated in > 9 weeks had a higher actuarial pelvic failure rate (35%), in contrast to 5% to 18% with shorter treatment times. For patients with T2 tumors who received 70-72 Gy, pelvic failure rate ranged from 0% to 32%, and there were no failures in 37 patients treated to higher doses. In patients with prostate-specific antigen values whose tumors were stage T1c, the chemical failure rate was 41% (60/147) with a tumor dose < 70 Gy, compared with 17% (4/24) in those who received higher doses. In patients with stage 2 disease who were treated with < 70 Gy, the chemical failure rate was 31%, and the rate was 12%-18% in those who received higher doses. In stage T3, the clinical pelvic failure rate ranged from 25% to 32% in the three elapsed time groups, and the chemical failure rate ranged from 48% to 69%, and there was no significant correlation with elapsed time or total irradiation dose. Cause-specific survival without chemical failure in patients with stage T1c disease at 10 years was 85%-90% in the three elapsed treatment time groups. In patients with stage T2 disease, the corresponding values were 80% and 90% for elapsed treatment times < 9 weeks, in contrast to 65% for patients treated > 9 weeks. In patients with stage T3 disease, cause-specific survival was about 60% in all elapsed treatment groups. There was no significant correlation of elapsed treatment time with urinary or rectal morbidity.

CONCLUSIONS

Patients treated with radiation therapy for stage T2 localized prostate carcinoma showed a greater incidence of pelvic and chemical failures and a lower cause-specific survival when elapsed treatment time was > 9 weeks in comparison with the failure and survival rates occurring with shorter times. Higher doses of irradiation (> 72 Gy) eliminate the influence of prolongation of treatment time on outcome.

Prostate cancer radiotherapy dose response: an update of the fox chase experience

PURPOSE

The effectiveness of increasing radiotherapy dose for men with prostate cancer was evaluated with reference to prognostic groups as defined by pretreatment serum prostate specific antigen (PSA), Gleason score, T stage and perineural invasion.

MATERIALS AND METHODS

There were 839 men treated between April 1989 and December 1997 with conformal radiotherapy alone. Cox multivariate analysis was used to establish important predictors of biochemical failure (BF) separately for patients with an initial pretreatment PSA (iPSA) of less than 10, 10 to 19.9, or 20 or greater ng/ml. Radiotherapy (RT) dose was evaluated as a continuous and categorical (dose groups of less than 72, 72 to 75.9 and 76 Gy or greater) variable.

RESULTS

At a median 63-month followup multivariate analysis demonstrated that iPSA and radiotherapy (RP) dose were the most significant predictors of BF, followed by Gleason score and T stage. Perineural invasion was not an independent correlate of outcome. RT dose was significant in all iPSA groups (less than 10, 10 to 19.9 and 20 or greater ng/ml). Gleason score was significant when iPSA was less than 10 ng/ml. T stage was significant when iPSA was 20 ng/ml or greater and it was borderline when iPSA was 10 to 19.9 ng/ml (p = 0.08). Prognostic subgroups were derived from these results and tested for an effect of RT dose on univariate analysis. Radiation dose was not a correlate of BF in the most favorable (PSA less than 10 ng/ml and Gleason score 2 to 6) and the most unfavorable (PSA 20 ng/ml or greater and stage T3-T4) prognostic groups but it was otherwise an influential determinant of outcome.

CONCLUSIONS

RT dose escalation to 76 Gy or greater improved patient outcome for all prognostic groups except those at the favorable and unfavorable extremes.

Neoadjuvant hormonal treatment and radiotherapy for prostate cancer

Adjuvant hormone treatment with radiotherapy has been demonstrated in two studies (Bolla and RTOG 8531) to be beneficial in patients with locally advanced prostate cancer. However, the vast majority of patients with early prostate cancer can be cured with radiotherapy alone. Subset analysis combining RTOG 8610 and RTOG 8531 has demonstrated a survival benefit only for patients with a biopsy Gleason score < or =6 after short-term neoadjuvant hormonal therapy. The results of ongoing research will further clarify the use of hormone treatment with radiotherapy in patients with low and intermediate risk.

Permanent Prostate Brachytherapy in Men with Clinically Localised Prostate Cancer

Permanent prostate brachytherapy techniques are associated with excellent biochemical control for patients with localised prostate cancer. Ten-year data show that permanent prostate brachytherapy is compatible with external beam irradiation or radical prostatectomy. However, treatment protocols and techniques for prostate brachytherapy vary between centres and there is little conformity of treatment protocols. The selection of patients for monotherapy or combined external beam irradiation and brachytherapy is controversial. The role of neoadjuvant androgen deprivation also remains unanswered in patients with localised prostate cancer. In addition, post-implant dosimetry may in fact be more significant for predicting outcome than the addition of adjuvant therapies, and should be a requirement when performing prostate brachytherapy. Data now seem to support specific computed tomography (CT)-based criteria to evaluate implant quality and delivered dose to the prostate. Unfortunately, prostate oedema and poor imaging techniques are limiting factors for evaluating implant dosimetry. Treatment planning techniques that use new treatment planning computers may assist in improving the implant procedure and dosimetry and are now available.

Radiotherapy for t3 prostate cancer

Throughout the past decade, significant improvements in optimizing the management of T3 prostate cancer have been made. Phase III randomized studies have demonstrated the superiority of combined hormone therapy and radiation therapy over radiation therapy alone. Radiotherapy dose escalation using conformal techniques has improved local control and lowered toxicity. These advances have changed the approach to treatment of T3 prostate cancer from that directed at palliation of symptoms to earlier interventions directed at prolongation of survival. The contemporary role of radiation therapy in clinical T3 prostate cancer in the context of other treatment options is reviewed in this article.

Mindless or mindful? Radiation oncologists' perspectives on the evolution of prostate cancer treatment

The evolution of radiation therapy treatment for prostate cancer has been striking over the last 10 years. Advances in brachytherapy (BT), external beam radiotherapy (EBRT), and the combination of EBRT + BT have led to improved biochemical and clinical results. This article describes these advances in the context of the treatment decision process. Key to this process is the assignment of patient risk, which is based on the results of conventional radiation dose and techniques. Using the 1992 AJCC palpation staging system, Gleason score, and pretreatment prostate-specific antigen, two different risk assessment algorithms were compared. Both gave comparable approximations of risk, although the single factor high-risk model was superior in differentiating those patients with the highest probability of failing treatment after radiotherapy. Such criteria are the foundation for treatment selection. Objective findings support BT alone or EBRT alone for low-risk patients, high-dose EBRT or EBRT + BT for intermediate-risk patients, and EBRT + androgen deprivation for high-risk patients. In summary, advances in radiation oncology have led to significant gains in prostate cancer control. Clinical prognostic factor-based patient selection is central to the optimization of outcome.

Late morbidity profiles in prostate cancer patients treated to 79-84 Gy by a simple four-field coplanar beam arrangement

PURPOSE

To describe the frequency and magnitude of late GI and GU morbidity in prostate cancer patients treated to high dose levels with a simple three-dimensional conformal technique.

METHODS AND MATERIALS

A total of 156 intermediate- and high-risk patients were treated between January 1, 1992 and February 28, 1999 with a simple four-field three-dimensional conformal technique to 79-84 Gy. All patients were treated with a four-field conformal technique; the prostate received 82 Gy and the seminal vesicles and periprostatic tissue 46 Gy. GI and GU toxicity was scored according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer Late Morbidity Grading Scale and compared using Kaplan-Meier estimates.

RESULTS

The late Grade 2 GI complication rate was 9% and 38% at 3 years for patients treated with and without rectal blocking, respectively (p = 0.0004). No Grade 3 late GI complications developed. The rate of Grade 2 late GU complications was 5%, 8%, and 12% at 12, 24, and 36 months, respectively. The Grade 3 late GU complication rate was 2% at 36 months. These differences were not statistically significant.

CONCLUSION

The treatment method described is a simple four-field conformal technique that can be easily implemented in the general radiation community. A dose of 79-84 Gy can be safely delivered to the prostate, with a 9% rate of late Grade 2 GI, 12% rate of late Grade 2 GU, and 2% rate of late Grade 3 GU complications.

Stage T1c prostate cancer: a heterogeneous category with widely varying prognosis

PURPOSE

Stage T1c prostate cancer is defined as nonpalpable disease diagnosed by needle biopsy. As more patients are being diagnosed early because of prostate-specific antigen (PSA) screening, the distribution of patients by stage has shifted dramatically. Although this group has traditionally been characterized as having early-stage disease and the best prognosis, on review of these patients, we instead found a very heterogeneous group with a wide spectrum of outcomes that depend on both patient (Gleason grade and pretreatment PSA) and treatment (dose) factors.

METHODS AND MATERIALS

A retrospective analysis was performed on 353 patients with stage T1c prostate adenocarcinoma who were referred for radiation therapy from 1989-1999. All patients underwent central review of pathology. Patients were treated with external-beam radiation to doses of 60-78 Gy; 66% of the patients were treated with a dose of 70 Gy or higher. Clinical local recurrence, nodal recurrence, distant metastases, and PSA relapse were recorded. Kaplan-Meier methodology was used to determine survival. For evaluation of prognostic variables, the patients were grouped by Gleason score (2-6, 7, 8-10), pretreatment PSA level (< 10, 10-20, > 20 ng/mL), and dose delivered to the prostate (< or = 70 Gy, > 70 Gy). The log-rank test was used for univariate analysis, and Cox-regression was used for multivariate analysis.

RESULTS

The median age was 69 years, and the median follow-up of surviving patients was 47 months. As a percentage of all patients with prostate cancer, stage T1c continually increased from 6% in 1989 to 47% in 1999. Of the 353 patients with T1c, 66% of the patients were in the Gleason group of 2-6, 27% had a Gleason score of 7, and 7% had a Gleason score of 8-10. Sixty-five percent of the group had a pretreatment PSA level of < 10 ng/ mL, 31% had a PSA level of 10-20 ng/mL, and 5% had a PSA level of > 20 ng/mL. For the entire group, the 8-year overall survival was 86%, and PSA relapse-free survival was 78%. By univariate analysis, Gleason score and pretreatment PSA were significant predictors of overall survival and PSA relapse-free survival. For PSA relapse-free survival, a radiation dose of more than 70 Gy was also a significant factor. By multivariate analysis, Gleason score, pretreatment PSA level, and radiation dose over 70 Gy were significant predictors of PSA relapse-free survival. As expected, patients with Gleason score < or = 6 and pretreatment PSA < 10 had an 8-year RFS of 90%, whereas patients with Gleason score of 8-9 and pretreatment PSA > 20 had a relapse-free survival of zero percent.

DISCUSSION

Contrary to general assumption, stage T1c prostate cancer is composed of a very heterogeneous group of patients with varying outcomes. When treatment modalities and institutional data are evaluated, the spectrum of disease must be accounted for by additional prognostic factors and subset analysis. Improvement in prostate imaging and multiple core biopsies may be helpful in better defining the extent of disease in the individual patient.

Dose response in prostate cancer with 8–12 years’ follow-up

PURPOSE

This communication reports the long-term results of the original group of prostate cancer patients who participated in the first prospective Fox Chase Cancer Center radiation dose escalation study for which 8-12 years of follow-up is now available.

METHODS AND MATERIALS

Between March 1, 1989 and October 31, 1992, 232 patients with clinically localized prostate cancer received three-dimensional conformal radiotherapy only at Fox Chase Cancer Center in a prospective dose-escalation study. Of these patients, 229 were assessable. The 8-, 10-, and 12-year actuarial rates of biochemical control (biochemically no evidence of disease [bNED]), freedom from distant metastasis (FDM), and morbidity were calculated. The Cox proportional hazards model was used to assess multivariately the predictors of bNED control and FDM, including pretreatment prostate-specific antigen (PSA) level (continuous), tumor stage (T1/T2a vs. T2b/T3), Gleason score (2-6 vs. 7-10), and radiation dose (continuous). The median total dose for all patients was 74 Gy (range 67-81). The median follow-up for living patients was 110 months (range 89-147). bNED control was defined using the American Society for Therapeutic Radiology and Oncology consensus definition.

RESULTS

The actuarial bNED control for all patients included in this series was 55% at 5 years, 48% at 10 years, and 48% at 12 years. Patients with pretreatment PSA levels of 10-20 ng/mL had statistically significant differences (19% vs. 31% vs. 84%, p = 0.0003) in bNED control when stratified by dose (<71.5, 71.5-75.6, and > 75.6 Gy, respectively) on univariate analysis. For the 229 patients with follow-up, 124 (54%) were clinically and biochemically without evidence of disease. Sixty-nine patients were alive at the time of last follow-up, and 55 patients were dead of intercurrent disease. On multivariate analysis, radiation dose was a statistically significant predictor of bNED control for all patients and for unfavorable patients with a pretreatment PSA <10 ng/mL. For the patients with a pretreatment PSA level of 10-20 ng/mL, the radiation dose was a statistically significant predictor across all groups. No radiation dose response was seen for those patients with a pretreatment PSA level >20 ng/mL, although large numbers of patients are required to demonstrate a difference. The radiation dose, Gleason score, and palpation T stage were significant predictors for the entire patient set, as well as for those with pretreatment PSA levels between 10 and 20 ng/mL. The FDM rate for all patients included in this series was 89%, 83%, and 83% at 5, 10, and 12 years, respectively. For patients with pretreatment PSA levels <10 ng/mL, all four covariates (radiation dose, Gleason score, pretreatment PSA, and palpation T stage) were significant predictors of distance metastasis. Using the Radiation Therapy Oncology Group morbidity scale, no difference was noted in the frequency of Grade 2 and 3 genitourinary and Grade 3 gastrointestinal morbidity when patients in this data set were stratified by radiation dose. However, a significant increase occurred in Grade 2 gastrointestinal complications as the radiation dose increased.

CONCLUSION

The long-term results of the original Fox Chase radiation dose escalation study with >9 years of median follow-up confirm the existence of a dose response for both bNED control and FDM. The dose response in prostate cancer is real, and the absence of biochemical recurrence after 8 years demonstrates the lack of late failure and suggests cure.

Pathologic evidence of dose-response and dose-volume relationships for prostate cancer treated with combined external beam radiotherapy and high-dose-rate brachytherapy

PURPOSE

The clinical significance of postradiotherapy (RT) prostate biopsy characteristics is not well understood relative to the known prognostic factors. We performed a detailed pathologic review of posttreatment biopsy specimens in an attempt to clarify their relationship with clinical outcome and radiation dose.

METHODS AND MATERIALS

Between 1991 and 1998, 78 patients with locally advanced prostate cancer were prospectively treated with external beam RT in combination with high-dose-rate brachytherapy at William Beaumont Hospital and had post-RT biopsy material available for a complete pathologic review. Patients with any of the following characteristics were eligible for study entry: pretreatment prostate-specific antigen level > or =10.0 ng/mL, Gleason score > or =7, or clinical Stage T2b-T3cN0M0. Pelvic external beam RT (46.0 Gy) was supplemented with three (1991-1995) or two (1995-1998) ultrasound-guided transperineal interstitial (192)Ir high-dose-rate implants. The brachytherapy dose was escalated from 5.50 to 10.50 Gy per implant. Post-RT prostate biopsies were performed per protocol at a median interval of 1.5 years after RT. All pre- and post-RT biopsy specimen slides from each case were reviewed by a single pathologist (N.S.G.). The presence and amount of residual cancer, most common RT-effect score, and least amount RT-effect score were analyzed. The median follow-up was 5.7 years. Biochemical failure was defined as three consecutive prostate-specific antigen rises.

RESULTS

Forty patients (51%) had residual cancer in the post-RT biopsies. The 7-year biochemical control rate was 79% for patients with negative biopsies vs. 62% for those with positive biopsies with marked RT damage vs. 33% for those with positive biopsies with no or minimal RT damage. A greater percentage of positive pre-RT biopsy cores (p = 0.01), lower total RT dose (p = 0.001), lower dose per implant (p = 0.001), and greater percentage of positive post-RT biopsy cores (p = 0.01) were each associated with biochemical failure (Cox regression, univariate analysis). For patients with <25% positive post-RT biopsy cores, the 7-year biochemical control rate was 81% vs. a 62% biochemical control rate for those with 25-49% positive cores and only 32% for those with > or =50% positive cores (p = 0.01). On Cox multiple regression analysis, only the percentage of positive pre-RT biopsy cores and RT dose remained significantly associated with biochemical failure. Of all the factors analyzed, only the pretreatment cancer volume and lower RT dose were significantly associated with residual cancer and/or residual cancer with no or minimal RT damage. A greater percentage of positive pre-RT biopsy cores was associated with both a positive post-RT biopsy (p = 0.08) and a greater percentage of positive post-RT biopsy cores (p = 0.04). A lower total RT dose was associated with both a positive post-RT biopsy (p = 0.08) and a greater percentage of positive post-RT biopsy cores (p = 0.02). For patients who received <80 Gy (equivalent in 2-Gy fractions), 73% had positive post-RT biopsies vs. a 56% biopsy positivity rate for those who received 84-90 Gy and only 39% for those who received > or =92 Gy (p = 0.07).

CONCLUSION

Patients with positive post-RT biopsies are more likely to experience biochemical failure, especially when the RT damage is minimal. Patients who have a larger pretreatment tumor volume or receive a lower RT dose are more likely to demonstrate post-RT biopsy positivity and biochemical failure.

Prostate cancer radiation dose response: results of the M. D. Anderson phase III randomized trial

PURPOSE

A randomized radiotherapy dose escalation trial was undertaken between 1993 and 1998 to compare the efficacy of 70 vs. 78 Gy in controlling prostate cancer.

METHODS AND MATERIALS

A total of 305 Stage T1-T3 patients were entered into the trial and, of these, 301 with a median follow-up of 60 months, were assessable. Of the 301 patients, 150 were in the 70 Gy arm and 151 were in the 78 Gy arm. The primary end point was freedom from failure (FFF), including biochemical failure, which was defined as 3 rises in the prostate-specific antigen (PSA) level. Kaplan-Meier survival analyses were calculated from the completion of radiotherapy. The log-rank test was used to compare the groups. Cox proportional hazard regression analysis was used to examine the independence of study randomization in multivariate analysis.

RESULTS

There was an even distribution of patients by randomization arm and stage, Gleason score, and pretreatment PSA level. The FFF rates for the 70- and 78 Gy arms at 6 years were 64% and 70%, respectively (p = 0.03). Dose escalation to 78 Gy preferentially benefited those with a pretreatment PSA >10 ng/mL; the FFF rate was 62% for the 78 Gy arm vs. 43% for those who received 70 Gy (p = 0.01). For patients with a pretreatment PSA <or=10 ng/mL, no significant dose response was found, with an average 6-year FFF rate of about 75%. Although no difference occurred in overall survival, the freedom from distant metastasis rate was higher for those with PSA levels >10 ng/mL who were treated to 78 Gy (98% vs. 88% at 6 years, p = 0.056). Rectal side effects were also significantly greater in the 78 Gy group. Grade 2 or higher toxicity rates at 6 years were 12% and 26% for the 70 Gy and 78 Gy arms, respectively (p = 0.001). Grade 2 or higher bladder complications were similar at 10%. For patients in the 78 Gy arm, Grade 2 or higher rectal toxicity correlated highly with the proportion of the rectum treated to >70 Gy.

CONCLUSION

An increase of 8 Gy resulted in a highly significant improvement in FFF for patients at intermediate-to-high risk, although the rectal reactions were also increased. Dose escalation techniques that limit the rectal volume that receives >or=70 Gy to <25% should be used.

Lack of radiation dose response for patients with low-risk clinically localized prostate cancer: a retrospective analysis

PURPOSE

The need for dose escalation for patients with low-risk clinically localized prostate cancer remains controversial. In this study, we report our pooled institutional experience of low-risk patients treated with a range of "standard" radiation doses to assess outcome in regard to biochemical failure and to determine whether a dose-response relationship exists within this conventional dose range.

METHODS AND MATERIALS

Patients with low-risk clinically localized prostate cancer (T1 or T2a, Gleason grade <or=6, and prostate-specific antigen <or=10 ng/mL) treated at Joint Center for Radiation Therapy-affiliated institutions between October 1989 and September 1997 were retrospectively analyzed for freedom from biochemical failure. The dose was prescribed volumetrically with 95% normalization to between 5760 and 6900 cGy (6100 and 7300 cGy ICRU reference point dose). Patients were stratified into 3 groups with relatively equal numbers of patients (<6660, 6660, and >6660 cGy). To ensure that any differences in biochemical failure between patients at the lower and higher ends of the dose range used were not masked by analysis of the entire cohort, patients receiving <or=6500 cGy or >or=6800 cGy were subsequently analyzed separately. Biochemical failure was defined per the ASTRO consensus definition. The log-rank test was used to assess for differences in follow-up and time to biochemical failure. A Kaplan-Meier plot of time to biochemical failure for the initial 3 subgroups was generated.

RESULTS

A total of 264 patients were identified. Sixteen patients whose dose was not recorded in the database were excluded from analysis. The median follow-up was 35 months. No significant differences were found in baseline prostate-specific antigen, Gleason grade, or clinical stage among the groups. The overall actuarial rate of 5-year freedom from biochemical failure was 80.2%. By dose level, the 5-year biochemical failure-free rate was 79.2%, 78.4%, and 84.5% for <6660 cGy, 6660 cGy, and >6660 cGy, respectively. These differences were not significant. Subsequently, 45 patients receiving <or=6500 cGy were compared with 23 patients receiving >or=6800 cGy. The difference between these groups was not significant. The 5-year freedom from biochemical failure rate for the patients receiving <or=6500 cGy was 89.9%.

CONCLUSION

Within a range of doses considered standard for treatment of low-risk clinically localized prostate cancer during an 8-year period, no improvement in biochemical freedom from failure was noted with the higher doses. The overall 5-year rate of freedom from biochemical failure is consistent with that reported by others with standard and escalated external beam doses used in this low-risk population. A prospective randomized study is necessary to define the optimal dose in this patient population.

Preliminary observations on biochemical relapse-free survival rates after short-course intensity-modulated radiotherapy (70 Gy at 2.5 Gy/fraction) for localized prostate cancer

PURPOSE

To compare the preliminary biochemical relapse-free survival rates between short-course intensity-modulated radiotherapy (SCIM-RT) delivering 70 Gy in 28 fractions and three-dimensional conformal radiotherapy (3D-CRT) delivering 78 Gy in 39 fractions.

METHODS AND MATERIALS

Between January 1998 and December 1999, 166 patients were treated with SCIM-RT and 116 with 3D-CRT. The SCIM-RT cases were treated to 70 Gy (2.5 Gy/fraction) using 5 intensity-modulated fields using a dynamic multileaf collimator. The BAT transabdominal ultrasound system was used for localization of the prostate gland in all SCIM-RT cases. The 116 3D-CRT cases were treated to 78.0 Gy (2.0 Gy/fraction). The study sample therefore comprised 282 cases; 70 Gy in 28 fractions is equivalent to 78 Gy in 39 fractions for late-reacting tissues, according to the linear-quadratic model. The median follow-up for all cases was 25 months (range 3-42). The median follow-up was 21 months for the SCIM-RT cases (range 3-31) and 32 months for the 3D-CRT cases (range 3-42). The follow-up period was shorter for the SCIM-RT cases, because SCIM-RT was started only in October 1998. Biochemical relapse was defined as 3 consecutive rising prostate-specific antigen levels after reaching a nadir. The analysis was then repeated with a more stringent definition of biochemical control: reaching and maintaining a prostate-specific antigen level of < or =0.5 ng/mL. Radiation Therapy Oncology Group toxicity scores were used to assess complications.

RESULTS

For the 282 patients, the biochemical relapse-free survival rate at 30 months was 91% (95% confidence interval 88-95%). The biochemical relapse-free survival rate at 30 months for 3D-CRT vs. SCIM-RT was 88% (95% confidence interval 82-94%) vs. 94% (95% confidence interval 91-98%), respectively. The difference was not statistically significant between the two treatment arms (p = 0.084). The multivariate time-to-failure analysis using the Cox proportional hazards model for clinical parameters showed the pretreatment prostate-specific antigen level (p <0.001) and biopsy Gleason score (p <0.001) to be the only independent predictors of biochemical relapse. Clinical T stage (p = 0.66), age (p = 0.15), race (p = 0.25), and neoadjuvant androgen deprivation (p = 0.66) were not independent predictors of biochemical failure. SCIM-RT showed only a trend toward a better outcome on multivariate analysis (p = 0.058). Late rectal toxicity was limited; the actuarial combined Grade 2 and 3 late rectal toxicity rate at 30 months was 5% for SCIM-RT vs. 12% for 3D-CRT (p = 0.24). Grade 3 late rectal toxicity (rectal bleeding requiring cauterization) occurred in a total of 10 patients. The actuarial Grade 3 late rectal toxicity rate at 30 months was 2% for the SCIM-RT cases and 8% for the 3D-CRT cases (p = 0.059). Late urinary toxicity was rare in both groups.

CONCLUSION

With the currently available follow-up period (< or =30 months), the hypofractionated intensity-modulated radiotherapy schedule of 70.0 Gy delivered at 2.5 Gy/fraction had a comparable biochemical relapse profile with the prior 3D-CRT schedule delivering 78.0 at 2.0 Gy/fraction. The late rectal toxicity profile has been extremely favorable. If longer follow-up confirms the favorable biochemical failure and low late toxicity rates, SCIM-RT will be an alternative and more convenient way of providing dose escalation in the treatment of localized prostate cancer.

[Conformal radiotherapy in prostate cancer: for whom and how?]

External radiotherapy is one of the modalities used to cure localized prostate carcinoma. Most of localized prostate carcinomas, specially those of the intermediate prognostic group, may benefit from escalated dose above 70 Gy at least as regard biochemical and clinical relapse free survival. 3D-CRT allows a reduction of the dose received by organs at risk and an increase of prostate dose over 70 Gy. It is on the way to become a standard. Intensity modulated radiation therapy increases dose homogeneity and reduces rectal dose. These methods necessitate rigorous procedures in reproducibility, delineation of volumes, dosimetry, daily treatment. They need also technological and human means. It is clear that localized prostate cancer is a good example for evaluation of these new radiotherapy modalities.

High-dose-rate brachytherapy in the treatment of carcinoma of the prostate

BACKGROUND

Although radical prostatectomy for localized disease is considered as a standard of care, external-beam radiotherapy and brachytherapy are equally effective. We report on the technique and preliminary results of high-dose-rate (HDR) brachytherapy using a temporary iridium-192 implant technique.

METHODS

The authors reviewed the literature on the techniques, treatment protocols, and results of HDR brachytherapy in the treatment of carcinoma of the prostate, and they report their own protocols, technique, and results.

RESULTS

The combination of HDR brachytherapy and external irradiation has been well tolerated by all 200 patients in our series, with less than 3% grade 3 late complications and with 95% PSA relapse-free survival with a median follow-up of 24 months.

CONCLUSIONS

HDR brachytherapy may be the most conformal type of irradiation in the treatment of carcinoma of the prostate regardless of tumor size, anatomical distortion, and organ mobility.