The importance of local control in the treatment of prostatic cancer

MRI-guided focal or integrated boost high dose rate brachytherapy for recurrent prostate cancer

Background and purpose

Locally recurrent prostate cancer after radiotherapy merits an effective salvage strategy that mitigates the risk of adverse events. We report outcomes of a cohort enrolled across two institutions investigating MRI-guided tumor-targeted salvage high dose rate brachytherapy (HDR-BT).

Materials and methods

Analysis of a prospective cohort of 88 patients treated across two institutions with MRI-guided salvage HDR-BT to visible local recurrence after radiotherapy (RT). Tumor target dose ranged from 22-26 Gy, using either an integrated boost (ibBT) or focal technique (fBT), delivered in two implants over a median of 7 days. Outcome metrics included cancer control and toxicity (CTCAE). Quality of life (QoL-EPIC) was analyzed in a subset.

Results

At a median follow-up of 35 months (6 -134), 3 and 5-year failure-free survival (FFS) outcomes were 67% and 49%, respectively. At 5 years, fBT was associated with a 17% cumulative incidence of local failure (LF) outside the GTV (vs. 7.8% ibBT, p=0.14), while LF within the GTV occurred in 13% (vs. 16% ibBT, p=0.81). Predictors of LF outside fBT volumes included pre-salvage PSA>7 ng/mL (p=0.03) and interval since RT less than 5 years (p=0.04). No attributable grade 3 events occurred, and ibBT was associated with a higher rate of grade 2 toxicity (p<0.001), and trend towards a larger reduction in QoL sexual domain score (p=0.07), compared to fBT.

Conclusion

A tumor-targeted HDR-BT salvage approach achieved favorable cancer control outcomes. While a fBT was associated with less toxicity, it may be best suited to a subgroup with lower PSA at later recurrence. Tumor targeted dose escalation may be warranted.

Management of patients with biochemical recurrence after local therapy for prostate cancer

Nearly three-quarters of a million American men who have been treated with prostatectomy and/or radiation therapy experience an increasing prostate-specific antigen level known as biochemical recurrence. Although androgen-deprivation therapy remains a reasonable option for some men with biochemical recurrence, deferring androgen ablation or offering nonhormonal therapies may be appropriate in patients in whom the risk of clinical or metastatic progression and prostate cancer-specific death is low. A risk-stratified approach informed by the patient's prostate-specific antigen kinetics, comorbidities, and personal preferences is recommended to determine the best management approach.

Salvage Cryosurgery for Recurrent Prostate Carcinoma after Radiotherapy

Cryotherapy is a salvage treatment for patients with biopsy-proved prostatic adenocarcinoma recurrent after radiotherapy. Proper sampling, labeling, and analysis of prostate biopsies allows prompt diagnosis, identification of important prognostic parameters, and planning of an appropriate therapeutic strategy. Whereas androgen-suppressive therapy is associated with only a temporary benefit, transperineal salvage cryosurgery offers a potentially curative option for patients with localized disease, even those with significant comorbidities. Technological advances, including computerized treatment planning and miniaturized cryoprobes, may provide further therapeutic advantages and lower complication rates. Cryotherapy should be included among the established therapeutic options for recurrence after radiotherapy.

Management of the Patient with a Rising PSA Alone

PSA-only recurrence after definitive RP or RT for PCA is an increasingly com-mon scenario. The very definition of advanced prostate cancer is changing. Multimodal therapy improves cancer-specific outcomes especially in men with high-risk disease. After RP, a detectable serum PSA has been considered suggestive of PCA recurrence. After RT, the ASTRO definition of BCR has been widely used to define BCR. Both of these definitions of BCR are subject to dispute. The kinetics of a rising PSA (PSA doubling time) appears to be the best surrogate marker for disease risk, clinical progression, and ultimately cancer-specific death. Therapeutic options include salvage RT after primary RP or systemic HT through surgical/chemical castration, antiandrogens, or nontraditional HT. Re-cent studies suggest that early HT can provide modest survival benefits, but at both an economic cost and decreased quality of life. The diminished side effects of an oral antiandrogen are appealing, and may be as efficacious as castration therapies in low-volume disease. More clinical trials are needed to determine the best treatments, alone and in combination. The potential opportunities for novel therapeutic agents with low associated morbidity are great.

Role of Salvage Radical Prostatectomy for Recurrent Prostate Cancer After Radiation Therapy

Patients with isolated local recurrence of prostate cancer after radiation therapy may potentially be cured of their disease by salvage radical prostatectomy (RP). The stage-specific 5-year cancer-control rates of salvage RP resemble those of standard RP. However, the ability to effectively administer salvage treatment to patients with radiorecurrent disease is compromised by the lack of diagnostic tests with sufficient sensitivity and specificity to detect local recurrence at an early stage while it is amenable to local salvage therapy. By the time biochemical recurrence is declared using the current American Society for Therapeutic Radiology and Oncology definition, the majority of patients have advanced local disease, precluding successful local salvage therapy. When salvage RP is performed at prostate-specific antigen levels of 10 ng/mL or less, an estimated 70% of patients are free of disease at 5 years. With better patient selection and technical modifications, the morbidity associated with salvage RP has improved substantially. Rates of urinary incontinence and anastomotic stricture are acceptable, although one third of patients will experience these complications. Salvage cryotherapy is a minimally invasive alternative to salvage RP, but cancer-control rates appear to be inferior and it does not provide a clear advantage over salvage RP in terms of reduced morbidity. Patients with local recurrence after radiation therapy are at increased risk of metastatic progression and cancer-specific mortality. Currently, salvage RP represents the only curative treatment option for these patients. Salvage RP may favorably alter the natural history of biochemical recurrence after radiation therapy, but it must be instituted early in the course of recurrent disease to be effective.

Transperineal Salvage Cryosurgery (SC) for Prostate Adenocarcinoma

Criteria used for the diagnosis and treatment of recurrent prostate adenocarcinoma after radiotherapy are examined according to recently published studies in the literature. The diagnosis of recurrence is confirmed by the histological test of a biopsy performed due to the gradual increase in prostate-specific antigen (PSA). Proper sampling, nomenclature and analysis of prostate biopsies allow an early diagnosis to identify some important prognostic parameters and to plan the most appropriate therapeutic strategy for every single case. Androgen suppressive therapy only induces a temporary benefit in these patients. Transperineal salvage cryosurgery (SC) represents a recognized effective treatment option. Technological advances, including computerized treatment planning and miniaturized cryoprobes, allow further potential therapeutic advantages and reduce complications. Results of SC are promising even in patients with other comorbidities; therefore, it is useful to include it among therapeutic instruments for failures following radiotherapy.

Treating the Biochemical Recurrence of Prostate Cancer After Definitive Primary Therapy

As increasing numbers of men are living longer with prostate cancer, larger proportions will eventually present to our collective practices with increasing prostate-specific antigen (PSA) levels. Such PSA relapses, conservatively estimated to affect approximately 50,000 men each year, have become the most common form of advanced prostate cancer. Salvage radiation therapy and salvage prostatectomy have important roles in our therapeutic armamentarium and should be valid options for young, healthy men. Counseling patients regarding expectations for cancer control and treatment morbidity has become better because of reports from larger series of patients who have had salvage radiation therapy and surgery. Some patients may not be appropriate candidates for salvage local therapies. A growing body of evidence suggests early hormonal therapy improves progression-free survival (PFS) and could alter cancer-specific survival. This benefit seems to be greatest when hormonal therapy is initiated while PSA levels are low, before clinically measurable disease becomes apparent. However, there is a cost to be paid in side effects and health care dollars when androgen deprivation is administered over prolonged periods. The nonsteroidal antiandrogen agent bicalutamide could offer PFS equivalent to that seen with castration without the complications of androgen deprivation. Observational data seem to indicate that individuals at high risk could also receive benefit from therapy administered before PSA detection. The potential opportunities for novel therapeutic agents with low associated morbidity are great.

Biochemical recurrence after definitive prostate cancer therapy. Part II: Treatment strategies for biochemical recurrence of prostate cancer*

PURPOSE OF REVIEW

Through the prostate-specific antigen era, the proportion of men less than 55 years old with newly diagnosed prostate cancer more than doubled to almost 15%. As increasing numbers of men are living longer with prostate cancer, larger proportions will eventually present to our collective practices with rising prostate-specific antigen levels. Such prostate-specific antigen relapses, conservatively estimated to affect approximately 50 000 men each year, have become the most common form of advanced prostate cancer in the current period.

RECENT FINDINGS

Increasing evidence suggests that early hormonal therapy improves progression-free survival and may alter the cancer-specific survival. However, there is a cost to pay in side-effects when androgen deprivation is administered over prolonged periods. The non-steroidal anti-androgen bicalutamide may offer an equivalent progression-free survival to castration without the complications of androgen deprivation. Observational data seem to indicate that high-risk individuals (i.e. those with high-grade, high-stage disease or a prostate-specific antigen doubling time less than 12 months) may also receive benefit from early therapy.

SUMMARY

The definition of advanced prostate cancer has changed. Multimodal therapy improves cancer-specific outcomes especially in men with high-risk disease. The potential opportunities for novel therapeutic agents with low associated morbidity are great.

SALVAGE SURGERY FOR RADIORECURRENT PROSTATE CANCER: CONTEMPORARY OUTCOMES

PURPOSE

We present a 30-year experience with performing salvage surgery in patients with persistent prostate cancer (PCA) after definitive radiotherapy.

MATERIALS AND METHODS

Patients with biopsy proven PCA following definitive radiotherapy who underwent salvage surgery were identified retrospectively (1967 to 2000). Prostate specimens were evaluated by a single pathologist. Progression-free survival (PFS) and cancer specific survival (CSS) estimates were made with multivariate analysis of outcome predictors. Complications were reviewed.

RESULTS

Sufficient information was available on 199 patients, including 138 with retropubic prostatectomy (RP) and 61 with cystoprostatectomies (CP). Median followup was 7.0 years. Rectal injury rates (5% for RP and 10% for CP) remained stable, while transfused units of blood decreased. Urinary extravasation (15% of cases) and bladder neck contracture (22%) were the most common complications. Urinary continence (0 pads) improved from 43% to 56% of patients (p = 0.17) with an additional 20% requiring 1 or fewer pad daily. Overall 10-year CSS in all patients undergoing salvage surgery was 65%. Patients undergoing RP fared better than those needing CP (10-year CSS 77% vs 38%, p <0.001 and median PFS 8.7 vs. 4.4 years, p <0.001). Tumor ploidy, percent 4/5 Gleason grade and pathological stage were strong predictors of outcome, while margin status and preoperative prostate specific antigen had minimal predictive strength.

CONCLUSIONS

Significant PFS and CSS can be expected following salvage surgery for radioresistant PCA. Several pathological features of the removed prostate are predictive of survival. The surgical risks of salvage surgery are now defined. Morbidity rates, including continence, have moderately improved with time.

Rising prostate-specific antigen after primary prostate cancer therapy

An estimated 20-40% of men experience a biochemical recurrence within 10 years of definitive prostate cancer treatment. No single prostate-specific antigen (PSA) value is invariably associated with clinical metastasis or cancer-specific survival; PSA kinetics might prove to be a more important predictor of eventual progression-free survival and cancer-specific survival than absolute PSA level alone. With only one-third of patients progressing from biochemical recurrence to clinical disease, therapeutic morbidity should not outpace risk of disease progression. Salvage radiation therapy following radical prostatectomy has widely variable long-term biochemical control rates (from 18 to 64% depending on the follow-up period). Early hormonal therapy delivered as castration or complete androgen blockade might delay clinical metastasis in patients with high-risk pathologic disease; however, the adverse effects and morbidity of long-term therapy must not be underestimated. Non-steroidal antiandrogens as monotherapy for early biochemical recurrence, particularly for younger men who wish to preserve their libido and sexual potency, have received considerable attention, but there are conflicting data on long-term outcomes. Because of their favorable adverse-effect profiles, non-traditional therapies that exert localized hormonal or cellular effects are receiving considerable attention for treatment of early, PSA-only recurrence. Data from animal models provide a rationale for the use of these therapies, but there is a lack of evidence to support prolongation of progression-free survival or cancer-specific survival.

Radical prostatectomy for the patient with locally advanced prostate cancer

The proper management of patients with locally advanced adenocarcinoma of the prostate has been contentious and too frequently based on antiquated misconceptions. Non-extirpative treatments, even when combined with neoadjuvant hormonal therapy, are inferior to the surgical removal of the prostate for controlling local progression and distant dissemination of the cancer. Radical prostatectomy combined with early adjunctive hormonal therapy for patients with nodal metastasis is superior to all other forms of therapy and should be considered the standard of care. This approach provides survival rates comparable with patients with clinically organ-confined prostate cancer.

Salvage radical prostatectomy for recurrence of prostate cancer after radiation therapy

The goal of primary radiation therapy in the treatment of prostate cancer is to eradicate all of the local tumor. Although patients with relapsing disease after radiation therapy differ in their risk of death from prostate cancer, many will develop local progression, metastasis, and death. The recognition that local recurrence after radiation therapy portends a poor prognosis has led to the development of improved methods for early detection of recurrence and the development of alternative treatment strategies for radioresistant cancers. This article reviews knowledge regarding radiation failure and the role of salvage radical prostatectomy for men with local recurrence after radiation therapy for prostate cancer.

The management of high risk prostate cancer

PURPOSE

A major problem that urologists encounter is the recurrence of prostate cancer after local therapy or the failure of primary therapy. There is no consensus on the treatment of these groups of patients. The role of radiotherapy, hormonal therapy or chemotherapy must be defined.

MATERIALS AND METHODS

A comprehensive literature review of the current management of recurrence after primary therapy in prostate cancer was performed using MEDLINE, a review of current urology and oncology journals, and abstracts from recent urology meetings. The data collected focused on the role of radiotherapy, hormonal therapy and chemotherapy in this setting.

RESULTS

Defining a high risk group of patients using Gleason score, seminal vesicle or pelvic lymph node involvement and prostate specific antigen recurrence time is important for treating the problem early in disease course. Adjuvant radiotherapy cannot offer a survival advantage but it provides longer biochemical recurrence-free survival. Early administration of salvage radiotherapy in adequate doses provides a success rate similar to that of adjuvant radiotherapy in patients with low prostate specific antigen. Although there is no good evidence that early androgen deprivation definitely prolongs patient survival, increased time to progression in addition to excellent palliation with early hormonal therapy was reported in the majority of trials. Early trials of the use of chemotherapy showed improved survival rates with adjuvant chemotherapy alone or with a combination of hormonal therapy, especially in patients with nonmetastatic disease.

CONCLUSIONS

Although analysis of current literature revealed that patients who have recurrence after primary therapy would benefit from radiotherapy, hormonal therapy, chemotherapy or a combination of therapies, additional prospective randomized studies are needed to support these findings.

Primary radiation therapy for localized prostate cancer

Prostate cancer in men is similar to breast cancer in women; both cancers rank first, respectively, in incidence and are normally responsive to radiation therapy. In addition, advances in mammography help detect earlier breast cancers, and the development and refinement of prostatic specific antigen (PSA) has resulted in early detection of low-stage localized prostate cancers. This has generated debate over the proper management of localized prostate cancer. While there have not been any controlled, prospective, randomized trials of sufficient power to compare the various local therapies, based on the current available data, the three commonly used local modalities, surgery, and external beam radiation therapy and brachytherapy (radioactive seed implant), have similar efficacy controlling the disease up to 10 years in many patients. Technological advances in treatment delivery and planning have improved the treatment of prostate cancer with external-beam radiotherapy using three-dimensional conformal radiotherapy (3DCRT), ultrasound-guided transperineal implant, or intensity-modulated radiotherapy (IMRT), as well as proton or neutron beam based therapies.

Three-dimensional controlled interstitial hyperthermia combined with radiotherapy for locally advanced prostate carcinoma--a feasibility study

PURPOSE

To perform a feasibility study of three-dimensional spatially controlled interstitial hyperthermia for locally advanced prostate cancer.

METHODS AND MATERIALS

Twelve patients with prostate cancer (T3NxM0) were treated with conventional external beam radiotherapy and one interstitial hyperthermia treatment. Hyperthermia was delivered with the 27-MHz multielectrode current source (MECS) interstitial hyperthermia technique on an outpatient basis. Guided by transrectal ultrasonography, 12 catheters (range 7-16) were placed in the prostate through a template. Two electrodes per probe were inserted. Thermometry (average 100 sensors) was performed from within the probes for online temperature control. Additional thermometry was done in the prostate, rectum, urethra, and bladder. Reconstruction was done by sonography. Prostate perfusion was estimated from the thermal decay at the end of treatment. The full three-dimensional temperature distribution was calculated.

RESULTS

No toxicities greater than Grade 2 were recorded. A learning curve for implantation, position verification, reconstruction, and temperature simulation was experienced. Perfusion was 47 mL/100 g/min (range 30-65). The average measured temperature was T(90) (90% of the prostate reached a temperature of at least:) 39.9 degrees C and T(50) 44.1 degrees C. The average calculated temperatures were lower: T(90), 39.4 degrees C and T(50), 41.8 degrees C, because the entire prostate was taken into account. The tumor temperatures were T(90), 40.7 degrees C and T(50), 43.0 degrees C. The bladder and rectal temperatures were below the safety limits.

CONCLUSION

Multielectrode-current-source interstitial hyperthermia is technically feasible and well tolerated. It was not possible to achieve the goal temperature of 42-43 degrees C because of high perfusion and implantation limitations.

Magnetic resonance spectroscopy of the malignant prostate gland after radiotherapy: a histopathologic study of diagnostic validity

PURPOSE

Accurate spatial representation of tumor clearance after conformal radiotherapy is an endpoint of clinical importance. Magnetic resonance spectroscopy (MRS) can diagnose malignancy in the untreated prostate gland through measurements of cellular metabolites. In this study we sought to describe spectral metabolic changes in prostatic tissue after radiotherapy and validate a multivariate analytic strategy (based on MRS) that could identify viable tumor.

METHODS AND MATERIALS

Transrectal ultrasound-guided prostate biopsies from 35 patients were obtained 18-36 months after external beam radiotherapy. One hundred sixteen tissue specimens were subjected to 1H MRS, submitted to histopathology, and analyzed for correlation with a multivariate strategy specifically developed for biomedical spectra.

RESULTS

The sensitivity and specificity of MRS in identifying a malignant biopsy were 88.9% and 92% respectively, with an overall classification accuracy of 91.4%. The diagnostic spectral regions identified by our algorithm included those due to choline, creatine, glutamine, and lipid. Citrate, an important discriminating resonance in the untreated prostate gland, was invisible in all spectra, regardless of histology.

CONCLUSIONS

Although the spectral features of prostate tissue markedly change after radiotherapy, MRS combined with multivariate methods of analysis can accurately identify histologically malignant biopsies. MRS shows promise as a modality that could integrate three-dimensional measures of tumor response.

Feasibility of permanent implants for prostate cancer after previous radiotherapy in the true pelvis

BACKGROUND AND PURPOSE

Permanent seed implantation was used in the management of primary and recurrent prostate cancer in patients who had been treated previously by radiotherapy of the true pelvis.

MATERIAL AND METHODS

Between 1993 and 1998 a total of 21 patients received an I-125 implant after radiotherapy for bladder cancer (two patients), anal cancer (one patient), seminoma (two patients) and prostate cancer (16 patients). Two seminoma and 10 prostate cancer patients were treated after earlier definitive external beam radiation therapy (EBRT), while the bladder and anal cancer were initially treated with EBRT plus iridium implantation. Six prostate cancer patients were initially treated by brachytherapy alone. The interval between the two treatments was longer in patients with radiotherapy for other malignancies than prostate cancer.

RESULTS

After EBRT no serious late toxicity was observed. However, 1/6 patients who had two seed implants experienced serious complications, resulting in a vesico-rectal fistula.

CONCLUSIONS

The permanent seed implantation with I-125 is feasible after previous radiotherapy in the prostate area. Also a second implant is possible, but may result in severe complications, depending on the initial dose and interval between the two treatments.

Curative external beam radiotherapy for prostate carcinoma: results in 231 patients treated in Lyon

BACKGROUND

Radical prostatectomy and external beam radiation therapy (EBRT) are the mainstays of treatment of prostate cancer with curative intent. The possible development of radiation proctitis and rectal bleeding are major concerns when using EBRT. Recently, conformal radiotherapy has been introduced in an attempt to improve the results of EBRT. This paper presents an overview of the Lyon experience using standard EBRT with doses of 68 Gy, and reports the preliminary results of a study of conformal radiotherapy with dose escalation.

METHODS

From 1981 to 1995, EBRT was used to treat 231 patients with localized adenocarcinomas of the prostate. The dose of EBRT was 68 Gy/34 fractions/7 weeks using a four-field box technique with 18-MeV photons. A feasibility study of conformal radiotherapy was commenced in 1996. To date, 145 patients have been treated with doses escalating from 68 to 80 Gy.

RESULTS

In the EBRT group of 231 patients, the 5-year overall survival was 80.3%. Anorectal function was scored as excellent in 90% of patients. Rectal bleeding was seen in 14.3% of patients and required local treatment in only seven. In the group treated with conformal radiotherapy, the preliminary results indicate good early tolerance.

CONCLUSION

The curative treatment of patients with prostate cancer using EBRT gives good long-term survival with low rectal toxicity. Conformal radiotherapy appears to be an interesting approach to improve local control and perhaps survival.

Diagnosis of prostate cancer in needle biopsies after radiation therapy

Interpretation of postirradiation needle biopsies is a major diagnostic challenge for the pathologist because of substantial radiation-induced changes in benign and malignant prostatic tissue. Reports that have systematically evaluated the histopathologic findings in postirradiation needle biopsies are limited. In this study, we evaluated 46 histologic features in 29 postirradiation needle biopsy specimens from 29 patients. All patients had recurrent cancer on needle biopsies after external beam radiation, and all subsequently underwent salvage radical prostatectomy and bilateral pelvic lymphadenectomy. Patient age ranged from 57 to 78 years (mean, 61 years). The interval from radiation therapy to biopsy ranged from 1.0 to 17 years (mean, 3.9 years). Histologic features that were helpful in the diagnosis of cancer after radiation therapy included infiltrative growth, perineural invasion, intraluminal crystalloids, blue mucin secretions, the absence of corpora amylacea, and the presence of coexistent high-grade prostatic intraepithelial neoplasia. Benign glands usually showed nuclear enlargement (86%) and prominent nucleoli (50%), and therefore, these cytologic features alone were not reliable for the diagnosis of cancer after irradiation. Postirradiation needle biopsies underestimated the prostatectomy Gleason grade in 35% of cases and overestimated it in 14% of cases; these results were similar to published reports from patients not receiving radiation therapy. There was a major discrepancy in degree of radiation effect between radical prostatectomy and biopsies. Moderate or severe radiation effect on cancer was present in 48% of needle biopsy specimens, whereas 94% of radical prostatectomy specimens had no or minimal radiation effect on cancer when the areas with the least amount of radiation effect were chosen for quantification. These findings indicate that quantification of radiation effect in needle biopsy specimens was inaccurate and potentially misleading. Conversely, Gleason grade in postirradiation needle biopsy specimens appeared to provide useful predictive information and should be reported.

[Conformal radiotherapy of prostatic cancer: a general review]

Recent progress in radiotherapeutic management of localized prostate cancer is reviewed. Clinical aspects--including dose-effect beyond 70 Gy, relative role of conformal radiation therapy techniques and of early hormonal treatment--are discussed as well as technical components--including patient immobilization, organ motion, prostate contouring, beam arrangement, 3-D treatment planning and portal imaging. The local control and biological relapse-free survival rates appear to be improved by high dose conformal radiotherapy from 20 to 30% for patients with intermediate and high risk of relapse. A benefit of overall survival is expected but not yet demonstrated. Late reactions, especially the rectal toxicity, remain moderate despite the dose escalation. However, conformal radiotherapy demands a high precision at all steps of the procedure.

Treatment changes in prostatic hyperplasia and cancer, including androgen deprivation therapy and radiotherapy

Substantial and characteristic changes occur in the microscopic appearance and immunophenotype of the hyperplastic prostate and adenocarcinoma following androgen deprivation therapy and radiotherapy. These changes are rarely seen in untreated cancer, and in the authors' opinion, the combinations of features following therapy are sufficiently distinctive to warrant recognition. Pathologists must be aware of these distinct changes because of the reliance placed on nuclear and nucleolar size in the identification of prostate cancer, particularly in small specimens and lymph node metastases.

Prevalence and distribution of prostatic intraepithelial neoplasia in salvage radical prostatectomy specimens after radiation therapy

High-grade prostatic intraepithelial neoplasia (PIN) is the most likely precursor of prostate cancer. The effect of radiation therapy (RT) on the prevalence of PIN is uncertain. We studied 86 patients who underwent salvage radical prostatectomy after irradiation failure at the Mayo Clinic. The prevalence, volume, multicentricity, spatial proximity to cancer, and architectural patterns of PIN were evaluated. High-grade PIN was identified in 53 (62%) of 86 prostatectomy specimens. Multiple architectural patterns were usually observed, including tufting in 87%, micropapillary in 66%, cribriform in 38%, and flat in 17%. The mean volume of PIN was 0.12 cm3 (range, 0.05-1.20 cm3). PIN was usually multicentric (70%), with a mean number of PIN foci of 2.5 (range, 1-10). Ninety-four percent of PIN foci were located within 2 mm of invasive cancer. There was no correlation between PIN and pathologic stage, surgical margin, tumor size, DNA ploidy, post-RT Gleason score, time interval from RT to biopsy-proven recurrence, postoperative prostate-specific antigen level, distant metastasis-free survival, or cancer-specific survival. Our examination of salvage radical prostatectomy specimens indicated that the prevalence and extent of PIN appeared to be reduced after RT compared to published studies of prostatectomies without prior RT.

Calculated effects of displacement errors in external beam radiotherapy of prostatic adenocarcinoma

In order to evaluate the impact on the biological effective dose (BED) of irradiation delivered to a tumour with large displacement errors (LDE) and to estimate the effect on local control, simulated treatment of prostatic adenocarcinoma was performed. The calculation of BED in combination with the critical-voxel model and the LQ model was used to evaluate the effect of different combinations of LDEs. The model is called the Dose Volume Inhomogeneity Corrected BED (DVIC-BED) model. The dose-response curve was assumed to follow Poisson statistics. Different combinations of radiobiological parameters were used to test the model. A simulated clinical treatment with a dose of 66-80 Gy in 2 Gy fractions was carried out to evaluate displacement errors and non-optimal dose distributions. Five random LDEs excluding 33% of the target volume corresponded to an overall dose reduction of 3-5 Gy compared with a 10 Gy reduction if 100% of the target is missed five times. A 5 Gy decrease in dose corresponds to a reduction in clinical or chemical control up to 10-25% in the interval 65-85 Gy. LDEs in different directions are less deleterious than errors occurring in the same direction. Different alpha/beta-ratios (3-15) had little effect on the DIC-BED, but the effect of different alpha values (0.05, 0.2 and 0.5) was large. However, the results depend on radiobiological parameters for prostatic adenocarcinoma, which not are well known, and further studies in the field should be encouraged.

Fractionated radiotherapy of rat prostatic adenocarcinoma (Dunning R3327-PAP) in nonanesthetized animals

BACKGROUND

The dose-response effect of fractionated external beam radiotherapy on nonanesthetized rats bearing the androgen-sensitive prostatic adenocarcinoma Dunning R3327-PAP was studied.

METHODS

The radiation was given with a photon beam from a 4-MeV linear accelerator in doses from 4 to 11 Gray per fraction during 5 consecutive days. When the tumors with low and intermediate radiation doses relapsed into regrowth, the rats were castrated. Tumor volumes and rat weights were followed, and at the end of the study a morphometric analysis of the tumors was done.

RESULTS

Fractionated irradiation induced a dose-dependent delay in tumor growth in hormonally intact rats. Castration stopped the tumor regrowth, showing that some of the tumor cells were still hormone-sensitive. The study was facilitated by the nonanesthesia procedure.

CONCLUSIONS

The Dunning R3327-PAP hormone-sensitive rat tumor is sensitive to radiotherapy in a dose-dependent way. Regrowing, irradiated tumors contain hormone-sensitive cells. This work provided basic knowledge for further experimental studies of the effects of radiation on prostatic adenocarcinoma.

Predictors of survival for prostate carcinoma patients treated with salvage radical prostatectomy after radiation therapy

BACKGROUND

Salvage radical prostatectomy is a treatment option for patients with recurrent cancer following radiation therapy. This study was conducted to identify predictors of survival for patients treated with salvage radical prostatectomy.

METHODS

The authors studied 86 prostate carcinoma patients who underwent salvage radical prostatectomy for locally persistent or recurrent prostate carcinoma at Mayo Clinic between 1967 and 1996. The mean interval from radiation therapy to biopsy-proven recurrence was 3.7 years (range, 6 months to 17 years). Patient age at surgery ranged from 51 to 78 years (median, 66 years). The mean follow-up after surgery was 5.8 years (range, 1.0-15.2 years). Cox proportional hazards models were used to identify clinical and pathologic factors associated with distant metastasis free survival and cancer specific survival.

RESULTS

Actuarial distant metastasis free survival, cancer specific survival, and overall survival were 83%, 91%, and 85% at 5 years and 69%, 64%, and 54% at 10 years, respectively. In multivariate analysis, radical prostatectomy Gleason score and DNA ploidy were independent predictors of distant metastasis free survival and cancer specific survival.

CONCLUSIONS

Postirradiation Gleason score and DNA ploidy were highly predictive of the clinical outcomes of patients treated by salvage radical prostatectomy after radiation therapy.

[Radiotherapy of stage T1-T2 M0 prostatic adenocarcinoma. Analysis of the carcinologic results of a multicenter study of 610 patients. Groupe Radiothérapie de la Commission de Coopération Médicale Intercentres (CCMI)]

PURPOSE

Retrospective analysis of the results of radiotherapy in localized prostatic adenocarcinoma. Complications were excluded.

PATIENTS AND METHODS

Six-hundred-and-ten T1-T2 adenocarcinomas of the prostate were treated with continuous courses of external beam radiation therapy in 19 participating Institutes between January 1983 and January 1988. The mean follow-up was 10.4 years; the mean age of patients at the beginning of radiotherapy was 68.5 years.

RESULTS

A 10-year, local control had been achieved in 86% of T1-T2 (81.4% for T2). The 5- and 10-year metastatic relapse rates were 25.3% and 30% (29% and 38.1% for T2), respectively. At 10 years, 62.4% of T1-T2 were recurrence-free; overall survival rate was 45.8% and cause-specific survival rate was 70.5%; 29.9% of T1-T2 patients were alive and disease-free. T category (TNM), pathologic grade, pelvic lymph node status, local tumor control, and obstructive ureteral symptoms were correlated with survival. The influence of pelvic nodes radiation, dose, overall treatment time, previous endocrine treatment, and transuretral resection was not significant for disease-free survival (alive and disease-free) and other endpoints.

CONCLUSION

There was no difference between the French series (1975-1982 and 1983-1988). The results of the literature are comparable to ours. As far as prognostic factors are concerned, this report provides evidence that the explainable variables which influence survival depend on the tumor and patient status.

[Indications and results of exclusive radiotherapy in early prostatic adenocarcinoma]

Prostate adenocarcinoma incidence are rising rapidly, especially in early stages. Even if some of these carcinomas may be latent or slow growing either spontaneously or under hormonal therapy, most patients 75 years old or less presenting a localized tumor, T1b-c, T2, T3, N0, M0, whatever the grading, will require treatment with curative intent: radical prostatectomy, external beam radiation therapy (ERT) and/or brachytherapy. After ERT limited to the prostate or including seminal vesicles and/or pelvic lymph nodes, the overall survival and the survival without clinical evolution at 5, 10 and 15 years are good. However survival rates without biochemical evolution are about 30% lower and 70% or less at 5 years for the more favorable group (T < or = T2a and Gleason < 7 and PSA < 10 ng/mL). Brachytherapy alone yields good results for the same favorable group. In the unfavorable group (T > or = 2c and Gleason > or = 7 and PSA > or = 20 ng/mL), adjuvant hormonal therapy improves survival. Conformal radiation therapy allows an increase in dose to the tumor by about 15% without increasing complications. It can increase the biological remission rate in the intermediate group (T < or = 2a or Gleason > or = 7 or PSA > or = 20 ng/mL).

Combined treatment with temporary short-term high dose rate iridium-192 brachytherapy and external beam radiotherapy for irradiation of localized prostatic carcinoma

PURPOSE

To evaluate the treatment outcome after radical radiotherapy of localized prostate cancer in 50 patients (38 patients with stage T1-2 and 12 patients with stage T3) after a median follow-up time of 45 months (range 18-92 months).

METHODS

The treatment was given by combination of external beam radiotherapy (50 Gy) and brachytherapy (2 x 10 Gy). The brachytherapy was given using TRUS-guided percutaneously inserted temporary needles with a high dose rate remote afterloading technique with Ir-192 as the radionuclide source. Three target definitions and dose levels inside the prostate gland were used. Local control was evaluated by digital rectal examination, TRUS-guided biopsies and serum PSA evaluations.

RESULTS

Clinical and biopsy verified local control was achieved in 48 of the 50 (96%) patients; for stage T1-2 in 37 of 38 (97%) patients and for stage T3 in 11 of 12 (92%) patients. A posttreatment serum PSA level < or =1.0 ng/ml was seen in 42 (84%) patients, values from >1.0 to < or =2.0 ng/ml were seen in four (8%) patients and values exceeding 2.0 were seen in four (8%) patients. The late toxicity was minimal.

CONCLUSION

The local control results and the minimal toxicity after the combined radiotherapy treatment are promising. However, long term results are necessary before general use.

Long-term results of retropubic permanent 125iodine implantation of the prostate for clinically localized prostatic cancer

PURPOSE

The historical series of retropubic prostate radioactive source implantation from the Memorial Sloan-Kettering Cancer Center has served as the framework for the current transperineal implant approaches used in the treatment of localized prostatic cancer. We report the final assessment of the 15-year outcome.

MATERIALS AND METHODS

Between March 1970 and December 1987, 1,078 patients with biopsy proved adenocarcinoma of the prostate were treated at our cancer center with permanent implantation of 125iodine via a retropubic approach. In addition, all patients underwent bilateral pelvic lymphadenectomy before implantation. The clinical stages of disease were B1 in 234 patients (22%), B2 in 472 (44%), B3 in 145 (14%) and C in 227 (20%). Of the patients 733 (68%) had pathologically negative lymph nodes, whereas 345 (32%) had positive lymph nodes at lymph node dissection. Median followup was 11 years.

RESULTS

Multivariate analysis identified nodal involvement, high grade disease, clinical stage B3/C and implant doses less than 140 Gy, as independent predictors of local relapse. Independent predictors of distant metastases included nodal involvement, stage B3/C disease and poorly differentiated histological status. The local recurrence-free survival rates for patients with negative nodes at 5, 10 and 15 years were 69, 44 and 24%, respectively. The distant metastases-free survival rates at 5, 10 and 15 years for patients with negative lymph nodes were 59, 36 and 21%, respectively.

CONCLUSIONS

125Iodine implantation of the prostate via the retropubic approach was associated with a greater than expected incidence of local relapse at 15 years. Technical limitations of the retropubic technique resulting in suboptimal distribution of the isotope within the prostate are believed to be the explanation for the inferior local control outcome. Although long-term results are not yet available, the 5-year results of the computer optimized transperineal prostate implantation suggest that improved implant techniques will translate into a greater likelihood of tumor control.

Pretreatment p53 immunoreactivity does not infer radioresistance in prostate cancer patients

PURPOSE

To test, in a clinical context, the hypothesis that p53 aberrations, assessed by immunoreactivity, are related to radioresistance as suggested by several experimental studies.

METHODS AND MATERIALS

Sixty patients with prostate cancer who underwent transurethral resection of the prostate or biopsy prior to definitive external beam therapy were retrospectively identified. The endpoint in the study was cancer specific survival. The nuclear accumulation of the aberrant p53 protein was evaluated by immunohisto-chemistry with the pantropic, monoclonal Ab-6 anti-p53 antibody (clone DO-1) on pretreatment biopsies. Immunoreactivity was related to stage, grade, and cancer-specific survival.

RESULTS

There was a correlation between p53 immunoreactivity and low tumor stage (p < 0.001), but no relation between p53 status and grade was found. Moreover, no significant difference was found in cancer-specific survival between the p53 positive tumors (109 months) and the p53 negative tumors (99 months).

CONCLUSIONS

No disadvantage regarding survival was seen for patients with p53 immunoreactive tumors, implicating that p53 immunoreactivity does not infer radioresistance in prostate cancer. This suggests that the p53 inactivation may be a less important determinant of tumor response to radiotherapy in some human cancers than in the previously studied experimental situations. Thus, other mechanisms may be more important in determining outcome after radiation. However, the series is small and data should be interpreted with caution.

The "critical volume tolerance method" for estimating the limits of dose escalation during three-dimensional conformal radiotherapy for prostate cancer

PURPOSE

To describe the "Critical Volume Tolerance" (CVT) method for defining normal tissue tolerance during 3D-based dose escalation studies for prostate cancer.

METHODS AND MATERIALS

The CVT method predicts the tolerance to radiation for "in series"-type functional units based on the assumption that tolerance depends on a critical threshold "low-volume high-dose region." The data used for describing this model were generated from 3D analysis of randomly selected patients with prostate cancer. Commonly used coplanar four-and six-field conformal (SFC) techniques were chosen as the comparison techniques. For purposes of comparison, rectal tolerance was assumed to be reached following whole pelvic irradiation using a four-field box technique to 50 Gy, followed by a conedown boost to 70 Gy using bilateral 9 x 9 cm 120 degree arcs as popularized by investigators from Stanford University (SUH).

RESULTS

Based on the average dose volume histograms for the patients studied, the maximum safe increase in dose for the SFC technique compared to the SUH technique, would be 10% if 30% of the rectal volume was the critical dose limiting volume (CVT = 30%), 5% if the CVT = 10%, or greater than 20% if the CVT = 40%. Commonly used four-field conformal techniques would not be expected to allow significant escalation of the dose without increasing the risk of complications.

CONCLUSIONS

The CVT method is relatively simple, and data generated based on it can be used to support normal tissue complication probability equations. The CVT method can be verified or modified as partial tolerance data become available. Based on the CVT model, sophisticated treatment techniques should allow a modest increase in the total dose of radiation delivered to the prostate without an increase in late complications.

Should asymptomatic progression following definitive local treatment for prostate cancer be treated?

Asymptomatic progression following definitive therapy for prostate cancer can take the form of a detectable prostate-specific antigen (PSA) or local recurrence following radical prostatectomy or a rising PSA or palpable recurrence following radiotherapy. Options for treatment include hormonal therapy, radiotherapy, salvage surgery, and experimental therapies. Although such forms of treatment have known effects on intermediate endpoints, such as reduction of PSA, the overall effect on survival and quality of life is uncertain.

Prostate cancer

This synthesis of the literature on radiotherapy for prostate cancer is based on 53 scientific articles, including 4 randomized studies, 3 prospective studies, and 44 retrospective studies. These studies involve 52005 patients. The literature provides no apparent evidence to motivate radiotherapy, or any treatment, for highly differentiated T0 tumors. Some findings suggest that radiotherapy or surgery may be indicated for poorly differentiated tumors. The literature however shows no differences in tumor effects between these two methods for treating T0 tumors. Radiotherapy is milder and less mutilating. Conclusions cannot be drawn from the literature concerning whether surgery (radical prostatectomy) or external radiotherapy is preferable for T1 and T2 tumors. Most probably, some patients are more suitable for surgery, others for radiotherapy. More patients are, nevertheless, candidates for radiotherapy. The value of external radiotherapy for T3 tumors is documented. Radiotherapy is valuable as palliative treatment for T4 tumors. Radiotherapy may be valuable as localized, symptom-relieving treatment for generalized prostate cancer. Treatment given via a few high fractions saves patients' time, hospitalization, and resources. Concerning individualized treatment, the differentiation grade is important for the choice of treatment method, mainly in early, but even in late clinical stages. This may involve choosing between radiotherapy and endocrine therapy, or even choosing between radiotherapy and surgery. The value of external radiotherapy increases as the differentiation grade of the tumor decreases. It is essential to treat patients at facilities that have the diagnostic potential to establish the differentiation grade of tumors. The value of postoperative radiotherapy has not yet been demonstrated at any clinical stage of prostate cancer. Treatment results from interstitial brachytherapy alone appear to be clearly inferior to the results from other methods. The value of combining interstitial/external radiotherapy should be studied further.

High failure rate associated with long-term follow-up of neoadjuvant androgen deprivation followed by radical prostatectomy for stage C prostatic cancer

OBJECTIVE

To evaluate whether neoadjuvant androgen deprivation before radical prostatectomy decreases tumour stage in patients with stage C prostatic cancer and to estimate the efficacy of cancer control achieved with this form of treatment.

PATIENTS AND METHODS

Thirty men (mean age 65 years, range 52-74) with clinical stage C adenocarcinoma of the prostate were included in a phase II trial of neoadjuvant androgen deprivation (luteinizing hormone-releasing hormone agonist and an antiandrogen) before radical prostatectomy. The timing and extent of the changes in serum prostate specific antigen (PSA) levels and both prostate and cancer volume were recorded. Twenty-six men underwent radical prostatectomy with pelvic lymphadenectomy, two had pelvic lymphadenectomy alone, one had pelvic lymphadenectomy with radiotherapy and one refused additional treatment despite significant reductions in tumour volume and PSA while undergoing androgen deprivation.

RESULTS

The toxicity of the treatment was low. Significant reductions in prostatic volume (mean 35%), tumour volume (mean 50%) and PSA concentrations (mean 96%) occurred in all patients, with the maximum reductions recorded during the first 2 months of androgen deprivation. However, despite significant physiological changes in prostate and tumour volume, tumour stage was reduced in only four patients. Of the patients who were surgically staged 41% were ultimately identified as having more advanced disease, including lymph node metastases in 21%. Overall, with a mean follow-up of 32.7 months, 72% of patients had evidence of disease recurrence, including detectable PSA. Of 26 patients who underwent radical prostatectomy, local recurrence occurred in five (19%), distant recurrence in one (4%) and both local and distant recurrence in one (4%).

CONCLUSIONS

This study suggests that tumour stage reduction is uncommon in patients with stage C prostatic cancer treated with neoadjuvant androgen deprivation followed by radical prostatectomy. Furthermore, local and distant recurrences, as well as detectable levels of PSA, are common after such treatment.

External beam radiotherapy of localized prostatic adenocarcinoma. Evaluation of conformal therapy, field number and target margins

The purpose of the present study was to identify factors of importance in the planning of external beam radiotherapy of prostatic adenocarcinoma. Seven patients with urogenital cancers were planned for external radiotherapy of the prostate. Four different techniques were used, viz. a 4-field box technique and four-, five- or six-field conformal therapy set-ups combined with three different margins (1-3 cm). The evaluations were based on the doses delivered to the rectum and the urinary bladder. A normal tissue complication probability (NTCP) was calculated for each plan using Lyman's dose volume reduction method. The most important factors that resulted in a decrease of the dose delivered to the rectum and the bladder were the use of conformal therapy and smaller margins. Conformal therapy seemed more important for the dose distribution in the urinary bladder. Five- and six-field set-ups were not significantly better than those with four fields. NTCP calculations were in accordance with the evaluation of the dose volume histograms. To conclude, four-field conformal therapy utilizing reduced margins improves the dose distribution to the rectum and the urinary bladder in the radiotherapy of prostatic adenocarcinoma.

Primary radiation therapy in the treatment of localized prostatic cancer

Prostatic carcinoma is one of the leading causes of male cancer deaths. However, the routine diagnostic and therapeutic strategies have not yet been established. Although the outcome of surgical and radiotherapeutical approaches has frequently been reported to be comparable, the profile of side effects is different. This could offer the basis for selecting the treatment of choice in individual cases. During the last decade the radiotherapeutical technique has markedly improved, in part due to the achievements in the field of computer assisted tomography planning and conformal technique; the outcome of side-effects has decreased with concurrent increase in the rate of local control. The prescribing, recording and reporting of irradiation have also recently developed, as well as the staging of the disease. Therefore we consider it timely to review progress in this subject and to emphasize the role of radiotherapy in the treatment of localized prostatic cancer.

Influence of radiotherapy on node-positive prostate cancer treated with androgen ablation

PURPOSE

Patients with node-positive prostate cancer that is regionally localized (T1-4, N1-3, M0) have a relatively poor prognosis when a single-treatment modality such as radical surgery, definitive radiotherapy, or androgen ablation is used. While promising results using radical surgery and androgen ablation have been reported, there are no data to support an analogous approach using local radiotherapy and androgen ablation. In this retrospective review, the outcome after local radiotherapy and early androgen ablation (XRT/HORM) was compared to early androgen ablation alone (HORM).

METHODS AND MATERIALS

Between 1984 and 1992 there were 181 patients treated with HORM and 27 patients treated with XRT/HORM at the University of Texas M. D. Anderson Cancer Center. The nodal status of all patients was established pathologically by lymph node dissection, which was terminated after frozen section confirmation of involvement. In the majority of cases androgen ablation was by orchiectomy. The median dose to the prostate in XRT/HORM group was 66 Gy. The median follow-up was 45 months; 49 months for the HORM group and 25 months for the XRT/HORM group.

RESULTS

The distribution of prognostic factors between the HORM and XRT/HORM groups was similar, with the exception of tumor grade. There was a significantly larger proportion of high grade tumors in the HORM group. In terms of actuarial disease outcome, at 4 years the results of patients in the HORM group were significantly worse, including a rising prostate specific antigen (PSA) of 53%, any disease progression of 32%, a rising PSA or disease progression of 55%, and local progression of 22%. None of the patients in the XRT/HORM group failed biochemically or clinically. To determine the impact of grade on these findings, the analyses were repeated, using only those with grade 2 tumors. A similar pattern was evidenced with significantly worse actuarial outcome at 4 years for the HORM group using the endpoints of a rising PSA (46%), any disease progression (24%), and a rising PSA or disease progression (47%).

CONCLUSION

Node-positive prostate cancer patients with regionally localized disease fared significantly better when combined local radiotherapy and early androgen ablation were used, as compared to early androgen ablation alone. Although the number of patients in the XRT/HORM group was small and follow-up was short, the combined treatment had a dramatic effect on disease outcome and, therefore, a larger prospective randomized trial is warranted.

Field displacement during external radiotherapy in prostatic adenocarcinoma treated with radioactive 198Au implants and external irradiation

The purpose of this work was to study displacement error and internal movements of the prostate during external beam radiotherapy. Verification films in the frontal (n = 194) and lateral (n = 64) portals were investigated in 14 patients treated with radioactive 198Au implants. Displacement errors of two implants were investigated. In seven patients, filling of the rectum and the bladder with contrast medium or isotonic saline was performed during CT investigation for planning purposes to detect movements of the prostate. Most (95%) of the displacement errors were less than 10 mm in the frontal portal and less than 15 mm in the lateral portals. No correlation to the patient's weight was found. The displacement errors were randomly distributed. The spatial relations between the implants were not altered during the treatments. Small movements of the prostate were observed. To conclude, the positioning system employed at present (laser) can be sufficient for the margins used (2 cm). In lateral portals, however, the system did not have the ability to detect a possible systematic displacement error from simulator to accelerator. The intention is to decrease the margins to 1 cm, which will necessitate a better positioning system.

Salvage radical prostatectomy: outcome measured by serum prostate specific antigen levels

We reviewed our experience with salvage radical prostatectomy for locally recurrent cancer in 40 patients to assess the current complication rate and the results using prostate specific antigen (PSA) as an indicator of treatment outcome and to identify better criteria for the selection of appropriate candidates for this operation. Most recurrent cancers were detected by digital rectal examination (26 patients) or increasing serum PSA levels (10). The operation was technically challenging, with 6 rectal injuries (15%), 2 requiring temporary colostomy. Serious technical complications were more common (31%) among the 29 patients who underwent pelvic lymphadenectomy at the time of initial radiotherapy than among the 11 treated with external irradiation alone (9%). Urinary incontinence persisted in 18 of 31 evaluable patients (58%) and was successfully corrected with an artificial urinary sphincter in 9. A total of 21 patients (54%) had pathologically advanced disease (seminal vesicle invasion and/or lymph node metastases). Preoperative PSA levels but not clinical stage or biopsy grade correlated with pathological stage (p < 0.03). If the PSA was less than 10 ng./ml. only 15% of the patients had an advanced pathological stage, compared to 86% if the PSA was 10 or more. After 2 to 97 months (mean 39) 2 patients died of metastatic prostatic cancer, 5 had distant metastases and none had symptomatic local recurrence. At 5 years the actuarial nonprogression rate measured by PSA was 55 +/- 20%. The only pretreatment factor predictive of progression was the serum PSA level. If the PSA was less than 10 ng./ml. the actuarial rate of progression was significantly lower than if the PSA was greater than 10 (p < 0.05). The best results were in the subset of 18 patients with cancer confined to the prostate or immediate periprostatic tissue: 82% had no progression at 5 years. Within each of these pathological stages the results of salvage prostatectomy were similar to those for standard radical prostatectomy in patients with no prior irradiation. Although technically challenging, salvage prostatectomy provides excellent control of radio-recurrent cancer confined to the prostate or immediate periprostatic tissue and is best performed before the preoperative PSA level increases to greater than 10 to 20 ng./ml.

Phase II trial of external beam radiation with etanidazole (SR 2508) for the treatment of locally advanced prostate cancer

PURPOSE

To evaluate the efficacy and toxicity of the addition of etanidazole (ETA) to external beam radiation.

METHODS AND MATERIALS

Fifty eight previously untreated patients with locally advanced adenocarcinoma of the prostate were entered on a Phase II trial of etanidazole (ETA) combined with standard external beam radiation therapy. ETA was given concurrently with irradiation. Four patients received less than 25% of the intended dose of ETA and were ineligible for further analysis. The stage of the remaining patients were T2c-11, T3-39, T4-1, bulky local recurrence after prostatectomy-1, and T3, N1-2.

RESULTS

Forty-five of 54 patients (83.3%) achieved a clinical complete response (CCR) in the prostate and seminal vesicles as judged by digital rectal exam (DRE). Responses were rapid with a median time to CCR of 3.4 months, range 0-22.8 months. Local control was maintained in 82% of the patients who achieved a CCR. Fifteen of 32 eligible patients with a normal DRE underwent prostate biopsies from 12-20 months after treatment, seven had negative biopsies (46.6%). Distant metastases occurred in 18 patients (33.3%). Pretreatment prostatic specific antigen (PSA), Gleason score, and stage were not associated with treatment outcome in a univariate analysis.

CONCLUSION

While ETA plus radiation was associated with a rapid CCR, the overall treatment outcome of these patients appeared to be similar to published reports of patients receiving RT alone. The rapid response rate may imply biologic activity of the ETA. In future trials, it may be reasonable to focus on patients at lower risk for the subsequent development of distant disease.