Transcutaneous ultrasound level check for selective dorsal rhizotomy.

AIM: Single-level selective dorsal rhizotomy (SDR) surgery requires an intra-operative level check to identify the L1 vertebral level or the conus medullaris. Typically, this requires a pre-operative or intra-operative x-ray. We present our experience using initial transcutaneous ultrasound as an alternative to x-ray level check. METHODS: A prospective SDR database was used to identify patients. The operation notes were reviewed to identify the level check method and any complications or wrong-level surgery. RESULTS: Data are reported for the first 160 SDR surgeries performed within our centre, mean age 6.47 years (range 2.5-19 years). The first 11 patients had combined x-ray and transcutaneous ultrasound for pre-incision level check. This allowed the neurosurgeon to assess the accuracy and feasibility of using transcutaneous ultrasound instead of x-ray. The subsequent 149 patients had ultrasound alone for transcutaneous pre-incision level check. An intra-operative ultrasound level check was performed for all patients following skin incision and dissection down to the spinal lamina. In this way, the conus level was confirmed before dural opening. For all patients at all ages, the combination of initial transcutaneous ultrasound followed by intra-operative ultrasound allowed accurate identification of the conus. There were no instances of wrong-level surgery. Learning points are presented within this paper. CONCLUSION: Combined use of transcutaneous ultrasound followed by intra-operative ultrasound can allow accurate identification of the conus, saving radiation exposure and potentially improving theatre efficiency. Appropriate training and experience are required for any neurosurgeon using these techniques.

Radiosurgery for skull base malignancies and nasopharyngeal carcinoma.

PURPOSE: Patients with skull base lesions present a challenging management problem because of intractable symptoms and limited therapeutic options. In 1989 we began treating selected patients with skull base lesions using linac stereotactic radiosurgery. In this study the efficacy and toxicity of this therapeutic modality is investigated. METHODS AND MATERIALS: Forty-seven patients with 59 malignant skull base lesions were treated with linac radiosurgery between 1989 and 1995. Eleven patients were treated for primary nasopharyngeal carcinoma using radiosurgery as a boost (7 Gy-16 Gy, median: 12 Gy) to the nasopharynx after a course of fractionated radiotherapy (64.8-70 Gy) without chemotherapy. Another 37 patients were treated for 48 skull base metastases or local recurrences from primary head and neck cancers. Eight of these patients had 12 locally recurrent nasopharyngeal carcinoma lesions occuring 6-96 months after standard radiotherapy, including one patient with nasopharyngeal carcinoma who developed a regional relapse after radiotherapy with a stereotactic boost. Lesion volumes by CT or MRI ranged from 0 to 51 cc (median: 8 cc). Radiation doses of 7.0 Gy-35.0 Gy (median: 20.0 Gy) were delivered to recurrent lesions, usually as a single fraction. RESULTS: All 11 patients who received radiosurgery as a nasopharyngeal boost after standard fractionated radiotherapy remain locally controlled (follow-up: 2-34 months, median: 18). However, one patient required a second radiosurgical treatment for regional relapse outside the initial radiosurgery volume. Thirty-three of 48 (69%) recurrent/metastatic lesions have been locally controlled, including 7 of 12 locally recurrent nasopharyngeal lesions. Follow-up for all patients with recurrent lesions ranged from 1 to 60 months (median: 9 months). Local control did not correlate with lesion size (p = 0.80), histology (p = 0.78), or radiosurgical dose (p = 0.44). Major complications developed after 5 of 59 treatments (8.4%), including three cranial nerve palsies, one CSF leak, and one trismus. Complications were not correlated with radiosurgical volume (p = 0.20), prior skull base irradiation (p = 0.90), or radiosurgery dose > 20 Gy (p = 0.49). CONCLUSION: Stereotactic radiosurgery is a reasonable treatment modality for patients with skull base malignancies, including patients with primary and recurrent nasopharyngeal carcinoma. The dose distribution obtained with stereotactic radiosurgery provides better homogeneity than an intracavitary implant when used as a boost for nasopharyngeal lesions, especially lesions which involve areas distant to the nasopharyngeal mucosa.

Gastrointestinal cancer after treatment of Hodgkin's disease.

PURPOSE: This study aimed to quantify the risk of gastrointestinal cancer following Hodgkin's disease treatment according to age at treatment, type of treatment, and anatomic sites. METHODS AND MATERIALS: Cases were identified from the records of 2,441 patients treated for Hodgkin's disease between 1961 and 1994. Follow-up averaged 10.9 years, representing 26,590 person-years of observation. Relative risks (RR) for gastrointestinal cancer incidence and mortality were computed by comparison with expected annualized rates for a general population matched for age, sex, and race. RESULTS: Gastrointestinal cancers developed in 25 patients. The incidence RR was 2.5 [95% confidence interval (CI), 1.5-3.5] and mortality RR was 3.8 (CI, 2.4-4.7). Sites associated with significantly increased risks included the stomach [RR 7.3 (CI, 3.4-13.8)], small intestine [RR 11.6 (CI, 1.9-38.3)], and pancreas [RR 3.5 (CI, 1.1-8.5)]. Risk was significantly elevated after combined modality therapy, RR 3.9 (CI, 2.2-5.6). The risk after radiotherapy alone was 2.0 (CI, 1.0-3.4), not a statistically significant elevation. The RR for gastrointestinal cancer was greatest after treatment at young age and decreased with advancing age. It was significantly elevated within 10 years after treatment [RR 2.0 (CI, 1.1-3.5)] and increased further after 20 years [RR 6.1 (CI, 2.5-12.7)]. Risk assessed by attained age paralleled risk according to age at treatment. Fifteen cases of gastrointestinal cancers arose within the irradiation fields. CONCLUSION: Patients treated for Hodgkin's disease are at modestly increased risk for secondary gastrointestinal cancer, especially after combined modality therapy and treatment at a young age. Risk was highest more than 20 years after treatment, but was significantly elevated within 10 years. Gastrointestinal sites with increased risk included the stomach, pancreas, and small intestine.

The accuracy of dose localization for an image-guided frameless radiosurgery system.

A compact X-band accelerator mounted on a robotic arm is under development for frameless stereotaxic radiosurgery. The therapy beam is aimed at the lesion by an imaging system comprised of two diagnostic x-ray cameras that view the patient during treatment. Patient position and motion are measured by the cameras and communicated in real time to the robotic arm for beam targeting and patient motion tracking. The tests reported here measured the pointing accuracy of the therapy beam and the present targeting and tracking capability of the imaging system. The results show that the system achieves the same level of targeting precision as conventional frame-based radiosurgery.

Linear accelerator-based stereotaxic radiosurgery for brain metastases:the influence of number of lesions on survival.

PURPOSE: To evaluate the influence of the number of brain metastases on survival after stereotaxic radiosurgery and factors that affect the risk of delayed radiation necrosis after treatment. MATERIALS AND METHODS: Between March 1989 and December 1993, 120 consecutive patients underwent linear accelerator-based stereotaxic radiosurgery for brain metastases identified by computed tomography (CT) or magnetic resonance imaging (MRI) scans. The influence of various clinical factors on outcome was assessed using Kaplan-Meier plots of survival from the date of radiosurgery, and univariate and multivariate analyses. RESULTS: The median survival time was 32 weeks. Progressive brain metastases, both local and regional, caused 25 of 104 deaths. Patients with two metastases (n = 30) or a solitary metastasis (n = 70) had equivalent actuarial survival times (P = .07; median, 37 weeks; maximum, 211+ weeks). Patients treated to three or more metastases (n = 20) had significantly shorter survival times (P < .002; median, 14 weeks; maximum, 63 weeks). Prognostic factors associated with prolonged survival included a pretreatment Karnofsky performance status > or = 70% and fewer than three metastases. Delayed radiation necrosis at the treated site developed in 20 patients and correlated with prior or concurrent delivery of whole-brain irradiation and the logarithm of the tumor volume. CONCLUSION: Survival duration is equivalent for patients with one or two brain metastases and is similar to that reported for patients with a solitary metastasis managed by surgical resection and whole-brain irradiation. Survival after radiosurgery for three or more metastases was similar to that reported for whole-brain irradiation.

Thermal treatment parameters are most predictive of outcome in patients with single tumor nodules per treatment field in recurrent adenocarcinoma of the breast.

PURPOSE: In previously reported studies using radiation therapy (XRT) and hyperthermia (HT) for treatment of superficial metastases from adenocarcinoma of the breast, we have identified several pretreatment and treatment parameters that correlated with rate of initial complete response (ICR) recorded at 3 weeks and duration of local control (DLC). These parameters include minimal intratumoral temperature, Tmin, and the temperature exceeded by 90% of the measured intratumoral temperatures, T90. Recently, others have shown that thermal dose defined as the cumulative time of isoeffective treatments with T90 = 43 degrees C (CUM EQ MIN T90 43) was predictive of complete response in superficial tumors. We have assessed the prognostic value of several formulations of this parameter for both ICR and DLC in a relatively uniform patient population treated with XRT-HT. METHODS AND MATERIALS: The corresponding EQ MIN T90 43 were calculated for 332 HT treatments in 111 HT fields in 83 patients who started treatment between October 1982 and May 1992. Each field contained only one measurable superficially located nodular tumor recurrence or metastasis from adenocarcinoma of the breast that was treated with XRT-HT, had mapped or multiple point temperatures recorded, and had at least one posttreatment follow-up evaluation. The thermal doses from all treatments delivered to a field were added to obtain the total thermal dose, SUM EQ MIN T90 43. Logistic and life-table multivariate analyses were performed to determine which pretreatment parameters (including initial T-stage, prior XRT, and tumor volume at the time of HT) and treatment parameters (including XRT dose, Tmin, T90, thermal dose, and hormonal therapy) best correlated with ICR and DLC. RESULTS: Of the treatment parameters tested, SUM EQ MIN T90 43 had the strongest correlation with both ICR (p = 0.0002) and DLC (p = 0.0014). Also, SUM EQ MIN T90 43 contributed to the best multivariate models predictive of ICR and DLC. CONCLUSION: For this relatively uniform patient population, we have confirmed that SUM EQ MIN T90 43 is the treatment parameter most strongly correlated with not only response following XRT-HT, but also duration of local control. This formulation of thermal dose should permit prescriptions to be written for HT treatments. Prospective trials designed to confirm this thermal dose relationship are to be encouraged.

Prostate specific antigen after radiotherapy for prostate cancer: a reevaluation of long-term biochemical control and the kinetics of recurrence in patients treated at Stanford University.

PURPOSE: We evaluated prostate specific antigen (PSA) evidence for control of prostatic cancer after irradiation. MATERIALS AND METHODS: We studied 110 patients for whom more than 2 PSA measurements were obtained to establish trends and the initial measurement was done between April 1985 and January 1988. RESULTS: A total of 42 patients (38%) had stable, normal PSA levels with followup averaging 12.4 years (range 4.4 to 24.8). Increasing clinical stage or Gleason score correlated significantly with risk for PSA relapse, as did pretreatment PSA level. Short PSA doubling times were associated with distant metastasis rather than with local recurrence. CONCLUSIONS: We found that irradiation durably controlled 38% of prostatic cancers of various stages and grades and is unlikely to accelerate tumor growth.

Control of prostate cancer with radiotherapy: long-term results.

The long-term outcome for 1,245 patients with carcinoma of the prostate treated with external beam radiation therapy is presented. The median survival for all patients without evidence of distant metastases but irrespective of T stage of the primary tumor, histopathological grade or lymph node status was 10 years compared to 15 years for an age-matched cohort of California men. The cause specific survival at 15 years was 52%. The data base is subdivided into a series of subsets that demonstrate the impact of T stage, Gleason pattern score and lymph node involvement on long-term outcome. The best results were shown in stages T1 and T2a cases with histopathologically proved negative lymph nodes. Survival at 15 years was 53%, which was essentially identical to the 55% survival rate of an age-matched cohort. The actuarial survival at 15 years for all stages T1 and T2N0M0 cancer patients was 45% compared to 56% for an age-matched cohort.

Radiotherapy for prostatic cancer: patient selection and the impact of local control.

OBJECTIVE: To analyze the long-term results of external beam radiation therapy in patients under the age of sixty treated with early-stage prostate cancer. A comparison is also made between patients with early-stage, node-negative disease and those with locally advanced node-negative prostate cancer. METHODS: In this retrospective study, 54 patients who were treated with external beam radiation, when under the age of sixty with Stanford stage T1a and T1b (equivalent to urologic stage B1), are compared to 75 patients with similar staged disease who were sixty to seventy years old at time of treatment. In addition, 17 men who underwent open lymph node dissection with Stanford stage T1a and T1b N0M0 (equivalent to urologic stage B1, pathologic node negative) were compared to 30 patients with Stanford stage T3N0M0 (equivalent to urologic stage C, pathologic node negative) prostatic carcinoma. RESULTS: Patients under the age of sixty with clinically staged early prostate cancer exhibited a similar rate of local and metastatic control when compared to men treated when sixty to seventy years of age. Overall survival was not different than the expected survival in both groups. In patients with laparotomy-proven node-negative prostate cancer, those with locally advanced tumors had a poorer rate of local control, disease-specific survival, freedom from relapse, and survival when compared to patients with early-stage disease. CONCLUSIONS: These results suggest that men under sixty years old are candidates for radiotherapy, and these results are comparable to those attained with prostatectomy. Treatment approaches for controlling bulky local disease in patients without lymph node metastases have a potential to improve local control that may have an impact on survival.

Prostate-specific antigen kinetics after external beam irradiation for carcinoma of the prostate.

PURPOSE: A mathematical model that describes the kinetics of prostate-specific antigen measured in patients who received therapeutic doses of radiation therapy is presented. The clinical implications of the model are also investigated. METHODS AND MATERIALS: Data from 122 patients treated at Stanford University between December 1985 and December 1990 were used. The general form of the model contains five parameters, two associated with a decreasing exponential, two with a rising exponential and one additional constant. A nonlinear steepest-descent procedure that minimized chi-squared was used to determine the parameters producing the best fit to a patient's data. The correlation of the model parameters with clinical findings was investigated using standard statistical techniques including multivariate life-table and logistic regression. RESULTS: The data for all patients could be fit with either a decreasing exponential with or without the additional constant (nonrelapsing pattern with two or three parameters) or with a decreasing plus rising exponential (relapsing pattern with three or four parameters). In no instance were all five parameters of the general model required to describe a patient's data. Three of 61 patients with nonrelapsing patterns experienced clinical relapse, whereas 36 of 61 patients with relapsing patterns did. The logarithm of the initial prostate-specific antigen level and the corresponding model parameter correlated with T-stage and Gleason score. Among the patients with relapsing patterns, the nadir in antigen level occurred within 2 years of the start of treatment and the time to nadir, as calculated from the model parameters, was associated with the probability of clinical relapse. In no instance was the rate of initial decline ever exceeded by the rate of subsequent rise. CONCLUSION: The model is capable of describing the kinetics of prostate-specific antigen levels found in patients after receiving radiation therapy. The parameters derived from the model are strong correlates with clinical findings and patient outcome.

Predictors of survival after a positive post-irradiation prostate biopsy.

PURPOSE: Considerable debate persists in the urologic oncology literature with regard to the optimum management of patients with a positive post-irradiation prostate biopsy. This analysis characterizes a group of such patients who have had a favorable course without intervention. METHODS AND MATERIALS: Between 1956 and 1991, 116 patients have had a positive prostate biopsy 12 or more months post-irradiation without hormonal intervention or evidence of distant relapse. The population had an age range of 42 to 82 years (median - 61). American Joint Committee on Cancer stages included 1 T1, 70 T2, 44 T3, and 1 T4. Median actuarial survival for the entire population was 14.4 years (range = 2.2-21.5 years) from presentation and 5.2 years from re-biopsy. RESULTS: Fifty-one of the 116 patients developed metastases subsequent to re-biopsy and 65 remain free from distant relapse. Among these 65 patients, 50 remain alive and otherwise well, 11 have died of other causes, and only four have succumbed to their local disease. The best predictor of distant relapse subsequent to re-biopsy was digital rectal exam. Forty-one of the 51 patients later developing metastases had an abnormal digital rectal exam compared to 37 of 65 with sustained distant control (p = .01). CONCLUSION: These data demonstrate that long-term, disease-free (other than re-biopsy) survival is common following a "positive" post-irradiation biopsy without intervention especially among patients with a normal digital rectal exam. Therefore, routine re-biopsy without clinical indications is not a useful practice.

Radiation induced height impairment in pediatric Hodgkin's disease.

PURPOSE: To quantitate the impairment in skeletal growth from radiation treatment, we reviewed height measurements among children with Hodgkin's disease irradiated at Stanford University Medical Center between 1965 and 1986. METHODS AND MATERIALS: One hundred and twenty-four children with Hodgkin's disease, in whom long-term follow-up data were available, became the subjects for this analysis. They all had baseline height measurements within 1 year of radiation treatment, a final height measurement beyond age 15 for boys and 13 for girls, and a minimum time interval between baseline and final measurement of 2 years. A baseline and final percent height, as compared to a reference standard, was calculated for each patient. The difference between these two figures was used to assess height impairment. The study group was divided into age and treatment groups and a comparative analysis between these groups was performed. RESULTS: Height impairment was most severe among children who were given high dose radiation to the entire spine when pre-pubertal in age. These patients demonstrated a 7.7% (p < 0.0001) average height impairment, which equates to a height loss of 13 cm or two standard deviations of the U.S. population mean. Pubertal and post-pubertal patients given similar heavy treatment as well as pre-pubertal patients given light treatment also demonstrated some impairment of skeletal growth, however, the loss was not deemed clinically significant. Comparison of standing versus sitting height impairment did not show evidence of disproportionate final growth impairment. CONCLUSION: Treatment regimens that use low doses of radiation for pediatric Hodgkin's disease are thus not associated with clinically significant impairment of skeletal growth, as measured by standing and sitting heights.

Computed tomography assessment of splenic size as a predictor of splenic weight and disease involvement in laparotomy staged Hodgkin's disease.

PURPOSE: To evaluate how well splenic size predicts the risk of splenic Hodgkin's disease and to assess how accurately splenic dimensions on computerized tomographic scans predict spleen size and involvement by Hodgkin's disease. METHODS AND MATERIALS: Splenic weights were obtained from laparotomies performed on 897 patients who presented with Hodgkin's disease and were compared with histologic involvement using logistic regression. Splenic dimensions were measured from preoperative computerized tomographic scans in 94 of these patients, and unidimensional splenic measurements [length (L), width (W), thickness (T)] and their products were compared with splenic weight at laparotomy using linear regression. RESULTS: Hodgkin's disease involved 42% of the spleens at laparotomy and 31% of those assessed by computerized tomography. Splenic weight averaged 198 +/- 5 g (range 40-2000 g). Weight and involvement were greater with "unfavorable" histologies (mixed cellularity, lymphocyte depletion, and unclassified Hodgkin's disease: 229 +/- 12 g; 62.7% involved) than with "favorable" histologies (nodular sclerosing, lymphocyte predominant, and interfollicular Hodgkin's disease: 191 +/- 5 g; 37.8% involved). Splenic weight was the strongest independent risk factor correlated with Hodgkin's disease in univariate and multivariate analyses in all patients and the only identifiable univariate risk factor among those with computerized tomographic scans. For most patients, however, splenic weight poorly predicted involvement: The probability of involvement never fell below 20% and exceeded 80% when splenic weight exceeded 270 g with unfavorable histologies or 685 g in favorable histologies. Spleens of average weight had a probability of involvement of 36% with favorable histologies, 70% with unfavorable histologies. Unidimensional measurements of the spleen on computed tomography correlated poorly with splenic weight, but their product correlated well (Correlation coefficients: L: 0.73; W: 0.65; T: 0.78; [0.344485 x L x W x T]: 0.94). CONCLUSIONS: Splenic weight is the strongest factor correlating with the risk of splenic involvement by Hodgkin's disease and can be accurately estimated from three-dimensional measurements on computed tomographic scans, but not from unidimensional measurements. However, splenic weight is not a sensitive predictor of involvement of the spleen by Hodgkin's disease. Therefore, treatment approaches to Hodgkin's disease must be based upon intermediate risks of splenic involvement for most clinically staged patients.

Major histocompatibility complex class I and class II antigen expression in diffuse large cell and large cell immunoblastic lymphomas. Absence of a correlation between antigen expression and clinical outcome.

The major histocompatibility complex (MHC) class I (HLA-A, B, C) and class II (HLA-DR) antigens are involved in cell-to-cell recognition and in regulating the immune response. Others have shown previously that MHC class I and class II antigens may be absent in a subset of malignant lymphomas, prompting the hypothesis that the absence of MHC antigen expression may be one of the mechanisms involved in the growth and dissemination of malignant lymphomas (by allowing a neoplasm to escape immune surveillance). To address this hypothesis, we analyzed MHC class I and class II (HLA-DR) antigen expression by diffuse large cell and large cell immunoblastic lymphomas in 88 and 117 patients, respectively, using frozen sections and the monoclonal antibodies W6/32 (HLA-A, B, C), anti-beta 2-microglobulin, and L203 (HLA-DR). Although there were no statistically significant clinical differences by MHC class II antigen expression, a small group of patients with MHC class I antigen-negative lymphomas were significantly younger (P = 0.03), less often had small neoplasms (P = 0.03), and were treated with doxorubicin-based chemotherapy more frequently (P = 0.04) than those with antigen-positive lymphomas. However, neither MHC class I nor class II antigen expression by the lymphomas consistently correlated with patient survival or freedom from relapse. This lack of correlation was true for all patients assessed, as well as for the subsets of patients with B-cell lymphomas, T-cell neoplasms, or those treated with doxorubicin-based chemotherapy. In accordance with previously published studies, stage, presence of B symptoms, and treatment with doxorubicin-based chemotherapy were of prognostic importance in univariate or multivariate analyses for survival or freedom from relapse. The findings may be considered evidence against the hypothesis that the absence of MHC class I or II antigen expression by malignant lymphomas plays a role in their tumorigenicity. However, we cannot completely exclude the possibility that the therapies used for this group of patients may have obscured any effect that MHC antigen expression exerts on prognosis.

Temperature differentials between treatment and pretreatment temperatures correlate with local control following radiotherapy and hyperthermia.

PURPOSE: To evaluate the influence of pretreatment tumor temperatures and the temperature differential between treatment and pretreatment temperatures on local tumor control in patients who underwent combined radiation therapy and hyperthermia. METHODS AND MATERIALS: Mapped intratumoral temperatures were measured immediately prior to and during hyperthermia in 138 hyperthermia fields among 59 patients with nodular (60 fields) or diffuse (78 fields) superficially-located tumors. In the nodular subgroup there were 40 fields with adenocarcinomas (31 breast, two prostate, seven other primary sites), six melanomas, nine squamous cell carcinomas, and five other histologies. The fields with diffuse tumor involvement consisted of 77 adenocarcinomas (67 breast, 10 other) and one melanoma. The maximum, minimum, and average temperatures were determined for both the pretreatment (pTmax, pTmin, pTave) and treatment (Tmax, Tmin, Tave) distributions and the differences, Dm = Tmin-pTmax, and Da = Tmin-pTave, computed. These quantities were averaged over treatments to produce the corresponding mean quantities for each hyperthermia field. Univariate and multivariate analyses were performed to determine treatment and pretreatment parameters which best correlated with the duration of local control. RESULTS: Pretreatment tumor temperatures were significantly lower than the oral temperatures with mean pTmax, mean pTmin, and mean pTave of 36.2 degrees C, 34.2 degrees C, and 35.4 degrees C, respectively. For the adenocarcinomas with diffuse involvement within the hyperthermia field, the covariates best correlating with local control duration on univariate analysis were concurrent radiation dose (p = 0.0026), Dm (p = 0.009), pTmax (p = 0.012) and Da (p = 0.036). Lower pTmax and larger Dm and Da were predictive for longer local control. In multivariate analyses, all thermal parameters lost power, however, the best model included Dm which was significant at the p = 0.040 level. For the nodular subgroup, nonthermal parameters and dichotomized thermal parameters were of prognostic significance for local control. CONCLUSION: For fields diffusely involved with adenocarcinoma significant correlations with duration of local control have been demonstrated both for a) low pretreatment temperatures and b) large differentials between treatment and pretreatment intratumoral temperatures. These correlations were also found in a dichotomized description for fields with nodular tumors. The results support the concept that pretreatment hypothermic conditions can lead to an increase in thermal sensitization and may help explain the excellent clinical results noted in the treatment of superficial tumors with radiation and hyperthermia. Further exploitation of this approach by planned cooling of superficially-located recurrent tumors prior to hyperthermia treatment warrants investigation.

Prostate specific antigen after external beam radiotherapy for prostatic cancer: followup.

Between 1986 and 1989, 117 patients with pretreatment and serial posttreatment prostate specific antigen values received external beam radiotherapy at our hospital. Followup ranged from 0.6 to 5.9 years (mean 2.7). No patient had hormonal manipulation before distant recurrence. Biochemical relapse, defined as an increasing prostate specific antigen level after treatment, was observed in 44 patients. To date 30 of these 44 patients (68%) have had clinical relapse. The prognostic factors of advanced local stage, high Gleason score and high elevations of pretreatment prostate specific antigen values predicted for biochemical relapse and subsequent clinical failure. The interval between biochemical and clinical relapse was 156 +/- 46 days. Biochemical relapse is an important end point that can be used to determine the effect of treatment in prostatic cancer research.

Correlation of thermal parameters with outcome in combined radiation therapy-hyperthermia trials.

Many studies utilizing combined hyperthermia (HT) and radiation therapy (XRT) in the treatment of advanced or recurrent malignancies have reported a correlation between some measure of the minimum temperature achieved and outcome. Previous reported studies at Stanford have demonstrated a statistically significant correlation between the duration of local control and Tmin, the mean over treatments of the minima of (a) measured intratumoral temperatures in fields which contained diffuse or nodular tumours, or (b) measured interstitial temperatures in fields treated for microscopic residual disease. Recently, T90, the mean of the temperatures above which 90% of all measured intratumoral temperatures fall, has been proposed as an alternative characterization of the efficacy of the HT treatment that reportedly has a superior correlation with outcome. To test this hypothesis, T90 was computed by two different methods for three groups of patients treated at Stanford with XRT-HT for superficially located tumor recurrences. Tmin was found to be strongly correlated with T90 calculated by both methods. All three thermal parameters correlated with complete response at 3 weeks and with local control, although Tmin usually demonstrated the strongest correlation.