Mutant, wild type, or overall p53 expression: freedom from clinical progression in tumours of astrocytic lineage.

Abnormalities of the p53 tumor-suppressor gene are found in a significant proportion of astrocytic brain tumours. We studied tumour specimens from 74 patients evaluated over 20 years at the Massachusetts General Hospital, where clinical outcome could be determined and sufficient pathologic material was available for immunostaining. p53 expression studies employed an affinity-purified p53 monoclonal antibody, whose specificity was verified in absorption studies and, in a minority of cases, a second antibody recognising a different epitope of p53. Significant overexpression of p53 protein was found in 48% of the 74 tumours included in this series and high levels of expression were associated with higher mortality from astrocytic tumours (P<0.001, log rank). Multivariate analyses revealed that immunohistochemically detected p53 was an independent marker of shortened progression-free and overall actuarial survival in patients with astrocytic tumours, suggesting that increased expression of p53 plays an important role in the pathobiology of these tumours. In a subset of 36 cases, coding regions of the p53 gene were completely sequenced via SSCP and direct DNA sequencing, revealing that overexpression of p53 protein is not always associated with point mutations in conserved exons of the p53 gene. Finally, we confirmed p53 protein expression in early-passage human glioma cell lines of known p53 mutational status and immunostaining scores. Although grade continues to be the strongest prognostic variable, the use of p53 staining as a prognostic indicator, in contrast to mutational DNA analyses, may be a useful adjunct in identifying patients at higher risk of treatment failure.

Intraoperative optimized inverse planning for prostate brachytherapy: early experience.

PURPOSE: To demonstrate the feasibility of an intraoperative inverse planning technique with advanced optimization for prostate seed implantation. METHODS AND MATERIALS: We have implemented a method for optimized inverse planning of prostate seed implantation in the operating room (OR), based on the genetic algorithm (GA) driven Prostate Implant Planning Engine for Radiotherapy (PIPER). An integrated treatment planning system was deployed, which includes real-time ultrasound image acquisition, treatment volume segmentation, GA optimization, real-time decision making and sensitivity analysis, isodose and DVH evaluation, and virtual reality navigation and surgical guidance. Ten consecutive patients previously scheduled for implantation were included in the series. RESULTS: The feasibility of the technique was established by careful monitoring of each step in the OR and comparison with conventional preplanned implants. The median elapsed time for complete image capture, segmentation, GA optimization, and plan evaluation was 4, 10, 2.2, and 2 min, respectively. The dosimetric quality of the OR-based plan was shown to be equivalent to the corresponding preplan. CONCLUSION: An intraoperative optimized inverse planning technique was developed for prostate brachytherapy. The feasibility of the method was demonstrated through an early clinical experience.

Automated treatment planning engine for prostate seed implant brachytherapy.

PURPOSE: To develop a computer-intelligent planning engine for automated treatment planning and optimization of ultrasound- and template-guided prostate seed implants. METHODS AND MATERIALS: The genetic algorithm was modified to reflect the 2D nature of the implantation template. A multi-objective decision scheme was used to rank competing solutions, taking into account dose uniformity and conformity to the planning target volume (PTV), dose-sparing of the urethra and the rectum, and the sensitivity of the resulting dosimetry to seed misplacement. Optimized treatment plans were evaluated using selected dosimetric quantifiers, dose-volume histogram (DVH), and sensitivity analysis based on simulated seed placement errors. These dosimetric planning components were integrated into the Prostate Implant Planning Engine for Radiotherapy (PIPER). RESULTS: PIPER has been used to produce a variety of plans for prostate seed implants. In general, maximization of the minimum peripheral dose (mPD) for given implanted total source strength tended to produce peripherally weighted seed patterns. Minimization of the urethral dose further reduced the loading in the central region of the PTV. Isodose conformity to the PTV was achieved when the set of objectives did not reflect seed positioning uncertainties; the corresponding optimal plan generally required fewer seeds and higher source strength per seed compared to the manual planning experience. When seed placement uncertainties were introduced into the set of treatment planning objectives, the optimal plan tended to reach a compromise between the preplanned outcome and the likelihood of retaining the preferred outcome after implantation. The reduction in the volatility of such seed configurations optimized under uncertainty was verified by sensitivity studies. CONCLUSION: An automated treatment planning engine incorporating real-time sensitivity analysis was found to be a useful tool in dosimetric planning for prostate brachytherapy.

Phase I trial of photodynamic therapy in the treatment of recurrent superficial transitional cell carcinoma of the bladder.

OBJECTIVES: A Phase I trial of photodynamic therapy (PDT) in the treatment of superficial transitional cell carcinoma (TCC) of the bladder was performed. METHODS: Twenty patients with recurrent superficial TCC of the bladder after receiving a mean of 2.6 (range 1 to 6) courses of intravesical therapy were treated with PDT. The photosensitizer Photofrin II dose was 1.5 or 2.0 mg/kg. A 630-nm intravesical red laser was used to activate the photosensitizer 2 days after administration of Photofrin II. A 0.01% intralipid solution was used as a bladder-filling medium to scatter light and achieve more homogeneous light distribution. Light doses from 5.1 to 25.6 J/cm2 (total dosage 1500 to 5032 J) were used to illuminate the bladder. RESULTS: Twenty patients underwent 21 treatments with PDT. Complications included asymptomatic reflux in 4 patients. One other patient, treated at the highest total light dose, experienced bladder contraction and fibrosis. Nine patients (45%) had no tumor evident at cystoscopy, on random biopsies, or in urinary cytology at the 3-month evaluation after treatment. Four patients remained without recurrent disease for 23 to 56 months. Sixteen of 20 (80%) patients experienced recurrence, and 8 of the 16 underwent cystectomy. CONCLUSIONS: An intravenous photosensitizer dose of 1.5 mg/kg Photofrin II followed by light energy in the range of 13 J/cm2 (total light dose 2500 to 3250 J) was defined as a safe treatment parameter and resulted in tumor responses. With present technologies, administration of PDT requires careful dosimetry.

The life shortening effects of treatment with doxorubicin and/or local irradiation on a cohort of young C3Hf/Sed mice.

The long-term consequences of treating a cohort of C3Hf/Sed mice in early life with either local-field single dose radiation, systemic doxorubicin, or both, are reported in this study. Significant life shortening was observed in all treatment groups. Median survival times (days) from time of treatment were: control, 690; 35 Gy, 560; 70 Gy, 460; 5 mg/kg doxorubicin, 580; 10 mg/kg doxorubicin, 350; 35 Gy + 5 mg/kg doxorubicin, 510; 70 Gy + 10 mg/kg doxorubicin, 310. Mice receiving hind limb irradiation died principally from induced sarcomas in a dose dependent fashion (80% after 70 Gy and 55% after 35 Gy). Those treated with doxorubicin alone showed an increase in the actuarial incidence of spontaneous malignancies but died mainly from non-malignant causes. Histological examination did not reveal any characteristic cardiac, renal or pulmonary lesions. Doxorubicin did not increase the rate of development of radiation induced sarcomas in mice treated with combined modality.

Radiation therapy in the treatment of difficult giant cell tumors.

Thirteen patients with giant cell tumors of bone have been treated by radiation therapy because surgery was not feasible or unacceptably disfiguring. Seven patients were treated for primary giant cell tumors of the bone, four for recurrent disease, and three for metastasis (one presented with both distant metastasis and local recurrence after primary surgery). The follow-up time ranged from 18 months to 13 years, with a mean of 6.5 years. All patients except one are alive. Local control was achieved in 11 patients (85%). One patient whose tumor was located in the sacrum had no gross response and at 5 months was subjected to a partial sacrectomy. A second patient had local regrowth 1 year after treatment; salvage surgery was successful. There have been no long-term complications of radiation therapy. This study confirms that for patients with giant cell tumor of bone, radiation therapy offers an effective alternative to complex or difficult surgery and constitutes a good treatment method to medically inoperable patients.

Role of hypovolemic hemoconcentration in dose-dependent flow decline observed in murine tumors after intraperitoneal administration of glucose or mannitol.

Responses of tumor microcirculation (RBC flux) to i.p. glucose or mannitol injections were studied in early generation isotransplants of a spontaneous C3Hf/Sed mouse fibrosarcoma (FSaII). RBC flux in superficial tumor microregions was assessed using laser Doppler flowmetry. After administration of glucose or mannitol (a nonmetabolized sugar alcohol), a dose-dependent reduction in laser Doppler flow, and a dose-dependent increase in systemic hematocrit occurred concurrently. Maximum flow reductions induced by i.p. glucose or mannitol were statistically indistinguishable for equal osmotic load. Maximum decreases in RBC flux for glucose or mannitol were 20 and 25% (1.25 mg/g i.p.), 42 and 48% (2.5 mg/g i.p.), 72 and 60% (5 mg/g i.p.), and 80 and 75% (10 mg/g i.p.), respectively. Maximum increases in systemic hematocrit ranged from 18% (1.25 mg/g glucose i.p.) to 33% (10 mg/g glucose i.p.). Examination of RBC count, blood hemoglobin concentration, and fluid accumulation in the abdominal cavity after glucose or mannitol administration were all compatible with a significant shift of intravascular/extracellular water into the abdominal cavity with resultant systemic hypovolemic hemoconcentration. RBC volume and mean hemoglobin content of RBC remained unchanged with glucose loading. The data suggest that reductions in laser Doppler flow are predominantly caused by hypovolemic hemoconcentration following i.p. administration of hyperosmolar sugar solutions. Changes in laser Doppler flow due to specific glucose-mediated or glucose-related phenomena are probably of minor importance in the murine tumor system investigated. Future studies on murine tumors, examining for specific effects of glucose on metabolism and/or therapy, should not use i.p. administration of hyperosmolar solutions.

Effect of temperature on blood flow and hypoxic fraction in a murine fibrosarcoma.

The effect of hypo to hyperthermic temperatures on tumor blood flow and hypoxic cell fractions was studied in a murine fibrosarcoma transplanted in the hind leg of anesthetized mice. The blood flow to the tumor was assessed by the determination of the uptake of Thallium-201; the hypoxic cell fraction was estimated from cell survival curves derived from data based on lung colony assay. Over a temperature range of 18 degrees to 46 degrees C, the maximal blood flow occurred at 35 degrees C which was approximately two times greater than that at room temperature (24 degrees C) or at 39 degrees C. The hypoxic cell fraction at 35 degrees C was 11%, and was significantly less than that at 24 degrees C or at 39 degrees C. The hypoxic cell fractions at 24 degrees C and at 39 degrees C were 45% and 32%, respectively. These results suggest that the optimal radiation sensitivity of peripherally located tumors can be obtained by warming the tumors to temperatures where maximal blood flow and minimal hypoxic cell fraction occur.

Tumor size dependent changes in a murine fibrosarcoma: use of in vivo 31P NMR for non-invasive evaluation of tumor metabolic status.

Tumor tissue contains viable hypoxic regions that are radioresistant and often chemoresistant and may therefore be responsible for some treatment failures. A subject of general interest has been the development of non-invasive means of monitoring tissue oxygen. Pulse Fourier transform 31P NMR spectroscopy can be used to estimate intracellular nucleotide triphosphates (NTP), phosphocreatinine (PCr), inorganic phosphate (Pi) and pH. We have obtained 31P NMR spectra as an indirect estimate of tissue oxygen and metabolic status in a C3H mouse fibrosarcoma FSaII. Sequential spectra were studied during tumor growth in a cohort of animals and peak area ratios for several metabolites were computed digitally by computer. During growth, tumors showed a progressive loss of PCr with increasing Pi, and most tumors greater than 250 mm3 in volume had little or no measurable PCr. The smallest tumors (38 mm3 average volume) had PCr/Pi ratios of 1.03 +/- .24, whereas tumors 250 mm3 or more had an average PCr/Pi ratio of 0.15 +/- .04. Similarly derived NTP/Pi ratios decreased with tumor size, but this change was not significant (p = .17). Radiobiologic hypoxic cell fractions were estimated using the radiation dose required to control tumor in 50% of animals (TCD50) or by the lung colony technique. Tumors less than 100 mm3 had a hypoxic cell fraction of 4% (TCD50) while tumors 250 mm3 had a 40% hypoxic cell fraction (lung colony assay). These hypoxic fraction determinations correlated well with the depletion of PCr and decline in NTP/Pi ratios seen at 250 mm3 tumor volumes. Tumor spectral changes with acute ischemia were studied after ligation of the tumor bearing limb and were similar to changes seen with tumor growth. PCr was lost within 7 minutes, with concurrent increase in Pi and loss of NTP. Complete loss of all high energy phosphates occurred by 40 minutes of occlusion. In vivo tumor 31P NMR spectroscopy can be used to estimate tissue metabolic status and may be useful in non-invasive prediction of hypoxic cell fraction, reoxygenation, and radiation treatment response.