Factors affecting recurrence rates in superficial bladder cancer.

A prospective study of all patients with superficial bladder cancer diagnosed in Northern Alberta (population 1.2 million) from 1977 to 1983 was performed to establish patterns of recurrence. Of the 761 patients with all stages of bladder cancer at diagnosis, 642 were deemed to be free of disease after primary treatment consisting of transurethral resection, fulguration, or laser surgery. Follow-up of these patients showed that approximately two-thirds of first recurrences occur within 18 months of diagnosis and that more of these patients have died of unrelated causes (n = 73) than of bladder cancer (n = 34). Censored disease-free interval comparisons showed that initial recurrences occurred sooner in patients with multifocal rather than unifocal disease and also sooner in females than in males. Known risk factors (occupational exposure to chemicals and cigarette smoking) and suspected risk factors (coffee consumption and artificial sweetener use) had no effect on disease-free interval and are not related to tumor multiplicity.

Nuclear magnetic resonance spectroscopy and sensitizer-adduct measurements of photodynamic therapy-induced ischemia in solid tumors.

Dunning R3327-AT prostate carcinomas growing in Fischer X Copenhagen rats were treated with interstitial photodynamic therapy (PDT--15 mg/kg Photofrin II 4 hours before illumination with 630-nm light via four parallelly implanted optical fibers) at different light intensities. Forty to 60 minutes after treatment, 31P-nuclear magnetic resonance spectra of tumors in anesthetized animals were obtained at 2.35 Tesla using surface coil localization. Areas under resonance peaks were normalized to the area under the peak of a phosphorus standard positioned at a fixed distance on the opposite side of the surface coil. Tumor concentrations of phosphomonoesters and phosphodiesters showed no change after tumor light doses up to 3000 J. Phosphocreatine, alpha-adenosine triphosphate (ATP), beta-ATP, and gamma-ATP signals decreased and inorganic phosphate signals increased with increasing light doses. The intratumor pH did not change significantly at these short times after PDT. In other R3327-AT and R3327-H tumor-bearing animals, [3H]misonidazole was administered 30 minutes prior to PDT treatments of both tumors. Twenty-four hours later, the tumors were resected in toto, and levels of retained [3H]misonidazole were determined in lased tumor specimens by liquid scintillation procedures. The amount of [3H]misonidazole activity in tumor tissue (covalently bound after hypoxic reduction) increased with light doses up to 3000 J. Sensitizer-adduct formation was found to correlate with the ratio of the concentration of inorganic phosphate to that of beta-ATP, both of which are presumed measures of tumor oxygenation status. These measurements have high-lighted the heterogenous nature of the oxygenation status of these experimental tumors. The precision of each assay for estimating tumor oxygenation is discussed.

Treatment of Dunning R3327-AT rat prostate tumors with photodynamic therapy in combination with misonidazole.

Fischer X Copenhagen rats bearing Dunning R3327-AT tumors were treated with hematoporphyrin derivative and red light (630 nm from an argon-driven dye laser) alone or in combination with the hypoxic cell radiosensitizer, misonidazole (MISO). In vitro studies had suggested that hypoxia might significantly decrease the cytotoxicity of photodynamic therapy (PDT) and labeling with [14C]MISO had revealed a significant fraction of viable hypoxic cells in this tumor. PDT alone resulted in a growth delay of 8.8 days but no tumor cures were observed. The administration of MISO (i.p. at 0.5 mg/g) 33 min prior to PDT resulted in an average growth delay of 15.2 days and tumor cures (local control at 33 days) in 20% of animals treated. If MISO at a similar dosage was administered 30 min after PDT an average growth delay of 16.3 days was measured and tumor cure was observed in 70% of the animals treated. These results suggest that the hypoxic cell fraction in R3327-AT tumors might be a limitation to their curability by PDT. The addition of MISO and/or other hypoxic cell cytotoxic agents to PDT procedures may provide an effective means of treating PDT-resistant hypoxic cells in solid tumors.

Photosensitization by anticancer agents 21: new perylene- and aminonaphthoquinones.

Hypocrellins are under intensive investigation as photosensitizing agents for photodynamic therapy (PDT). A recent advance in the synthesis of hypocrellin congeners resulted in the production of an amino-substituted hypocrellin-B, and its "half chromophore." Both compounds exhibit stronger red light absorption than previously reported hypocrellins, and, therefore, merit investigation as photosensitizers.

Measurement of PDT-induced hypoxia in Dunning prostate tumors by iodine-123-iodoazomycin arabinoside.

Photodynamic therapy (PDT) is known to produce vascular damage in solid tumors resulting in secondary ischemia and tumor cell death from hypoxia. The oxygenation status of both non-treated and PDT-treated Dunning R3327-AT prostate tumors growing in Fischer X Copenhagen rats was investigated with the novel hypoxic marker, 123I-iodoazomycin arabinoside (IAZA). Both qualitative and quantitative data from planar scintigraphy of anesthetized tumor-bearing rats showed increased retention of 123I-IAZA in tumors treated with PDT. Tumor perfusion in the same tumors was measured with 99mTc-hexamethylpropyleneamine oxime (HM-PAO). Region of interest analyses revealed an inverse correlation between tumor hypoxia measured by 123I-IAZA and tumor perfusion as measured by 99mTc-HMPAO (coefficient of correlation, r = -0.72). Planar images of 2-mm frozen sections from a large tumor showed 123I-IAZA selectively retained in the region that had been treated with PDT. This and other iodinated azomycin nucleosides, labeled with 123I, show promise for monitoring tumor oxygenation status non-invasively and, in particular, for monitoring the effectiveness of interstitial PDT treatments where perfusion shutdown is a major mechanism of tumor response.

Treatment of refractory Parkinson's disease with adrenal medullary autografts utilizing two-stage surgery.

Treatment of refractory PD with autologous adrenal medullary implants utilizing two-stage surgery warrants further investigation. This transplantation technique is associated with prolonged transplant area BBB disruption which may require a change in medical treatment strategies including the withdrawal of peripheral dopa decarboxylase inhibitors and possible intravenous or intraventricular dopamine therapy. Of 5 patients receiving adrenal medullary transplants, 3 have demonstrated varying degrees of clinical improvement which has persisted for the duration of the study. The positive correlation between clinical outcome and caudate function (i.e., 6-fluorodopa PET scans) suggests a positive influence of the transplantation procedure on the diseased striatum. Whether or not the grafted tissue remains viable for an extended period is currently being investigated utilizing 6-FDG-PET studies. Because of the presence of persistent BBB disruption, we surmise that at least viability of implanted fenestrated adrenal medullary capillaries exists. We conclude that this prolonged leakage is the result of the implanted tissue rather than the cavitation procedure as prolonged BBB disruption was not witnessed in a control group of patients with post-traumatic cerebral contusions or in Parkinson's patients subjected to thalamotomies. Whether two-stage surgery results in increased graft viability, and host neuronal sprouting, leading to prolonged clinical improvement and slowing the progression of PD awaits continued longitudinal (greater than 24 months) studies.

Protection against light-activated photofrin II killing of tumor cells by nitroimidazoles.

Nitroimidazoles are good quenchers of triplet state porphyrins in chemical systems, thereby inhibiting singlet oxygen formation and type II photodynamic reactions. Photobiological studies were performed with EMT-6 tumor cells in vitro utilizing Photofrin II (PII) in combination with etanidazole (ETAN), misonidazole (MISO), and trifluoromisonidazole (TF-MISO). After short-term (1 h) exposure of cells to PII, 5 mM ETAN and MISO had no effect on photoinactivation while 5 mM TF-MISO had a small but significant protective effect. When the intracellular oxygen level was equilibrated with 0.3% oxygen in the gas phase, all three nitroimidazoles produced significant photoprotection at concentrations as low as 0.3 microM. After long-term (24 h) exposure of cells to PII, all three nitroimidazoles demonstrated large photoprotective effects under both aerobic and 0.3% oxygen conditions. At equal concentrations of nitroimidazole, photoprotection was greatest for the most lipophilic compound (TF-MISO) and least effective for the most hydrophilic compound (ETAN). These studies suggest that nitroimidazoles can quench triplet state porphyrins (within cells) to reduce intracellular concentrations of singlet oxygen, the putative toxin in PII photoinactivation. In addition, after long-term exposures to PII when porphyrins have partitioned into cellular membranes and lipid environments, the lipophilicity of this class of photoprotector correlates with effectiveness in these mammalian cells.

Oxygen dependency of tumor cell killing in vitro by light-activated Photofrin II.

Asynchronous populations of mouse EMT-6 tumor cells were treated with Photofrin II and exposed to various doses of 630 nm light in slowly stirred suspensions which had been equilibrated with various concentrations of oxygen. Survival curves were generated with cells exposed to 20 micrograms/ml Photofrin II in tissue culture medium for 1 h, a procedure which made it possible to remove more than 50% of the drug by washing. It is expected that under these conditions the drug would be loosely bound to cell surface and plasma membranes and in the cellular cytosol. Survival curves were also generated with cells exposed to 5 micrograms/ml Photofrin II for 20-24 h, a procedure which resulted in greater than 90% of the drug being tightly bound within cells, presumably to cellular lipids and membranes. Oxygen was obligatory for killing cells which had been exposed for both "short term" and "long term" to Photofrin II. After 30-40 min of pregassing cells with nitrogen gas which contained precise levels of oxygen, the concentration required to reduce rates of cell killing to 50% of maximum was approximately 0.5% O2 (gas phase) for short-term drug exposures and less than or equal to 0.05% O2 for long-term drug exposures. Even after pregassing times of 90-120 min prior to light administration, a Km of approximately equal to 0.1% O2 was observed for cells exposed to the drug for the longer time. When the same cells were exposed to 137Cs gamma rays in this irradiation chamber, no change in radiation sensitivity was observed after 30 min of pregassing cells with all oxygen concentrations studied.(ABSTRACT TRUNCATED AT 250 WORDS)

The effectiveness of short-term versus long-term exposures to Photofrin II in killing light-activated tumor cells.

Asynchronous populations of mouse EMT-6 tumor cells were exposed to various doses of 630-nm light in slowly stirred aerobic suspensions after both short-term and long-term exposures to Photofrin II. All survival curves are characterized by a "threshold" light dose below which no cell inactivation occurs followed by a steep light-dose response. Both the shoulder widths and the inactivation curve slopes are functions of Photofrin II concentration. After high doses of light where survival levels are 0.003 and lower, "resistant tails" are observed on some survival curves. Light doses required to inactivate 50% of tumor cell populations were obtained from whole survival curves and their reciprocals (1/D50% survival) used as inactivation "rates". The amount of Photofrin II within cells was measured by a fluorescence assay. Per unit of fluorescence, this photosensitizer is at least 10 times more effective after long-term than after short-term exposures. After long-term exposures, both fluorescence activity and photosensitizing effectiveness are retained in washed cells for several hours. After short-term exposures, a majority of both the fluorescence and photosensitizing activity is lost by multiple washings or stirring in tissue culture medium without drug. These data suggest that the cellular compartments associated with photosensitization after short-term exposures to Photofrin II are probably different from the cellular compartments associated with photosensitization after long-term exposures to the drug. The data are consistent with known properties of the monomeric and oligomeric components of Photofrin II.

Hypocrellins as photosensitizers for photodynamic therapy: a screening evaluation and pharmacokinetic study.

Hypocrellin compounds were selected as potential photosensitizers for photodynamic therapy (PDT) owing to their high quantum yields of singlet oxygen (1O2), and facility for site-directed chemical modification to enhance phototoxicity, pharmacokinetics, solubility, and light absorption in the red spectral region, among other properties. Parent hypocrellins A and B share an absorption peak at 658 nm. These molecules may therefore be considered useful progenitors of derivatives which absorb more strongly in the red, considering that the ideal sensitizer should absorb in the 650-800 nm range, beyond the absorption range of hemoglobin and melanin, and where light penetration in tissues is maximized through reduced scattering. A series of pure, monomeric hypocrellin derivatives was tested for properties of dark cytotoxicity and photosensitizing potential by clonogenic assay in monolayer cultures of EMT6/Ed murine tumor cells. Their respective toxicities are reported on a molar basis. The in vitro screening assay has, to date, resulted in the selection of four hypocrellin derivatives for further development as photosensitizers for PDT. Cellular uptake for photosensitizing doses of selected compounds was determined by fluorimetry. Dose escalation studies in rodents indicate that potentially photosensitizing doses promote no demonstrable systemic toxicity.

Iridium-192 brachytherapy in the treatment of cancer of the prostate.

Aggressive radiotherapy was used in 170 patients with advanced localized carcinoma of the prostate. After pelvic lymphadenectomy, 192Ir brachytherapy was used to deliver 3500 cGy to the prostate within 2 days. External-beam therapy (4500 cGy) was then given to a total of 8000 cGy. Random biopsies 18 months afterward were negative for residual cancer in 62 of 83 patients (75%), and 37 of 45 patients (82%) with pathologically proved localized disease remain without evidence of disease. Morbidity was significantly reduced in the most recent 70 patients by improvements in technique. The authors believe such therapy should be considered for patients with advanced stage B2 or C disease in particular.

Optical dosimetry for interstitial photodynamic therapy.

An approach to photodynamic treatment of tumors is the interstitial implantation of fiber optic light sources. Dosimetry is critical in identifying regions of low light intensity in the tumor which may prevent tumor cure. We describe a numerical technique for calculating light distributions within tumors, from multiple fiber optic sources. The method was tested using four translucent plastic needles, which were placed in a 0.94 X 0.94 cm grid pattern within excised Dunning R3327-AT rat prostate tumors. A cylindrical diffusing fiber tip, illuminated by 630 nm dye laser light was placed within one needle and a miniature light detector was placed within another. The average penetration depth in the tumor region between the two needles was calculated from the optical power measured by the detector, using a modified diffusion theory. Repeating the procedure for each pair of needles revealed significant variations in penetration depth within individual tumors. Average values of penetration depth, absorption coefficient, scattering coefficient, and mean scattering cosine were 0.282 cm, 0.469 cm-1, 250 cm-1 and 0.964, respectively. Calculated light distributions from four cylindrical sources in tumors gave reasonable agreement with direct light measurements using fiber optic probes.

Photodynamic therapy dosimetry in postmortem and in vivo rat tumors and an optical phantom.

Dosimetry in photodynamic therapy as currently practiced is empirical in that it does not account for optical properties of the target lesion. However, since light attenuation in tissue is unpredictable, measurements of optical properties are needed to ensure optimal light dose delivery. Further improvements in the uniformity of light dose distribution in tumors can be afforded by implanting multiple light sources. A technique is described in which the use of multiple cylindrical sources was combined with measurements of light energy fluence rate in the tumor. Six sources were placed within translucent plastic needles, which were inserted into tumors in a parallel array. Tumor attenuation characteristics were measured by placing a miniature light detector in one needle, while illuminating a cylindrical source in another, nearby, needle. This process was repeated for different needle pairs. In one postmortem and two in vivo tumors the absorption coefficient, transport scattering coefficient and penetration depth ranged from 0.56-0.81 cm-1, 9.4-15.2 cm-1 and 1.7-2.3 mm, respectively. Apparent penetration depths for in vivo tumors changed with time, during experiments. Predictions of dosimetry were generally consistent with direct measurements of light in tumors. Somewhat better agreement was observed in an optical phantom.

Optical properties of experimental prostate tumors in vivo.

The optical properties of tumor tissue provide important information for optimizing treatment plans in photodynamic therapy, especially when interstitial application by multiple fibers is planned. Near infrared light, required to activate novel photosensitizers, should facilitate improved light penetrance of tumor tissue compared with 630 nm light used for activating Photofrin II. We have measured light energy fluence rates for 630 and 789 nm light along radial tracks from a single laterally diffusing optical fiber centrally implanted into Dunning R3327-AT and R3327-H rat prostate tumors in anesthetized rats. A total of 20 R3327-AT and 10 R3327-H tumors were used in this study with volumes from 2.6 to 13.3 cm3. Light track data were analyzed by an empirical model that described light attenuation. At 630 nm, light attenuation coefficients (LAC) were approximately 1.9 x higher than those at 789 nm for both tumors with the well-differentiated, well-perfused tumor (R3327-H) attenuating to a greater extent than did the rapidly growing anaplastic tumor (R3327-AT). The intertumor variation of LAC was greater than the spatial variations observed within individual tumors. LAC were a function of tumor volume for only 630 nm light in the R3327-AT tumors.

Lasers in the treatment of cancer of the prostate. An overview.

The results of therapy of prostate cancer with laser therapy either in the experimental animal model or in human application are preliminary and rudimentary. Difficulty in access to the prostate, variability in depth of laser penetration and problems in assessment of therapeutic attempts makes it impossible to be dogmatic about re the future application. The tumour does however respond to Nd: YAG and P. D. T. therapy and it is possible that the crude attempts to date will be supplanted in the future by more refinements that will enable laser energy to be harnessed.

Analysis of tissue optical coefficients using an approximate equation valid for comparable absorption and scattering.

New photosensitizers activated by longer wavelengths than 630 nm light used with Photofrin II are under evaluation by various groups for the treatment of malignancies. Any increase in tumour volume destroyed by these agents as compared to Photofrin II will be partly determined by tissue penetrance at the longer wavelengths. Attenuation coefficients were measured for various tissues at 630 nm and the more penetrative near infrared wavelength of 789 nm. A new model of light propagation in tissue is shown to be accurate for arbitrary ratios of absorption and scattering, by comparison with a rigorous solution to the transport equation. Absorption and transport scattering coefficients of tissues at 630 and 789 nm were obtained by fitting this model to optical attenuation measurements. In vitro tissues included bovine heart, kidney and tongue, pig liver and fat, and chicken muscle; in vivo tissues included Dunning R3327-AT and R3327-H tumours. The penetration depth was found to be 1.35-2.25 times greater at 789 than 630 nm, depending on tissue type. The greatest differences in penetration between the two wavelengths were in the highly pigmented tissues. These substantial increases in penetration in the infrared may be important in future applications of photodynamic therapy.