Hyperthermia induces doxorubicin release from long-circulating liposomes and enhances their anti-tumor efficacy

PURPOSE

To examine the possibility that hyperthermia would accelerate drug release from long-circulating liposomes, and enhance their antitumor activity.

METHODS AND MATERIALS

Liposomes were prepared by thin film hydration technique. Hyperthermia was induced by ultrasound apparatus and a water bath heating system. The antitumor efficacy of treatment against RIF-1 tumor in C3H mice was evaluated by the tumor growth delay assay.

RESULTS

In vitro drug release experiments demonstrated that increase in temperature from 37 degrees C to 41 degrees C resulted in about a sixfold increase in doxorubicin (DOX) release in a 1-h period. Increasing the temperature to 43 degrees C, resulted in only a modest additional drug release. Drug uptake studies showed that local hyperthermic treatment immediately following the drug administration dramatically enhanced Stealth liposome-encapsulated doxorubicin (S-DOX) uptake by tumors, but did not do so for free DOX. At 42 degrees C and at a dose of 10 mg/kg, the accumulation of S-DOX was about 10-fold and 2.5-fold higher than that with free drug and S-DOX at 37 degrees C, respectively. The antitumor efficacy study confirmed our hypothesis that the addition of hyperthermia to the treatment of RIF-1 tumors with doxorubicin encapsulated in long-circulating liposomes would enhance antitumor effects. Two hyperthermia treatments given at 24-h intervals appeared to be the most promising method of combining heat and long-circulating liposomes. The increased antitumor activity was not accompanied by increased toxicity, as determined by the body weight of the mice.

CONCLUSION

Local hyperthermic treatment is able to accelerate DOX release from long-circulating liposomes, increase tumor uptake, and enhance their antitumor efficacy. The combination of local hyperthermia and long-circulating liposomes appears to show considerable promise in the treatment of localized diseases.

Cross-resistance to cisplatin in cells resistant to photofrin-mediated photodynamic therapy

This study shows that a Photofrin-induced photodynamic therapy-resistant variant (RIF-8A) of a radiation-induced fibrosarcoma-1 cell line (RIF-1) is cross-resistant to cis-diamminedichloroplatinum(II) (cisplatin). This is the first study to show cross-resistance to cisplatin in photodynamic therapy-resistant variants in vitro. Resistance does not appear to be the result of elevated glutathione levels since neither the resistant variant (RIF-8A) nor the parental line (RIF-1) varied in total glutathione levels. However, cisplatin-DNA adduct levels differed significantly between the two cell types. Immediately following a 1-h exposure to cisplatin (50 microM), RIF-1 cells contained 44.6 +/- 2.0 (SEM) pg platinum/micrograms DNA while RIF-8A cells contained 24.8 +/- 6.3 pg platinum/micrograms DNA. In addition, the resistant variant had decreased plasma and mitochondrial membrane potentials. The plasma and mitochondrial membranes of the resistant variant accumulated 3- and 3.6-fold less rhodamine 123, respectively. The difference in rhodamine 123 accumulation could not be attributed to elevated P-glycoprotein expression because both the parental line and the variant contained similar amounts of P-glycoprotein. In conclusion, alterations in the plasma and/or mitochondrial membrane potentials may provide cells with a survival advantage when challenged with either photodynamic therapy or cisplatin in vitro. This appears to be a novel mechanism of resistance.

Development of anaplastic changes in low-grade astrocytomas of childhood

The authors present their experience with six children who developed anaplastic astrocytomas after receiving treatment for low-grade astrocytomas. Five children were from a series of 55 children with optic chiasmatic-hypothalamic gliomas who have been studied since 1976. The sixth child initially had a low-grade astrocytoma of the thalamus. The mean age of the children at initial presentation was 5.3 years. Five children were treated with surgery and radiation therapy; one child with a chiasmatic-hypothalamic glioma received radiation therapy alone. The amount of external radiation therapy used in all children was 50-52.5 Gy delivered in standard fractionations over approximately 6 weeks to include the volume of the original tumor plus a margin of 2 cm. The time to anaplastic transformation varied between 2 and 10 years (mean, 6.4 years). At tumor recurrence, the children had seizures or symptoms and signs of raised intracranial pressure. The location of the second tumor in all patients was either at the primary site or within the field of radiation therapy. Five of the six children underwent a second craniotomy and subtotal resection of their malignant gliomas. One child had positive cerebrospinal fluid cytology and multiple intraspinal metastatic tumor nodules detected by magnetic resonance imaging. On histopathological examination, four children had anaplastic astrocytoma, and two had glioblastoma multiforme. Four of the six children have died of their anaplastic astrocytomas (mean time from diagnosis of anaplastic astrocytoma to death, 10 months). Two children underwent chemotherapy and spinal irradiation for their anaplastic astrocytomas, and are currently alive and undergoing treatment. The possible mechanisms by which anaplastic tumors have developed in children treated previously for low-grade astrocytomas is discussed. The data suggest that radiation therapy may have played an integral role in the genesis of anaplastic astrocytomas in these children.

Osteosarcoma following radiation treatment for meningioma: report of a case and effective treatment with chemotherapy

A case of effective chemotherapy in postirradiation sarcoma is reported. A 30-year-old woman underwent a subtotal resection of a benign mixed meningioma followed by a course of radiotherapy. Five years later she developed a skull tumor which was resected. Histological study showed sarcomatous change corresponding most likely to a postirradiation osteosarcoma. Adjuvant chemotherapy (methotrexate, carboplatin, and VP16) was given. A progression occurred 8 months later and the patient was treated unsuccessfully with tamoxifen, LHRH, and later with high dose methotrexate and carboplatin. Six months later a lung metastasis was discovered and she received four cycles of IVP (ifosfamide, vepeside, cisplatin) alternating with IVA (ifosfamide, vepeside, adriamycin). Within 4 months the primary and lung tumours had decreased substantially without evidence of progression at follow-up 5 months later. We conclude that IVP/IVA regimen is a potentially useful therapy when an osteosarcoma of the skull is in progression.

Protective effects of recombinant human interleukin-1 alpha in doxorubicin-treated normal and tumor-bearing mice

Experiments were performed to determine whether treatment with recombinant human IL-1 alpha (rhuIL-1 alpha) would protect C3H mice from the toxic effects of the widely used chemotherapeutic agent, doxorubicin (DXR). Pretreatment of mice with rhuIL-1 alpha was found to protect 85-90% of mice tested from the acute toxic effects of a lethal dose of doxorubicin (25 mg/kg). Late deaths (> 20 days post-DXR) were observed in a substantial proportion (40-45%) of rhuIL-1 alpha-pretreated mice. However, the data clearly demonstrate a beneficial effect of rhuIL-1 alpha pretreatment on the overall survival of mice challenged with DXR, since both the median survival (32 days) and proportion (53%) of surviving mice were significantly increased (P < 0.0001) compared to the control group (8 days and 14%, respectively). The beneficial effects mediated by rhuIL-1 alpha treatment were both dose- and schedule-dependent and were associated with decreases in the level and duration of DXR-induced neutropenia, and amelioration of the suppressive effects of DXR on myeloid progenitor cells (granulocyte/monocyte colony forming units) as evidenced by milder depressions in marrow cellularity and enhanced recovery of granulocyte/monocyte colony forming unit activity. Finally, pretreatment of mice bearing a solid tumor with rhuIL-1 alpha permitted effective dose escalation with DXR that resulted in decreased tumor growth rates and increased survival (90%) as compared to non-rhuIL-1 alpha-treated groups (20% survival). Thus, effective chemotherapeutic dose escalation is made feasible by rhuIL-1 alpha pretreatment of mice, but may ultimately be limited by nonhematological toxicities associated with DXR.

Topical toremifene: a new approach for cutaneous melanoma?

The distribution of topically applied toremifene (0.5-1 mg/day for 5 days) in the ultraviolet B (UVB)-induced Monodelphis domestica opossum melanoma model was examined. The mean concentration of toremifene measured in the skin was 1200 nmol/g, or > 500 times that detected in any other tissues (blood, brain, liver, testicles, heart, uterus, eyes). In plasma, toremifene could be detected in only one animal of six (0.04 nmol/ml). Intraperitoneal administration of 0.5 mg toremifene daily for 5 days in three female animals resulted in a mean uterus concentration of 22.9 nmol/g, or 400-fold that achieved by topical administration of 0.5 mg/day in three other female Monodelphis (0.05 nmol/g). The cytostatic effect of toremifene was studied in three human melanoma cell lines and three experimental cell lines derived from UVB-induced melanocytic nevi in M. domestica. Toremifene had a cytostatic effect on all cell lines (50% growth-inhibitory concentrations, 5.8-9.6 microM). Topical toremifene administration yields high local concentration with minimal systemic distribution. In addition, toremifene has a cytostatic effect at achievable concentrations in a variety of melanomatous cell lines.

Protection against metastasis of radiation-induced thymic lymphosarcoma and weight loss in C57Bl/6NCr1BR mice by an autoclave-resistant factor present in soybeans

We have investigated the ability of Bowman-Birk inhibitor, a protease (trypsin and chymotrypsin) inhibitor, to protect against radiation-induced thymic lymphosarcoma in C57Bl/6NCr1BR mice. Fifty-five 7-week-old male mice were randomized into 11 groups and gavaged 5 days per week with purified Bowman-Birk inhibitor, Bowman-Birk inhibitor concentrate, and autoclaved Bowman-Birk inhibitor concentrate. Following 7 days of gavage, those mice undergoing total-body or sham total-body irradiation received 1.7 Gy weekly for 4 weeks. At 6 months following the radiation exposure, all mice were sacrificed and examined histopathologically. Samples of Bowman-Birk inhibitor concentrate, purified Bowman-Birk inhibitor, and autoclaved Bowman-Birk inhibitor concentrate were evaluated with thin-layer chromatography. The mice treated with total-body irradiation and autoclaved Bowman-Birk inhibitor had significantly (P < 0.05) fewer deaths, lower average grade of lymphosarcoma, and larger fat stores compared to those treated with total-body irradiation and water gavage. The results for the total-body-irradiated mice receiving Bowman-Birk inhibitor concentrate suggested an effect midway between these two groups. Thin-layer chromatography analysis indicated that sterols and the phospholipids varied in the three different samples in a way that approximately corresponded with the observed effects. We have observed that an autoclave-resistant factor in soybeans is capable of reducing metastasis of radiation-induced lymphosarcoma and weight loss in C57Bl/6NCr1BR mice, presumably by preventing the extension and metastasis of cancer cells. Thus, in addition to the anticarcinogenic Bowman-Birk inhibitor, there appears to be another anticarcinogenic agent in soybeans which is capable of inhibiting the later stages of cancer cell development.

Determination of absolute phosphate metabolite concentrations in RIF-1 tumors in vivo by 31P-1H-2H NMR spectroscopy using water as an internal intensity reference

The absolute metabolite quantification method of Thulborn and Ackerman [J. Magn. Reson. 55, 357 (1983)] in which the tissue water proton signal is used as an internal intensity standard and its more recent variation in which NMR peak intensities are referenced to that of the natural abundance deuterium signal of water [Li et al., SMRM Abstr. 2, 825 (1988); Song et al., Magn. Reson. Med. 25, 45 (1992) have been implemented to obtain absolute phosphate metabolite concentrations in subcutaneous RIF-1 tumors during untreated growth and following treatment with 5-fluorouracil. The equivalence of these two hydrogen isotopes as intensity standards and the validity of their use in the determination of absolute metabolite concentrations in vivo by NMR has been demonstrated. On matched in vivo and extract tumor samples (n = 5), excellent agreement has been obtained between nucleoside triphosphate concentrations determined by NMR and those derived by HPLC analysis for the control tumors. Following 3 days of untreated growth, absolute concentrations of phosphate metabolites in RIF-1 tumors (n = 10) decreased significantly, except for the Pi concentration which did not vary. For the treated tumors (n = 10) there were no changes in metabolite concentrations except for a decrease in the PCr and, possibly, Pi concentrations. The PCr/Pi ratio in the latter tumors did not change. These observations suggest that changes in absolute metabolite concentrations may be more sensitive indices of response to therapy than changes in metabolite peak amplitude ratios, a parameter commonly used to express in vivo NMR data.

Photodynamic therapy of chemically- and ultraviolet B radiation-induced murine skin papillomas by chloroaluminum phthalocyanine tetrasulfonate

Photodynamic therapy (PDT) of cancer combines irradiation of tumors with visible light following selective uptake of the photosensitizer by the tumor cells. PhotofrinR-II (Pf-II) is the only photosensitizer which is in clinical use in PDT, whereas chloroaluminum phthalocyanine tetrasulfonate (AlPcTS) has also shown promise in preclinical studies. In most such studies, the effectiveness of the photosensitizers has been assessed in implanted tumor model systems rather than in model systems where tumors are allowed to grow in their own connective tissue matrix. In this study the pharmacokinetics, tumor ablation capability and cutaneous photosensitization response of AlPcTS have been assessed in mice bearing chemically- and ultraviolet B radiation (UVB)-induced benign skin papillomas. When tumor-bearing animals were injected intraperitoneally with AlPcTS (5 mg/kg body wt), maximum tumor:normal skin ratio of 2.4 was observed at 48 h, at which time the mice were irradiated within the absorption spectrum of the photosensitizer. In tumor ablation studies with SENCAR mice bearing chemically-induced skin tumors, AlPcTS resulted in greater than 80% ablation in tumor volume at 20 days post-irradiation. In cutaneous photosensitization response, AlPcTS produced only transient effects (no effect after 24 h) in SENCAR mice. Pharmacokinetics data, tumor ablation effects and cutaneous photosensitization response of AlPcTS were comparable in SKH-1 hairless mice bearing UVB-induced skin tumors. Our data indicate that AlPcTS produces significant photodynamic effects towards the ablation of murine skin tumors, and that it does not produce prolonged cutaneous photosensitivity.

5-chlorodeoxycytidine, a radiosensitizer effective against RIF-1 and Lewis lung carcinoma, is also effective against a DMBA-induced mammary adenocarcinoma and the EMT-6 tumor in BALB/c mice

5-Chlorodeoxycytidine (CldC), coadministered with modulators of pyrimidine metabolism, is an effective radiosensitizer of murine tumors. Past studies that utilized RIF-1 tumors in C3H mice and Lewis lung carcinoma (LLC) in BDF1 mice have been extended with an emphasis on using multiple cycles of drug administration followed by irradiation of LLC and the use of two additional tumor models. Four of seven cures of BDF1 mice bearing LLC were obtained with three doses of 20 Gy irradiation, in which the first and third dose were preceded by a "Standard Protocol" that includes N-(phosphonacetyl)-L-aspartic acid (PALA), 5-fluorodeoxycytidine (FdC), tetrahydrouridine, and the radiosensitizer, 5-chlorodeoxycytidine. No cures were obtained in groups of mice receiving radiation alone or drugs alone, and there were no "no takes" in untreated control groups (six mice/group). Extensive tumor inhibition, exceeding that obtained with drugs or radiation alone, was obtained with two cycles of drugs and radiation combined when a dimethybenzanthracene-induced mammary adenocarcinoma was used in BALB/c mice. With the EMT-6 tumor in BALB/c mice, doses of 10 and 20 Gy were administered 9 and 16 days after tumor implantation, each preceded with the Standard Protocol; this resulted in a tumor growth delay of 24 days. No tumor growth delay occurred with drugs or radiation alone. The omission of PALA, FdC or CldC from the Standard Protocol resulted in loss of tumor control, which was obtained with the complete protocol. The fact that 5-chlorodeoxycytidine is an effective radiosensitizer in four rodent tumor systems is compelling evidence that it has potential as a radiosensitizer of human tumors, especially in view of its tumor selectivity and its resistance to catabolism when used with modulators of its metabolism, and in view of the high levels of the key enzymes in human tumors, which can convert 5-chlorodeoxycytidine to 5-chlorodeoxyuridine triphosphate, the proximate radiosensitizer.

Protection by WR-2721 and WR-151327 against late effects of gamma rays and neutrons

Two thiophosphoroate compounds WR-2721 and WR-151327 were assessed for their ability to modify the deleterious effects (life shortening and carcinogenesis) of fission-spectrum neutrons (kerma-weighted mean energy of 0.85 MeV) or gamma rays on B6CF1 hybrid mice. Male and female mice, 200 of each sex per experimental group, were irradiated individually at 110 days of age. Radioprotectors (400 mg/kg of WR-2721 or 580 mg/kg of WR-151327) were administered intraperitoneally 30 min prior to irradiation. Neutron doses were 10 cGy or 40 cGy and gamma ray doses were 206 cGy or 417 cGy. Animals were housed five to a cage; cage locations in the holding rooms were randomized by computer. Animals were checked daily and all deceased animals were necropsied. WR-2721 afforded protection against both neutron- and gamma-ray-induced carcinogenesis and subsequent life shortening. Cumulative survival curves for unirradiated mice of either sex were unaffectecd by protectors. WR-2721 protected irradiated groups against life shortening by approximately 10 cGy of neutrons or 100 cGy of gamma rays. WR-151327 was as effective as WR-2721 against neutron irradiation.

Combination therapy: lonidamine, hyperthermia, and chemotherapy against the RIF-1 tumor in vivo

Lonidamine enhances the cytotoxicity in vitro of several conventional antitumor drugs as well as that of hyperthermia (HT). We have investigated the possibility that such enhancement can also be demonstrated in vivo against the RIF-1 tumor system. Two assays were used to examine antitumor activity: tumor growth delay and clonogenicity of cells obtained from tumors from treated animals. We used drug (and HT) doses that by themselves did not achieve significant cell killing. The drugs whose interaction with lonidamine was tested were: cis-diamminedichloroplatinum (CDDP), mitomycin C (MMC), bleomycin, 5-fluorouracil, and nitrosourea. Of these only CDDP and MMC yielded positive data. Both assays gave essentially the same results, showing that antitumor activity reflected direct cell killing. CDDP and MCC activity was also enhanced by HT. When we combined all three modalities, however, the results of the trimodality therapies were no better than that of individual bimodality treatments. These last results suggest that lonidamine and HT have similar mechanisms, most likely inhibition of repair of DNA damage. Our data do suggest that lonidamine may have a role in multidrug therapies that include either CDDP or MMC as a component of the treatments.

Bacteriochlorophyll-a as photosensitizer for photodynamic treatment of transplantable murine tumors

Bacteriochlorophyll-a (bChla), which absorbs light of 780 nm wavelength, was tested for in vivo photodynamic activity in the SMT-F and RIF transplantable mouse tumor systems. High performance liquid chromatography (HPLC) analysis of tissue extracts showed that bChla was rapidly degraded in vivo to bacteriopheophytin-a (bPheoa) and other breakdown products. These were also photodynamically active, and tumor response could be achieved over a wavelength range of 660 to 780 nm, while tumor cure was restricted to wavelengths of 755 (bPheoa) to 780 nm. A photosensitizing product absorbing at 660 nm was also present in isolated tumor cells. Photodynamic cell kill of tumor cells isolated from tumors after bChla accumulation in vivo, using 775 or 780 nm light in vitro, was exponential up to 20-40 J cm-2. Above this light dose little or no further damage could be achieved, which is an indication of the rapid photobleaching of these sensitizers. In vivo, vascular occlusion occurred readily if light treatment was delivered shortly after sensitizer administration, but was delayed if light treatment was carried out 24 h after injection. Although up to 70% of tumor cells were lethally damaged after completion of in vivo light treatment, concurrent severe vascular destruction seemed necessary for tumor cure. Normal tissue photosensitivity totally subsided within 5 days after sensitizer administration.

Isolation and initial characterization of mouse tumor cells resistant to porphyrin-mediated photodynamic therapy

Photodynamic therapy (PDT)-resistant variants of the RIF-1 mouse tumor cell line have been isolated following a protocol of repeated porphyrin incubation and light treatments. Two porphyrin incubation procedures, employing either an extended (16 h) or a short (1 h) incubation, were used in order to obtain cell strains exposed to conditions with differing intracellular photosensitizer localization. Two clones from each PDT porphyrin incubation protocol were selected for in vitro and in vivo analyses based on degree of resistance and plating efficiency. Resistant variants had increased protein content and were larger than the parental RIF-1 cells. In vitro growth rates were similar for all cell strains. Both 16-h PDT-resistant variants exhibited modest resistance to ionizing radiation and one of the 16-h PDT-resistant variants demonstrated increased sensitivity to hyperthermia. The PDT-resistant variants did not exhibit a multidrug resistance phenotype nor did they have altered porphyrin uptake properties. The parental and resistant RIF cells had comparable basal levels of antioxidant enzymes, reduced glutathione and stress proteins, but the number of cells required to produce in vivo tumor growth in 50% of inoculated animals was increased for all PDT-resistant variants. The resistant cells exhibit a stable phenotype and should be useful in studies designed to define PDT mechanisms of action.

Response to chemotherapy of non-small cell bronchial rat tumours growing subcutaneously or in the lung

Seven rat bronchial cancers of various grades of differentiation were used to study responses to single doses of cytostatic drugs (mitomycin C, cisplatin, methotrexate, TCNU, CCNU, ifosfamide) when growing subcutaneously or in the lung. The endpoint was growth delay as calculated from tumour volume measurements using vernier callipers or radiography. Substantial differences were observed between the tumour lines in their response to the chemotherapeutic agents. The response of tumours implanted in the lung was less than that of flank implants of the same tumour line. TCNU and ifosfamide were the most consistently effective drugs, yielding growth delays of at least two tumour volume doubling times in the majority of the lines studied.

Application of charge-coupled device technology for measurement of laser light and fluorescence distribution in tumors for photodynamic therapy

Laser and fluorescence light distributions with applications for photodynamic therapy were measured in mouse tumors using a non-invasive electronic optical imaging system. The system consists of a liquid-nitrogen-cooled, charge-coupled-device (CCD) array camera under computer control with 576 x 384 detection elements having dimensions of 23 microns x 23 microns. The available dynamic range of the array is approx. 10(3), and the effective wavelength range is 400-1000 nm. An interstitially placed cylindrical diffusing optical fiber was used to provide tumor illumination. The light distribution pattern from the fiber was determined by immersing the cylindrical diffusing tip in a fluorescing solution and recording the emission image. Fluorescence imaging facilitates an accurate measurement of light intensity distribution while avoiding problems associated with the directional nature of other detection methods used with diffusing fibers. Radiation-induced fibrosarcoma tumors on C3H mice were grown to about 1 cm diameter for in vivo recording of light distribution from the tumor volume and for determination of effective light penetration distance at 18 wavelengths in the range 458-995 nm. Endogenous tumor fluorescence and Photofrin II fluorescence intensity were measured over the wavelength range 585-725 nm to investigate the possible application of CCD imaging technology for drug distribution measurements. Model experiments were begun to evaluate the relative importance of potential distortions of light distribution measurements using this approach.

Altered O6-alkylguanine-DNA alkyltransferase activity in cell strains originating from mouse skin tumors induced by UV irradiation

O6-Alkylguanine-DNA alkyltransferase (AGT) activity was assayed in the extracts of 47 cell strains originating from mouse skin tumors induced by UV irradiation. They were also examined for the sensitivity to 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride by colony formation. The AGT activity (fmol/mg protein) of the tumor cell strains varied widely and the mean +/- SE was 72.5 +/- 9.37, while the AGT activity of the nontumor cell strains was 134 +/- 17. Among 47 strains, 6 strains showed extremely low or no AGT activity, about 5 fmol/mg protein or less, and were hypersensitive to 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride. Long-term culture of the tumor cells did not change the AGT activity except in some strains which might have had coexisting normal cells in the population in early passages. All strains showed similar UV sensitivity regardless of AGT activity. This is the first report which demonstrates that about 13% of newly induced tumor cell strains are deficient in AGT activity similar to Mer-/Mex- phenotype that was found in approximately 20% of the established human tumor cell strains.

Ultraviolet radiation in skin ageing and carcinogenesis: the role of retinoids for treatment and prevention

The mechanisms of UV-induced ageing and carcinogenesis of the skin have been elucidated in animals and humans, and both UVB and UVA radiation have been shown to have deleterious effects on the skin. Thus the use of solaria which deliver mostly UVA radiation is not safe. There is also an increased risk of ageing when using therapeutic UV sources. UV radiation is beneficial in many cases of skin disorders such as psoriasis, atopic eczema, acne and pruritus. Nevertheless by careful patient selection and follow-up the risks of UV can be minimised when treating patients with artificial UV radiation. During recent years there has been intensive research into the development of agents which prevent harmful effects of radiation. The retinoids are particularly interesting as they enhance skin repair after UV damage, have an anticarcinogenic effect and are effective for treating precancerous lesions such as solar keratosis and as adjuvant therapy for skin cancers. Topical retinoids are already used for the treatment of actinic skin damage, and systemic retinoids are also used in certain groups of patients who have an increased risk of contracting skin cancers such as xeroderma pigmentosum.

Sarcomas (other than Ewing's) of flat bones in children and adolescents. A clinicopathologic study

The clinicopathologic features and response to therapy of 28 patients with non-Ewing's flat bone sarcoma treated at St. Jude Children's Research Hospital, Memphis, Tennessee, over a 25-year period were reviewed. Twenty-two patients had osteosarcoma, four malignant fibrous histiocytoma, one chondrosarcoma, and one fibrosarcoma. Ages at diagnosis ranged from 3 to 24 years (median, 15 years). Primary sites were craniofacial bones in ten patients, pelvis eight, scapula four, ribs two, metatarsal bones two, clavicle one, and vertebra one. All primary tumors were associated with soft tissue extension; none of the patients had metastatic disease at presentation. Six cases represented second malignancies that arose 5 to 16 years after irradiation for an unrelated tumor. Complete excision was possible in ten patients, eight of whom received postoperative chemotherapy. Five of these patients remain free of disease 1.8+ to 13+ years (median, 8.1 years) from diagnosis. Prolonged remissions after adjuvant chemotherapy were achieved in only two of 18 patients after incomplete surgical resection or biopsy. The median survival time in this group was 1 year (range, 0.2-7.7+ years). The remaining 16 patients had progressive local disease, but only two developed concurrent metastases. Thus, complete surgical resection appears to maximize disease-free survival in patients with non-Ewing's flat bone sarcoma. For the large percentage of patients in whom total resection is not possible, because of soft tissue extension and local invasion of bulky tumors, preoperative chemotherapy may increase the likelihood of complete excision and improve long-term survival.

Transtentorial herniation caused by an intracranial mass lesion following high-dose methotrexate

A patient with intracranial osteosarcoma that arose 16 years after radiation therapy for hereditary retinoblastoma developed fatal cerebral edema and brainstem herniation after she received a single dose of intravenous methotrexate. Autopsy demonstrated extensive necrosis of the tumor mass, as well as necrotizing vascular damage within the neoplasm. Although high-dose methotrexate has been shown to be useful in the treatment of primary osteogenic sarcoma, the tumoricidal effects of therapy appear to have caused a fatal rise in intracranial pressure.

[Intracranial fibrosarcoma fifteen years after radiotherapy in bilateral retinoblastomas: effect of combined chemotherapy with cisplatin and VP-16]

We report intracranial fibrosarcoma which developed after radiotherapy for bilateral retinoblastomas. A 16-year-old boy was admitted with swelling of his left eyelid as his chief complaint on September 10, 1987. He had a past history of bilateral retinoblastomas at one year of age, which was treated by bilateral ophthalmectomy and postoperative radiotherapy; 50 Gy to right eye and 60 Gy to left eye. Until fifteen years old, he had no trouble except blindness. On admission, a dumb-bell type huge tumor with the destruction of the orbital roof was demonstrated on CT scan and MRI. The tumor was composed of solid orbital tumor and cystic tumor located in the left frontal lobe. On September 18, partial removal of the orbital tumor and evacuation of the intracranial cyst following embolization of the left external carotid artery was performed. The histological diagnosis of the tumor was fibrosarcoma. For the residual tumor, combined radiochemotherapy was carried out. The patient was treated with intravenous administration of 20 mg/m2 of cisplatin and 60 mg/m2 of VP-16 daily for five days and then whole brain radiotherapy of 26 Gy. On March 27, 1988, he obtained a complete remission of the tumor and was discharged without neurological deficit except blindness. In this case, we have presented a radiation-induced secondary tumor after a treatment of bilateral retinoblastomas. Although the tumor was highly proliferative and invasive fibrosarcoma, we could control it well by multimodality treatment including surgery, radiation and chemotherapy. It is noteworthy that combined chemotherapy with cisplatin and VP-16 was effective against this type of tumor.

Inhibition of radiogenic mammary carcinoma in rats by estriol or tamoxifen

Mammary carcinomas have been induced by 3.5 Gy whole-body gamma radiation administered at age 40 to 50 days to virgin female Sprague-Dawley rats. In 142 irradiated controls carcinoma incidence averaged 7.8% in survivors observed less than 300 days and 38.3% of those surviving longer (P less than 0.001 by t test). Mammary cancer promotion was inhibited by two methods: estriol (E3) 638 micrograms/month (2.2 microns/mo) subcutaneously for natural life span begun 2 weeks after exposure reduced cancer incidence from 76% in controls to 48% after 331 to 449 mean days observation until neoplasia was palpable (P less than 0.02 by chi-square analysis). Uterine weights were similar in control and treated groups, and were 15% to 18% greater than uteri of nonirradiated controls from other simultaneous experiments. Six monthly 638-micrograms doses of 17 alpha ethinyl estriol (EE3) reduced tumors from 88% in controls to 64% (P less than 0.05 by chi-square analysis) and delayed cancer onset (P less than 0.01-0.04 by life table analysis). Ethinyl estradiol (EE2) after 6 months' treatment similarly delayed mammary tumor development reducing incidence to 75% (NS), with a six-fold increase in nonmammary epithelial malignant tumors. Estriol administration begun between 3 days before to 5 days after radiation did not alter mammary cancer incidence in six experiments. Monthly implantation of 2.5 mg tamoxifen (4.44 microns/mo) started 2 weeks after radiation reduced mammary cancer incidence from 83% to 14% after 307 to 314 days' observation (P less than 0.001 by chi-square analysis). Treated rats had atrophic ovaries and uteri consistent with blockade of endogenous estradiol activity. Short-term parenteral E3 or EE3 therapy using 10 to 30 micrograms/kg/day (35-100 microns/kg/day) rapidly differentiated virgin rat mammary glands without impairment of subsequent estrus cycles and offers an alternative to castration or life-long antiestrogen therapy for reduction of risk of radiogenic mammary carcinoma.

Tretinoin therapy for precancerous skin

Although few actinic keratoses eventuate as squamous cell carcinomas, these precancerous lesions cannot be ignored. A medical regimen of topical tretinoin use and sun protection appears to be effective in treating and preventing these precancers, with the added cosmetic benefits of ameliorating the alterations which accompany sun damage on exposed skin.

Oxygen limitation of direct tumor cell kill during photodynamic treatment of a murine tumor model

The relationship between levels of in vivo accumulated photosensitizer (Photofrin II), photodynamic cell inactivation upon in vitro or in vivo illumination, and changing tumor oxygenation was studied in the radiation-induced fibrosarcoma (RIF) mouse tumor model. In vivo porphyrin uptake by tumor cells was assessed by using 14C-labeled photosensitizer, and found to be linear with injected photosensitizer dose over a range of 10 to 100 mg/kg. Cellular photosensitivity upon exposure in vitro to 630 nm light also varied linearly with in vivo accumulated photosensitizer levels in the range of 25 to 100 mg/kg injected Photofrin II, but was reduced at 10 mg/kg. Insignificant increases in direct photodynamic cell inactivation were observed following in vivo light exposure (135 J/cm2, 630 nm) with increasing cellular porphyrin levels. These data were inconsistent with expected results based on in vitro studies. Assessment of vascular occlusion and hypoxic cell fractions following photodynamic tumor treatment showed the development of significant tumor hypoxia, particularly at 50 and 100 mg/kg of Photofrin II, following very brief light exposures (1 min, 4.5 J/cm2). The mean hyupoxic cell fractions of 25 to 30% in these tumors corresponded closely with the surviving cell fractions found after tumor treatment in vivo, indicating that these hypoxic cells had been protected from PDT damage. Inoculation of tumor cells, isolated from tumors after porphyrin exposure, into porphyrin-free hosts, followed by in vivo external light treatment, resulted in tumor control in the absence of vascular tumor bed effects at high photosensitizer doses only.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful treatment of a radiation-associated extradural osteosarcoma with chemotherapy in an adolescent girl

Bone sarcomas are the most common second malignant neoplasms in survivors of a malignant solid tumor in childhood. In contrast to de novo tumors, secondary bone cancers are typically associated with a poor prognosis, reflecting both a preponderance of primary sites that preclude complete resection in the flat bones of the axial skeleton, and the tendency for local invasiveness or distant metastasis. We describe a patient who developed malignant extradural osteosarcoma of the temporal bone 6 years after successful treatment for a malignant cerebellar astrocytoma with surgical resection and local irradiation. A complete resection of the sarcoma was not possible; however, she achieved a biopsy-proven complete response after intensive chemotherapy with ifosfamide, followed by cisplatin and doxorubicin. At age 13, she remains free of recurrence 3 years after completing all therapy. In view of the rarity of prolonged disease control after incomplete resection for osteosarcoma, this report suggests the value of intensive combination chemotherapy in achieving a durable unmaintained remission in our patient.

Suppressive therapy of thyroid nodules in patients with previous radiotherapy to the head and neck

This is a prospective, randomized study of 431 patients with palpable thyroid nodules who had previous radiotherapy for benign disorders of the head and neck area to determine the response of the thyroid nodules to suppressive therapy and the incidence of thyroid cancer in patients who could not be suppressed and had surgery. A complete response was achieved within 6 months in 18.3 percent of the patients, and in an additional 26 percent of patients between 7 and 12 months postoperatively. Twenty percent of the patients showed complete disappearance of nodules after 1 to 2 years of suppressive therapy. Twenty-two percent who underwent surgery showed carcinoma. If suppressive therapy is to be used, a trial of 1 year rather than 3 or 6 months, as often recommended, may be appropriate.

Combined effects of host antitumor immune responses and chemotherapy. Studies with hexamethylmelamine

The antitumor activity of hexamethylmelamine (HMM) was tested in various mouse tumor models in the presence or absence of host-vs-tumor graft responses. The drug was moderately active against Sarcoma-180 growing in different strains of non-sensitized mice. Strong protection was afforded when recipients were preimmunized with irradiated tumor cells 15 days before tumor challenge followed by HMM treatment. The drug did not show antitumor activity against two radiation-induced lymphomas of congenic mice of B10 background, inoculated into H-2 compatible hosts, or into mice incompatible for subregions of H-2. In this model HMM increased mortality of allogeneic mice presumably through impairment of host-vs-lymphoma graft resistance. In conclusion this study shows that synergistic or antagonistic effects can be obtained by combining chemotherapy with antitumor immune responses.

Hyperthermic potentiation of photodynamic therapy employing Photofrin I and II: comparison of results using three animal tumor models

Hyperthermia induced by a microwave source (2,450 MHz) was used alone and in combination with photodynamic therapy (PDT) to treat the SMT-F, EMT-6, and RIF animal tumors in vivo. PDT was administered using either Photofrin I or II as the photosensitizer and an argon-pumped tunable dye laser (630 nm) as the light source. Greater than additive increases in long-term tumor control were achieved when hyperthermia was given immediately post-PDT in the SMT-F and RIF tumor systems. Only additive (or independent) increases in tumor control were achieved when hyperthermia was given immediately before PDT in all these tumor systems and when heat was applied post-PDT using the EMT-6 tumor. In a series of experiments using the SMT-F tumor, it was observed that decreases in PDT drug or light doses could be offset (in terms of tumor control) by the addition of a subsequent heat treatment. This result, along with others presented, indicates the clinical potential of PDT and hyperthermia as adjuvant cancer modalities.

Postradiation sarcoma involving the spine

Postradiation sarcomas arising many years after treatment of cancer are long term sequelae of therapy. We describe the clinical features, radiographic findings, and results of treatment in 13 patients with such sarcomas encountered over a 6-year period. Of these patients, 9 had bone sarcomas and the remaining 4 had paraspinal tumors arising from adjacent soft tissue and nerve. The primary cancer for which radiation was given included Hodgkin's disease (4 patients), breast cancer (2 patients), cervix cancer (2 patients), and a variety of others (5 patients). The latent interval to the occurrence of the second neoplasm varied from 6 to 30 years (median, 10 years) after treatment of the original tumor. Despite aggressive treatment, the overall prognosis was poor. The median survival was 8 months, with only 3 surviving more than 2 years. Although rare, postradiation sarcoma should be considered in the differential diagnosis of patients presenting with late onset of spinal pain or neurological symptoms after clinical remission of an original cancer.

Experimental studies on high-dose methotrexate with citrovorum factor chemotherapy for 89Sr-induced osteosarcoma murine model

Experimental chemotherapy using high-dose methotrexate (MTX) with citrovorum factor (CF) was performed on ddN strain mice bearing 89Sr-induced osteosarcoma and the antitumor efficacy was analyzed through autoradiography ([3H]thymidine). The administration was done using sustained infusion via the tail vein using our own device to maintain certain elevated blood levels of the drugs. As the first experiment, MTX was administered to 4 different groups of mice with dose levels of 250, 500, 1,000, 2,000 mg/kg for 6 hours followed by CF 200 mg/kg for 24 hours. It was found that the blood levels of MTX were maintained at 10(-4) M by the dosage of 500 mg/kg, but no higher levels were achieved by increasing dosage. Tissue such as the small intestine and the bone marrow recovered from the toxicity of MTX in about 1 week after the dosage of 500 mg/kg. In tumors, on the other hand, the tissue showed a gradual recovery with time, but the uptake of [3H]thymidine by the tissue was not restored to the pretreatment level. When the antitumor efficacy of a single dosage of 1,000 mg/kg and 2 dosages of 500 mg/kg each with 1 week interval were compared, the latter was definitely more effective. It was, therefore, concluded that the administration of the drugs should be done repeatedly with optimum doses of MTX and CF rather than with ultrahigh doses of MTX and CF all at once.

Malignant fibrous histiocytoma developing in irradiated sacral chordoma

Malignant fibrous histiocytoma (MFH), arising at the site of a sacral chordoma 8 years after massive radiotherapy, is described. Initially, the patient received 7000 rad to the sacral area and, on recurrence, 5 years later, an additional 4000 rad. Two years later, a sacral mass was noted again. Biopsy then revealed MFH; chest x-ray showed multiple lung metastases. A combination chemotherapy, consisting of cyclophosphamide, vincristine, adriamycin (doxorubicin), and DTIC, resulted in a 6 month partial response. Subsequently, the patient died because of progressive metastatic disease. At autopsy, 8 years after diagnosis, both the sacral lesion and the lung metastases proved to be MFH, and no residual chordoma was found.

Receptor-dependent antiproliferative effects of corticosteroids in radiation-induced fibrosarcomas and implications for sequential therapy

Competitive binding studies with [3H]dexamethasone and Scatchard analysis demonstrated a single class of high-affinity, low-capacity glucocorticoid receptor sites in 105,000 x g cytosols from radiation-induced fibrosarcomas. In vivo, both dexamethasone (DEX) and methylprednisolone treatments resulted in dose-dependent inhibition of tumor growth and cell proliferation. Changes in the sensitivity of the clonogenic cell population to 3 mM hydroxyurea were used to assess changes in the clonogenic cell proliferation during and after treatments with DEX or methylprednisolone. Neither methylprednisolone nor DEX given every 12 hr for three doses resulted in significant cell kill in the clonogenic fraction. However, changes in the hydroxyurea sensitivity of the clonogenic population after cessation of DEX treatments indicated G1 cell cycle progression delay with transient enrichment of S-phase clonogenic cells 24 to 48 hr after cessation of DEX treatments. The duration of the DEX-induced progression delay and the timing of maximal S-phase cellularity after DEX was directly correlated with the level of glucocorticoid receptors in the treated tumors. Using regrowth delay to assess the efficacy of kinetically directed sequential chemotherapy, the effectiveness of vincristine, given after DEX, was highly sequence dependent, with the most effective treatment interval being coincident with maximal S-phase clonogenic fraction. Other studies indicated that the effectiveness of cyclophosphamide could also be increased by time sequencing after DEX.

Suppressive therapy for postirradiation thyroid nodules

From the thyroid screening program at the Roswell Park Memorial Institute in Buffalo, New York, 85 patients with thyroid nodules who had received previous irradiation to the head and neck were identified. The diagnosis was confirmed microscopically by needle aspiration cytology and the patients were treated with thyroid replacement therapy. In 24 patients, the nodules disappeared completely; a partial response (more than 50% reduction in size) was seen in 26; 11 patients were improved (20% to 50% reduction in size); 14 had stable disease (less than 20% reduction in nodule size) and in 10 the condition progressed (an increase of more than 20% in nodule size). Six of 21 patients who underwent operation had well differentiated tumours. The number of cases of Hashimoto's thyroiditis (14) was high. Suppressive therapy will separate those patients whose nodules will disappear completely and who will thus be spared operation. Continued follow-up of such patients is essential. All other patients should be offered operation since thyroid nodules are malignant in 30% of cases.

Statistical methods for censored survival data

Methods of statistical analysis of censored survival times are briefly reviewed and illustrated by application to clinical trials data. These include estimation of the survival curce, nonparametric tests to compare several survival curves, tests for trend, and regression analysis. Extensions of the methodology are made for application to epidemiologic case-control studies. These are used to estimate relative risks for leukemia associated with radiation exposures. A final section provides some annotated references to the recent literature.

Influence of presensitization with allogeneic lymphoma cells on the growth and response to therapy of radiation-induced lymphomas in mice

Congenic mice were sensitized with viable H-2-incompatible radiation-induced lymphomas (RIL), challenged with syngeneic RIL and treated with bis-chloroethyl-nitrosourea. Either enhancement or inhibition of RIL was found in presensitized mice, depending on the tumor-host system used.

Influence of steroid hormones on the carcinogenicity of 90Sr

Groups of female CBA-mice were given 90Sr (14.8 kBq/g-0.4muCi/g--bodyweight) alone or in combination with polyestrodiolphosphate, methylprednisolone or nortestosterone, respectively. When 90Sr was given in the first combination, the frequency of osteosarcomas was significantly increased whereas the tumour latency time was decreased compared to mice given 90Sr alone. In combination with nortestosterone such effects were not found, whereas the combination 90Sr + methylprednisolone resulted in a strong reduction of the osteosarcoma incidence and a prolonged tumour latency time. The latter experiment was repeated in a larger experiment whereby the results were confirmed.