Explicit dosimetry for photodynamic therapy: macroscopic singlet oxygen modeling

Singlet oxygen ((1)O(2)) is the major cytotoxic agent responsible for cell killing for type-II photodynamic therapy (PDT). An empirical four-parameter macroscopic model is proposed to calculate the "apparent reacted (1)O(2) concentration", [(1)O(2)](rx), as a clinical PDT dosimetry quantity. This model incorporates light diffusion equation and a set of PDT kinetics equations, which can be applied in any clinical treatment geometry. We demonstrate that by introducing a fitting quantity "apparent singlet oxygen threshold concentration" [(1)O(2)](rx, sd), it is feasible to determine the model parameters by fitting the computed [(1)O(2)](rx) to the Photofrin-mediated PDT-induced necrotic distance using interstitially-measured Photofrin concentration and optical properties within each mouse. After determining the model parameters and the [(1)O(2)](rx, sd), we expect to use this model as an explicit dosimetry to assess PDT treatment outcome for a specific photosensitizer in an in vivo environment. The results also provide evidence that the [(1)O(2)](rx), because it takes into account the oxygen consumption (or light fluence rate) effect, can be a better predictor of PDT outcome than the PDT dose defined as the energy absorbed by the photosensitizer, which is proportional to the product of photosensitizer concentration and light fluence.

Explicit dosimetry for photodynamic therapy: macroscopic singlet oxygen modeling

Singlet oxygen ((1)O(2)) is the major cytotoxic agent responsible for cell killing for type-II photodynamic therapy (PDT). An empirical four-parameter macroscopic model is proposed to calculate the "apparent reacted (1)O(2) concentration", [(1)O(2)](rx), as a clinical PDT dosimetry quantity. This model incorporates light diffusion equation and a set of PDT kinetics equations, which can be applied in any clinical treatment geometry. We demonstrate that by introducing a fitting quantity "apparent singlet oxygen threshold concentration" [(1)O(2)](rx, sd), it is feasible to determine the model parameters by fitting the computed [(1)O(2)](rx) to the Photofrin-mediated PDT-induced necrotic distance using interstitially-measured Photofrin concentration and optical properties within each mouse. After determining the model parameters and the [(1)O(2)](rx, sd), we expect to use this model as an explicit dosimetry to assess PDT treatment outcome for a specific photosensitizer in an in vivo environment. The results also provide evidence that the [(1)O(2)](rx), because it takes into account the oxygen consumption (or light fluence rate) effect, can be a better predictor of PDT outcome than the PDT dose defined as the energy absorbed by the photosensitizer, which is proportional to the product of photosensitizer concentration and light fluence.

[Locally advanced soft-tissue sarcomas. An innovating triad to avoid amputation: isolated limb perfusion, TNFalpha, and free microsurgical flap]

We retrospectively studied the benefits of isolated limb perfusion combined with TNFalpha administration and free flap reconstruction in locally advanced soft-tissue sarcomas of the limbs. Between 2000 and 2008, we treated 37 patients (22 women and 15 men) with locally advanced soft tissue sarcomas. The sarcomas were located in the lower and upper limbs in respectively 26 and 11 cases, and had a mean diameter of 15 cm and 12 cm, respectively. They were multifocal in 8 cases and recurrent in 15 cases. Seventeen patients received neoadjuvant chemotherapy. Sarcoma excision was combined with a complementary procedure in 10 patients (vascular graft or nerve anastomosis). Reconstruction was performed with free flaps of the latissimus dorsi (n = 31), transverse rectus abdominis myocutaneous flaps (n = 4) or free forearm flaps (n = 2). Early postoperative radiotherapy was administered in 25 cases. Three major improvements were made in recent years, namely isolated limb perfusion, TNFalpha administration, and free flap reconstruction two months after resection of residual sarcoma. There were no early postoperative deaths. The procedure lasted a median of 7 hours. Two free flaps necrotized, and a new free flap was created with success. Tumor excision was stage R0 in 29 cases (clean margins), R1 in 7 cases (microscopic residue), and R2 in one case (macroscopic residue). With a median follow-up of 5 years, there were no local recurrences in R0 patients, and the overall survival rate was 65%. The limb was preserved in 78% of cases. Thirteen patients developed pulmonary metastases and seven of them died between the first and fifth years of follow-up. Isolated limb perfusion and free flap reconstruction permitted more extensive tumor excision. Amputation was avoided in 78% of our 37 patients, and early postoperative radiotherapy was possible in 25 cases.

N-acetylcysteine protects melanocytes against oxidative stress/damage and delays onset of ultraviolet-induced melanoma in mice

PURPOSE

UV radiation is the major environmental risk factor for melanoma and a potent inducer of oxidative stress, which is implicated in the pathogenesis of several malignancies. We evaluated whether the thiol antioxidant N-acetylcysteine (NAC) could protect melanocytes from UV-induced oxidative stress/damage in vitro and from UV-induced melanoma in vivo.

EXPERIMENTAL DESIGN

In vitro experiments used the mouse melanocyte line melan-a. For in vivo experiments, mice transgenic for hepatocyte growth factor and survivin, shown previously to develop melanoma following a single neonatal dose of UV irradiation, were given NAC (7 mg/mL; mother's drinking water) transplacentally and through nursing until 2 weeks after birth.

RESULTS

NAC (1-10 mmol/L) protected melan-a cells from several UV-induced oxidative sequelae, including production of intracellular peroxide, formation of the signature oxidative DNA lesion 8-oxoguanine, and depletion of free reduced thiols (primarily glutathione). Delivery of NAC reduced thiol depletion and blocked formation of 8-oxoguanine in mouse skin following neonatal UV treatment. Mean onset of UV-induced melanocytic tumors was significantly delayed in NAC-treated compared with control mice (21 versus 14 weeks; P = 0.0003).

CONCLUSIONS

Our data highlight the potential importance of oxidative stress in the pathogenesis of melanoma and suggest that NAC may be useful as a chemopreventive agent.

Durable response of a radiation-induced, high-grade cerebellar glioma to temozolomide

BACKGROUND

Radiation-induced high-grade gliomas are a rare but serious late complication of radiotherapy. We report a patient with radiation-induced cerebellar high-grade glioma who had a durable response to temozolomide.

PATIENTS AND METHODS

Case report of a 77-year-old woman with a radiation-induced, high-grade cerebellar glioma that responded durably to temozolomide.

RESULTS

Our patient developed a cerebellar high-grade glioma 9 years after treatment for a stage IV (T4N0M0) supraglottic laryngeal squamous cell carcinoma with cisplatinum and fluorouracil chemotherapy, and subsequently focal head and neck radiotherapy. Patient was treated with radiation and concurrent temozolomide (only partially due to toxicity) and was stable for 1 year without further adjuvant treatment. Subsequently the tumor recurred and the patient had a dramatic and durable response to standard 5 day dosing of adjuvant temozolomide.

CONCLUSION

High-grade gliomas are a late complication of radiation to the central nervous system and may respond to chemotherapy.

Therapy-related acute promyelocytic leukemia after treatment with radioiodine for thyroid cancer: case report with literature review

Therapy-related acute promyelocytic leukemia (t-APL) is a rare but known complication of chemotherapy and/or radiation therapy. Approximately 200 cases of t-APL have been reported in the literature up until now. The development of t-APL after radioiodine therapy is very rare, keeping in mind the very low doses of radiation exposure of the patient. We present a case of a 47-year-old woman with t-APL t15;17(q22;q21) developed after radioiodine treatment for thyroid carcinoma. The patient was treated with chemotherapy and achieved complete response lasting for 3(+) years. The patient's excellent response to treatment supports the data of the relevant literature that t-APL is associated with a better therapeutic result than the other subtypes of secondary acute myeloid leukemia (AML).

Glioblastoma multiforme following cranial irradiation and chemotherapy for acute lymphocytic leukaemia. Report of 3 cases

The most common secondary neoplasms which occur following cranial radiation therapy are sarcoma and meningioma. The occurrence of glioblastoma multiforme following radiation and chemotherapy in acute lymphocytic leukaemia (ALL) is rare. We report 3 cases of glioblastoma multiforme in children developing 11-72 months following completion of chemotherapy/radiotherapy for ALL. The exact cause for the development of glioblastoma multiforme following therapy for ALL is not clear. A genetic predisposition may be essential for the occurrence of such a highly malignant primary brain tumour in leukaemia patients, irrespective of radiation and/or chemotherapy. The pathogenesis and surgical management are discussed, and the literature on the subject is reviewed.

Solitary extramedullary plasmacytoma and granulomatous sialadenitis of the parotid gland preceding a B-cell non-Hodgkin's lymphoma

A patient with swelling of the left parotid gland of four-months' duration, sicca syndrome (xerophthalmia and xerostomia) and a history of progressive systemic sclerosis with an incomplete form of the CREST syndrome was referred to our department. On ultrasound a parotid mass of reduced echogenicity without any enlarged cervical lymph nodes was found. Ultrasonographically guided fine-needle biopsy could not provide any definitive diagnosis. After partial parotidectomy with complete tumor removal the histologic exam showed an extramedullary plasmacytoma with concurrent non-necrotizing granulomatous sialadenitis of the parotid gland. Complete systemic work-up excluded multiple myeloma, leukemia, lymphoma and sarcoidosis. Post-operative radiotherapy of the left parotid region and left neck including the supraclavicular lymph node area was performed. Six months after surgery an aggressive B-cell non-Hodgkin's lymphoma was diagnosed.

Neoadjuvant chemotherapy for radioinduced osteosarcoma of the extremity: The Rizzoli experience in 20 cases

PURPOSE

Evaluate treatment and outcome of 20 patients with radioinduced osteosarcoma (RIO). Because of previous primary tumor treatment, RIO protocols were different from others we used for non-RIO.

PATIENTS AND METHODS

Between 1983 and 1998, we treated 20 RIO patients, ages 4-36 years (mean 16 years), with chemotherapy (two cycles before surgery, three postoperatively). The first preoperative cycle consisted of high-dose Methotrexate (HDMTX)/Cisplatinum (CDP)/Adriamycin (ADM) and the second of HDMTX/CDP/Ifosfamide (IFO). The three postoperative treatments were performed with cycles of MTX/CDP; IFO was used as single agent per cycle repeated three times.

RESULTS

Two patients received palliative treatment because their osteosarcoma remained unresectable after preoperative chemotherapy. The remaining 18 patients had surgery (7 amputations, 11 resections); histologic response to preoperative chemotherapy was good in 8 patients, poor in 10. At a mean follow-up of 11 years (range, 7-22 years), 9 patients remained continuously disease-free, 10 died from osteosarcoma and 1 died from a third neoplasm (myeloid acute leukemia). These results are not significantly different from those achieved in 754 patients with conventional osteosarcoma treated in the same period with protocols used for conventional treatment. However, this later group had an 18% 3-year event-free survival after treatment of relapse vs. 0% in the RIO group.

CONCLUSION

Treated with neoadjuvant chemotherapy RIO seem to have an outcome that is not significantly different from that of comparable patients with conventional primary high grade osteosarcoma (5-year event-free survival: 40% vs. 60%, p = NS; 5-year overall survival 40% vs. 67%, p < 0.01).

Reproducibility and Expression of Skin Biomarkers in Sun-Damaged Skin and Actinic Keratoses

OBJECTIVES

To explore p53 and proliferating cell nuclear antigen (PCNA) expression and polyamine content as biomarkers in skin cancer chemoprevention trials, we evaluated their expression in early stages of UV-induced squamous cell tumorigenesis.

METHODS

Biopsies were collected from three groups: 78 subjects with sun damage on forearms, 33 with actinic keratosis (AK) on forearms, and 32 with previous squamous cell carcinoma. Participants with sun damage were randomized to sunscreen or no sunscreen.

RESULTS

We found significant differences in p53 and polyamines in forearms from the sun-damaged group (11.5 +/- 1.2% for p53, 65.5 +/- 1.9 nmol/g for putrescine, and 187.7 +/- 3.3 nmol/g for spermidine) compared with the group with sun damage plus AK (20.9 +/- 2.3% for p53, P = 0.0001; 81.7 +/- 3.9 nmol/g for putrescine, P = 0.0001; 209.4 +/- 8.2 nmol/g for spermidine, P < 0.06). PCNA was not different. When lesion histology was considered, there was a stepwise significant increase in p53 in biopsies without characteristics of AK compared with early AK (P = 0.02) and AK (P = 0.0006) and a similar pattern for PCNA with the only significant difference between early AK and AK. There was a stepwise increase in putrescine and spermidine in normal, sun-damaged forearm, forearm from subjects with AK, and the AK lesion itself (P < 0.0001). No significant differences in p53 or polyamines were seen in 3-month biopsies or, as a result of sunscreen use, although PCNA in the sun-damaged group not using sunscreen decreased significantly.

CONCLUSIONS

p53 expression and polyamines in skin were elevated in early stages of skin tumorigenesis and were not affected by sunscreen, adding validity to their use as biomarkers in skin cancer chemoprevention trials.

Metachronous secondary atypical meningioma and anaplastic astrocytoma after postoperative craniospinal irradiation for medulloblastoma

INTRODUCTION

Malignant brain tumors have been reported to occur after childhood irradiation more frequently than in the nonirradiated population.

DISCUSSION

In this study, we report the case of a 15-year-old boy treated for medulloblastoma with surgery and craniospinal radiotherapy, who developed a meningioma 18 years after initial treatment and subsequently an anaplastic astrocytoma 23 years after primary treatment. The meningioma was resected without complications. The patient is currently alive but with recurrent astrocytoma after a complete remission on temozolomide monotherapy. Second malignancies are a rare, potentially devastating risk in cancer survivors, with risk continuing lifelong.

Outcome of postradiation osteosarcoma does not correlate with chemotherapy response

Postradiation osteosarcoma is a rare tumor with a historically poor prognosis. Recent reports concerning the prognosis of the disease have been conflicting. We ascertained the long-term outcome of patients with this disease treated in the era of contemporary chemotherapy. Twenty-seven patients diagnosed with postradiation osteosarcoma and treated with chemotherapy and surgical resection from 1980-2003 were identified. Demographics, anatomic location, stage, chemo- therapy, necrosis rate, recurrence and metastatic rates were recorded; Kaplan-Meier survival rates were estimated. The median age was 54 years (range, 12-86 years). Nineteen patients were female and eight patients were male. Median followup was 39.2 months (range, 0-218 months). Twenty-two patients received induction chemotherapy for a mean of four cycles (range, 2-6 cycles). Mean tumor necrosis was 63.5%. Seven patients had 90% necrosis; four of these patients died of their disease. The mean survival was 23 months, and the 5-year disease free survival estimate was 27.2%. Histologic response to chemotherapy did not correlate with survival. Patients who had a latency of greater than 10 years after radiation had a better prognosis. Unlike conventional osteosarcoma, response to chemotherapy (necrosis) did not have prognostic significance. Current chemotherapy regimens fail to impact survival in postradiation osteosarcoma.

LEVEL OF EVIDENCE

Therapeutic study, level IV (retrospective comparative study).

Effects of UVB on E prostanoid receptor expression in murine skin

Prostaglandin E2 (PGE2) upregulation in response to UV light exposure is a significant factor in the development of non-melanoma skin cancer. It is known that PGE2 signals via the E prostanoid receptors, EP1-4, but the role that each receptor plays in skin carcinogenesis is unclear. Immunohistochemical analysis of EP receptor staining in unirradiated and UVB-exposed SKH-1 mouse skin demonstrated the localization of EP1 and EP2 to the plasma membrane of differentiated epidermal keratinocytes. In contrast, the EP3 receptor localized to the basal layer of the epidermis in unirradiated skin and throughout the epidermis in UVB-exposed skin. In unirradiated skin, cytoplasmic EP4 staining was seen throughout the epidermis, in dermal leukocytes, and in vascular endothelium. However, UVB exposure resulted in relocalization of the EP4 receptor to the plasma membrane of keratinocytes, with no change in the dermal staining pattern. In tumors isolated from UVB-exposed mice, EP1 and EP2 staining was detected in the more differentiated cells surrounding keratin pearls, whereas EP3 and EP4 were detectable throughout the tumors. Differential expression of the EP receptors suggests that each receptor may play a distinct role in skin tumor development.

Caffeine and caffeine sodium benzoate have a sunscreen effect, enhance UVB-induced apoptosis, and inhibit UVB-induced skin carcinogenesis in SKH-1 mice

Topical application of caffeine sodium benzoate (caffeine-SB) immediately after UVB irradiation of SKH-1 mice enhanced UVB-induced apoptosis by a 2- to 3-fold greater extent than occurred after the topical application of an equimolar amount of caffeine. Although topical application of caffeine-SB or caffeine enhanced UVB-induced apoptosis, both substances were inactive on non-UVB-treated normal skin. Topical application of caffeine-SB or caffeine (each has UVB absorption properties) 0.5 h before irradiation with a high dose of UVB decreased UVB-induced thymine dimer formation and sunburn lesions (sunscreen effect). Caffeine-SB was more active than an equimolar amount of caffeine in exerting a sunscreen effect. In additional studies, caffeine-SB strongly inhibited the formation of tumors in UVB-pretreated 'high-risk mice' and in tumor-bearing mice, and the growth of UVB-induced tumors was also inhibited. Caffeine-SB and caffeine are the first examples of compounds that have both a sunscreen effect and enhance UVB-induced apoptosis. Our studies suggest that caffeine-SB and caffeine may be good agents for inhibiting the formation of sunlight-induced skin cancer.

In Vivo Stability and Photodynamic Efficacy of Fluorinated Bacteriopurpurinimides Derived from Bacteriochlorophyll-a

The stable bacteriopurpurinimide (788 nm, epsilon: 38,600 in CH2Cl2), obtained by reducing the corresponding unstable Schiff base (803 nm, epsilon: 50,900 in CH2Cl2) that was isolated by reacting bacteriopurpurin methyl ester with 3,5-bis-(trifluoromethyl)benzylamine, produced promising photosensitizing efficacy. 1H NMR, mass spectrometry, and HPLC analyses confirmed the structures of new bacteriopurpurinimides and the metabolic product. The preliminary in vivo photosensitizing efficacy of this stable bacteriopurpurinimide was determined in C3H mice bearing radiation induced fibrosarcoma tumors as a function of variable drug doses. A drug dose of 1.0 micromol/kg and light exposure of 135 J/cm2 (75 mW/cm2; 24 h postinjection) at 796 nm for 30 min produced a 60% long-term tumor cure (3/5 mice were tumor-free on day 90). Colocalization study of the stable bacteriopurpurinimide with MitoTracker Green confirmed some mitochondrial localization. The fluorescein-exclusion assay and histological staining of CD31 confirmed vascular stasis at various time points post-PDT (post photodynamic therapy). The treatment parameters (time for maximum drug uptake and wavelength for light irradiation) were determined by in vivo reflectance spectroscopy.

Radiation-induced angiosarcoma of the breast shows major response to docetaxel after failure of anthracycline-based chemotherapy

We report on the case of a patient with a diagnosis of an uncommon breast tumour, namely a radiation-induced angiosarcoma, which was primarily refractory to anthracycline-based chemotherapy, but highly sensitive to docetaxel. Although the sarcomas in general tend to be relatively refractory to taxanes, there is some evidence that the angiosarcomas may be sensitive to these agents. This is particularly well documented with paclitaxel, but may also be the case with docetaxel.

Response to chemotherapy of a radiation-induced glioblastoma multiforme

BACKGROUND

Radiation-induced glioblastoma multiforme (GBM) is particularly resistant to treatment and therapeutic options are limited. We report a patient with a radiation-induced GBM who had a complete response to carmustine and survived for 44 months.

PATIENTS AND METHODS

Case report of a 38-year-old man with a radiation-induced GBM that responded to carmustine.

RESULTS

Our patient developed a left occipital GBM 35 years after a left cerebellar astrocytoma was treated with surgery and radiation therapy (4500 rad). The GBM was treated with subtotal resection followed by four cycles of carmustine; a complete response was achieved. He relapsed 34 months after diagnosis and with further surgery survived 44 months from his diagnosis of GBM.

CONCLUSION

GBMs may be a late complication of radiation treatment for pediatric brain tumors. If further radiotherapy is not a therapeutic option, chemotherapy may result in prolonged survival.

Noninvasive monitoring of murine tumor blood flow during and after photodynamic therapy provides early assessment of therapeutic efficacy

PURPOSE

To monitor tumor blood flow noninvasively during photodynamic therapy (PDT) and to correlate flow responses with therapeutic efficacy.

EXPERIMENTAL DESIGN

Diffuse correlation spectroscopy (DCS) was used to measure blood flow continuously in radiation-induced fibrosarcoma murine tumors during Photofrin (5 mg/kg)/PDT (75 mW/cm2, 135 J/cm2). Relative blood flow (rBF; i.e., normalized to preillumination values) was compared with tumor perfusion as determined by power Doppler ultrasound and was correlated with treatment durability, defined as the time of tumor growth to a volume of 400 mm3. Broadband diffuse reflectance spectroscopy concurrently quantified tumor hemoglobin oxygen saturation (SO2).

RESULTS

DCS and power Doppler ultrasound measured similar flow decreases in animals treated with identical protocols. DCS measurement of rBF during PDT revealed a series of PDT-induced peaks and declines dominated by an initial steep increase (average +/- SE: 168.1 +/- 39.5%) and subsequent decrease (59.2 +/- 29.1%). The duration (interval time; range, 2.2-15.6 minutes) and slope (flow reduction rate; range, 4.4 -45.8% minute(-1)) of the decrease correlated significantly (P = 0.0001 and 0.0002, r2= 0.79 and 0.67, respectively) with treatment durability. A positive, significant (P = 0.016, r2= 0.50) association between interval time and time-to-400 mm3 was also detected in animals with depressed pre-PDT blood flow due to hydralazine administration. At 3 hours after PDT, rBF and SO2 were predictive (P < or = 0.015) of treatment durability.

CONCLUSION

These data suggest a role for DCS in real-time monitoring of PDT vascular response as an indicator of treatment efficacy.

Early detection of tumor response to chemotherapy by 3'-deoxy-3'-[18F]fluorothymidine positron emission tomography: the effect of cisplatin on a fibrosarcoma tumor model in vivo

We have assessed the potential of [18F]fluorothymidine positron emission tomography ([18F]FLT-PET) to measure early cytostasis and cytotoxicity induced by cisplatin treatment of radiation-induced fibrosarcoma 1 (RIF-1) tumor-bearing mice. Cisplatin-mediated arrest of tumor cell growth and induction of tumor shrinkage at 24 and 48 hours, respectively, were detectable by [18F]FLT-PET. At 24 and 48 hours, the normalized uptake at 60 minutes (tumor/liver radioactivity ratio at 60 minutes after radiotracer injection; NUV60) for [18F]FLT was 0.76 +/- 0.08 (P = 0.03) and 0.51 +/- 0.08 (P = 0.03), respectively, compared with controls (1.02 +/- 0.12). The decrease in [18F]FLT uptake at 24 hours was associated with a decrease in cell proliferation assessed immunohistochemically (a decrease in proliferating cell nuclear antigen labeling index, LI(PCNA), from 14.0 +/- 2.0% to 6.2 +/- 1.0%; P = 0.001), despite the lack of a change in tumor size. There were G1-S and G2-M phase arrests after cisplatin treatment, as determined by cell cycle analysis. For the quantitative measurement of tumor cell proliferation, [18F]FLT-PET was found to be superior to [18F]fluorodeoxyglucose-PET (NUV60 versus LIPCNA: r = 0.89, P = 0.001 and r = 0.55, P = 0.06, respectively). At the biochemical level, we found that the changes in [18F]FLT and [18F]fluorodeoxyglucose uptake were due to changes in levels of thymidine kinase 1 protein, hexokinase, and ATP. This work supports the further development of [18F]FLT-PET as a generic pharmacodynamic readout for early quantitative imaging of drug-induced changes in cell proliferation in vivo.

Diet as a factor in behavioral radiation protection following exposure to heavy particles

Major risks associated with radiation exposures on deep space missions include carcinogenesis due to heavy-particle exposure of cancer-prone tissues and performance decrements due to neurological damage produced by heavy particles. Because exposure to heavy particles can cause oxidative stress, it is possible that antioxidants can be used to mitigate these risks (and possibly some health risks of microgravity). To assess the capacity of antioxidant diets to mitigate the effects of exposure to heavy particles, rats were maintained on antioxidant diets containing 2% blueberry or strawberry extract or a control diet for 8 weeks prior to exposure to 1.5 or 2.0 Gy of accelerated iron particles at Brookhaven National Laboratory. Following irradiation rats were tested on a series of behavioral tasks: amphetamine-induced taste aversion learning, operant responding and spatial learning and memory. The results indicated that the performance of the irradiated rats maintained on the antioxidant diets was, in general, significantly better than that of the control animals, although the effectiveness of the diets ameliorating the radiation-induced deterioration in performance varied as a function of both the specific diet and the specific endpoint. In addition, animals fed antioxidant diets prior to exposure showed reduced heavy particle-induced tumorigenesis one year after exposure compared to the animals fed the control diet. These results suggest that antioxidant diets have the potential to serve as part of a system designed to provide protection to astronauts against the effects of heavy particles on exploratory missions outside the magnetic field of the earth.

Photodynamic therapy using a novel photosensitizer, ATX-S10(Na): comparative effect with 5-aminolevulinic acid on squamous cell carcinoma cell line, SCC15, ultraviolet B-induced skin tumor, and phorbol ester-induced hyperproliferative skin

Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) is available for the treatment of actinic keratosis (AK). Recently, we developed a new PDT photosensitizer, ATX-S10(Na), and have shown that ATX-S10(Na) PDT is effective for the treatment of various human skin diseases, such as squamous cell carcinoma, Bowen's disease, basal cell carcinoma, and psoriasis. In the present study, we compared the effects of ATX-S10(Na) PDT and ALA PDT on hyperproliferative skin induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), on the squamous cell carcinoma cell line, SCC15, in vitro, and on UVB-induced skin tumors in vivo. TPA treatment induced epidermal acanthosis, which was more markedly suppressed by ATX-S10(Na) PDT than by ALA PDT. ATX-S10(Na) PDT more effectively eliminated UVB-induced AK and squamous cell carcinoma (SCC) than ALA PDT. Furthermore, both ATX-S10(Na) PDT and ALA PDT induced the death of SCC15 cells, and the effect of ATX-S10(Na) PDT was greater than that of ALA PDT. Our results indicate that ATX-S10(Na) PDT might be more effective than ALA PDT for the treatment of various skin diseases.

Successful imiquimod treatment of multiple basal cell carcinomas after radiation therapy for Hodgkin's disease

We present a case of a 55-year-old male patient who developed five basal cell carcinomas 23 years after radiation therapy of Hodgkin's disease. In 1980 he received radiation therapy twice. Due to relapses, he was treated with aggressive polychemotherapy and underwent autologous stem cell transplantation, which then led to complete remission. Until now he is in complete remission. However, multiple superficial basal cell carcinomas have developed on irradiation fields that have been successfully treated by imiquimod.

Genetics of papillary thyroid cancer initiation: implications for therapy

Papillary thyroid cancers are the most common thyroid malignancy. They usually carry a favorable prognosis, although patients with invasive or metastatic tumors that no longer trap radioiodine do less well. There is mounting experimental support for a central role of mutations leading to constitutive activation of MAP kinase effectors in the pathogenesis ofthis disease. Thus activating mutations of the tyrosine receptor kinases RET and NTRK, and of the intracellular signaling effectors RAS and BRAF are present in a mutually exclusive fashion in more than 70% of cases. These mutations are believed to arise at early stages of cancer development, and may be important in tumor maintenance. Hence, compounds that inhibit kinase activity of effectors signaling distally along this pathway may prove effective in treating advanced forms of the disease.

Treatment-induced changes in tumor oxygenation predict photodynamic therapy outcome

Photodynamic therapy (PDT) requires oxygen to cause tumor damage, yet therapy itself can deplete or enhance tumor oxygenation. In the present work we measured the PDT-induced change in tumor oxygenation and explored its utility for predicting long-term response to treatment. The tissue hemoglobin oxygen saturation (SO(2)) of murine tumors was noninvasively measured by broadband diffuse reflectance spectroscopy. In initial validation studies, the oxyhemoglobin dissociation curve for mouse blood was accurately recreated based on measurements during deoxygenation of a tissue phantom of mouse erythrocytes. In vivo studies exhibited excellent correlation between carbogen-induced changes in SO(2) and pO(2) of radiation-induced fibrosarcoma tumors measured by reflectance spectroscopy and the Eppendorf pO(2) histograph, respectively. In PDT studies radiation-induced fibrosarcoma tumor SO(2) was measured immediately before and after Photofrin-PDT (135 J/cm(2), 38 mW/cm(2)). Animals were subsequently followed for tumor growth to a volume of 400 mm(3) (time-to-400 mm(3)) or the presence of tumor cure (no tumor growth at 90 days after treatment). In animals that recurred, the PDT-induced change in tumor SO(2), i.e., relative-SO(2) (SO(2) after PDT/SO(2) before PDT) was positively correlated with treatment durability (time-to-400 mm(3)). The predictive value of relative-SO(2) was confirmed in a second group of animals with enhanced pre-PDT oxygenation due to carbogen breathing. Furthermore, when all of the animals were considered (those that recurred and those that were cured) a highly significant association was found between increasing relative-SO(2) and increasing probability of survival, i.e., absence of recurrence. As independent variables, the SO(2) after PDT, the pre-PDT tumor volume, and light penetration depth all failed to predict response. As an independent variable, the SO(2) before PDT demonstrated a weak negative association with treatment durability; this association was driven by a correlation between decreasing pre-PDT SO(2) and increasing relative-SO(2). These data suggest that monitoring of PDT-induced changes in tumor oxygenation may be a valuable prognostic indicator.