Increased survival in brain metastatic patients treated with stereotactic radiotherapy, omega three fatty acids and bioflavonoids.

Stereotactic radiotherapy represents a method to effectively treat brain metastases with high precision and with high doses. Few acute toxicities are associated with stereotactic radiotherapy, however delayed reactions may occur and after six months, 20% of patients can develop radionecrosis. To avoid this adverse effect, in patients with metastases localized in critical brain areas, a supplementation of Omega three fatty acids and bioflavonoids has been used. At the end of 1997, we initiated a series of retrospective studies to test the efficacy of stereotactic radiotherapy on 405 patients, and the prognostic importance on survival of various variables among which this type of supplementation. From the comparison of various survival curves with the Cox multivariate analysis, it emerged that the patients using this supplementation had a decreased risk ratio and an improvement in survival time. A decreased number of radionecrosis was noted. We suggest their use as radioprotectors.

Tumor microcirculation and its significance in therapy: possible role of omega-3 fatty acids as rheological modifiers.

Despite the great efforts to find new drugs or devices to suppress cancer cells, attempts to modify microcirculation and therefore the state of tumor cells and their surrounding normal tissues have not been given the attention they deserve. Solid tumors are composed of highly heterogeneous populations of malignant, stromal and inflammatory cells in a continuously adapting extracellular matrix. All of the above components interact and regulate each other to produce distinct microenvironments within the tumor mass. Abnormal microcirculation plays a particular role in the maintenance of this anomalous condition and favors the formation of metastasis, but on the other hand provides the therapist with an important site for intervention. In this brief overview we attempt to outline three aspects: (a) how the anomalous tumor blood flow provokes the nonuniform distribution of oxygen and nutrients within the tumor mass, thus determining different responses to the various cancer therapies; (b) how hemorheology is the clinical parameter most easily modified and (c) how omega-3 essential fatty acids are natural drugs that could be used in this sense beyond their antitumoral properties.

Tumor interstitial fluid: misconsidered component of the internal milieu of a solid tumor.

The tumor interstitial fluid (TIF) is a fluid phase present in the extracellular space of all tumors whose importance in oncology is seldom recognized. In order to stimulate other researchers to give it the due importance, a review of the available data (including our own) is provided. An hypothesis is presented for the genesis, fate and role of the TIF in the processes of invasion, growth and metastatization. Open questions regarding the TIF's role in tumor response to therapy are raised.

Characterization of the metabolism of perinecrotic cells in solid tumors by enzyme histochemistry.

Hypoxic tumor cells resist most therapies and cause tumor regrowth when their environment improves. Identifying the adaptation strategies to hypoxia would help develop better tailored cancer therapies. Ehrlich carcinomas implanted on mice were analyzed histochemically for the following enzyme activities: lactate, succinate and glucose-6-phosphate dehydrogenases, dihydrofolate reductase, purine nucleoside phosphorylase, xanthine oxidoreductase, and acid phosphatase. With the exception of xanthine oxidoreductase, which was not active in tumor cells, and of succinate dehydrogenase the activity of which was not significatively altered, all other activities were much higher in perinecrotic cells with respect to cells close to blood vessels. These data suggest the integration of metabolic paths allowing purine and lipid biosyntheses. Degradation products from the necrosis are presumed to be employed as surrogates of blood-borne nutritive substances by cells distant from the vascularization.

Adjuvant therapy with essential fatty acids (EFAs) for primary liver tumors: some hypotheses.

Hepatocarcinoma is responsible for approximately 1 million deaths annually. It is usually discovered at an advanced stage and, if inoperable, has a poor prognosis. New therapies combining chemotherapy, hyperthermia, radiotherapy and immunomodulators have been recently attempted with various levels of success. Once the tumor is detected at an early stage, some possibilities of cure seem to emerge either by intratumoral percutaneous injection (PEI) of alcohol or by chemoembolization and interstitial hyperthermia. When the tumor volume is more than 5 cm, these therapies are less successful and radiotherapy can be used. All the techniques described have some limits; PEI, for instance, does not achieve a complete eradication of lesions > 3 cm and a non-homogenous alcohol distribution within the tumor leads to areas of necrosis. Radiotherapy, even if effective, is limited by dose-related radiation hepatitis. Another important limiting factor is the incomplete response to therapy and tumor recurrence. Essential fatty acids, especially gamma linolenic acid (GLA) and eicosapentaenoic acid (EPA) are discussed here for their ability to control primary tumor proliferation and increase response to chemotherapy, radiotherapy and hyperthermic treatment, thanks to their effects on cellular membranes (increased lipoperoxidation and modification of tumor stroma).

Enzyme histochemical studies on tumor blood vessels.

The oxygenation, the growth rate and the metastatic potential of a solid tumor depend on its vascularization and, in particular, on angiogenesis; a therapeutic approach affecting angiogenesis has been suggested as an alternative to conventional ones. Especially the study of the metabolism in the cells of the vessel wall should be a useful prerequisite for this approach. In this connection, an enzyme histochemical study was performed to characterize the blood vessels in a solid tumor (Ehrlich carcinoma). The following enzymes were considered: (a) alkaline phosphatase, involved in the transcellular phosphate transport and in the response to inflammatory and growth promoting factors; (b) dihydrofolate reductase, involved in the metabolism of tetrahydrofolate (for the synthesis of nucleic acids and the metabolism of serine and glycine); (c) purine nucleoside phosphorylase, involved in the degradation of purines and, in particular, of extracellular ATP and ADP; (d) xanthine oxidoreductase, engaged in the same degradation path and leading to the formation of urate, a strong antioxidant. Various patterns of enzyme activities were observed in the vessel wall. In particular, thin linear capillaries (presumed to be host capillaries penetrating the tumor) were identified for the intense positivity of alkaline phosphatase, dihydrofolate reductase and purine nucleoside phosphorilase; tortuous capillaries with variable diameters (presumed to be induced by angiogenesis from the host vessels) were negative for the alkaline phosphatase and expressed an heterogeneous pattern for the dihydrofolate reductase. All the data suggest a different vessel behaviour concerning the response to cytokines and to inflammatory stimuli.

Neglected factors in cancer treatment: cellular interactions and dynamic microenvironment in solid tumors.

Solid tumors are "organoids" consisting of highly heterogeneous populations of malignant, stromal and inflammatory cells and dynamic extracellular matrix. In particular, distinct cellular microenvironments are observed. The survival strategies of malignant cells might therefore be highly differentiated, causing the high genotypic and phenotypic instability characteristic of malignant cells in vivo. A constant interplay between the tumor compartments and the host immune and hemostatic systems determines the behavior of the tumor. A description of typical microenvironments and of cellular and matrix interactions is provided. Based on these, it is here postulated that: (a) any cancer treatment, by influencing differently the various tumor compartments, will alter previously established equilibria; (b) the behavior (growth, invasiveness, metastatic potential, resistance to further treatment) of a malignancy after treatment might be altered with respect to what is assumed in terms of effect of the treatment on the malignant cells alone.

Omega-3 fatty acids as coadjuvant treatment in AIDS.

Human immunodeficiency virus (HIV), is able to replicate in many human cells such as helper lymphocytes, monocytes/macrophages and glial cells. Monocytes/macrophages must be considered an important reservoir of HIV in vivo and a producer of cytokines such as Interleukin-1 (IL1) and tumor necrosis factor (TNF). These substances lead to an autocrine feedback loop that produces an increased virus replication and a secondary induction of other cytokines such as Interleukin 6 (IL6) and granulocyte-macrophage colony stimulating factor (GM-CSF). These cytokines all together may be responsible for many clinical aspects of the disease such as headache, fever, anorexia, subtle cognitive changes, motor disfunctions and cachexia. The future strategies in the treatment of AIDS must be a combination of drugs acting on different points of viral replication and with synergistic potential. Omega 3 polyunsaturated fatty acids (omega-3) can be considered a candidate for their pleiotropic effects on immunological and metabolic systems. In particular, their use is considered for their ability to decrease IL1 and TNF production by monocytes/macrophages, as demonstrated by many authors. The decreased induction of these cytokines and consequently of IL6 and acute phase proteins may have beneficial effects on many clinical manifestations of AIDS such as cachexia.

Tumor angiogenesis: evidence of new blood channels from plasma infiltrations.

Stroma formation in Ehrlich carcinoma, studied with histochemical and TEM techniques, is similar to wound healing. In this tumour mast cells, macrophages, adipocytes, platelets and fibrin seem to co-operate locally with malignant cells in regulating stroma formation. The gaps opened in the tumor parenchyma by plasma outpouring from local blood vessels seem to offer easy routes for endothelial cell migration towards ill-nourished areas, and may explain the irregular aspect of tumor microvascularity.

Tumor hypoxia, reoxygenation and oxygenation strategies: possible role in photodynamic therapy.

The concept of hypoxia and its role in tumor therapy are currently under re-evaluation. Poor oxygenation is no longer visualized as an independent feature promoting necrosis and resistance to treatments, but rather as one of the several interdependent microenvironmental parameters associated with impaired blood perfusion. Tumor cells display several survival strategies and remain clonogenic for long periods in nutrient-deprived situations. Reoxygenation may cause lethal damage, improve the response to therapy, or else allow the cell variants adapted to hypoxia to resume proliferation with enhanced aggressiveness and resistance to treatment. The blood supply parameters, oxygenation status and metabolism of malignant cells are discussed here from the standpoint of tumor photodynamic therapy. The role of the tumor interstitial fluid as oxygen- and sensitizer-carrier is discussed. Techniques for assessing tumor oxygenation and for mapping hypoxic territories are described. Strategies for locally improving the oxygenation levels or for selectively destroying the hypoxic populations are outlined.

In situ lactate dehydrogenase patterns as markers of tumour oxygenation.

The histochemical patterns of lactate dehydrogenase, LDH, are here proposed as indicators of the local levels of oxygenation of malignant tissue. This parameter has outstanding importance in determining the tumour aggressiveness and response to treatment. The tetrazolium salt reaction previously proposed for the mapping of hypoxia has been improved by the use of polyvinyl alcohol as a tissue stabilizer. The intracellular coloured products of this reaction appear in two distinct forms, diffuse and granular, which we previously postulated to be indicative of LDH isoenzymes soluble and bound, respectively. Solubility is promoted by H-LDH subunits preferentially synthesized under good oxygenation; binding to membranes is favoured by the presence of M-LDH subunits preferentially active under poor oxygeneration. A reversible shift between the two forms apparently regulates the cells' metabolic adaptation to different stress situations. We assume that the anoxic shock protein LDHk exists exclusively in the bound form. In the Ehrlich carcinoma model previously employed, we verify a drift towards the exclusive presence of the granular form as the section's depth increases and/or when the cuff width decreases. This trend is ascribed to a progressive worsening of the local oxygenation levels. At the tumour interface, a chronic inflammatory tissue (notoriously highly hypoxic) is characterized by a granular LDH activity. New models of hypoxia are proposed and discussed for explaining the patterns here described and observed also in other studies, namely those derived from hyperviscosaemia, damaged endothelia, fibrosis, anaemia, poor ventilation and impaired cardio-vascular system.

Stroma formation in Ehrlich carcinoma. I. Oedema phase. A mitosis burst as an index of physiological reoxygenation?

Tumor stroma induction has been shown closely to resemble wound repair process, both involving the replacement of a fibrin gel by vascularized connective tissue. In such a process the initial phase of hyperpermeability of blood vessels leads to diffuse oedema. It is here reported that cell loosening and a remarkably high mitotic burst were observed in Ehrlich carcinoma in regions in contact with the exudate, particularly at the perinecrotic (hypoxic) region. This suggests both an enhanced cell detachment from the tumour parenchyma and an improvement of the microenvironment, the exudate thus appearing as beneficial to the malignant cells contributing to the reoxygenation of formerly hypoxic regions. The temporary and well-localized concentration of mitoses in inner tumour areas has perhaps been disregarded by the pathologists engaged in mitosis counting for tumour grading. Peripheric and intraparenchymal concentrations of mast cells, lipid pools and platelets were seen in apparently key geometric disposition for controlling fibrin deposition and angiogenesis. Hypoxia is known to cause resistance to oxygen-dependent treatments and to facilitate cell detachment; normal fibroblasts respond and survive under hypoxic conditions by exhibiting features of the malignant phenotype. During reoxygenation, gene instability, cellular heterogeneity and increased drug resistance and metastatic spread have been reported. A reoxygenation process can also be deduced from several other histochemical and morphological patterns observed in this study. The findings here reported thus suggest that the oedema phase is a crucial phase regulating growth, invasion and dissemination of tumour cell populations, that should be specifically addressed therapeutically.