TRAUMA AS A CAUSE OF LOCALIZATION OF BLOOD-BORNE METASTASES: PREVENTIVE EFFECT OF HEPARIN AND FIBRINOLYSIN

Genetic pathways linking hemostasis and cancer

Oncogenic events impact interactions of cancer cells with their surroundings. Amongst the most consequential, in this regard, is the influence on angiogenesis, inflammation and hemostasis. Indeed, mutant oncogenes (EGFR, HER2, RAS, MET, PML-RARα) are known to alter the expression of angiogenic and pro-inflammatory factors, as well as change the cancer cell coagulome, including the levels of tissue factor (TF) and other mediators (PAI-1, COX2). Accompanying losses of tumour suppressor genes (PTEN, p53), and changes in microRNA (miR-19b, miR-520) facilitate these effects. Transforming genes may also trigger ectopic production of coagulation factors (e.g. FVII) by cancer cells and their release and properties of procoagulant microparticles (MPs). By deregulating protease activated receptors (PAR1/2) oncogenes may also change tumour cell responses to coagulation factor signalling. These changes act in concert with microenvironmental factors (hypoxia), stress responses (therapy) and differentiation programs, including epithelial-to-mesechymal transitions (EMT) and through tumour initiating cell (TIC) compartment. In so doing, the coagulation system influences early (initiation, angiogenesis), intermediate (growth, invasion) and late stages (metastasis, relapse) of cancer progression. In fact, TF may act as a molecular switch that controls the transition between dormant, latent and progressive/metastatic disease. TIC-like cells may play a role in these effects, as they express TF and PAR-1/2, and respond to stimulation with their agonists. As major human malignancies (e.g. glioblastoma) are increasingly recognized to consist of a spectrum of molecularly distinct disease subtypes driven by specific genetic pathways, so too may their patterns of interaction differ with the coagulation system. A better understanding of these linkages may be a source of new diagnostic, prognostic and therapeutic opportunities.

Tumour transfer to bone graft donor site: a case report and review of the literature of the mechanism of seeding

Purpose. Transmission of malignant tumour cells to a bone graft donor site is a rare complication of bone grafting.We report a case of seeding of malignant fibrous histiocytoma from the femur to a pelvic bone graft donor site.

Discussion. We review the literature, discuss the possible mechanism of tumour transfer and offer advice aimed at avoiding this complication.

Metastatic non-small cell lung carcinoma with involvement of extremity musculature: case report and review of the literature

Hematogenous dissemination of non-small cell lung carcinoma (NSCLC) metastatic to skeletal musculature in the absence of osseous involvement is an infrequent occurrence. We retrospectively reviewed our institution's indexed database for patients evaluated from 1975 through 1997 who were diagnosed as having skeletal musculature metastases from NSCLC. Eight men and 2 women were identified (age range, 51-80 years at time of metastases). Four primary adenocarcinomas, 4 primary lung squamous cell carcinomas (SCCs), and 2 poorly differentiated primary NSCLCs were identified. Approximate tumor sizes ranged from 10 cm3 to 288 cm3. External-beam radiation therapy was used in 7 of 10 cases; complete surgical excision was performed in 3 cases. Patients with known neoplasm who have extremity pain and negative findings on bone scan should be evaluated for soft tissue tumor involvement because such findings significantly affect clinical management. One case of lung SCC metastatic to the quadratus femoris muscle in a 63-year-old man is discussed in detail.

The potential role of integrin receptor subunits in the formation of local recurrence and distant metastasis by mouse breast cancer cells

BACKGROUND

The mechanisms by which surgical injury fosters tumor growth are examined.

METHODS

TA3Ha mouse breast tumor line and its subline (TA3AD) differing in their metastatic abilities as tested by two models were used. In model a, TA3Ha/TA3AD tumors were grown in the mammary fat pads of mice and then surgically removed with a curative intent. In model b, TA3Ha/TA3AD cells were injected intravenously into mice subjected to liver or spleen wedge resection. Frequency of tumor formation at various sites was assessed. Expression of integrin, immunoglobulin, and proteoglycan cell adhesion receptors on TA3Ha and TA3AD cells was examined by flow cytometry. The roles of these receptors in metastasis were examined by blocking them by selected ligands and/or antibodies.

RESULTS

Frequencies of local recurrence and axillary metastasis after surgical resection, were 43% (32/74), and 37% (27/74) with TA3Ha tumors and 4% (1/29) at both sites with TA3AD tumors. Tumors at surgically injured spleen and the liver were seen in 75% (141/189) and 45% (107/240) of the mice with TA3Ha cells and in 8% (3/38) and 10% (4/42) of the mice with TA3AD cells. alpha 5 and CD44 receptors were expressed by TA3Ha cells but not by TA3AD cells. Other receptors examined were similarly expressed by both cell lines. Blocking of alpha 5 receptor by fibronectin reduced tumor implantation in a dose-dependent manner.

CONCLUSIONS

The data suggest a correlation among the ability to implant at surgically injured sites, to form local recurrence, and to express the fibronectin receptor subunit.

Does transurethral resection of a clinically benign prostate gland increase the risk of developing clinical prostate cancer? A 10-year follow-up study

BACKGROUND

Theoretical considerations have raised the suspicion that transurethral resection of the prostate (TURP) may increase the risk of developing prostate cancer in clinically benign prostate glands. Previous studies have not shown an increased risk among men who had undergone TURP for benign prostatic hyperplasia compared with the risk in age-matched control subjects. However, in all of these studies, all men with stage T1 prostate cancer in the TURP-group were excluded, possibly creating a bias, because no similar exclusion could be made for the controls.

METHODS

The incidence and mortality of clinical prostate cancer were studied in 198 patients who had TURP and in 203 age-matched male control subjects. In both groups, all patients with known prostate cancer and patients with suspected cancer by digital rectal examination were excluded from the study. However, patients with stage T1 cancer found by the TURP were included in the comparison between the groups.

RESULTS

The mean age in the two groups was 67 +/- 6 years. The patients were followed for an average of 10.2 +/- 1.2 years and 10.4 +/- 1.8 years in the TURP group and the control group, respectively. Clinical prostate cancer developed in six patients who had TURP and subsequently in five control (odds ratio, 0.8 [0.2-3.1]; P < 0.97). Before follow-up, three men in each group died because of prostate cancer (odds ratio, 1.3 (0.24-7.45); P < 0.97).

CONCLUSIONS

The results of this study suggest that neither benign prostatic hyperplasia nor TURP increased the risk of developing clinical prostate cancer over the next 10 years in patients with a benign prostate gland determined by rectal examination before TURP.

Abdominal wall metastases following laparoscopy

Only 18 cases of recurrence at the sites of cannula insertion after laparoscopy have been reported in the literature, ten of them in the past year. The period between laparoscopic surgery and presentation of wound metastasis varies widely, from 7 days to 10 months; the lesions are typically hard, craggy and painful. The most likely mechanism is direct implantation of viable exfoliated tumour cells but three aspects specific to laparoscopy may also be important. First, there may be increased exfoliation of tumour cells following manipulation by laparoscopic instruments of an unsuspected malignancy. Second, there may be repeated close contact between tumour-laden instruments and the port. Third, the passage of resected tissue through a small incision may coat the wound with potentially malignant cells.

Paracrine growth regulation of human colon carcinoma organ-specific metastasis

The process of cancer metastasis consists of a series of steps resulting in the spread of malignant cells beyond the site of origin and formation of metastases in distant organs. The outcome of this nonrandom process depends, in part, on the interaction of unique tumor cells with a compatible organ microenvironment. The molecular basis of the intrinsic capacity of distinct malignant cells to colonize specific organs and the degree to which host factors influence this process is under intense investigation. Biological analyses of human colon carcinoma tumors obtained from surgical specimens and implanted orthotopically into athymic nude mice revealed that these tumors are heterogeneous for metastatic properties. Moreover, recent evidence using this model suggest that whereas nonmetastatic and highly metastatic cells can grow at local sites, growth in the secondary liver-specific site was associated only with highly metastatic HCC cells. These cells also respond to mitogenic signals produced by damaged normal tissues, suggesting that physiological signals can be utilized by neoplastic cells. Molecular characterization of highly metastatic HCC cells selected in the nude mouse model as well as in situ mRNA hybridization of archival HCC surgical specimens for specific growth factor receptors correlated with the malignant cell's ability to respond to organ-specific growth factors. This article will focus on biological and molecular evidence supporting the hypothesis that organ-derived, paracrine growth factors regulate the site-specific growth of receptive malignant cells that possess the appropriate receptors.

Inhibition of tumor implantation at sites of trauma by Arg-Gly-Asp containing proteins and peptides

We report on the inhibition of wound implantation by TA3Ha mammary carcinoma cells by Arg-Gly-Asp containing proteins and peptides using a hepatic wedge resection model. Intravenously injected TA3Ha cells rarely form tumor in the liver of syngeneic mice, but after hepatic wedge resection, 45% (107/240) of the mice develop tumors in the hepatic wound. Hepatic wound implantation is significantly (P = 0.01) inhibited by pretreating the cells with whole mouse plasma, but not with fibrinogen-depleted plasma or serum. Tumor inhibition is also achieved by pretreatment of cells with fibrinogen (P = 0.05-0.0004), fibronectin (P = 0.007) and laminin, but not by albumin. The active domain appears to be the RGDS sequence since the deca- and tetrapeptides containing RGDS inhibit wound implantation (P less than 0.05). However, the tetrapeptide Arg-Gly-Glu-Ser has no such activity. None of these agents affects ascites tumor formation by the intraperitoneally injected cells, suggesting that anchorage independent growth of cells is not affected. We propose that proteins and peptides containing RGD occupy the binding sites and prevent the cells from interacting with cell adhesion proteins in healing wounds. Proteins and/or peptides containing RGD may be useful for preventing local recurrence in postsurgical cancer patients.

Inhibition of tumor implantation at sites of trauma by plasminogen activators

The authors report on the influence of plasminogen activators (PA) on implantation of TA3Ha mammary tumor cells in the healing hepatic wounds of syngeneic strain A mice. Intravenously injected TA3Ha cells, although they rarely metastasize to the liver, formed tumors in the hepatic wounds of a significant percent (42%, P less than 0.0001) of mice. The frequency of tumor formation declined as the interval between surgery and tumor cell inoculation was increased. Furthermore, preexposure of cells to fibrinogen, fibronectin, laminin, or peptides containing the arginine-glycine-aspartic acid-serine residues dramatically reduced the frequency of tumor formation in the hepatic wounds. These results indicate that TA3Ha cells interact with fibrinogen-related proteins in the wound to aid their attachment and growth. Because these proteins are susceptible to digestion by plasmin, PA were used in this study to examine whether administration of these drugs to the mice would modulate tumor formation in the liver wounds. Among the PA tested, human plasmin B-chain-streptokinase complex (B-SK) and recombinant tissue plasminogen activator (t-PA) inhibited tumor implantation in a dose-related manner. Administration of 900 units (U) of B-SK or 3300 U of t-PA per mouse reduced the frequency of tumor formation from 42% to 0% (P = 0.02) and 11% (P = 0.02), respectively. The B-SK was complexed with p-nitrophenyl-p-guanidinobenzoate; it did not activate the plasminogen or inhibit tumor formation in the hepatic wounds. Although urokinase activated the plasminogen, it did not inhibit tumor implantation in the hepatic wound. Heparin, an anticoagulant that prevents conversion of fibrinogen to fibrin without being fibrinolytic, had no influence on tumor formation in the hepatic wounds. The PA can generate plasmin that digests the cell attachment proteins in wounds and consequently inhibits tumor cell attachment.

Radiation enhancement of metastasis: a review

Virtually every modality employed in the treatment of cancer has demonstrated an adverse effect upon metastasis under some conditions. This review surveys the experimental and clinical literature pertaining to the untoward effects of ionizing radiation upon metastatic processes. Two processes are described: (1) enhancement of metastases following local tumor irradiation; (2) localization of metastasis in previously irradiated normal tissues. In the first process the experimental evidence indicates a local effect of irradiation upon the tumor-stroma interface. It predominates under conditions of non-curative radiation doses. There is no proof that this process occurs in clinical practice, but a review of data provides suggestive evidence for its existence following non-curative therapy. The second process is documented both experimentally and clinically. It requires the presence of viable, circulating tumor cells and appears mediated through vascular damage. The few clinical reports suggest that this effect is rare in practice. The clinical significance of both processes appears small under conditions of effective tumor therapy, but it is speculated that inadequate tumor irradiation, or irradiation of normal tissues with uncontrolled tumor elsewhere, may be deleterious.

The influence of surgical trauma on experimental metastasis

Influence of surgical trauma on experimental metastasis in healing wounds is investigated using a transplantable murine mammary carcinoma cell line, TA3Ha. Intravenous injection of 10(5), 10(6), and 2 x 10(6) TA3Ha cells into syngeneic Strain A mice led to liver or kidney tumor development in none of the 96, ten, and ten mice tested, respectively. In contrast, injection of 10(5) cells into mice immediately after hepatic wedge resection performed using milliwatt carbon dioxide laser and electrocautery resulted in tumor formation at the site of trauma in 21/37 (57%) and 25/52 (48%) mice, (P less than 0.001) respectively. Similar results were obtained in mice subjected to partial nephrectomy using the laser (nine of 18) and electrocautery (eight of 13). These results clearly demonstrate that surgical trauma renders a nonprivileged organ susceptible to experimental metastasis formation, and that at least in this model both laser and electrocautery have similar effects. Tumor cell injection 1, 7, and 10 days posthepatic surgery resulted in 36%, 20%, and 0% tumor formation, respectively, indicating that the earlier events in wound healing support tumor implantation and/or growth better than those later on. Frequency of tumor formation at sites of trauma in the peritoneum induced by scalpel blade, laser, and electrocautery were 28%, 50% and 82%, respectively. Peritoneal tumors were seen in 33% of the nonsurgical mice. Skin incisions induced with the three above probes had little influence on experimental metastasis formation. Thus the influence of trauma on tumor formation is not uniform in every organ.

Partial nephrectomy in mice with milliwatt carbon dioxide laser and its influence on experimental metastasis

We have developed a surgical model to perform partial nephrectomy in mice using the milliwatt CO2 laser and have used this model for studying the influence of the sequel of surgery on experimental tumor metastasis. Strain A mice were subjected to partial nephrectomy using the milliwatt CO2 laser. The surgical procedure was time efficient, the blood loss was minimal, and the postoperative mortality was 6%. Immediately after surgery, the wound consisted of a superficial layer of charring and a deeper layer of thermal damage (coagulative necrosis). The wound healing was completed within 30 days and was accompanied by fibroblast infiltration and tubular regeneration but minimal inflammatory response. Seventy surgical mice were injected I.V. with TA3Ha murine mammary adenocarcinoma cells at different intervals (immediately to 30 days) after surgery. Among 38 mice inoculated with tumor cells immediately or up to 3 days after surgery, 18 (47%) showed histologically confirmed tumors at the site of surgical trauma. None of the 38 unoperated kidneys showed any evidence of tumor. This difference is statistically significant at a P value of less than 0.001. As the interval between surgery and tumor inoculation was increased to 7, 15, and 30 days, the frequency of tumor formation at the site of surgery decreased to 20% (2/10), 14% (2/14), and 0% (0/8), respectively. The results demonstrate that a) partial nephrectomy in mice is feasible with minimal mortality or apparent morbidity, b) the laser-induced surgical trauma favors implantation and growth of tumors, c) the frequency of tumor formation is related to the stage of wound healing, and d) the tumors are anatomically related to the healing wound but do not invade into the parenchymal tissue.

Skeletal muscle metastases from lung cancer

Hematogenous metastases to the limb skeletal muscles are extremely rare. Better understanding of the mechanisms resulting in the relative resistance of skeletal muscle to metastases could have bearing on therapeutic interventions for prevention of metastases. Three patients with non-small cell lung cancer and metastases in the proximal limb muscles are presented. Skeletal muscle metastases may present as painful masses in the proximal skeletal muscles. Subcutaneous and osseous metastases which are more frequent must be excluded by careful physical examination, bone scan and x-rays. Computed tomography (CT) can confirm the location of the tumor within the fascial planes of skeletal muscles and may help in the accurate delineation of the radiation portal. The tumor can be diagnosed and more common causes, such as hematoma or abscess, can be excluded by thin needle aspiration with cytologic examination. Clinical recognition of metastases in this unusual site is important based on our report that total tumor dose of 3600 to 4200 cGy of radiation in fractions of 300 cGy, 5 days a week, is effective in palliation of swelling and pain.

Solitary pulmonary metastasis: an enigma

Lung metastases, which are an expression of the new phase of the underlying neoplastic disorder, have been treated in the recent years by multiple disciplinary approach. When the metastases to the lungs are multiple, it is indicative of extensive tumor burden, and the organ plays an insignificant role in the distribution of the metastases in the different lobes of the lungs. However, when the pulmonary metastases appear after a prolonged disease-free interval it becomes an enigma; when the metastases are solitary, the majority (over 80% in this series) are located in the upper zone of the lungs. This study of 28 patients with solitary lung metastases explores the possible etiology of this clinical observation and proposes that the pattern of perfusion and anatomopathological features of the upper lobes are the main reasons why these lobes are prevalently the sites for solitary lung metastases.

Hamster cheek pouch carcinoma: effect of incision and cortisone on growth, invasion, and metastasis

After cheek pouch carcinomas were induced in hamsters by the application of dimethylbenzanthracene (DMBA) to the right pouch for 13 weeks, the animals were divided into four groups and observed for seven more weeks. The control group received no further treatment, two experimental groups had incisional biopsies performed on tumors in their pouches, one of these also received injections of cortisone throughout the 20-week experimental period, and a fourth group received cortisone only. The wet weights of the cancerous cheek pouches were determined, and the submandibular and parotid salivary glands with associated cervical lymph nodes, the lungs, and the liver were examined with light microscopy. The cancerous pouches of the animals that received cortisone weighed significantly less than those of animals that received no cortisone but had incisional biopsies of the tumors. There was no significant difference in the degree of histodifferentiation of the tumors among the four groups. The animals in the two groups that received cortisone had significantly more tumors that were invasive than did the animals that did not receive cortisone. Cervical lymph node metastasis occurred in 21% to 38% of the animals but was not significantly different in the four groups. Distant metastases to the lungs or the liver were not found. Incisional biopsy of the tumors stimulated local growth of the cheek pouch tumors, and systemic cortisone administration produced more invasive cheek pouch tumors.

Occult adenocarcinoma metastatic to a skin graft donor site

Internal malignancies present with metastases to the skin 0.4% of the time. Cutaneous metastases not uncommonly develop in areas of damaged skin such as radiodermatitis and surgical scars. This report involves a 78-year-old male with metastatic adenocarcinoma from an unknown primary site that presented in a split-thickness skin graft donor site. This appears to be the first reported case of internal malignancy metastatic to skin altered by grafting.

The influence of antiserotonin treatment with ketanserin on the pulmonary lodgement of circulating tumour cells in normal and traumatized rats

As shown in earlier studies, the lodgement of circulating tumour cells in the lungs is reduced by thrombocytopenia in both normal and traumatized rats. Other experiments have shown that thrombocytopenia and antiserotonin treatment with ketanserin, which has a selective effect on 5-HT2 receptors, decrease the hepatic lodgement of intraportally injected tumour cells. The present studies show that treatment with ketanserin also reduces the lodgement of i.v.-injected tumour cells in the lungs in both normal and traumatized rats.

Generation of a complement-derived chemotactic factor for tumor cells in experimentally induced peritoneal exudates and its effect on the local metastasis of circulating tumor cells

A chemotactic factor for tumor cells was found in inflammatory exudate fluids induced by giving intraperitoneal injections of glycogen to Sprague-Dawley rats. The quantity of chemotactic activity and the period of time during which it could be detected correlated with the inflammatory reaction, measured by the cellular composition of the exudates and their content of protein and lysosomal enzymes. In gel filtration the chemotactic factor behaved mainly as a molecule having a molecular weight of approximately 6000 daltons. Its biologic activity was blocked by antiserums directed against C5 but not by antiserums against C3 or C4. In these two respects, the factor generated in vivo has the same properties as a previously described chemotactic factor that can be generated in vitro by proteolysis of purified C5 or C5a. Chemotactic activity was not detected in the glycogen-induced peritoneal exudates of rats depleted of serum complement by cobra venom factor. Intravenously injected Walker tumor cells arrested and formed metastases in the mesenteries of rats with peritonitis in greater numbers than in normal controls, animals depleted of complement during the experimental period, or animals given intraperitoneal injections of the vasopermeability agent, histamine. The growth of tumor cells in vitro was not promoted by peritoneal exudate fluids, nor was the number of metastases on vivo greater than in negative controls, in animals in which peritonitis was induced 24 hours after the intravenous injection of tumor cells. It is argued that chemotactic mechanisms can contribute to the formation of metastases at sites of tissue injury.

Inflammatory oncotaxis after testing the skin of the cancer patient

A case is presented in which a patient with Dukes C adenocarcinoma of the sigmoid colon subsequently developed a soft tissue metastasis at the site of a marked delayed type hypersensitivity response to the commonly used skin test antigen Dinitrochlorobenzene (DNCB). A possible cause and the implications of this rare occurrence are discussed. It is concluded that the inflammatory response to DNCB and the subsequent metastasis in this patient were causally related. Physicians who utilize skin testing in cancer patients should be aware of the possibility of "inflammatory oncotaxis" with the development of metastatic lesions in unusual places.

The influence of trauma, Dextran 1000, and Dextran 40 on the lodgement of circulating tumor cells

Earlier studies have shown that trauma and infusion of Dextran 1000 increased the formation of pulmonary metastases after i.v. tumor cell injection in rats. Infusion of Dextran 40 enhanced the pulmonary metastasis formation in traumatized but not in non-traumatized animals. In this study tumor cells labelled with a radioactive isotope were used to register the lodgement circulating tumor cells after trauma and infusion of Dextran 1000 and Dextran 40. It was found that the pulmonary lodgement of tumor cells was increased after trauma and infusion of Dextran 1000. Dextran 40 did not influence the lodgement in a significant way either in normal or in traumatized animals. Thus, the increased formation of metastases after trauma and infusion of Dextran 1000 seems to depend upon an increased tumor cell lodgement.

Studies on mechanisms involved in metastasis formation from circulating tumor cells. Factors influencing tumor cell lodgement during normal and post-traumatic conditions

As shown in earlier studies the formation of metastases after i.v. tumor cell injection in rats is increased in the immediate post-traumatic period and treatment with heparin, thrombocytopenia, and defibrinogenation decreases the formation of metastases. Thrombocytopenia also inhibits the stimulating effect of trauma on metastasis formation. The results of the studies reported in this paper show that the changes of metastasis formation induced by the factors mentioned above with few exceptions are well correlated to the lodgement of the injected tumor cells. Thus, heparin treatment and thrombocytopenia decrease the pulmonary lodgement of i.v. injected tumor cells. Trauma increases the pulmonary lodgement of i.v. injected tumor cells but when trauma is combined with thrombocytopenia, the effect of thrombocytopenia dominates and the pulmonary lodgement of tumor cells decreases when compared to control conditions. Despite this, trauma still gives rise to increased tumor cell lodgement during thrombocytopenia.

Digestion of the fifth component of complement by leukocyte enzymes. Sequential generation of chemotactic activities for leukocytes and for tumor cells

Leukocytes contain within their lysosomal granules enzymatic activity that will generate from C5 chemotactic activity for leukocytes (neutrophils) and tumor (Walker carcinosarcoma) cells. Similar activity has been found in phagocytic supernatant fluids from neutrophils and in purified preparations of the leukocyte neutral proteases elastase and cathepsin G. White leukotactic activities can be generated from either the third (C3) or the fifth (C5) components of complement, only C5 serves as a source for generation of the chemotactic activity for tumor cells. As has been previously shown with trypsin, the C5-related chemotactic activities generated by leukocyte proteases are time-dependent: leukotactic activity appears early, then disappears, and is replaced by chemotactic activity for tumor cells. The generation of these chemotactic activities from C5 is blocked by prior treatment of leukocyte preparations with the neutral protease inhibitor Trasylol. The demonstration that enzyme activities from leukocytes have the ability to generate tumor cell chemotactic factors from C5 suggests a possible mechanism by which the development of metastatic lesions may be promoted at sites of tissue injury or inflammation.

Cancer metastasis: a product of tumor-host interactions

Metastasis continues to be the most devastating event for the patient with an established primary cancer. The most significant therapeutic problems are: (1) treatment of patients with established macrometastases, (2) identification of patients who have micrometastases and (3) the development of adequate adjunctive therapies for micrometastases. It is hoped that our evolving understanding of the biology of experimental metastasis and the high level of premium quality laboratory research ongoing in this area will result in further resolution of this clinical problem or, at least, a better understanding of this most extreme expression of the malignant phenotype.

Wound implantation--A surgical hazard

A review of the literature on wound implantation together with a report on an unusual case of implantation of squamous carcinoma at the site of a gastrostomy is presented.

Heparin, dextran 1000 and metastasis formation after I.V. tumour cell injection in dextran non-sensitive rats

The present study of the effect of heparin and dextran 1000 on the metastasis formation after i.v. tumour cell injection in dextran non-sensitive rats using a syngeneic 20-methylcholanthrene induced fibrosarcoma showed that heparin treatment decreased with formation of pulmonary metastases in animals both untreated and treated with dextran 1000. Treatment with dextran 1000 increased the formation of pulmonary metastases in animals both untreated and treated with heparin and the effect of dextran 1000 was thus not affected by heparin treatment. Heparin did not have any direct action on the tumour cells, which influenced metastasis formation. The data suggest that heparin acts as an anticoagulant with decreased microthrombus formation around lodged cells and that dextrax 1000 stimulates metastasis formation primarily by mechanisms other than intravascular coagulation.

The role of blood platelets in experimental metastases

After the intravenous injection of Walker 256 tumour cells into rats the platelet count decreased rapidly and remained low during the following period of observation. The platelet decrease was closely related to the number of cells injected. Intra-arterial tumour cell injections required a considerably higher tumour cell count to produce a comparable thrombocytopenia. Non-viable tumour cells and tumour cell fragments induced a similar decrease of circulating platelets. Neither viable tumour cells nor tumour cell fragments aggregated rat platelets in vitro. The presence of fibrin monomers in tumour cell injected animals suggested intravascular fibrin deposition; the plasma fibrinogen level, however, did not decrease significantly. Isotope studies using (51)Cr labelled platelets revealed a rapid disappearance of the platelets from the circulation and their trapping in the lung-the primary site of tumour cell lodgement. Dipyridamole and ancrod pretreatment did not influence the decrease of platelets and their accumulation in the lung after tumour cell injection. In contrast, heparin completely prevented the thrombocytopenia and the platelet trapping in the lung. From the present experiments it is concluded that embolic tumour cells lead to early endothelial damage, resulting in local thrombin formation with subsequent irreversible platelet aggregation.

Hemopoietic colony-forming units in regenerating mouse liver: suppression by anticoagulants

After hepatic injury induced by carbon tetrachloride, mitotically active hematopoietic cells of nonhepatic origin localize in the liver as judged by an increase in colony-forming nodules in the spleens of lethally irradiated recipient mice on intravenous injection of cells from these livers. The administration of warfarin suppresses the localization of colony-forming units in the regenerating liver by inhibiting the coagulation mechanism of the donor animals.