Prophylactic irradiation to the contralateral breast for BRCA mutation carriers with early-stage breast cancer.

BACKGROUND: Women who carry germ-line mutations in BRCA1/2 are at very high risk of developing breast and ovarian cancer. Breast conserving therapy is associated with a similar risk of ipsilateral cancer recurrence in BRCA carriers compared with non-carriers. However, the risk of subsequent contralateral breast cancer in carriers is markedly increased. Therefore, mastectomy of the diseased breast along with risk reducing mastectomy of the contralateral breast is often advocated for BRCA carriers who are treated for early breast cancer. Yet, many BRCA carriers forgo this option for fear of harmful effects and choose breast conserving treatment and observation instead. In Israel, BRCA-associated breast cancer is relatively common. Accordingly, a national protocol was devised for this enriched population. PATIENTS AND METHODS: In this Institutional Review Board-approved phase II trial, the option of prophylactic irradiation to the contralateral breast, in addition to standard loco-regional treatment, was offered to BRCA carrier patients treated for early breast cancer who declined contralateral mastectomy. The primary end point was contralateral breast cancer. RESULTS: Between May 2007 and October 2017, 162 patients were enrolled. Eighty-one patients opted for standard loco-regional treatment including surgery and radiation to the involved side (control arm) and 81 patients chose additional contralateral breast irradiation (intervention arm). At a median follow-up of 58 months, 10 patients developed contralateral breast cancer in the control arm at a median of 32 months, as compared with 2 patients in the intervention arm who developed contralateral breast cancer 80 and 105 months after bilateral breast irradiation (log-rank P = 0.011). CONCLUSIONS: Among BRCA carrier patients treated for early breast cancer, the addition of contralateral breast irradiation was associated with a significant reduction of subsequent contralateral breast cancers and a delay in their onset. CLINICAL TRIAL: Phase II, comparative two-arm trial (NCT00496288).

European Society for Medical Oncology (ESMO) Program for the integration of oncology and Palliative Care: a 5-year review of the Designated Centers' incentive program.

BACKGROUND: In 1999, the National Representatives of European Society for Medical Oncology (ESMO) created a Palliative Care Working Group to improve the delivery of supportive and palliative care (S + PC) by oncologists, oncology departments and cancer centers. They have addressed this task through initiatives in policy, education, research and incentives. As an incentive program for oncology departments and centers, ESMO developed a program of Designated Centers (DCs) for programs meeting predetermined targets of service development and delivery of a high level of S + PC. METHOD: The history, accreditation criteria and implementation of the DC incentive program is described. RESULTS: Since 2004, 75 centers have applied for designation and 48 have been accredited including 34 comprehensive cancer centers (CCCs) in general hospitals and seven freestanding CCCs. Perceived benefits accrued from the accreditation included the following: improved status and role identification of the center, positive impact on daily work, positive impact on business activity and positive impact on funding for projects. CONCLUSIONS: The accreditation of DCs has been a central to the ESMO initiative to improve the palliative care provided by oncologists and oncology centers. It is likely that many other oncology departments and cancer centers already meet the criteria and ESMO strongly encourages them to apply for accreditation.

Magnetic resonance guided focused ultrasound surgery. Ablation of soft tissue at bone-muscle interface in a porcine model.

BACKGROUND: Pain management treatments of patients with bone metastases have either efficacy problems or significant side effects. Percutaneous radiofrequency ablation has recently proved to be of palliative value. Magnetic resonance guided focused ultrasound surgery (MRgFUS) uses focused ultrasonic energy to non-invasively create a heat-coagulated lesion deep within the body in a controlled, accurate manner. The surgeon can monitor and control energy deposition in real time. This technology represents a potential treatment modality in oncological surgery. We investigated the ability of two MRgFUS methods to accurately and safely target and ablate soft tissue at its interface with bone. MATERIALS AND METHODS: Heat-ablated lesions were created by MRgFUS at the bone-muscle interface of 15 pigs. Two different methods of energy delivery were used. Temperature rise at the target adjacent to bone was monitored by real time MR thermal images. Results were evaluated by MRI (magnetic resonance imaging), nuclear scanning and by histopathological evaluation. RESULTS: Soft tissue lesion sizes by both methods were in the range of 1-2 cm in diameter. Targeting the focus 'behind' the bone, achieved the same result with a single sonication only. Follow up MRI and histopathological examination of all lesions showed focal damage at its interface with bone and localized damage to the outer cortex on the side closer to the targeted tissue. There was no damage to non-targeted tissue. CONCLUSION: MRgFUS by both energy deposition methods can be used to produce controlled well-localized damage to soft tissue in close proximity to bone, with minimal collateral damage.

Predominance of TH1 response in tumor-bearing mice and cancer patients treated with AS101.

BACKGROUND: Several studies have recently suggested that the immune response to malignant growths is regulated by distinct patterns of type 2 cytokine production. These cytokines, regulating the cytotoxic T-lymphocyte response in patients with advanced cancers, may be associated with disease progression. Evidence suggests that the T Helper 1 (TH1) and T Helper 2 (TH2) types of reaction are reciprocally regulated in vivo. The immunomodulator AS101 (ammonium trichloro[dioxoethylene-O,O']tellurate) was found to stimulate mouse and human cells to proliferate and secrete a variety of cytokines. Clinical trials using AS101 on cancer patients are now in progress. PURPOSE: The aim of this study was to evaluate the ability of AS101 to modulate TH1 and TH2 responses in tumor-bearing mice and in patients with advanced cancer. In addition, we investigated the association between the predominance of each type of response with the antitumoral effects of AS101. METHODS: Mice into which Lewis lung carcinoma (3LL) had been transplanted (n = 221) and cancer patients (n = 13) were treated with AS101 on alternate days, at 10 micrograms/mouse intraperitoneally, or for the patients, at 3 mg/m2 intravenously. The types were sarcoma, melanoma, and colon, lung, ovarian, and renal cancers. Cytokine levels were determined by immunoassay kits and compared with the paired Student's t test: in mice, they were tested in spleen cell supernatants; in humans, in sera and mononuclear cell supernatants. The chi-squared test was used to compare tumor volumes. All P values represent two-sided tests of statistical significance. RESULTS: Our results show that treatment of mice and patients with AS101 results in a clear predominance in TH1 responses, with a concomitant decrease in the TH2-type response. This was reflected by a significant enhancement in interleukin 2 (IL-2) and interferon gamma (IFN gamma) levels (P < .01) paralleled by a substantial decrease in IL-4 and IL-10 (P < .01). Moreover, the concentration of IL-12 was significantly increased (P < .01) in AS101-treated patients who also showed enhanced levels of natural and lymphokine-activated killer cell-mediated cytotoxicity. The statistically significant increases in IL-2 and IFN gamma levels, paralleled by the pronounced decrease in IL-4 and IL-10 in the AS101-treated mice, were associated with its antitumoral effects. In addition, systemic cotreatment of 3LL-transplanted mice with AS101 and anti-IL-12 antibodies partly abrogated the antitumoral effect of AS101. CONCLUSIONS: Immunotherapy with AS101 enhances TH1 function while interfering with the TH2 response. This TH1 trend may be related to the antitumor effects of AS101. IMPLICATIONS: Isolation and characterization of a distinct cytokine pattern in patients with advanced cancer treated with AS101 may contribute to the development of intervention strategies using this compound.

Efficacy of 6-diazo-5-oxo-L-norleucine and N-[N-gamma-glutamyl-6-diazo-5-oxo-norleucinyl]-6-diazo-5-oxo-norleucine against experimental tumors in conventional and nude mice.

The chemotherapeutic effects of 6-diazo-5-oxo-L-norleucine (DON) and N-[N-gamma-glutamyl-6-diazo-5-oxo-norleucinyl]6-diazo-5-oxo-norleucine (azotomycin) were evaluated in a spectrum of transplantable experimental tumor systems including xenografts of human tumors in athymic mice. Both drugs displayed remarkable activity against the murine leukemia L1210 and P388, the Colon Tumors C26 and C38 and the CD8F1 mammary tumor. No significant activity was observed against Lewis lung carcinoma, B16 carcinoma, B16 melanoma, and intracranial ependymoblastoma. DON and azotomycin also exhibited striking inhibitory effects on the growth of s.c. human tumor (MX-1 mammary, LX-1 lung and CX-1 and CX-2 colon) xenografts in athymic mice. With the exception of one colon xenograft (CX-1), all tumor lines were markedly responsive to both drugs. Tumor regressions below the initial tumor sizes of 100 to 300 mg, albeit temporary, were brought about by one course of treatment every 4 days for 3 doses (at optimal dose) with either drug. Although these drugs have been tested previously in the clinic and have shown only limited therapeutic effectiveness, they seem to worthy of a second and closer look in light of the recent laboratory results.

Enhancement of antitumor activity of alkylating agents by the radiation sensitizer misonidazole.

The influence of the radiosensitizer misonidazole on the effectiveness of several alkylating agents and cis-platinum against advanced solid murine tumors was investigated. Tumor regrowth delay, frequency of tumor regressions, and animal life span were used to evaluate misonidazole in combination with cyclophosphamide, L-phenylalanine mustard, 1-(2-chloroethyl)-3-trans-4-methylcyclohexyl)-1-nitrosourea, aziridinyl-benzoquinone, and cis-platinum. In the advanced M5076 ovarian carcinoma, misonidazole enhanced the activity of cyclophosphamide, L-phenylalanine mustard, 1-(2-chloroethyl)-3-trans-4-methylcyclohexyl)-1-nitrosourea, and aziridinyl benzoquinone, but not cis-platinum. In early B16 melanoma, misonidazole plus cyclophosphamide was no more effective than cyclophosphamide alone. In advanced Lewis lung carcinoma, misonidazole enhanced the antitumor activity of cyclophosphamide but not 1-(2-chloroethyl)-3-trans-4-methylcyclohexyl)-1-nitrosourea. Misonidazole, at 1000 mg/kg, increased the antitumor effectiveness of L-phenylalanine mustard and cyclophosphamide in M5076 tumors by factors of 2.2 and 1.8, but caused only a 1.2- and 1.3-fold increase in the myelotoxicity of these agents as determined by spleen colony assay of normal bone marrow. Misonidazole also increased the toxicity of cyclophosphamide and L-phenylalanine mustard in non-tumor-bearing mice but to a lesser degree than it enhanced antitumor activity. These results indicate that misonidazole is capable of enhancing the effects not only of ionizing radiation but of alkylating agents as well.

Prolonged circulation time and enhanced accumulation in malignant exudates of doxorubicin encapsulated in polyethylene-glycol coated liposomes.

In preclinical studies, a doxorubicin liposome formulation containing polyethylene-glycol (Doxil) shows a long circulation time in plasma, enhanced accumulation in murine tumors, and a superior therapeutic activity over free (unencapsulated) doxorubicin (DOX). The purpose of this study was to characterize the pharmacokinetics of Doxil in cancer patients in comparison with free DOX and examine its accumulation in malignant effusions. The pharmacokinetics of doxorubicin and/or liposome-associated doxorubicin were analyzed in seven patients after injections of equivalent doses of free DOX and Doxil and in an additional group of nine patients after injection of Doxil only. Two dose levels were examined, 25 and 50 mg/m2. When possible, drug levels were also measured in malignant effusions. The plasma elimination of Doxil followed a biexponential curve with half-lives of 2 and 45 h (median values), most of the dose being cleared from plasma under the longer half-life. Nearly 100% of the drug detected in plasma after Doxil injection was in liposome-encapsulated form. A slow plasma clearance (0.1 liter/h for Doxil versus 45 liters/h for free DOX) and a small volume of distribution (4 liters for Doxil versus 254 liters for free DOX) are characteristic of Doxil. Doxorubicin metabolites were detected in the urine of Doxil-treated patients with a pattern similar to that reported for free DOX, although the overall urinary excretion of drug and metabolites was significantly reduced. Doxil treatment resulted in a 4- to 16-fold enhancement of drug levels in malignant effusions, peaking between 3 to 7 days after injection. Stomatitis related to Doxil occurred in 5 of 15 evaluable patients and appears to be the most significant side effect in heavily pretreated patients. The results of this study are consistent with preclinical findings indicating that the pharmacokinetics of doxorubicin are drastically altered using Doxil and follow a pattern dictated by the liposome carrier. The enhanced drug accumulation in malignant effusions is apparently related to liposome longevity in circulation. Further clinical investigation is needed to establish the relevance of these findings with regard to the ability of liposomes to modify the delivery of doxorubicin to solid tumors and its pattern of antitumor activity.

Bone marrow-sparing and prevention of alopecia by AS101 in non-small-cell lung cancer patients treated with carboplatin and etoposide.

PURPOSE: The aim of this study was to evaluate the ability of the immunomodulator AS101 to prevent chemotherapy-induced neutropenia and thrombocytopenia and thus allow patients to receive full-dose antineoplastic agents according to protocol design. We also aimed to determine the production level of various hematopoietic growth factors in treated patients. PATIENTS AND METHODS: This study of 44 unresectable or metastatic non-small-cell lung cancer (NSCLC) patients was an open-label prospective randomized study of standard chemotherapy alone versus chemotherapy plus AS101. Each patient received carboplatin (300 mg/m2 intravenously [IV] on day 1 of a 28-day cycle, and etoposide (VP-16) (200 mg/m2 orally) on days 3, 5, and 7 of each cycle. AS101 was administered at 3 mg/m2 three times per week starting 2 weeks before chemotherapy. RESULTS: AS101, which manifested no major toxicity, significantly reduced neutropenia and thrombocytopenia and thus allowed all treated patients to receive full-dose antineoplastic agents, in contrast to only 28.5% of the control group. Continuous treatment with AS101 significantly reduced the number of days per patient of thrombocytopenia and neutropenia and did not provide protection to tumor cells as reflected by the higher overall response rate compared with the chemotherapy-alone arm. Interestingly, AS101 treatment also significantly prevented chemotherapy-induced alopecia. These effects correlate with the ability of AS101-treated patients to increase significantly the production of colony-stimulating factors (CSFs) interleukin-1 alpha (IL-1 alpha) and IL-6. CONCLUSION: AS101 has significant bone marrow (BM)-sparing effects and prevents hair loss in chemotherapy-treated patients, with minimal overall toxicity. These effects are probably due to increased production of IL-1 alpha, IL-6, and granulocyte-macrophage (GM)-CSF.

Overview of Taxol safety.

The safety profile of Taxol administered intravenously as a single agent has been established based on the experience of 655 patients. Of these patients, 253 were treated in nine phase I studies, and 402 were treated in eight disease-oriented phase II studies. Myelosuppression, specifically neutropenia, was the dose-limiting toxicity in all studies conducted in patients with solid tumors. Neutropenia was schedule dependent and was less severe when Taxol was administered via a 3-hour infusion. Severe hypersensitivity reactions were controlled in the phase II program with a premedication regimen consisting of dexamethasone, an antihistamine, and an H2 blocker. Cardiovascular toxicities were minimal and do not indicate constant electrocardiographic monitoring during Taxol infusions. Peripheral neuropathy was usually mild to moderate and dose related; however, it rarely caused treatment discontinuation. Additional adverse events associated with Taxol include arthralgia/myalgia, mucositis, nausea and vomiting, and alopecia.

Successful chemotherapy of recurrent intracranial germinoma with spinal metastases.

A recurrent CNS germinoma with subependymal and spinal metastases was treated by combination of cis-platinum, bleomycin, and vinblastine, resulting in disappearance of intracranial and spinal tumor. Second intracranial relapse responded again to the same combination chemotherapy. Response of spinal metastases to this combination chemotherapy has not been reported previously.

Adriamycin, vinblastine and mitomycin C as second-line chemotherapy in advanced breast cancer.

Thirty-six evaluable patients with metastatic measurable breast carcinoma previously treated with CMF or CMFVP were given second-line chemotherapy with Adriamycin, vinblastine, and mitomycin C (AVM), as follows: Adriamycin 20 mg/m2 and vinblastine 6 mg/m2 by i. v. push on days 1, 8, and 15, and mitomycin C 10 mg/m2 i. v. on day 1, every 6 weeks. Ten patients (28%) achieved partial remission (PR) lasting a median of 10 months, and eight patients (22%) experienced improvement of a lesser level than PR. An additional nine patients (25%) had disease stabilization; in the remaining nine patients (25%), persistent disease progression was observed. The median survival from the onset of AVM was 7 months for all patients; patients with PR survived a median of 13 months. Myelotoxicity was substantial and frequently interfered with the optimal administration of AVM, especially in patients with skeletal metastases; four patients were hospitalized with leukopenia and fever; all recovered promptly; one death was probably related to thrombocytopenia and CNS bleeding. Our results with AVM are similar to the average response rate published in the literature with the use of Adriamycin as a single agent in previously treated patients with advanced breast cancer.

Palliative medicine and the medical oncologist. Defining the purview of care.

The fusion of palliative medicine and medical oncology, in practice and in education, can provide a better standard of patient care, reduce the risk of oncologist burnout, and increase the likelihood of patient family and physician satisfaction. There need be no gulf between these disciplines, and only together do they represent truly comprehensive cancer care. The realization of this fusion will require the participation of individual clinicians, program directors, and the policy makers for cancer centers, professional organizations, and the health care regulatory authorities. It is a logical next step in the evolution of medical oncology.

The rediscovery of DON (6-diazo-5-oxo-L-norleucine).

DON (6-diazo-5-oxo-L-norleucine) and azotomycin are glutamine antagonists that were tested in human malignancies in the 1950s. Azotomycin demonstrated significant activity in colorectal cancer. DON is probably the active form of azotomycin. Recent impressive results for both of these agents in human tumor xenografts (especially the CX-2 colon tumor) have stimulated renewed clinical interest in DON, the more readily available agent. DON mechanism of action, clinical pharmacology, previous clinical data, and current phase I studies are discussed.

Selected anticancer drugs in Phase I trials in the United States (1979--1980).

Phase I trials in 1979 include some drugs representing totally new structures, new schedules of old compounds undergoing reevaluation, and second generation compounds. The rational development of analogs based on structure-activity relationships and on overcoming pharmacologic or toxicologic problems of parent compounds requires much future emphasis; two such examples (pentamethylmelamine and AZQ) are cited here. For all drugs, a plan of clinical development should ensure a more thorough initial evaluation as well as validation of concepts and systems that have prompted their introduction into the clinic. Establishment of clinical usefulness for the new structures, and particularly for three compounds herein reintroduced after a long period of oblivion, would constitute tangible proof of methodological and technological advances that have taken place in the development and clinical evaluation of anticancer drugs.

Indomethacin and dexamethasone treatment in experimental neoplastic spinal cord compression: Part 1. Effect on water content and specific gravity.

Water content and specific gravity were measured in the cervical, high thoracic, thoracic, and lumbar segments in an experimental model of neoplastic epidural spinal cord compression in rats harboring a thoracolumbar tumor. Increased content of water was observed only in the compressed lumbar cord segments of paralyzed rats (P less than 0.04). A progressive increase in specific gravity values of the compressed segments accompanied the increasing severity of neurological dysfunction (P less than 0.003 in paraplegic rats). Electron microscopy of the compressed cord revealed enlarged interstitial spaces, myelin breakdown, and extravasated blood cellular elements. Treatment with dexamethasone (10 mg/kg q 12 hr x 3) failed to reduce the increased content of water, but corrected specific gravity changes. Treatment with indomethacin (10 mg/kg q 12 hr x 3) reduced both elevated water content and specific gravity values back to normal levels. In untreated animals, the interval between the first neurological sign (limp tail) and paraplegia was 2.8 +/- 0.34 days (mean +/- SE). Treatment with dexamethasone lengthened this period by 28.6% (P less than 0.05); treatment with indomethacin lengthened it by 66.4% (P less than 0.005). We conclude that, because the specific gravity measurements in this model reflect complex pathophysiological processes, their translation into water content values is not advisable. Pharmacological intervention with indomethacin compares favorably with dexamethasone in reduction of spinal cord edema and in delaying the onset of paraplegia.

Selective route of doxorubicin administration improves outcome in experimental malignant epidural cord compression.

Epidural spinal cord compression was produced in adult Fischer rats by injection of 10(6) viable cells of malignant fibrous histiocytoma anterior to the T-13 vertebral body. Using a tracer dye, it was demonstrated that a portion of the inoculum was always present in the anterior epidural space at the time of inoculation. Paraplegia and incontinence occurred consistently on Days 14 to 27 (median, 23 +/- 3.0). By sequential computed tomographic scans, the growth of the paravertebral tumor was documented and its volume was calculated. A single dose of cisplatin (i.p., 6 mg/kg) or doxorubicin (DXR, i.v. jugular, 6 mg/kg) was administered on Day 1. On Day 18, tumor volume was significantly reduced by DXR (P less than 0.001) and cisplatin (P less than 0.01), but paraplegia continued to occur as in the untreated rats. Comparison of treatment outcome with DXR administered via the jugular vs. the tail vein revealed that both were equally effective in retarding the growth of the paravertebral tumor, and both caused a similar transient leukopenia. However, only the tail DXR brought about a significant delay in the onset of paraplegia (P less than 0.004) and significantly increased the survival (P less than 0.001). It is suggested that the lack of efficacy of systemic chemotherapy for tumors located in the epidural space is probably related to inadequate drug exposure. The improved outcome with tail DXR infusion may be explained by the regional spinal venous perfusion, which allows an increase in the local drug concentration during its first passage through the epidural venous plexus.

Cancer pain: knowledge and attitudes of physicians in Israel.

The effectiveness of cancer pain therapy is influenced by the attitudes and knowledge of the treating physicians. As part of a quality improvement project in the management of cancer pain, a survey of 236 medical practitioners was conducted. One hundred seventy-six respondents (74.5%) completed the survey. Fifty-two percent treated patients with cancer pain several times a week or more. Whereas 57.7% of physicians stated that 76-100% of patients could achieve a satisfactory outcome from analgesic therapy, only 17.2% of respondents reported that > 75% actually achieve a satisfactory outcome in their own experience. Unsatisfactory outcome was ascribed to inadequate pain relief (59.7%), or excessive central nervous system (CNS) side effects (43.3%). According to the responding physicians, the major barriers to effective relief include inadequate assessment of the pain and pain relief (65.3%), inadequate knowledge of pain therapy (57.9%), and physician reluctance to prescribe opioids (49.1%). Questions evaluating physician knowledge identified widely prevalent knowledge deficits in pain physiology, risk of addiction, use of adjuvant analgesics, opioid dosing, and treatment of side effects. Specialists in oncology tended to evaluate their knowledge more highly than others (P < 0.05). Despite this, there was no significant knowledge difference between oncologists and noncancer specialists. The data highlight some of the barriers to the successful management of cancer pain in Israel, the prevalence of knowledge deficits, and the common disparity between clinicians' self-assessment of clinical competence and their ability to respond correctly to questions on the management of cancer pain.

Tumor lysis syndrome in nonhematologic malignancies. Report of a case and review of the literature.

Tumor lysis syndrome (TLS), resulting from massive necrosis of neoplastic cells after chemotherapy, is a rare complication in nonhematologic malignancies. A 32-year-old woman suffering from a rapidly progressing breast adenocarcinoma metastatic to the liver and bones received a course of single-agent chemotherapy with mitoxanthrone and 4 days later developed the tumor lysis syndrome, and subsequently acute renal failure. The patient responded well to appropriate treatment. This case report points out that breast cancer can be extremely sensitive to chemotherapy and suggests that prophylaxis for tumor lysis syndrome should be considered in the subset of patients with breast carcinoma who have hepatic metastases and large tumor burdens.

CMF (cyclophosphamide, methotrexate, 5-fluorouracil) versus cnf (cyclophosphamide, mitoxantrone, 5-fluorouracil) as adjuvant chemotherapy for stage II lymph-node positive breast cancer: a phase III randomized multicenter study.

A multicenter phase III randomized study compared the efficacies of two adjuvant polychemotherapeutic regimens in 145 patients with stage II node-positive breast cancer. The standard chemotherapy combination, CMF (cyclophosphamide, methotrexate, 5-fluorouracil), was administered to 77 women. The experimental protocol, CNF (cyclophosphamide, mitoxantrone, 5-FU), in which mitoxantrone (Novantrone) replaced methotrexate, was given to 68 patients. Follow-up of the 145 patients by six participating hospitals showed no statistically significant difference (p = 0.6) between the two treatment regimens during a median follow-up of 4.5 years in terms of overall survival. There was, however, a significant advantage (p = 0.04) in the disease-free survival for those receiving mitoxantrone (mean survival 4.4 years for CNF versus 2.7 years for CMF). Toxic side effects associated with CNF (particularly alopecia and myelotoxicity) were relatively more frequent but acceptable and did not lead to dose reduction. In light of its association with improved disease-free survival in this study, larger studies should be undertaken on the role of mitoxantrone as adjuvant treatment in stage II breast cancer.

Experimental neoplastic spinal cord compression: evoked potentials, edema, prostaglandins, and light and electron microscopy.

Spinal cord compression was induced in Fischer rats by percutaneous inoculation of 10(6) cells of malignant fibrous histiocytoma anterior to the T13 vertebral body. Paraplegia and incontinence occurred in all animals after 14-27 days (median, 23 +/- 3.0 days). Autonomic dysfunction and a measurable increase in tumor volume were documented with the use of computer tomography. The tumor penetrated the vertebral bone, invaded the epidural space, and gradually compressed the lumbar spinal segments. Electron-microscopic examination revealed dilated intermyelin spaces containing exuded homogenous material and extravasated leukocytes and erythrocytes. Myelin breakdown was accompanied by the presence of lipid-laden macrophages. Sequential recording of somatosensory evoked potentials (SEP) revealed a progressive increase in the latency of the cervical responses, which preceded the onset of clinical signs. In the presence of paraplegia, spinal cord conductivity was abolished. The levels of the prostaglandins TXB2, 6-keto-PGF1 alpha, and PGE2 were measured in the compressed and remote spinal cord segments during the presymptomatic and symptomatic periods. Only PGE2 was significantly elevated (P less than 0.001) in the paraplegic rats, all along the spinal cord segments. A significant increase in water content was measured in the compressed lumbar segments in the presymptomatic period, and when paralysis set in it was increased in the adjacent low thoracic area as well. Tissue specific gravity was significantly increased only in paraplegic rats in the compressed (P less than 0.01) and the adjacent low thoracic areas (P less than 0.05) but no significant change occurred during the presymptomatic period. Multiple mechanisms play a role in the pathogenesis of neurologic symptoms in neoplastic spinal cord compression.(ABSTRACT TRUNCATED AT 250 WORDS)