Ira J. Spiro

GASTROINTESTINAL STROMAL TUMOR VERSUS INTRA-ABDOMINAL FIBROMATOSIS OF THE BOWEL WALL: A CLINICALLY IMPORTANT DIFFERENTIAL DIAGNOSIS

Intra-abdominal fibromatosis (IAF) is an uncommon benign neoplasm that usually occurs in the mesentery or retroperitoneum and may, on occasion, mimic a gastrointestinal stromal tumor (GIST). Differentiating between these two entities is important clinically because IAF is a benign tumor whereas GISTs frequently have malignant potential. In this study, the authors identified 13 cases of IAF with prominent involvement of the bowel wall as well as 35 GISTs of the small intestine, colon, or mesentery and analyzed their clinical, gross, histologic, immunophenotypic, and ultrastructural characteristics to identify important distinguishing features. Patients with IAF were younger (mean, 34 yrs) than patients with GIST (mean, 54 yrs). Both types of tumors tended to be large, but GISTs were soft and lobulated with hemorrhage, necrosis, or cystification whereas IAFs were firm, tan, and homogeneous. Histologic features characteristic of GIST included the presence of spindle or epithelioid cells with variable architecture, mitotic activity (range, <1-95 mitoses/50 high-power fields [hpf]; mean, 15 mitoses/50 hpf), nuclear atypia, and myxoid or hyalinized stroma. Necrosis and hemorrhage were seen in 16 and 25 tumors, respectively. In contrast, IAFs were composed of broad, sweeping fascicles of monotonous spindle cells with mitotic activity (range, <3-11 mitoses/50 hpf; mean, 4 mitoses/50 hpf), bland nuclear features, and finely collagenous stroma. Necrosis, hemorrhage, and myxoid degeneration were not seen. Immunohistochemical studies performed on a limited number of GISTs and IAFs demonstrated that cells expressed vimentin (100% GIST and IAF), CD117 (88% GIST and 75% IAF), CD34 (42% GIST and 0% IAF), smooth muscle actin (63% GIST and 75% IAF), muscle actin (75% GIST and 75% IAF), desmin (8% GIST and 50% IAF), and S-100 protein (16% GIST and 0% IAF). Ultrastructural analysis of 21 GISTs revealed incomplete smooth muscle differentiation in some tumors whereas IAFs were shown to have complete myofibroblastic/fibroblastic differentiation. Information regarding clinical outcome was available on 29 patients and revealed that three patients with histologically benign GISTs were alive with no evidence of disease at 5 months to 6 years (mean, 3.5 yrs) and one patient with a histologically benign tumor died of disease after 7 years. Of patients with histologically malignant GIST, one died of surgical complications, 10 were alive without disease at I to 13 years (mean, 5.4 yrs), four were alive with disease at 4 months to 15 years (mean, 3.8 yrs), three had disseminated disease at operation, and seven were dead of disease at 10 months to 3 years (mean, 2.2 yrs). Follow up of eight patients with IAF demonstrated that five were alive without disease at 4 months to 15 years (mean, 5.3 yrs) and three had recurrences at 1 (two patients) and 2 years (one patient). In summary, IAFs can have many features (large size, infiltration of adjacent structures, mitotic activity) that can cause diagnostic confusion with GISTs and, importantly, the degree of mitotic activity present in IAFs may overlap that seen in malignant GISTs. These entities can be distinguished primarily by their light microscopic and ultrastructural features but there is a notable overlap in their immunohistochemical profiles. The distinction between these neoplasms is important because there are important clinical implications for the patient.

The Effects of Cellular Glutathione Elevation on the Oxygen Enhancement Ratio

The radiation responses at various oxygen tensions were evaluated in V79 Chinese hamster cells under conditions where their nonprotein thiols, primarily glutathione (GSH), were elevated by 2-oxothiazolidine-4-carboxylate (OTZ). OTZ, when cleaved by intracellular oxoprolinase, provides the cell with cysteine which stimulates GSH synthesis. A 2-hr pretreatment with 10 mM OTZ elevated GSH to 200% of controls. This elevation in GSH offered no protection to aerated cells; however, for O2 tensions less than or equal to 40,000 ppm modest protection was observed as evidenced by an increase in oxygen enhancement ratio. GSH elevation afforded maximal protection between 1000 and 10,000 ppm O2; however, the extent of protection was relatively small (protection factor = 1.3).

THE EFFECT OF pH ON HYPERTHERMIC AND X RAY INDUCED CELL KILLING

Abstract Chinese hamster ovary cells in vitro were heated (42.5°C) before, during, or after X-irradiation (5 Gy). First, a slight degree of radioprotection was observed when cells were irradiated in acidic medimn compared to irradiation in alkaline medium; i.e., 10 Gy reduced survival to 0.0035 at pH 6.75 compared to 0.0010 at pH 7.45. Second, survival increased independent of pH as the time between irradiation and subsequent heat treatment was increased. Third, both heat treatments alone and combined heat and irradiation treatments in acidic medium produced more cell killing than treatments in alkaline medium; the amount of recovery from heat damage which subsequently interacted with radiation damage decreased as the pH was decreased from 7.40 to 6.70. Furthermore, inhibition of recovery was reflected primarily as an increase in the slope of the radiation survival curve; i.e., heating for 60 min 150 min before irradiation decreased the D 0 from 1.00 Gy for cells heated and irradiated under alkaline conditions ad to 0.70 Gy for cells treated under acidic conditions. The extravolation numbers were 5 and 6 for the respective curves.

Cellular and molecular repair of X-ray-induced damage: dependence on oxygen tension and nutritional status

Cellular and molecular repair was studied at 23 degrees C using split-dose recovery and alkaline elution techniques, respectively, as a function of cellular oxygen and nutrient conditions. Hypoxic cells (0.001% O2) in full medium showed a partial reduction in the level of sublethal damage (SLD) repair relative to aerated cells (21% O2, OER equal to 3.2 relative to 0.001% O2); the respective repair kinetics were similar with a common repair half-time of 30 min. Similarly, hypoxic cells showed a slight reduction in strand break rejoining capacity compared to aerated cells. Under nutrient deprivation, anoxic cells displayed no SLD repair or strand break repair, while aerated cells exhibited the same level of SLD and strand break repair as for well-fed cells. In addition, nutrient deprived cells at low O2 levels (0.03%, OER equal to 1.15) displayed normal SLD and strand break repair capability. These results indicate that both nutrient and O2 deprivation are necessary for complete inhibition of cellular and molecular repair, and low levels of O2 (0.03%) can effectively reverse this inhibition.

Sensitization of low-dose-rate irradiation by nonlethal hyperthermia.

To assess whether hyperthermia could radiosensitize cells irradiated at a low dose rate, Chinese hamster V79 cells were simultaneously heated and irradiated at 0.86 Gy/h. The data showed that heat treatments at 39 and 40 degrees C, which did not induce heat killing alone or high-dose-rate radiosensitization, resulted in enhanced cell killing with low-dose-rate irradiation. The dose-modification factor (ratio of the slopes of the curves for low dose rate and high dose rate) was reduced to 1.8 at 39 degrees C and 1.4 at 40 degrees C, compared to a value of 2.1 at 37 degrees C. These data indicate that nonlethal heat treatments can cause enhanced radiosensitization under low-dose-rate conditions. The implications of these results for interstitial thermoradiotherapy are discussed.

Effect of hyperthermia on isolated DNA polymerase-beta.

Hyperthermia has been shown to inhibit the activity of DNA polymerase-beta when either the intact Chinese hamster cells or partially purified enzyme samples from CHO cells are heated (42.2 or 45.5 degrees C). However, the loss of activity from heating isolated enzyme samples can be either greater or less than the loss from heating intact cells. For example, treating cells with the membrane-active agent procaine-HCl greatly sensitizes the cells to heat-induced loss of enzyme activity but has no effect on the heat sensitivity of isolated enzyme. Furthermore, the heat sensitivity of the isolated enzyme depends greatly on the purification steps and can be reduced by heating the enzyme in the presence of bovine serum albumin, activated DNA, or Langendorf salts. These observations, considered in relation to others in the literature, suggest that heat inactivation of polymerase-beta occurs from heat-induced changes in the intracellular environment, which in turn modify the direct thermal denaturation of the enzyme within the cell.

The Effect of Hypoxic Cell Sensitizers at Different Irradiation Dose Rates

The effect of 0.1-5 mM misonidazole and SR 2508 on hypoxic V79 cellular survival at acute (498 cGy/min) and low (890 and 933 cGy/h) irradiation dose rates was measured and compared. The experiments were designed to delineate the oxygen mimetic phenomenon and the preincubation effect of these chemicals at these dose rates. Linear regression analysis of the survival data in terms of the linear quadratic model yielded values of alpha and beta. In the absence of drug, the linear coefficient was independent of dose rate, whereas the quadratic term was greatly reduced at low dose rate. At all dose rates, the preincubation effect affected primarily the alpha term, with little influence on beta. In contrast, the oxygen mimetic phenomenon predominantly affected the beta term. Overall, the radiosensitizing ability of these drugs was higher at low dose rate than at acute dose rate.

Role of radiation therapy in management of patients with sarcoma of soft tissue

Sarcomas of soft tissue comprise a broad grouping of the various malignant tumors arising from the mesenchymal soft tissue at all sites within the body. In addition, the malignant tumors of peripheral nerves are included. There is a broad spectrum of histologic types; they are usually designated according to the apparent soft tissue of origin. In the U.S. there are approximately 5600 newly diagnosed patients with STS per year.

Effect of thoracic irradiation on t-lymphocyte subsets and the prognostic significance of solCD4 CD8 ratios in human lung cancer

In a prospective study, from 1983 to 1986, circulating T-lymphocyte subsets were measured in patients with lung cancer who received thoracic radiation therapy (RT) as either primary or postoperative treatment. Samples were collected from new and follow-up patients, either before and/or after RT. A total of 230 samples from 131 patients were analyzed. T-cell determinations were made using subset-specific monoclonal antibodies and flow cytometry. RT portals typically included the area of primary disease, the ipsilateral hilum, the mediastinum and the supraclavicular fossae. The mean dose for all patients was 57 Gy (range 36-70 Gy). Post RT samples were arbitrarily divided into the following time groups: O-3 months, 3-6 months 6-12 months, 12-24 months, 24-59 months and 160 months. Statistical significance was determined using Student’s T-test for comparisons of 2 groups and analysis of variance for comparisons of 3 or more groups. All described changes were statistically significant at the 95% confidence limit, unless otherwise stated (ie. n.s.). Analysis of data collected before and after RT showed a decrease in CD4 cells from 48% before RT to 32% at O-3 months post-RT and remained depressed beyond 60 months. CD8 cells increased from 24% before RT to 31% at O-3 months postRT. As a result of these changes, the mean CD4/CD8 ratio decreased from 2.33 to 1.41 at O-3 months after RT and stayed depressed beyond 60 months. This phenomenon was observed for all histologies. In 18 patients who had at least one sample drawn before and after RT, the individual CD4/CD8 ratio was observed to decrease in 16. CD3 cells were also observed to decrease from 69% before RT to 64% at O-3 months post-RT (n.s.) and to 55% at 3-6 months after RT and remained significantly below the pre-RT value beyond 60 months. Similarly, the %llA cells decreased following RT and remained significantly below pre-RT values beyond 60 months. Conversely, the %CDlO and %IA cells increased following RT, both peaking at 3-6 months post-RT. The total number of WBCs did not significantly change following treatment while the mean total number of lymphocytes decreased from 1832 before treatment to 1186 at O-3 months post-RT, and increased to 1400 at 12-24 months. In 49 patients who had 52 T-cell profiles measured prior to RT, we analyzed CD4/CD8 ratios with regard to histology, stage of disease and survival. There were 18 cases of adenocarcinoma, 15 squamous cell carcinomas, 11 small cell carcinomas, 3 large cell carcinomas and 2 cases of undifferentiated carcinoma. Within this group, there was no significant difference between small cell, adenocarcinoma and squamous histologies. In general, CD4/CD8 ratio increased with extent of disease. For T2 versus T3 tumors, CD4/CD8 ratios were 2.08 and 2.26 respectively (n.s.). For NO-l versus N2 CD4/CD8 ratios were 1.77 and 2.52, respectively. For MO versus Ml patients, CD4/CD8 ratios were 2.16 and 3.09, respectively. Patients with pretreatment CD4/CD8 ratios 2.00 had an average survival of 15.9 months. Similarly, patients with an absolute CD4 900 survived 14.9 months. No other T-cell subsets were significantly prognostic. These data indicate that low CD4 values and low CD4KD8 ratios are associated with a better prognosis and that thoracic RT may produce favorable redistribution of CD4/CD8 ratios.