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Biomedical subjects

H Sack

Publications and source records attributed to H Sack.

At least 55 records · Page 3Linked to original sources
PubMed1997

Chemo-radiotherapy for locally advanced head and neck cancer--long-term results of a phase II trial.

The feasibility and effectiveness of a combined chemo-radiotherapy treatment modality for locally advanced head and neck cancer was tested in a phase II trial. Between 1990 and 1993, 74 patients (20 female/54 male) with head and neck cancer stage III (n = 12) and IV (n = 62) were treated with accelerated radiotherapy (72 Gy) and simultaneous chemotherapy (5-FU, folinic acid, mitomycin C). The median follow-up time was 43 months (1-72). Complete remission (CR) was absent in 76% (56/74) of patients and, after subsequent resection of residual lymph nodes, another 8 patients achieved CR. The cumulative local control rate was 72% and disease-specific survival rate was 59% at 4 years. Two patients died with treatment-related conditions (pancytopenia, larynx oedema). By multivariate analysis, only lymph node status was an independent parameter for local control (P = 0.04). This treatment was feasible and toxicity was not a treatment-limiting factor. As a consequence, a German multicentre phase III trial was initiated in 1995.

Adult↗
PubMed1997

Treatment of follicular follicle centre lymphomas: current status and future perspectives.

Follicle centre lymphomas (FCLs) comprise the predominant subtype of indolent nodal lymphomas. Therapy is based on the stage of the disease and consists of extended field or total nodal irradiation in stages I and II. Patients with advanced stages III and IV may initially remain untreated and be watched until the occurrence of disease-related symptoms such as B-symptoms, haematopoietic insufficiency, lymphoma progression or bulky disease. On the occurrence of these signs a cytoreductive chemotherapy of mild to moderate intensity such as cyclophosphamide, vincristine, prednisone (COP) or mitoxantrone, chlorambucil, prednisone (MCP) should be initiated. In responding cases maintenance with interferon-alpha (IFN alpha) leads to a significant prolongation of the progression-free interval. Modifications of this approach include the upfront combination of IFN alpha with anthracycline containing combinations such as cyclophosphamide, doxorubicin, teniposide, prednisone (CHVP). New perspectives arise from the introduction of myelo-ablative radio-chemotherapy with subsequent stem-cell transplantation and antibody-based immunobiological therapies.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Differentiated thyroid cancer. Impact of adjuvant external radiotherapy in patients with perithyroidal tumor infiltration (stage pT4).

BACKGROUND: The role of adjuvant external radiotherapy in the survival of patients with differentiated thyroid cancer (DTC) is controversial. To our knowledge, no attempt has been undertaken thus far to assess the impact of this therapy with respect to the papillary and follicular types of thyroid cancer as separate entities. METHODS: Between 1979 and 1992, 238 patients with differentiated papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC) with Stage pT4 have been treated and followed in our clinic. One hundred sixty-nine patients free of metastases at the final staging, which was performed after the second radioiodine therapy, were included in this study. The standard treatment comprised total thyroidectomy, ablative radioiodine therapy, and thyroid-stimulating hormone-suppressive therapy with levothyroxin. Ninety-nine patients free of disease after the final staging received additional external radiotherapy to the neck (with a dose of 50-60 Gy), whereas the remaining 70 patients were treated with the standard treatment protocol only. Distributions of age, sex, and follow-up time were comparable in both irradiated and nonirradiated groups. Multivariate analysis of the influence of age, sex, histologic subtype, and lymph node status as well as of external radiotherapy on the time to first locoregional and distant failure (LDF), and the time to locoregional recurrence (LR), was accomplished using Cox's proportional hazard model. RESULTS: In patients with DTC, external radiotherapy was a predictive factor for improvement of both LR (P = 0.004) and locoregional and distant failure (P = 0.0003). When the time to first locoregional and distant failure was calculated separately for patients with PTC and FTC, there was a significant difference in the PTC group in favor of irradiated patients (P = 0.0001), whereas there was no effect of external radiotherapy in the FTC group (P = 0.38). Further analyses disclosed that this effect was significantly present only in patients with PTC and lymph node involvement (P = 0.002), whereas those without lymph node involvement did not benefit from an additional adjuvant radiotherapy (P = 0.27). Because none of the patients younger than age 40 years died due to the disease nor had progressive disease during follow-up, we reassessed our results in patients older than age 40 years. The effect of external radiotherapy could be confirmed in this subgroup of patients (P = 0.0009) and in the subgroup of lymph node positive patients older than age 40 years with invasive PTC (P = 0.01). CONCLUSIONS: In addition to total thyroidectomy, treatment with radioiodine, and TSH-suppressive therapy with thyroid hormone, adjuvant external radiotherapy improves the recurrence-free survival in patients older than age 40 years with invasive PTC and lymph node involvement.

Adenocarcinoma, Follicular↗
PubMed1996

Modeling plasmalemma ion transport of the aquatic plant Egeria densa.

Fresh-water plants generate extraordinarily high electric potential differences at the plasma membrane. For a deeper understanding of the underlying transport processes a mathematical model of the electrogenic plasmalemma ion transport was developed based on experimental data mainly obtained from Egeria densa. The model uses a general nonlinear network approach and assumes coupling of the transporters via membrane potential. A proton pump, an outward-rectifying K+ channel, an inward-rectifying K+ channel, a Cl- channel and a (2H-Cl)+ symporter are considered to be elements of the system. The model takes into consideration the effects of light, external pH and ionic content of the bath medium on ion transport. As a result it does not only satisfactorily describe the membrane potential as a function of these external physiological factors but also succeeds in simulating the effects of specific inhibitors as well as I-V-curves obtained with the patch-clamp technique in the whole cell mode. The quality of the model was checked by stability and sensitivity analyses.

Cell Membrane↗
PubMed1996

Combined preoperative chemotherapy and radiotherapy in patients with locally advanced esophageal cancer. Interim analysis of a phase II trial.

PURPOSE: The prognosis of patients with locally advanced esophageal cancer (LAEC) remains poor when treated with local modalities. An intensive preoperative program with chemoradiotherapy was used to evaluate the curative resection rate, pathologic response, and survival of patients with LAEC. PATIENTS AND METHODS: Ninety patients with LAEC were treated preoperatively with chemotherapy (three courses of fluorouracil, leucovorin, etoposide, and cisplatin [FLEP]) followed by concurrent chemoradiotherapy (one course of cisplatin plus etoposide in combination with 40 Gy of radiation). Transthoracic esophagectomy was performed 4 weeks after the end of radiation. RESULTS: Seventy-two patients were included in this evaluation. Forty-four (61%) underwent a complete tumor resection, and 16 (22%) had no tumor in the resected specimen (pathologic complete response [PCR]). The operative mortality rate was 15%. At a median follow-up time of 22 months (range, 12 to 41), the median survival duration of all 72 patients was 17 months (range, 1 to 41+). The calculated survival rates at 3 years were 33%, 42%, and 68% for all patients, patients after complete resection, and patients with PCR, respectively. CONCLUSION: This combined treatment modality is active in LAEC, with a PCR in 33% of the patients undergoing surgery. The results appear improved compared with those reported with surgery alone, by approximately doubling the 3-year survival rate. The high efficacy of preoperative chemoradiation warrants evaluation of the role of surgery in LAEC.

Adenocarcinoma↗
PubMed1996

Results of radiotherapy for 230 patients with stage I-II seminomas.

PURPOSE: The outcome of treatment of testicular seminoma in 230 patients with stage I and II disease was retrospectively evaluated in regard of survival, pattern of failure, radiation dose, treatment volume, acute and chronic side effects. PATIENTS AND METHODS: From 1978 to 1992, 230 male patients with the diagnosis of pure seminoma of the testis were treated by postoperative radiotherapy at the University of Essen. According to the Royal Marsden Staging System, 188 patients were presenting with stage I disease, 24 with stage IIA, 13 with stage IIB and 5 with stage IIC disease. All patients received irradiation to the paraaortic lymph nodes (median dose: 36 Gy). In 154 patients the ipsilateral iliac lymph nodes were additionally irradiated with or without inguinal lymph nodes and in 66 patients the contralateral pelvic nodes were included. Since 1987, the total dose was reduced to 26 Gy for microscopic disease. A mediastinal irradiation (median dose: 30 Gy) was performed in 22 patients. Eight patients with stage IIB and IIC disease were additionally treated with chemotherapy. RESULTS: Overall actuarial survival (Kaplan-Meier method) for all patients was 97.8% at 5 years and 96.5% at 10 years. Ten-year survival corrected for intercurrent mortality (n = 8) was 100%. In 5 patients recurrent disease (n = 5) was observed, in 6 patients seminoma occurred in the contralateral testis. For stage I seminoma the disease-free survival was 96.8%. For the whole group of stage II seminoma the DFS was 88.1%, for stage IIA 91.7% and for stage IIB 76.9%. In stage IIC no recurrences occurred. In general, the radiation therapy was well tolerated with minor side effects only. CONCLUSIONS: Postoperative radiotherapy for seminoma stage I, IIA and IIB alone offers excellent control and survival rates with tolerable side effects.

Adult↗
PubMed1996

[Radiotherapy of primary extranodal non-Hodgkin's lymphoma of the head and neck region. Results of a prospective multicenter study. Study Group NHL: early studies].

PURPOSE: To evaluate the long-term outcome of patients with limited-stage primary extranodal lymphoma of head and neck treated with definitive radiotherapy in low-grade and a combined radio- and chemotherapy in high-grade lymphoma. PATIENTS AND METHODS: Between January 1986 and August 1993, 63 patients with primary extranodal Non-Hodgkin lymphoma of head and neck region, stages IE and IIE were treated with radiotherapy. The histological classification followed the Kiel classification, staging the Ann Arbor classification. PATIENT CHARACTERISTICS: 33 male, 30 female; age 18 to 84 years; tumor localisation: tonsils 26, nasopharynx 7, oropharynx 8, paranasal sinus 11, salivary glands 7, floor of mouth/gingiva 3, larynx 1. Mean follow-up is 74 months. Low-grade lymphoma in stages I and II CS were treated with definitive radiation therapy according to the concepts of epithelial tumors of the same localisation (target volume and technique). The adjuvant dose was 30 Gy and in the tumor volume 40 Gy, 2 Gy daily. 28 patients were registered, 18 in stage I and 10 in stage II. High-grade lymphoma were treated with definitive radiation therapy according to the concepts of epithelial tumors of the same localisation, too. The dose was 40 respectively 50 Gy, followed by 4 courses of adjuvant chemotherapy with CHOP. Thirty-five patients were enrolled, of whom only 10 received chemotherapy. RESULTS: The overall 5-year survival rates were for low-grade 67% and for high grade lymphoma 88%. The corresponding relapse-free survival rates were 54/68%, respectively. Only 1 patient failed within the irradiated target volume. Recurrences occurred at sites distant to the irradiated volume in nodal and extranodal regions. Prognosis was influenced by histologic grade. Significant trends were not observed for other potential pretreatment parameters (age, stage, localisation, bulk). CONCLUSIONS: In stage I or II patients with low malignant non-Hodgkin's lymphoma of the head and neck, initial management with definitive external radiotherapy is appropriate and probably curative. In high-grade lymphoma of clinical stage IE with nonextensive tumor size definitive radiotherapy is possible in curative intention. Primary chemotherapy followed by radiation is probably preferable.

Adolescent↗
PubMed1995

Heterogeneity in the fractionation sensitivities of human tumor cell lines: studies in a three-dimensional model system.

PURPOSE: Current concepts to optimize the therapeutic gain of radiotherapy by hyperfractionation assume that human tumors are less sensitive to fractionation than late reacting normal tissues. The aim of this study was to investigate the extent of the intercell line heterogeneity of fractionation sensitivity of a wide variety of human tumor cell lines in a three-dimensional model system under fully oxic conditions using schedules with one to eight fractions. Biological characteristics of the tumors that correlate with fractionation sensitivity should be identified. METHODS AND MATERIALS: A total of 21 cell lines from human tumors maintained as multicellular spheroids consisting of 1000-1500 cells were given fractionated irradiation within a total treatment time of maximally 50 h. Complete dose-spheroid control curves were determined for each fractionation scheme. The spheroid control data were adequately described by the linear quadratic model assuming Poisson statistics. In addition, the induction of a G2 block by a fractionated test dose of seven 3 Gy fractions given at 6-h intervals was determined in spheroid cells using flow cytometry of propidium bromide stained cell nuclei. RESULTS: The fractionation sensitivities of human tumor cells in multicellular spheroids could be characterized by alpha/beta values, ranging from 2.8-37 Gy in dependence on the cell line. The log normally distributed alpha/beta values were positively correlated with the percentage increase in G2/M phase after the fractionated test dose compared to the controls (r = 0.72, p < 0.01), and were associated with the degree of tumor differentiation (p = 0.01, ANOVA F-test). No significant correlation between the log (alpha/beta) values and the surviving fractions at 2 Gy (SF2) or the total doses with 2 Gy per fraction necessary to control 50% of the spheroids (SCD50) was observed. Despite the intercell line variability of the alpha/beta values, the SCD50 values of the different cell lines, given with one and eight fractions or one fraction and 2 Gy per fraction, were closely associated (Spearman rank correlation coefficients: r = 0.89 or r = 0.90, p < 0.0001). CONCLUSION: Human tumor cell lines showed a marked heterogeneity in the fractionation sensitivity when irradiated as multicellular spheroids and assayed in situ using the spheroid control end point. Therefore, the therapeutic gain of altered fractionation also depends on those biological characteristics of each individual tumor that affects its fractionation sensitivity. Parameters that correlate with fractionation sensitivity of the tumor lines in the spheroid system were identified as grade of tumor differentiation and percentage increase in G2/M cells at the end of an eight-fraction schedule.

Humans↗