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Biomedical subjects

R R Weichselbaum

Publications and source records attributed to R R Weichselbaum.

At least 181 records · Page 10Linked to original sources
PubMed1991

Radiation-induced DNA double-strand break frequencies in human squamous cell carcinoma cell lines of different radiation sensitivities.

DNA neutral (pH 9.6) filter elution was used to measure radiation-induced DNA double-strand break (dsb) frequencies in eight human squamous cell carcinoma cell lines with radiosensitivities (D0) ranging from 1.07 to 2.66 Gy and D values ranging from 1.46 to 4.08 Gy. The elution profiles of unirradiated samples from more radiosensitive cell lines were all steeper in slope than the profiles from resistant cells. The shapes of the dsb induction curves were curvilinear and there was some variability from cell line to cell line in the dose-response for the induction of DNA dsb after exposures to 5-100 Gy 60Co gamma-rays. There was no relation between the shapes of the survival curves and the shapes of the dose-responses for the induction of DNA dsb. At low doses (5-25 Gy), three out of four of the more sensitive cell lines (D less than 2.5 Gy) had larger initial break frequencies than the more resistant lines (D greater than 3.0 Gy). Although the low-dose (5-25 Gy) elution results were variable, they do suggest that DNA neutral elution will detect differences between sensitive and resistant tumour cells in initial DNA dsb frequencies.

Carcinoma, Squamous Cell↗
PubMed1991

Survival and analysis of failure following hydroxyurea, 5-fluorouracil and concomitant radiation therapy in poor prognosis head and neck cancer.

Thirty-nine patients with head and neck cancer were entered into Phase I-II study of simultaneous radiation therapy with continuous infusion fluorouracil at 800 mg/m2/day and escalating doses of hydroxyurea. Twenty of these patients had recurrent disease after previous surgery and/or radiation therapy (group 1). Nineteen patients had not received prior local therapy but had advanced-stage disease (group 2). Cycles were repeated every other week until the completion of radiation therapy. The median follow-up was 32 months. Patients with recurrent disease were generally treated with palliative doses of radiation (median dose 5,000 cGy) while previously untreated patients received radiation with curative intent (median dose 7,040 cGy). The response rate for 15 evaluable patients with recurrent disease was 93% with 40% of patients achieving a complete response. For 17 evaluable patients without recurrent disease the response rate was 100%, with a complete response rate of 71%. This regimen exhibited a high activity and significant palliative benefit in group 1 patients. However the local control rate was 25% (5/20) because the majority of patients in this group eventually developed a local recurrence. The local control rate for group 2 patients was 84% (16/19). The higher local failure rate in group 1 patients appeared to be attributable to the palliative doses of radiation delivered and the fewer cycles of treatment received. We conclude that this regimen has palliative benefit in patients who have failed prior local therapy and has the potential for cure in patients with poor prognosis advanced stage disease as well.

Adult↗
PubMed1991

Chemotherapeutic and biologic radiation enhancement.

The main objectives of concomitant chemoradiotherapy are to increase local tumor control, decrease the incidence of distant metastases, and improve survival. In addition, concomitant therapy may reduce long-term cancer therapy morbidity either by reducing the need for radical surgery or by permitting the use of lower radiation doses. This article briefly summarizes the rationale for concomitant chemoradiotherapy and summarizes the most recent clinical experience for selected solid tumors. In addition, recent data that suggest additive or synergistic interaction between radiation and certain biologic response modifiers such as tumor necrosis factor and interferon are reviewed.

Combined Modality Therapy↗
PubMed1991

Regulation of tumor necrosis factor gene expression by ionizing radiation in human myeloid leukemia cells and peripheral blood monocytes.

Previous studies have demonstrated that ionizing radiation induces the expression of certain cytokines, such as TNF alpha/cachectin. However, there is presently no available information regarding the molecular mechanisms responsible for the regulation of cytokine gene expression by ionizing radiation. In this report, we describe the regulation of the TNF gene by ionizing radiation in human myeloid leukemia cells. The increase in TNF transcripts by x rays was both time- and dose-dependent as determined by Northern blot analysis. Similar findings were obtained in human peripheral blood monocytes. Transcriptional run-on analyses have demonstrated that ionizing radiation stimulates the rate of TNF gene transcription. Furthermore, induction of TNF mRNA was increased in the absence of protein synthesis. In contrast, ionizing radiation had little effect on the half-life of TNF transcripts. These findings indicate that the increase in TNF mRNA observed after irradiation is regulated by transcriptional mechanisms and suggest that production of this cytokine by myeloid cells may play a role in the pathophysiologic effects of ionizing radiation.

Cell Line↗
PubMed1991

Prognostic factors in advanced head and neck cancer patients undergoing multimodality therapy.

A retrospective analysis was performed to investigate potential prognostic factors for complete remission to neoadjuvant chemotherapy and overall survival in patients with previously untreated stage III and stage IV head and neck cancer. Eighty consecutive patients were treated in one of two studies investigating three or four courses of neoadjuvant chemotherapy. Before local therapy and surgery and/or radiotherapy, 29% attained a complete remission. No strong significant and independent predictor of complete remission was identified. Only nodal stage (N) was found moderately associated with complete remission (p = 0.06). Node-negative patients had higher remission rates. Less important predictors were tumor stage (T) and site of disease; nasopharyngeal patients had superior remission rates (56%). With a median followup of 45 months and estimated 3-year survival rate of 38% (median 23.7 months), individual factors predictive of survival included pretherapy weight loss, performance status, alcohol use, pretherapy serum albumin level, site of disease, and N stage. In multivariate testing weight loss was identified as the strongest independent predictor of survival (p less than 0.0001) and surpassed other health status measures, such as performance status and serum albumin level. In addition, N stage (p = 0.019) and alcohol use (p = 0.017) were found to be predictive. A cross-classification by N stage and weight loss revealed risk groups with distinctly different prognoses, which may be useful for design and analysis in future trials.

Adolescent↗
PubMed1991

Cisplatin and fluorouracil chemotherapy does not yield long-term benefit in locally advanced head and neck cancer: results from a single institution.

Fifty-one patients with locally advanced head and neck cancer were treated with three cycles of cisplatin at 100 mg/m2 followed by 5-day continuous infusion fluorouracil (5-FU) at 1,000 mg/m2/d as induction chemotherapy. Subsequent local therapy consisted of surgery for patients with resectable disease and/or radiotherapy. Three cycles of adjuvant chemotherapy were administered to patients with partial response (PR) or complete response (CR) to induction chemotherapy. Twenty-two patients (43%) had a clinical CR that was pathologically confirmed in 12 patients (24%), and 24 patients (47%) had a PR for an overall response rate of 90%. Local therapy included surgery in 24 patients (47%) and radiotherapy alone in 22 patients (43%). Adjuvant chemotherapy was administered to 32 patients (63%) frequently at great dose reduction. At a median follow-up of 90 months, the median survival is 22 months (95% confidence interval, 15 to 36 months), and the 5-year survival is 25%, with only five patients known to be alive and disease-free at this time. The median time to progression is 14 months, with 29 patients (57%) having documented progression of their head and neck cancer and eight (16%) having progression of a second neoplasm. Seven patients died of intervening medical events. This high incidence of second malignancies supports the continued investigation of chemoprevention for patients in CR. Despite the known high response rates achieved with cisplatin and 5-FU induction chemotherapy, the overall poor survival data reported here should lead to a thorough reexamination of the frequent administration of this regimen in the community.

Adolescent↗
PubMed1991

Temporal bone chemodectomas--comparing surgery and radiation therapy.

We reviewed the literature concerning curative treatment for chemodectomas of the temporal bone. Local control and complication rates were calculated from the published series for three therapeutic approaches: Surgery alone, radiation before or after surgery, and radiation alone. The local control rates were similar, 86%, 90%, and 93% respectively. Patients suffered a high rate of treatment-related morbidity following surgical excision of glomus jugulare lesions. Serious sequelae from radiation therapy were rare. We feel radiation therapy should be considered as primary treatment for glomus jugulare tumors.

Humans↗
PubMed1991

Radioresistant derivatives of radiosensitive CHO cells obtained following treatment with 5-azacytidine retain their sensitivity to cisplatin.

Treatment of the radiation-sensitive CHO mutant, xrs-5, with the demethylating agent 5-azacytidine results in the complete conversion to wild-type levels of X-ray resistance in 50% of the colonies examined (10/20). In addition to being sensitive to X rays, xrs-5 is also sensitive to the killing effects of the crosslinking agent cisplatin. The 5-azacytidine-treated xrs-5 cells which exhibit wild-type survival levels following exposure to X rays failed to demonstrate conversion to wild-type levels of resistance to cisplatin. These results support the hypothesis that increases in gene expression can alter the radioresistance of xrs-5 cells without influencing the cells' survival after exposure to cisplatin.

Animals↗
PubMed1991

Recent advances in radiation therapy for head and neck cancer.

The most efficacious treatment method for head and neck cancer is not yet defined. However, there have been some improvements made in the radiotherapy of head and neck cancer that are encouraging. Both hyperfractionated radiation therapy and accelerated radiation therapy have improved the local control rates in numerous primary sites, and the results of more rigorous prospective randomized studies, if positive, will justify more routine use of these techniques. The use of neutrons for unresectable salivary gland tumors has clearly been established as the treatment of choice. Local control as well as cosmetic outcome is excellent, with the only disadvantage being that neutron therapy is not as widely used as photon radiation. The same is true for charged particle therapy, the greatest utility of which appears to be for relatively small tumors adjacent to critical structures such as the brain and spinal cord. We also believe that intraoperative radiation therapy shows great promise and may soon be more widely available for the treatment of head and neck cancers. However, we believe that the most exciting advancement in the treatment of head and neck cancer is the use of concomitant radiation therapy and chemotherapy, a topic that is discussed in detail in another article in this issue.

Combined Modality Therapy↗
PubMed1991

Radiotherapy with concomitant chemotherapy for head and neck cancer.

Concomitant chemoradiotherapy has already resulted in statistically significantly improved disease-free and overall survival for patients with head and neck cancer. Although the differences observed so far have been small, it is of note that the improved outcome was achieved even though only single-agent chemotherapy was used. More recent, chemoradiotherapy schedules have employed more aggressive chemotherapy regimens, frequently with split-course radiotherapy. Several of these schedules have resulted in encouraging response and survival figures in phase II trials. At the same time, toxicities, usually in the form of mucositis, have also been increased. The role of these schedules in the management of patients with advanced head and neck cancer will need further evaluation, eventually using a randomized format comparing such a regimen with standard radiotherapy alone. Their use outside of clinical trials cannot be recommended yet.

Antineoplastic Agents↗
PubMed1990

Symmetrical chromosome rearrangements in cell lines established from human radiation-induced sarcomas.

We report the establishment of cell lines from six radiation-induced tumors, three osteosarcomas, and three soft tissue sarcomas. Cytogenetic analysis of the lines showed mostly balanced rearrangements in the osteosarcomas; the soft tissue sarcomas had more unstable karyotypes. The rearrangements observed were unlike those previously reported for spontaneously occurring tumors of the same histological type and were more typical of the long-term changes observed after radiation exposure.

Adolescent↗
PubMed1990

A randomized study comparing two regimens of neoadjuvant and adjuvant chemotherapy in multimodal therapy for locally advanced head and neck cancer.

Two regimens of neoadjuvant chemotherapy for previously untreated patients with locally advanced head and neck cancer were compared with the goal of identifying a regimen with a greater than 50% complete response (CR) rate. Patients with a performance status of 0 to 2 and normal end-organ function were randomized to receive either four cycles of neoadjuvant methotrexate, cisplatin, and continuous infusion 5-fluorouracil (5-FU) (MPF) (arm A), or four cycles of bleomycin, cisplatin, and methotrexate (PBM) alternating with cisplatin and 5-FU (PF) (arm B). Patients with a performance status of greater than 2 or a carbon monoxide diffusion capacity of less than 50% of the predicted value were assigned to the arm A regimen but were analyzed separately (arm C). Local therapy consisted of surgery (for patients with resectable disease) or radiation therapy followed by two cycles of adjuvant chemotherapy with the regimen that was administered initially. Of the 42 patients who were evaluated, 16 were randomized to arm A, 13 to arm B, and 13 to arm C. The clinical CR rate was 19% on arm A (95% confidence interval, 0% to 38%), 39% on arm B (95% confidence interval, 12% to 66%) (P = 0.41), and 54% on arm C (95% confidence interval, 27% to 81%). At a median follow-up time of 35 months, the 2-year actuarial survival rate was 61% on arm A, 69% on arm B (the P value was not significant), and 38% on arm C. The 2-year survival rate for all 42 patients who were treated was 57% and the median survival time was 31 months. Toxicities of neoadjuvant chemotherapy on all arms consisted of mild to moderate myelosuppression and renal toxicity. The incidence of moderate to severe mucositis was significantly higher on arm A than arm B (P = 0.02). Two cycles of adjuvant chemotherapy were administered to only 11 of 42 patients due to patient refusal or cumulative toxicity. In conclusion, both neoadjuvant chemotherapy regimens resulted in similar response and survival rates, but mucositis was more severe with arm A. However, since neither regimen was likely to cause a CR rate of greater than 50%, this study was closed to further patient accrual.

Adult↗
PubMed1990

Monosomy 12p in a radiation-induced germ cell tumor.

We report results of cytogenetic analysis of a cell line established from a radiation induced germ cell tumor. Tumors of this type are rare, and there is only one other report of chromosome analyses of solid tumors induced by radiotherapy (Cowan et al., 1990). The cells were grown for over a year, and harvested at passage 13. The karyotype was pseudodiploid, with several balanced translocations. Spontaneously occurring germ cell tumors are associated with i(12p). We did not observe an i(12p), but instead found monosomy of 12p and 7q22----q32.

Cell Line↗
PubMed1990

Radiation therapy in the treatment of cervical cancer: the University of Chicago/Michael Reese Hospital experience.

A retrospective analysis was conducted on 307 patients referred for radiation therapy at The University of Chicago and Michael Reese Hospital between 1971 and 1986. Median follow-up was 6.4 years. Treatment techniques varied during the time of the study. Actuarial disease-free survivals were 78%, 64%, 55%, 33%, 41%, and 60% for stage IB, IIA, IIB, IIIA, IIIB, and IVA, respectively. Stage, size of the cervical lesion, and hemoglobin level during treatment were prognostic factors. Treatment technique as well as time dose factors were analyzed with respect to survival, failures, and complications.

Adult↗
PubMed1990

Preoperative radiotherapy followed by radical vulvectomy with inguinal lymphadenectomy for advanced vulvar carcinomas.

A therapeutic alternative to exenteration for large locally advanced vulvar carcinoma involving the rectum, anus, or vagina is the use of preoperative radiation followed by radical surgery. Between 1980 and 1988, 13 patients with Stage III and 3 with Stage IV vulvar carcinoma involving the rectum/anus, urethra, or vagina were treated with 4000 rad to the vulva and 4500 rad to the inguinal and pelvic nodes followed by a radical vulvectomy and inguinal lymphadenectomy 4 weeks later. The overall 5 year cumulative survival was 45%. Twelve tumors regressed after radiation with 62.5% of the patients having visceral preservation while in 4 patients there was no major response to radiation and urinary or fecal diversion was required. Of the 6 recurrences 4 were central and 2 distant. Three patients with central recurrences had tumor within 1 cm of the vulvectomy margin. Complications included wet desquamation, inguinal wound separation, lymphedema, and urethral strictures. There were no operative deaths. It is concluded that the use of preoperative radiation followed by radical vulvectomy may be an alternative to pelvic exenteration in selected patients with advanced vulvar lesions.

Adult↗
PubMed1990

The interaction between recombinant human tumor necrosis factor and radiation in 13 human tumor cell lines.

Tumor necrosis factor (TNF) was cytotoxic at concentrations of 10 to 1000 units/ml to 12 of 14 human tumor cell lines. Synergistic or additive cell killing between TNF and radiation was observed in 7 of 10 tumor cell lines, while independent tumor cell killing by each agent occurred in two tumor cell lines. The maximum synergistic effect was observed when TNF was added 4-12 hr prior to irradiation. This interaction was absent when TNF was added after irradiation. TNF also reduced potentially lethal damage repair in 3 of 5 cell lines tested. Possible mechanisms of interaction of TNF and X rays including induction of hydroxyl radicals and subsequent DNA damage by TNF and radiation are discussed.

Animals↗
PubMed1990

Modeling of dose to tumor and normal tissue from intraperitoneal radioimmunotherapy with alpha and beta emitters.

Dose distributions for normal and tumor tissues from intraperitoneally administered radiolabeled antibodies have been calculated for 90-Yttrium (90Y), 131-Iodine (131I), and 211-Astatine (211At). The dose calculations use data on the activity of intraperitoneal fluid administered, the percent injected dose/gm uptake by tumor, biological half life, and a model for diffusion of antibody/radionuclide complex into peritoneal tissues. Calculations are performed for planar and hemispherical tumor shapes, ranging in size to establish the influence of geometry on dose distribution. Calculations for tumor geometry obtained from biopsies are also performed. When the activity is concentrated on or near the tumor surface, the maximum dose to a planar tumor for a 20 mci administration of 90Y is approximately 60 Gy, and falls rapidly to 50% of this value within 1 mm. However, for a hemispherical tumor, the dose is a maximum of 26 Gy, with an average of approximately 20 Gy. The surface dose from 131I (130 mci) is 240 Gy, and diminishes to 20 Gy in .05 cm in the planar case, whereas a hemispherical tumor receives a dose of 90 Gy over a large fraction of the volume, with the distal portions receiving 40 Gy. The surface dose for an administration of 70 mci of 211 At is 450 Gy and decreases to 50% of this value in 30 microns. Both surface geometry and tumor size are important determinants in the heterogeneity of tumor dose, as are the dose administered, antibody uptake, biodistribution, and residence time factors. These initial studies suggest that the size of disease which may be effectively treated is much less than the range of the particle emitted by radiolabeled antibodies. Furthermore, therapy is ultimately limited by the degree to which the antibody/radionuclide complex can diffuse and permeate the tumor.

Antibodies, Monoclonal↗