Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology
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Multicenter Study
Radiotherapy for early infradiaphragmatic Hodgkin's disease: the Australasian experience.
To review the Australasian results of Stage I and IIA Infradiaphragmatic Hodgkin's Disease (IHD) treated solely by irradiation. ⋯ The rate of control in IHD could perhaps be improved by avoiding involved field irradiation or by aggressive therapy with total nodal irradiation or combined modality chemo-irradiation in Stage II disease. Staging laparotomy does not appear to be indicated.
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Comparative Study
Differential effects of dose rate and superfractionation on survival and cell cycle of V79 cells from spheroid and monolayer culture.
Recent developments concerning brachytherapy suggest conditions for an equivalence between the common continuous low dose rate (CLDR) exposure and pulsed irradiation regimens (PDR), provided that total dose is administered in the same overall time. The respective theoretical considerations have been based solely on the phenomenon of sublethal damage recovery. The present study, therefore, aimed to assess a possible influence of growth state/cell cycle progression when CLDR and different super fractionation protocols are compared. ⋯ For monolayer cells, on the contrary, the scheme of hourly pulses was significantly more effective than the CLDR irradiation. As measured by flow cytometry, this different behaviour could be attributed to the accumulation of cycling cells in the radiosensitive G2/M phase (G2 block) during protracted exposure which was drastically more pronounced for the pulsed scheme compared to the CLDR condition. The observed principle phenomenon of a block to cell cycle progression from high dose rate pulses (at low overall dose rate) may be less expressed in (human) cells having a long G1 period, but if applicable to a clinical situation, an increase of acute effectiveness of a superfractionated brachytherapy protocol has to be considered.
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Using theoretical models based on radiobiological principles for the design of new treatment schedules for HDR and PDR brachytherapy, it is important to realise the impact of assumptions regarding the kinetics of repair. Extrapolations based on longer repair half times in a continuous LDR reference scheme may lead to the calculation of dangerously high doses for alternative HDR and PDR treatment schedules. We used the clinical experience obtained with conventional ERT and LDR brachytherapy in head and neck cancer as a clinical guideline to check the impact of the radiobiological parameters used. ⋯ For the acute effects (or tumor control) the best fits are obtained for repair half times of about 0.5 h, while for late effects the repair half times are at least 1 h and can be as high as 3 h. Within these ranges of repair half times for acute and late effects, the outcome of "alternative' HDR or PDR treatment schedules are discussed. It is predominantly the late reacting normal tissue with the longer repair half time for which problems will be encountered and no or only marginal gain is to be expected of decreasing the dose rate per pulse in PDR brachytherapy.
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Comparative Study
Concurrent 5-fluorouracil, mitomycin C and irradiation in locally advanced cervix cancer.
We reviewed 177 patients treated with radical radiotherapy for locally advanced (FIGO stages IIB, IIIA, IIIB) cervix cancer between January 1979 and December 1989. The radiotherapy was given by external beam treatment to the pelvis and by an intracavitary caesium insertion. Ninety-three patients also received chemotherapy which consisted of infusional 5-fluorouracil during the first and last weeks of the external beam component of the radiotherapy, combined with bolus mitomycin C (group A, 64 patients) or without mitomycin C (group B, 29 patients). ⋯ This increase in toxicity persisted through all follow-up time intervals. Patients in group B also demonstrated a higher rate of toxicity than group C, but this increase was limited to the first 6 months of follow-up. The use of mitomycin C in addition to radiotherapy and 5-fluorouracil should be regarded with caution, as other studies have also shown that toxicity is increased, but without improvements in survival.
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The results of 75 patients with soft-tissue sarcomas treated by the combination of local surgical excision plus postoperative radiotherapy are reported. Thirty-five tumors were situated in the extremities, 32 in the trunk, and eight in the head and neck. Twenty-eight tumors were high grade, 33 intermediate and 14 low grade. ⋯ The 5-year overall survival rate was 50.5% for the entire group. Following a univariate analysis of host tumor and treatment-related factors, a tumor site other than extremity (p < 0.05), high tumor grade (p < 0.01) unfavorable histology (p < 0.05), and incomplete tumor resection (p < 0.01) were found to significantly increase the risk of further tumor death. Multivariate analysis found high tumor grade (RR 5.6), and incomplete resection (RR 7) to be independent poor risk factors for survival.