Hypoxyradiotherapy of uterine cervix cancer to decrease of acute side-effects and treatment complications.

The authors have reported on preliminary results of hypoxyradiotherapy in the course of external irradiation in patients with uterine cervix cancer from a view-point of the occurrence of acute reactions and treatment complications. A mixture of nitrogen and oxygen containing 8.0 to 8.5% of O2 was used to provoke acute hypoxia during irradiation. The applied doses of external irradiation was simultaneously increased by 40%. On the basis of a randomized study with 120 patients, acute hypoxia was found to protect healthy tissues against post-radiation damage. When the doses of 96 Gy in the paracervical space and that of 75 Gy in the pelvic wall were applied, acute side-effects decreased significantly if compared with a conventional radiotherapeutic procedure (p less than 0.01). Radiological preconditions for using acute hypoxia in radiotherapy are discussed.

Tumor response and treatment complications in radiotherapy of localized prostate cancer.

The response of primary tumor to definitive radiation therapy and treatment related morbidity has been analysed in a group of 35 patients. All of them were treated with 20 MeV photon beam to a total dose of 67 to 71 Gy to the prostate. The effect of radiotherapy to a primary tumor were evaluated by means of repeated CT examination of the tumor volume. A statistically significant tumor regression was found to occur from the sixth month after finishing radiotherapy. The absolute majority of treatment complications was of the first grade. Neither moderate nor severe gastrointestinal or genitourinary complications were recorded. The follow-up data of our patients have confirmed that radiotherapy in localized prostatic carcinoma, when sophisticated techniques are employed, represents highly effective treatment modality which improved the quality of life in patients with prostate cancer.

Calculation of radiation doses in critical organs compared with in vivo dosimetry during brachytherapy of carcinoma of the uterine cervix.

In a group of 38 patients with carcinoma of the uterine cervix, radiation doses were measured by thermoluminiscent dosimeters (TLDs) placed in catheters introduced into the urinary bladder and rectum during a 24 h uterovaginal application of 226Ra. The values of radiation doses registered by the TLDs were compared to those calculated from roentgenograms made after 24 h. To calculate the radiation doses, we used the program Brachy 9.3-C of the planning unit Evados (Siemens, FRG). Using nonparametric comparison tests, no statistically significant differences were found between the values of radiation doses registered by TLDs and those calculated after 24 h of uterovaginal application of 226Ra. Only in the oral part of the rectum, at a distance of 10 cm and above from the anal orifice, there were differences between doses measured by TLDs and those calculated from roentegenograms made after 24 h of brachytherapy. These differences were caused by the movement of the flexible catheters carrying the TLDs.

Complications of radiotherapy of uterine cervix carcinoma.

The retrospective analysis of 242 patients treated for uterine cervix cancer at VUKEO Brno within 1977-1982 has been realized. The patients being only treated with radiotherapy alone using the external 42 MeV X-ray betatron beam irradiation of the pelvis, and the vaginal and intrauterine application of 226Ra, were included in this study. The complications of therapy were evaluated in accordance with the grade of severity, location and time of their source. The radiotherapeutical complications of the 2nd stage appeared for 27 patients (11.2%), and the complications of the 3rd stage appeared for 8 patients (3.3%). The total five-years' survival rate is 71%, 92% for 37 patients in the Ib stage, 78% for 105 patients in the IIa, b stages, and 54% for 100 patients in the IIIa, b stages.

Effect of small doses of 252Cf on the tumour regression in cervix uteri during combined radiotherapy.

The results of a randomized study on the regression rate of the cervix uteri tumour for a group of 56 patients, investigated during and after radiotherapy with 2 Gy dose of the 252Cf neutron component applied by means of intracavitary therapy at the beginning of the therapeutic cure are presented and compared with the conventional 226Ra therapy. It was found that the tumour regression curve after 252Cf irradiation is significantly steeper than the curve of the control group. The quantitative evaluation of the results regarding the time required for a 50% regression of the original tumour shows that a group of patients treated by 252Cf needs a 27 days' cure in comparison with 40 days' cure for patients treated only by gamma radiation. The regression rate of the irradiated tumours shows a difference of approximately 30% for the treatment using small doses of 252Cf.

Variations in dose distributions by the use of independent asymmetric jaws. A new technique for irradiation of localized carcinoma of the prostate.

The use of independent jaws set asymmetrically in the moving field technique with bilateral arcs allows the entirely new dose distributions be obtained. The basic principle of this technique is that, with the use of moving field technique with bilateral arcs, the independent jaw more proximate to the central ray (axis) of beam must always be on the side of the critical organ. In this area the characteristic deformation of isodoses and the formation of very steep dose slope occur. We consider as optimum technique for the target irradiation of the prostatic carcinoma the moving field technique with bilateral 105 degrees arcs with 20 MeV X-ray beam of linear accelerator and with independent jaws set asymmetrically, when the independent jaw more proximate to the central ray is always + 1.5 cm from the central ray of the beam.

[Regression of cervix uteri neoplasms in combined radiotherapy using low dose gamma-neutron irradiation]. / Regrese nádoru hrdla delozního v prubehu kombinované radioterapie s pouzitím malých dávek gama-neutronového zárení.

The authors compared the results in the regression of uterus cervix tumour after intracavital therapy with gamma-neutron irradiation by 252cf and conventional sources of radiation gamma 226Ra in the course of a combined radiotherapy procedure. On the basis of a randomized study in 20 patients for a group it became obvious that due to the irradiation of the tumour in the initial phase of therapeutic cycle by physical dose 2 Gy of neutron component of 252Cf in the point A there was an increased regression of the tumour process causing in the 6th week since the beginning of the therapy a significant difference in the size of the tumours in both groups of patients. The time period required for 50% tumour reduction from the beginning of the therapy proved to be 23 days in patients treated with the 252Cf nuclide as compared with 48 days in the group of patients after conventional therapy.

[Manual afterloading applicators for intracavitary brachytherapy]. / Aplikátory rucního afterloadingu pro intrakavitární brachyterapii.

A technical description of uterovaginal and rectal applicator system of manual afterloading is described. A simple solution while using domestic materials covering the requirements of present-day brachytherapy. The applicators proved to be suitable for gamma radiation sources as well as for gamma-neutron radiation of 252Cf sources.

[Radiotherapy of carcinoma of the prostate--5 years' experience]. / Radioterapie u karcinomu prostaty--petileté zkusenosti.

Forty three patients were treated for cancer of prostate by irradiation at the Radiotherapeutic Ward of the Research Institute of Clinical and Experimental Oncology in the years 1976 to 1981. The five-year period of survival in patients with a localized tumorous disease was 45%. The authors analyzed causes of unsuccessful therapy and evaluated complications of the therapy, the latter being mostly early postirradiation reactions. Possibilities of improving the results of treatment in optimizing the radiotherapy of the localized prostate cancer are outlined.

[Reoxygenation of tumors of the uterine cervix during combined radiotherapy using low dose gamma-neutron irradiation with californium-252]. / Reoxygenace nádoru hrdla delozního v prubehu kombinované radioterapie s pouzitím malých dávek gama-neutronového zárení kalifornia-252.

A polarographic method was used to follow the changes in oxygenation of a tumour of uterus cervix after intracavital irradiation by 252Cf by a physical dose of 2 Gy, applied at the beginning of a therapeutic cycle of combined radiotherapy. The results reached are compared with the results of tumour oxygenation in the course of a conventional therapeutic procedure. It has become apparent that even after the irradiation of a tumour of uterus cervix by a small dose of gamma-neutron radiation with 252Cf there is, beginning with 2nd week of therapy, a significant reoxygenation of the tumour population. The changes of oxygenation after a conventional irradiation have been less marked and reached, in the 4th week of therapy, only marginally significant increase. Differences in reoxygenation of tumours of uterus cervix were confirmed by analysis of the oxygen test. The importance of tumour reoxygenation after the application of 252Cf source of radiation for facilitation of its regression in a combined treatment with Californium-252 and gamma irradiation is discussed.

A technical equipment for workroom with californium-252 used for the gamma-neutron brachytherapy.

A proposal for the 252Cf intracavitary brachytherapeutic workroom with the description of the technical equipment for the radioactive source storage and manipulation and the personal protection against the gamma-neutron radiation is provided.

Optimization of radiation therapy in prostatic cancer.

The results of a study on the optimization of external irradiation of prostatic cancer are discussed. The study was performed with the aid of an automatic water phantom, an automatic densitometer, and a computerized treatment planning system using an anthropometric phantom Alderson. The following parameters were studied: Dose gradient, the size of areas of selected isodoses, and the shape of the 90% isodose. At present, we consider that the twosector biaxial arc technique characterized by an arc angle of 120 degrees, a distance of the arc axes of 3 cm, employing a 20 MeV X-ray of a linear accelerator is the optimal technique for target irradiation of carcinomas of the prostate.

Study of radiation dose fractionation in some tumor types.

In the presented work we have tested another fractionation schemes than simple fractionation in some so-called radioresistant tumors, i. e. in breast cancer and malignant melanoma. We have found the advantage of the irradiation with divided series (split irradiation) namely in malignant skin melanoma where we gained therapeutic results with 58% 5-year survival. Periodical irradiation especially with higher fractions once a week had encouraging success in advanced stages of the breast cancer where a single fraction of 8 Gy/tumor up to total dose of 40 Gy/tumor was determined as optimal. With the use of higher fractions more pronounced late postirradiation changes are to be expected. Fraction schemes were compared using NSD and TDF equations.