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Biomedical subjects

L E Blank

Publications and source records attributed to L E Blank.

At least 19 recordsLinked to original sources
PubMed2001

Office hours pulsed brachytherapy boost in breast cancer.

BACKGROUND AND PURPOSE: Radiobiological studies suggest equivalent biological effects between continuous low dose rate brachytherapy (CLDR) and pulsed brachytherapy (PB) when pulses are applied without interruption every hour. However, radiation protection and institute-specific demands requested the design of a practical PB protocol substituting the CLDR boost in breast cancer patients. An office hours scheme was designed, considering the CLDR dose rate, the overall treatment time, pulse frequency and tissue repair characteristics. Radiobiological details are presented as well as the logistics and technical feasibility of the scheme after treatment of the first 100 patients. MATERIALS AND METHODS: Biologically effective doses (BEDs) were calculated according to the linear quadratic model for incomplete repair. Radiobiological parameters included an alpha/beta value of 3 Gy for normal tissue late effects and 10 Gy for early normal tissue or tumour effects. Tissue repair half-time ranged from 0.1 to 6 h. The reference CLDR dose rate of 0.80 Gy/h was obtained retrospectively from analysis of patients' data. The treatment procedure was evaluated with regard to variations in implant characteristics after treatment of 100 patients. RESULTS: A PB protocol was designed consisting of two treatment blocks separated by a night break. Dose delivery in PB was 20 Gy in two 10 Gy blocks and, for application of the 15 Gy boost, one 10 Gy block plus one 5 Gy block. The dose per pulse was 1.67 Gy, applied with a period time of approximately 1.5 h. An inter-patient variation of 30% (1 SD) was observed in the instantaneous source strength. Taking also the spread in implant size into account, the net variation in pulse duration amounted to 38%. CONCLUSION: An office hours PB boost regimen was designed for substitution of the CLDR boost in breast-conserving therapy on the basis of the BED. First treatment experience shows the office hour regimen to be convenient to the patients and no technical perturbations were encountered.

Brachytherapy↗
PubMed2000

Iliocaval thrombosis: percutaneous treatment with hydrodynamic thrombectomy.

Mechanical thrombectomy is of growing importance for the treatment of thrombus. Although there are numerous reports about dialysis fistulae and arterial thrombosis, venous applications are currently not well known. We report that an extensive venous thrombotic occlusion can be treated with mechanical thrombectomy, without additional local lysis. This report deals with the indication and technique of venous mechanical thrombectomy and discusses the possible applications.

Humans↗
PubMed2000

Brachytherapy with transperineal (125)Iodine seeds for localized prostate cancer.

BACKGROUND AND PURPOSE: To analyze the treatment results of transperineal (125)Iodine seeds in localized prostate cancer. PATIENTS AND METHODS: Between 1985 and 1996, 102 patients with T1-T2 N0 prostate cancer were treated with transperineal (125)Iodine seed implants at the Academic Medical Centre in Amsterdam. Tumours were classified as T1c in four patients, T2a in 73 patients and T2b in 25 patients. The mean pre-treatment PSA was 17 ng/ml. The (125)Iodine seeds were implanted transperineally under transrectal ultrasound guidance. The mean prostate volume was 31 ml (range 15-48 ml). An average of 49 seeds (range 29-74) was implanted. The dose to the periphery of the prostate was 160 Gy. Until 1988, 27 patients had additional external pelvic irradiation to a dose of 40 Gy in 20 daily fractions of 2 Gy. RESULTS: The 5- and 7-year actuarial survival rates were 77 and 63%, respectively (median 102 months). Ten patients (9.5%) died from prostate cancer. The 5- and 7-year clinical progression rates were 12 and 17%, respectively. Biochemical failure rates at 5 and 7 years were 39 and 44%, respectively. Age, alkaline phosphatase, creatinine, differentiation grade, additional treatment, staging procedure, number of seeds, prostate volume, treatment period and PSA were analyzed as prognostic factors. Only pre-treatment PSA was a prognosticator of clinical and biochemical outcome but not of survival. Biochemical control at 6 years varied from 30% for pre-treatment PSA values higher than 20 ng/ml to 95% for values < or =8 ng/ml. Forty-one out of 49 patients who were sexually active before brachytherapy maintained sexual function during the follow-up. Complete urinary incontinence occurred in one patient. No rectal complications were seen in patients receiving brachytherapy alone. CONCLUSIONS: Transperineal (125)Iodine seeds brachytherapy in localized prostate cancer achieves a good clinical control and overall survival with acceptable late toxicity. Biochemical failure was strongly correlated to the pre-treatment PSA value.

Aged↗
PubMed1998

Pulse frequency in pulsed brachytherapy based on tissue repair kinetics.

PURPOSE: Investigation of normal tissue sparing in pulsed brachytherapy (PB) relative to continuous low-dose rate irradiation (CLDR) by adjusting pulse frequency based on tissue repair characteristics. METHOD: Using the linear quadratic model, the relative effectiveness (RE) of a 20 Gy boost was calculated for tissue with an alpha/beta ratio ranging from 2 to 10 Gy and a half-time of sublethal damage repair between 0.1 and 3 h. The boost dose was considered to be delivered either in a number of pulses varying from 2 to 25, or continuously at a dose rate of 0.50, 0.80, or 1.20 Gy/h. RESULTS: The RE of 20 Gy was found to be identical for PB in 25 pulses of 0.80 Gy each h and CLDR delivered at 0.80 Gy/h for any alpha/beta value and for a repair half-time > 0.75 h. When normal tissue repair half-times are assumed to be longer than tumor repair half-times, normal tissue sparing can be obtained, within the restriction of a fixed overall treatment time, with higher dose per pulse and longer period time (time elapsed between start of pulse n and start of pulse n + 1). An optimum relative normal tissue sparing larger than 10% was found with 4 pulses of 5 Gy every 8 h. Hence, a therapeutic gain might be obtained when changing from CLDR to PB by adjusting the physical dose in such a way that the biological dose on the tumor is maintained. The normal tissue-sparing phenomenon can be explained by an increase in RE with longer period time for tissue with high alpha/beta ratio and fast or intermediate repair half-time, and the RE for tissue with low alpha/beta ratio and long repair half-time remains almost constant. CONCLUSION: Within the benchmark of the LQ model, advantage in normal tissue-sparing is expected when matching the pulse frequency to the repair kinetics of the normal tissue exposed. A period time longer than 1 h may lead to a reduction of late normal tissue complications. This theoretical advantage emphasizes the need for better knowledge of human tissue-repair kinetics.

Animals↗
PubMed1998

New combined treatment of surgery, radiotherapy, and reconstruction in head and neck rhabdomyosarcoma in children: the AMORE protocol.

BACKGROUND: If no complete remission on chemotherapy is reached in head and neck rhabdomyosarcoma (RMS) in children, adjuvant radiotherapy and/or surgery are indicated. This often causes severe mutilation, and the prognosis is poor. Ablative surgery, moulage technique with afterloading brachytherapy, and reconstructive surgery, called the AMORE protocol, is developed for residual or recurrent disease after chemotherapy. METHODS: Ablative surgery with preservation of important structures is followed by the embedding of a gutta-percha mold in the created tissue defect. The wound bed is irradiated with Iridium192. Within 1 week, the defect is reconstructed with a muscle transplant. Fifteen children (mean age, 5.7 years) were treated accordingly. RESULTS: All patients were discharged within 4 weeks. Eleven patients are tumor-free, with a mean follow-up period of 2.8 years. No signs of radiation sequelae were observed. CONCLUSION: The preliminary results of this new, combined treatment are encouraging, if the advanced stage of disease is considered.

Brachytherapy↗
PubMed1997

Brachytherapy in orbital tumors.

PURPOSE: To evaluate whether the use of iridium-192 brachytherapy would reduce the incidence of complications noted with external beam radiation therapy in patients with orbital tumors. METHODS AND MATERIALS: This study is a retrospective review of a clinical series of 25 patients with various orbital tumors treated with brachytherapy between 1988 and 1995. RESULTS: Patients were observed for an average of 40 months (range, 16-88 months) during which one patient died of metastatic disease and 24 patients are alive with no evidence of disease. Recurrent disease was observed in four patients. In 3 patients, exenteration was necessary and in 22 patients, the eye was preserved. The visual acuities after therapy ranged from no light perception to 20/20 (average, 20/40). CONCLUSIONS: Since brachytherapy has been used as an alternative to exenteration, the results of this treatment have been excellent in most patients. However, in advanced disease, external radiation therapy or even mutilating surgery still remains inevitable.

Adolescent↗
PubMed1993

Analysis of biopsy findings and implant quality following ultrasonically-guided 125I implantation for localised prostatic carcinoma.

Transperineal ultrasound-guided 125I implantation was undertaken in 52 patients with localised prostate cancer. After implantation, ultrasound-guided biopsies were taken from the previous malignant areas every 6 months in all patients. The percentage of negative biopsies increased from 22% at 6 months to 50% at 48 months. Implant quality was analysed in 37 patients. The difference between isodose levels encompassing the prostate and the aimed levels of 160 Gy was taken as a measure of implant quality. A good quality implant (< 10% underdosage) was found in 43% of patients, a moderate quality (10-25% underdosage) in 35%, and a poor quality implant (> 25% underdosage) in 22%. A statistically significant correlation was found between the quality of the implant and resulting negative biopsy at the original tumour site. Determination of prostate specific antigen (PSA) was not possible from the beginning of the study but an analysis with biopsy findings, implant quality and prostate volume reduction during follow-up has been performed since 1989. A significant correlation was observed between implant quality and serum PSA, and also between volume reduction and serum PSA.

Aged↗
PubMed1992

Recurrent hemangiopericytoma and brachytherapy.

A 42-year-old woman had two recurrences following excision of a hemangiopericytoma of the left orbit. A third local excision was followed by postoperative brachytherapy (55 Gy in 100 hours). One year later there is no sign of recurrence and the side-effects are minimal.

Adult↗
PubMed1992

Treatment of localized prostatic carcinoma using the transrectal ultrasound guided transperineal implantation technique.

Treatment of localized prostate cancer by ultrasonically guided transperineal 125I implantation, in contrast to open 125I implantation, may allow for ideal distribution of the seeds and may therefore lead to better treatment results. 46 patients with localized prostatic carcinoma (T1-T2, G1-G3, N0, M0) have been treated since 1985, using this new technique. The longest follow-up is 64 months (median 30 months). The irradiation implantation dose to the prostate was 160 Gy. Assessed by ultrasonography an average prostate volume reduction of 20% was achieved at 6 months, increasing to 24% at 12 months, 39% at 24 months and 56% at 48 months. To evaluate response of the primary tumor systematic ultrasonically guided needle biopsies from the previous malignant prostate areas were performed in all patients every 6 months during follow-up. Tumor-negative biopsies were obtained in 33% of patients at 12 months, 40% at 24 months, progressively increasing to 50% at 48 months. Three patients developed distant metastases, and 6 died, of whom 1 patient due to prostate cancer. Morbidity from implantation has been low and the erectile function was preserved in all patients at 12 months postimplantation. The high percentage of tumor-positive biopsies during follow-up indicates that this technique fails to cure a significant proportion of patients.

Aged↗
PubMed1992

Dermal angiosarcoma of the breast: a complication of primary radiotherapy?

A 70-year-old female developed recurrent disease following radiotherapy for primary inoperable breast cancer 5.5 years previously. Salvage mastectomy was performed. Pathology revealed recurrent breast cancer, along with a second primary malignancy, a dermal angiosarcoma. Radical excision of recurrent angiosarcoma failed. Irradiation combined with hyperthermia showed good palliation. The angiosarcoma's possible relation to the initial radiotherapy is discussed.

Aged↗
PubMed1991

Leiomyosarcoma of large and small veins: clinical findings and results of treatment in six patients.

Vascular leiomyosarcomas are rare malignant tumours originating from the media of the vessel wall. Six patients (five women and one man, aged 44-66 years) have been treated for a vascular leiomyosarcoma located in the inferior vena cava (three patients), the suprarenal, the external iliac and an antecubital vein. In four patients, the tumour was large and extended beyond the vessel wall giving rise to a retroperitoneal mass. In two patients the tumour was confined to the inner wall of respectively a large and small vein, occluding the lumen; the former was in the inferior vena cava and the latter in an antecubital vein. Block resection was performed in all patients. The tumours showed mitotic indices ranging from 6-32 mitoses/10 high power fields. The five patients with retroperitoneal tumours received additional radiotherapy varying from 50.00-70.00 Gy, on the basis of either macroscopic residual tumour or indefinite radicality. One of these five patients developed distant metastases within 2.5 years without local recurrence, the other four had no evidence of recurrence at follow-up, 3-7 years (mean 4.2 years) after surgery. The results illustrate the role of adjuvant radiotherapy in the control of local recurrence, when resection in this type of tumour proves to be either non-radical or totally radical.

Adult↗
PubMed1989

Effect of N-acetylcysteine on the antiproliferative action of X-rays or bleomycin in cultured human lung tumor cells.

N-Acetylcysteine is currently being considered as a possible selective protector against pulmonary toxicity resulting from X-rays or chemotherapeutic treatment, but its clinical application awaits evidence that it does not interfere with the efficient killing of tumor cells. The capacity of N-acetylcysteine to protect against the antitumor activity of X-rays and of bleomycin was evaluated in a clonogenic cell-survival assay using SW-1573 human squamous lung carcinoma cells as a tumor model. Using the highest non-toxic dose of N-acetylcysteine (incubation for 2 days in the continuous presence of 10 mM) no effect on clonogenic cell killing by X-rays or bleomycin treatment could be detected, even though a twofold enhancement of endogenous glutathione was effectuated. Our data thus indicate that clinically relevant concentrations of N-acetylcysteine are incapable of protecting tumor cells against clonogenic killing by X-rays and by bleomycin.

Acetylcysteine↗
PubMed1988

Chestwall recurrences of breast cancer: results of combined treatment with radiation and hyperthermia.

In 35 patients with chestwall recurrences of breast carcinoma, 45 lesions were treated with combined radiation and hyperthermia. The majority of the lesions received 6 fractions of 4 Gy, twice a week during 3 weeks. Hyperthermia was administered within 30 min after irradiation, aiming a tumor temperature of 43 degrees C during one hour. The percentage of complete response (CR) was 57%. In small lesions, the percentage of CR was 80%. The mean duration of the response was 7 months. Response rate increased with increasing temperature. Particularly, mean temperature and isoeffect thermal dose correlated very well with response rate. In nine cases, comparative lesions were treated with either radiation alone or radiation combined with hyperthermia. The response rates were 3/9 and 7/9, respectively. Acute skin reactions were enhanced by the combined treatment. However, late skin reactions were not increased. Although the prognosis of patients with chestwall recurrences is determined by the presence of distant metastases, local control remains an important objective. Combined treatment with radiation and hyperthermia offers the possibility of obtaining a high local control rate particularly in relatively small lesions.

Adult↗
PubMed1986

Combined treatment with radiation and hyperthermia in metastatic malignant melanoma.

In 24 patients with metastatic malignant melanoma, combined treatment with radiation and hyperthermia was administered to 38 localizations, radiation alone to 8 comparative localizations and hyperthermia alone to 3 localizations. Hyperthermia was administered during one hour by using a 433 MHz microwave generator. The heat treatment was given within 30 min following irradiation. Although an intratumoral temperature of 43 degrees C was aimed, considerable variations occurred during one session and from session-to-session. Radiation schedules consisted in either one large fraction (6-8 Gy) once a week in 14-21 days or two fractions (4-5 Gy) twice a week in 21 days. In the group of patients receiving irradiation once a week, three heat treatments were administered. In the twice-a-week radiation schedule, six heat sessions were given. The overall complete response (CR) rate in patients receiving combined treatment was 50%. In the group of patients treated with hyperthermia and irradiation schedules of 8 Gy per fraction, the CR rate was 83%. Irradiation alone achieved 38% CR rate but some of these CR relapsed during follow-up whereas the comparative area treated with radiation and heat remained under control at this time. The lesions treated with heat alone did not show any response to treatment. Enhancement of the acute skin reactions was generally observed. However, because the total doses were relatively low, this enhancement did not constitute a clinical problem. CR appears to occur more frequently in small tumor sizes. The highest and lowest temperature ever registered during any session of hyperthermia did not seem to correlate with the tumor response.

Combined Modality Therapy↗