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Biomedical subjects

F Pozza

Publications and source records attributed to F Pozza.

At least 37 records · Page 2Linked to original sources
PubMed1990

Combined radiosurgery and external radiotherapy of intracranial germinomas.

Germinomas are successfully treated with radiation therapy; we have observed six cases that have been stereotactically irradiated by means of a linear accelerator (radiosurgery). In most cases a single dose of stereotactic irradiation effects the reduction of the tumor volume in a few days. External whole brain and, in two cases, spinal irradiation completed the treatment to avoid seeding of tumor cells. The technique and the advantages of this original therapeutical approach to intracranial germinomas are described and discussed.

Adolescent↗
PubMed1990

Linear accelerator radiosurgery of three-dimensional irregular targets.

Current radiosurgical techniques allow concentration of radiation from external sources into spherical targets. Nonspherical target volumes require a modification of the irradiation technique. Moreover, isodose shaping is sometimes necessary to spare nearby important radiosensitive structures. To meet these prerequisites we have introduced some technical refinements: (1) computer-controlled rectilinear translations of the target in combination with different angular positions of the source and (2) computer-controlled rotations of the target around a vertical axis in combination with different angular positions of the source. The first solution has proven efficient for treating irregular targets, while the second one was employed for focusing the radiation dose inside volumes obtained by rotation of ellipses.

Brain Neoplasms↗
PubMed1989

Correlation of growth fraction by Ki-67 immunohistochemistry with histologic factors and hormone receptors in operable breast carcinoma.

Breast cancer tissue samples obtained from 147 Stage I and II patients were tested with the monoclonal antibody Ki-67 and avidin-biotin-peroxidase complex in frozen sections. The percentage of cells with nuclear staining ranged from 5% to 65%. The frequency of Ki-67 positivity was classified in five groups: 0% (45/147 = 31%); 5-9% (38/147 = 26%); 10-19% (15/147 = 10%); 20-39% (24/147 = 16%) and greater than or equal to 40% (25/147 = 17%). The mean value was 20%, median 18% with standard deviation of 14.5%. A significant positive correlation was observed between the presence of high Ki-67 nuclear staining rate with pathological tumor size (p = 0.003), histologic grading (p = 0.04), and axillary lymph node metastases (p = 0.009). An inverse significant correlation was found between Ki-67 and estrogen receptor expression (p less than 0.001). No correlation was observed with progesterone receptor expression or menopausal status. The overall picture is of an inverse relationship between high growth fraction determined with Ki-67 antibody and tumor differentiation parameters. These correlations confirm those already reported by thymidine labeling index and flow cytometry methods. The proliferative rate determined with Ki-67 antibody may provide information regarding cell kinetics of breast carcinoma, potentially useful in identifying patients with a different clinical course in order to improve the therapeutic approach, by a rapid, practical and easily performed immunohistochemical method.

Antibodies, Neoplasm↗
PubMed1989

Low-grade astrocytomas: treatment with unconventionally fractionated external beam stereotactic radiation therapy.

Fourteen patients with nonoperable low-grade astrocytomas were treated with unconventionally fractionated stereotactic radiation therapy. The target volume was defined with computed tomography (CT) performed under stereotactic conditions. The treatment was carried out with a technique producing multiple noncoplanar arc irradiation, with the center of the target volume placed at the isocenter of the linear accelerator. A total dose of 16-50 Gy was administered in either one fraction or two fractions 8 days apart. The concentration of dose within the target volume allowed reduction of dose absorbed by adjacent critical structures of the intact brain. Patients were followed up for 11-48 months. Twelve of 14 patients had a partial or complete response to treatment, as demonstrated by CT. Stereotactic radiation therapy appears to be effective in the control of small radioresistant cerebral neoplasms, without damaging surrounding healthy tissues.

Adolescent↗
PubMed1989

Linear accelerator radiosurgery of cerebral arteriovenous malformations.

A technique for linear accelerator radiosurgery has been used in clinical practice since 1982. The technique is based on multiple intersecting arc irradiations focused on a stereotactic target. From November 1984 to October 1988, 97 patients with cerebral arteriovenous malformations have been treated. Seventy-nine patients suffered one or more than one hemorrhage. Four patients had progressive neurological symptoms. In 14 patients, epilepsy was the principal complaint. Stereotactic localization was performed by stereotactic angiography. Lesion dimensions varied from 4 to 40 mm in diameter. Doses from 18.7 to 40 Gy were delivered in one or two sessions. Mean follow-up is 17.1 months (from 1 to 49). Four instances of minor rebleeding were observed after treatment; 3 patients complained of transient neurological deterioration. Of 56 patients who were followed longer than 1 year, 50 underwent 12-month follow-up angiography. In 26 patients complete obliteration of the malformation was demonstrated (52%), in 12 patients subtotal obliteration was obtained (24%), in 11 patients the obliteration was evident but not significant (22%), and in 1 patient the AVM was unchanged. Other angiographic features in incompletely obliterated cases were a significant reduction of flow velocity through the malformation together with a reduction in diameter of both feeding arteries and draining veins.

Adolescent↗
PubMed1989

[Advanced stages of rectosigmoid cancer. The role of postoperative radiotherapy].

In patients with advanced rectosigmoid adenocarcinoma treated with radical surgery alone, loco-regional relapse rate is quite high (29%-60%). When postoperative radiotherapy is performed, loco-regional relapse rate sharply falls to 7%-15%. A series of 42 patients, stage B2, C1 and C2, is presented. All patients were treated with radical surgery and postoperative radiotherapy. Only two loco-regional relapses were found (5%). Overall actuarial survival at 5 years is 76% for B2, and 46% for C1 and C2. The authors conclude that adjuvant postoperative radiotherapy is useful in reducing loco-regional relapses, whereas survival seems to be improved only for stage B2 patients.

Adenocarcinoma↗
PubMed1988

Dosimetric considerations on multiple arc stereotaxic radiotherapy.

The aim of this paper is to present the physical and dosimetrical features of the stereotaxic radiosurgical method already published by the authors. This method concentrates the dose into the stereotaxic target volume, placed at the isocenter of a 4 MV X-ray beam. Computer calculations showed that: 9-17 arcs provide almost spherical dose distributions; the optimal photon beam quality is about 4-6 MV. The angle between adjacent rotation planes is 20-40 degrees and the arcs are 100-160 degrees wide. In this way the dose to healthy tissue is minimized. The dose distribution was experimentally verified both by ionometric and photodensitometric methods. The procedure for dose calculation at isocenter of fields as small as required by the radiotherapist, has been investigated.

Calibration↗
PubMed1988

[Small size breast cancer conservative surgical therapy and subsequent radiotherapy].

From february 1980 to december 1985, 115 breast carcinomas were treated with QU.A.RT. with limited surgery and following radiotherapy. Median age was 51 years (range 25 to 75). Surgical approach was quadrantectomy with axillary nodes dissection. Irradiation of residual breast was performed by an anterior high energy electron beam. 50 Gy in 25 fractions was the minimal dose to whole breast. In pN+ patients systemic adjuvant therapy was done. Local control was obtained in 111 cases. Local recurrence appeared in 4: 1 menopausal pT1 pNO and 3 premenopausal (1 pT1 pNO and 2 pT1 pN+) at respectively 31, 19, 22 months from diagnosis. Distant metastases appeared in 10 patients. 7 died for cancer and 3 are still alive. Cosmetic results were scored as good in 52, better than mastectomy in 26, unsatisfactory in 3, and not stated in 34. Our results are comparable to those of other Centers. Youth, axillary metastases and delay between surgery and radiotherapy appears to influence the risk of recurrence also in our series.

Adult↗
PubMed1987

New technique for three-dimensional linear accelerator radiosurgery.

A new method for external stereotactic focal irradiation of three-dimensional irregular target volumes is proposed. In this method the target is irradiated by a linear accelerator set in various angular positions around the isocenter. During the irradiation the target is translated in a direction perpendicular to the beam. By controlling the velocity of the translation it is possible to modify the configuration of therapeutic isodoses so as to make them follow the borders of the target.

Brain Diseases↗
PubMed1987

Linear accelerator radiosurgery of arteriovenous malformations.

Forty-five patients affected by cerebral arteriovenous malformations not suitable to open surgery have been treated by a radiosurgical technique employing a linear accelerator. One-year follow-up angiography is available for 10 cases. Therapeutic effect of focalized irradiation is presented.

Adolescent↗
PubMed1986

Radiosurgery using a 4MV linear accelerator. Technique and radiobiologic implications.

In the authors' technique, the stereotactically localized target is fixed to the isocenter of a 4 MV linear accelerator. The irradiation is carried out along 9-17 non-coplanar arcs distributed on a 160 degrees cylindrical sector. High doses (10-50 Gy) are delivered in one or two sessions. From 1982, 65 patients have been treated (shortest follow-up 6 months). The dose was chosen according to the pathology and to the volume of the lesion. Good clinical results have been obtained in low-grade gliomas, acoustic neuromas, arteriovenous malformations, and other selected types of intracranial lesions. Therapeutic effects in terms of clinical condition and size of the lesions have been plotted in relation to time elapsed and dose employed.

Adolescent↗
PubMed1985

Osteogenic osteosarcoma of the calvaria following radiotherapy for cerebellar astrocytoma: report of a case in childhood.

Sarcoma as a second malignant neoplasm following radiotherapy is a rare occurrence in childhood. A case of osteogenic osteosarcoma of temporoparietal bone that developed 56 months after irradiation for a cerebellar astrocytoma in a 10-year-old child is reported and the pertinent literature is briefly reviewed. The possibility of an association (in the same patient) between these two rather uncommon lesions is extremely unlikely. Therefore, it is possible that radiotherapy played a role in the induction of the sarcoma. The indolent course of the latter is stressed.

Astrocytoma↗
PubMed1985

Stereotactic radiosurgery utilizing a linear accelerator.

The authors have developed a radiosurgical technique based on multiple arc irradiations. The target is fixed to the rotational isocenter of a Varian 4 MV linear accelerator. The first irradiation is carried out while the radiating source is rotating on a 100-140 degrees arc. The patient is then rotated around a vertical axis passing through the target, and arc irradiations are repeated in different angular positions. By this technique it is possible to obtain very steep dose gradients at the borders of the target volume. High doses are usually delivered in two shots. 47 patients have been treated so far in a clinical trial that started in November 1982. The paper deals with the preliminary results (more than 6 months' follow-up) obtained in patients affected by nonresectable brain tumors and AVMs.

Adolescent↗
PubMed1985

External stereotactic irradiation by linear accelerator.

Stereotactic radiotherapy has two advantages: (a) the possibility of giving high radiation doses to small but spatially well-defined target volumes and (b) the presence of a stepped dose gradient between the target volume and the surrounding healthy tissues. To utilize these advantages, the authors built a new stereotactic head frame by which the intracranial target is fixed to the rotational isocenter of a 4-MV linear accelerator. The collimator openings are selected according to the volume and the three-dimensional configuration of the target, and the radiation dose is based on the radiosensitivity of the lesion. After the patient is fixed to the frame, the radiation source and the patient are rotated so that the target is irradiated through infinite portals distributed over the convexity of the skull. It is thereby possible to obtain very high radiation doses centered into the target with a stepped dose gradient. The preliminary radiodosimetric tests and the operative technique are described. The advantages of this technique compared to interstitial radiotherapy and Leksell's radiosurgery are emphasized. This noninvasive procedure has been used to treat a series of intracranial tumors.

Adolescent↗
PubMed1984

[Biopsy and stereotaxic radiotherapy of cerebral gliomas].

The Authors report their experience on a series of 125 patients that underwent stereotactic biopsy. The procedure has proved reliable and almost risk -free. The diagnosis obtained from the bioptic specimen by smear technique-cytological examination and by paraffin embedding-histological examination are compared. Neuropathologic data were also checked by the examination of the tumor bulk in cases that underwent surgical removal or autoptic verification. The preliminary results obtained in 8 patients with the new technique of external stereotactic irradiation by means of a linear accelerator are also shown.

Biopsy↗
PubMed1984

[Stereotaxic irradiation with a linear accelerator].

At least two fundamental requirements must subsist for every stereotaxic radiotherapy treatment: 1) a capacity to administer extremely high doses of radiation to small areas which have been precisely defined in three dimensions; 2) the presence of a steep gradient between adjacent isodose curves so that damage to the tissues close to the target may be reduced to the minimum. The authors have built a special stereotaxic device for the fixing of the head of the patient (together with the chosen intracranial target), once the indispensable neuroradiological evaluations and bioptic controls have been effected, at the isocenter of a linear accelerator (Varian Clinac 4). Once the dimensions of the collimator have been chosen in accordance with the volume and the three dimensional conformation of the target and the dose to be administered has been decided upon in accordance with the histological nature of the lesion, both the linear accelerator and the patient are rotated about the isocenter of the therapy unit. It this way it is possible to reach extremely high dosages with very steep isodose gradients, centered exclusively upon the target ("gamma knife"). The procedure employed is described in full. The dosimetric evaluations which preceded the use of the set-up in clinical practice are illustrated as well. The advantages that this technique offers when compared with interstitial brachytherapy and/or Leksell's radiosurgical procedures are stressed. The described procedure, which is entirely bloodless and thus applicable also to high vascularized lesions, has so far been used in a limited series of cases.

Brain Diseases↗
PubMed1983

Treatment of early stage Hodgkin's disease with radiation therapy plus short-cycle (3 MOPP) adjuvant chemotherapy.

Eighty-four consecutive, previously untreated patients with stage I, II A-B and IIIA Hodgkin's disease were treated with combined modality therapy including subtotal or total nodal irradiation, followed by three cycles of MOPP. MOPP was administered before radiotherapy in patients with systemic symptoms or with bulky disease. Seventy-six of 84 patients (90.5%) achieved complete remission, and 8 died from disease progression after a variable period of incomplete remission. Three of 76 (3.9%) relapsed, and 2 of them have been subsequently salvaged. Up to the present time, 70 patients are alive, without evidence of disease; 9 have died from Hodgkin's disease, 2 from acute non-lymphoblastic leukemia, and 3 from intercurrent causes. No death occurred from acute toxicity due to chemotherapy. Actuarial overall survival is 82.3% and freedom from relapse is 81.8% after 48 months' median observation (range: 12-111 months). No significant difference in survival and freedom from relapse has been observed with respect to age, sex, stage, presence or absence of unfavorable prognostic factors. The role of adjuvant chemotherapy and its use in a reduced number of cycles in early stage Hodgkin's disease are discussed.

Age Factors↗