| 1. |
- Nyman, Jan, 1956, et al.
(författare)
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Basal cell density in human skin for various fractionation schedules in radiotherapy.
- 1994
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Ingår i: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - 0167-8140. ; 33:2, s. 117-24
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the epidermal basal cell density (BCD) in human skin were determined during and immediately after fractionate radiotherapy. The basal cells are one of the target cell types responsible for acute skin reactions and measuring the BCD is a histological method for studying the time course and degree of reaction. Thirty-two patients with breast cancer participated in this study. They received postmastectomy radiotherapy to the thoracic wall. A 3-mm punch biopsy was taken from the irradiation field once a week for 6-10 weeks and the linear basal cell density was determined. Standard fractionation at two different dose levels (40 and 50 Gy) as well as hypofractionation and accelerated treatment have been investigated. For the first 3 weeks we found a constant decline in the BCD (about 0.8%/day), independent of dose and fractionation schedule. Using the nadir value as endpoint we found a dose-response relationship between 40 and 50 Gy, and for total effect (TE)-values in the range 430-1015. Compared to standard fractionation, hypofractionation showed somewhat less effect and accelerated fractionation showed significantly less effect. The reduced effect of accelerated fractionation is interpreted as a result of lack of cell cycle redistribution of cells between the two daily fractions in this type of tissue. The removal rate of dead or doomed cells could also affect the results for schedules with different overall time. The results of BCD were also compared to erythema.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 2. |
- Nyman, Jan, 1956, et al.
(författare)
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Prognostic factors for local control and survival of cancer of the oral tongue. A retrospective analysis of 230 cases in western Sweden.
- 1993
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Ingår i: Acta oncologica (Stockholm, Sweden). - 0284-186X. ; 32:6, s. 667-73
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Tidskriftsartikel (refereegranskat)abstract
- During the 19-year period from 1970 to 1988, 289 cases of squamous cell carcinoma of the oral tongue were diagnosed in Western Sweden. In 230 of these, treatment regimens and results were analysed in an attempt to define prognostic factors for local control and survival. Tumour stages were: T1 26%, T2 32%, T3 30% and T4 13%. Nodal disease was seen in 32% of the patients. Sixty per cent of the patients had surgery, 74% external with or without combination with interstitial irradiation; and 32% received chemotherapy. The local control rate at five years was 59% (T1 66%, T2 67%, T3 44% and T4 0%). Survival at five years was 37% (T1 61%, T2 51%, T3 19% and T4 0%). By a multivariate procedure we demonstrate that the tumour related variables T-category, N-category and extension to the tonsillar region had a significant association with survival. Extension to the tonsillar region, extension to the floor of the mouth and level of neck nodes were significantly associated with local-regional control.
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| 3. |
- Burnet, N G, et al.
(författare)
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Prediction of normal-tissue tolerance to radiotherapy from in-vitro cellular radiation sensitivity.
- 1992
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Ingår i: Lancet. - 0140-6736. ; 339:8809, s. 1570-1
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Tidskriftsartikel (refereegranskat)abstract
- The success of radiotherapy depends on the total radiation dose, which is limited by the tolerance of surrounding normal tissues. Since there is substantial variation among patients in normal-tissue radiosensitivity, we have tested the hypothesis that in-vitro cellular radiosensitivity is correlated with in-vitro normal-tissue responses. We exposed skin fibroblast cell lines from six radiation-treated patients to various doses of radiation and measured the proportions surviving. There was a strong relation between fibroblast sensitivity in vitro and normal-tissue reactions, especially acute effects. Assessment of radiosensitivity could lead to improved tumour cure rates by enabling radiation doses to be tailored to the individual.
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| 4. |
- Burnet, N G, et al.
(författare)
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The relationship between cellular radiation sensitivity and tissue response may provide the basis for individualising radiotherapy schedules.
- 1994
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Ingår i: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - 0167-8140. ; 33:3, s. 228-38
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Tidskriftsartikel (refereegranskat)abstract
- There is a wide variation in normal tissue reactions to radiotherapy and in many situations the severity of these reactions limits radiotherapy dose. Clinical fractionation studies carried out in Gothenburg have demonstrated that a large part of the spectrum of normal tissue reactions is due to differences in individual normal tissue sensitivity. If this variation in normal tissue reactions is due to differences in intrinsic cellular radiosensitivity, it should be possible to predict tissue response based on measurement of cellular sensitivity. Here we report the initial results of a study aimed at establishing whether a direct relationship exists between cellular radiosensitivity and tissue response. Ten fibroblasts strains, including four duplicates, were established from a group of patients in the Gothenburg fractionation trials who had received radiotherapy following mastectomy. Skin doses were measured and both acute and late skin changes were observed following radiotherapy. Right and left parasternal areas were treated with different dose fractionation schedules. Clonogenic assays were used to assess intrinsic cellular radiosensitivity, and all experiments were carried out without prior knowledge of the clinical response, or which strains were duplicates. Irradiation was carried out using 60Co gamma-rays at high dose-rate (HDR) of 1-2 Gy/min and low dose-rate (LDR) of 1 cGy/min. A spectrum of sensitivity was seen, with SF2 values of 0.17-0.28 at HDR and 0.25-0.34 at LDR, and values of D0.01 of 5.07-6.38 Gy at HDR and 6.43-8.12 Gy at LDR. Comparison of the in vitro results with the clinical normal tissue effects shows a correlation between cellular sensitivity and late tissue reactions, which is highly significant with p = 0.02. A correlation between cellular sensitivity and acute effects was noted in the left-sided parasternal fields, but not the right. This is thought to be coincidental, and without biological significance. Our results suggest that cellular sensitivity might form the basis for the development of an assay system capable of predicting late normal tissue effects to curative radiotherapy, which might allow dose escalation in some patients. Increased local control and cure, with unchanged or improved normal tissue complications, could result from such individualised radiotherapy prescriptions.
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| 5. |
- Nyman, Jan, 1956, et al.
(författare)
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Changes in the basal cell density in pig skin after single radiation doses with different dose rates.
- 1991
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Ingår i: Acta oncologica (Stockholm, Sweden). - 0284-186X. ; 30:6, s. 753-9
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Tidskriftsartikel (refereegranskat)abstract
- Radiation-induced changes in the basal cell density (BCD) and the labelling index (LI) in the epidermis of pig skin were used to compare the effect of high and low dose rate irradiation. Single doses of 6, 12 and 24 Gy were applied at 1.5 and 0.02 Gy/min with two equal 137Cs sources. Punch biopsies were taken daily for 40 days. The linear BCD was calculated from histological sections. The LI was determined by an in vitro H3-thymidine labelling technique. We found a degenerative phase in the basal cell layer with a linear cell loss of 2% per day, independent of the dose and dose rate. The time and level of the minimum BCD were dose and dose rate dependent. The LI data indicated an increased proliferation rate after a 25% reduction in BCD, i.e. before the nadir was reached. From the BCD data an iso-effective dose factor of 1.8 was estimated for the two dose rates used, which was consistent with that determined from macroscopic scoring. The BCD can be used as an endpoint for comparison of different radiotherapy modalities and gives, together with the LI, further information on the time-course of the proliferation changes in the tissue.
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