Ulrich Oppitz

Stereotactic Radiotherapy of Targets in the Lung and Liver

Background: Stereotactic irradiation of extracranial targets offers a non-invasive treatment modality for patients with localized tumors, which are not amenable for surgery or other invasive approaches because of age or impaired medical condition. The purpose of the study was the evaluation of the method to achieve local control of irradiated targets in relation to treatment toxicity. Patients and Methods: Irradiation was performed as hyperfractionated treatment in three fractions of 10 Gy each, normalized to the PTV enclosing 65% isodose with patient fixation in a stereotactic body frame. The isocenter was localized by stereotactic coordinates. Targets were circumscribed tumors in the lung (n = 27) and liver (n = 24) not amenable for other treatment modalities: primary lung cancer (n = 12), local recurrences of lung cancer (n = 4), lung metastases (n = 11), liver metastases (n = 23) and one cholangiocellular carcinoma. Median CTV/PTV for targets in the lung was 57/113 cm3 (min/max 5–277 cm3/17–343 cm3) and for targets in the liver 50/102 cm3 (min/max 9–516 cm3/42–772 cm3). Median follow-up for targets in the lung was 8 months (2–33) and 9 months (2–28) for liver targets. Local control was defined as complete or partial remission and stable disease, measured by repeated CT scans after 6 weeks and in 3 months intervals. Treatment toxicity was evaluated according to the WHO score. Results: Crude local control was 85% for pulmonary targets and 83% for hepatic targets. Actuarial local control after 1 and 2 years was 76% and 76% for lung tumors and 76% and 61% for liver tumors. Actuarial overall patient survival was 48% after 1 year and 21% after 2 years for targets in the lung and 71% and 43% for targets in the liver. No acute grade 3–5 side effects were observed. Serious late toxicity occurred in two patients: a chronic ulceration of the esophagus at a target close to the mediastinum after 3 months (grade 3) and fatal bleeding from the pulmonary artery after 9 months (grade 5) in a previously irradiated patient. It remained unclear, whether the bleeding was a side effect of irradiation or due to tumor infiltration. Conclusion: Hypofractionated stereotactic irradiation of targets in the lung and liver is a locally effective treatment with actuarial local control rates of 76% after 1 year and 61–76% after 2 years without relevant acute toxicity. Severe late toxicity did not occur, if targets close to the mediastinum were avoided.Hintergrund: Prüfung eines hypofraktionierten, stereotaktischen Behandlungsansatzes für Bestrahlung lokalisierter Raumforderungen in der Lunge und Leber hinsichtlich lokaler Tumorkontrolle und Nebenwirkungen. Patienten und Methode: Stereotaktische Bestrahlung in drei Fraktionen à 10 Gy, normalisiert auf die PTV-umschließende 65%-Isodose mit Patientenfixierung im stereotaktischen Körperrahmen. Insgesamt wurden 27 Lungentumoren (zwölf primäre und vier lokoregionär rezidivierte Bronchialkarzinome, elf Metastasen) und 24 Lebertumoren (23 Metastasen, ein cholangiozelluläres Karzinom) behandelt. Das CTV/PTV für Lungenherde betrug im Median 57/113 cm3 (min/max 5–277 cm3/17–343 cm3), für Leberherde 50/102 cm3 (min/max 9–516 cm3/42–772 cm3). Die mediane Nachbeobachtungszeit betrug 8 Monate (2–33) für Lungen- und 9 Monate (2–28) für Leberherde. Lokale Kontrolle wurde definiert als computertomographisch komplette oder partielle Remission sowie Wachstumsstopp 6 Wochen sowie in Intervallen von 3 Monaten nach Therapie. Die Nebenwirkungen wurden nach WHO klassifiziert. Ergebnis: Lokale Kontrolle betrug numerisch in der Lunge 85%, in der Leber 83%, aktuarisch in der Lunge 76% nach 1 und 2 Jahren, in der Leber 76% nach 1 Jahr, 61% nach 2 Jahren. Das aktuarische Gesamtüberleben lag nach 1 und 2 Jahren bei Lungenherden bei 48% und 21% bzw. bei Leberherden bei 71% und 43%. Akut traten keine Nebenwirkungen Grad 3–5 auf. Als Spätnebenwirkung wurden eine chronische Ösophagitis (Grad 3) bei einem dicht am Mediastinum gelegenen Tumor sowie eine fatale Blutung aus der Arteria pulmonalis beobachtet, bei der jedoch auch eine tumorbedingte Arrosionsblutung nicht auszuschließen war. Schlussfolgerung: Die stereotaktische Bestrahlung von Lungen- und Leberherden ist eine effektive Bestrahlungsform mit aktuarischen lokalen Kontrollraten bis zu 76% nach 1 Jahr bzw. 61–76% nach 2 Jahren. Die Akuttoxizität war gering; schwere Spätnebenwirkungen traten nicht auf, wenn Zielvolumina in der Nähe des Mediastinums vermieden wurden.

Stereotactic radiotherapy of extracranial targets: CT-simulation and accuracy of treatment in the stereotactic body frame.

BACKGROUND AND PURPOSE Evaluation of set-up accuracy and analysis of target reproducibility in the stereotactic body frame (SBF), designed by Blomgren and Lax from Karolinska Hospital, Stockholm. Different types of targets were analyzed for the risk of target deviation. The correlation of target deviation to bony structures was analyzed to evaluate the value of bones as reference structures for isocenter verification. MATERIALS AND METHODS Thirty patients with 32 targets were treated in the SBF for primary or metastatic peripheral lung cancer, liver metastases, abdominal and pelvic tumor recurrences or bone metastases. Set-up accuracy and target mobility were evaluated by CT-simulation and port films. The contours of the target at isocenter level, bony structures and body outline were compared by matching the CT-slices for treatment planning and simulation using the stereotactic coordinates of the SBF as external reference system. The matching procedure was performed by using a 3D treatment planning program. RESULTS Set-up accuracy represented by bony structures revealed standard deviations (SD) of 3.5 mm in longitudinal, 2.2 mm in anterior-posterior and 3.9 mm in lateral directions. Target reproducibility showed a SD of 4.4 mm in longitudinal, 3.4 mm ap and 3.3 mm in lateral direction prior to correction. Correlation of target deviation to bones ranged from 33% (soft tissue targets) to 100% (bones). CONCLUSION A security margin of 5 mm for PTV definition is sufficient, if CT simulation is performed prior to each treatment to correct larger target deviations or set-up errors. Isocenter verification relative to bony structures is only safe for bony targets but not for soft tissue targets.

Stereotactic radiotherapy of primary liver cancer and hepatic metastases

The purpose was to evaluate the clinical results of stereotactic radiotherapy in primary liver tumors and hepatic metastases. Five patients with primary liver cancer and 39 patients with 51 hepatic metastases were treated by stereotactic radiotherapy since 1997. Twenty-eight targets were treated in a “low-dose”-group with 3×10 Gy (n = 27) or 4×7 Gy (n = 1) prescribed to the PTV-encl. 65%-isodose. In a “high-dose”-group patients were treated with 3×12 − 12.5 Gy (n = 19; same dose prescription) or 1×26 Gy/PTV-enclosing 80%-isodose (n = 9). Median follow-up was 15 months (2–48 months) for primary liver cancer and 15 months (2–85 months) for hepatic metastases. While all primary liver cancers were controlled, nine local failures (3–19 months) of 51 metastases were observed resulting in an actuarial local control rate of 92% after 12 months and 66% after 24 months and later. A borderline significant correlation between dose and local control was observed (p = 0.077): the actuarial local control rate after 12 and 24 months was 86% and 58% in the low-dose-group versus 100% and 82% in the high-dose-group. In multivariate analysis high versus low-dose was the only significant factor predicting local control (p = 0.0089). Overall survival after 1 and 2 years was 72% and 32% for all patients and was impaired due to systemic progression of disease. No severe acute or late toxicity exceeding RTOG/EORTC-score 2 were observed. Stereotactic irradiation of primary liver cancer and hepatic metastases offers a locally effective treatment without significant complications in patients, who are not amenable for surgery. Patient selection is important, because those with low risk for systemic progression are more likely to benefit from this approach.

3D-recurrence-patterns of gliobastomas after CT-planned postoperative irradiation

BACKGROUND AND PURPOSE The introduction of computed-tomography as an advanced planning tool for the irradiation of intracranial tumours led to a controversial discussions about the optimal target-volume for the primary and postoperative treatment of malignant gliomas. This study analyses the three-dimensional tumour regrowth pattern relative to the treated volume which included the macroscopic preoperative tumour and 2-cm safety margin. MATERIALS AND METHODS Seventy-nine patients with histologically-confirmed Glioblastoma multiforma and documented recurrence who were irradiated in our department between 1990 and 1996 were reviewed. With the help of a computer program written for this purpose, the PTV of the CT-based treatment plan was reconstructed and its spatial outline compared with the reconstructed volume of the recurrent tumour in the control CT-study. RESULTS In 33 out 34 patients for which the CT-study showing tumour-recurrence was available the recurrence was completely situated within the original 90%-isodose. Only one tumour surpassed the outside surface of the PTV but was predominantly situated within the original tumourbed and suggests a tumour-regrowth within the high dose volume. CONCLUSIONS The above results show that target-volumes based on the preoperative size of the enhanced tumour mass well cover the site of recurrence in nearly all cases. The findings suggest dose escalation to a more restricted volume.

Impact of target reproducibility on tumor dose in stereotactic radiotherapy of targets in the lung and liver

BACKGROUND AND PURPOSE Previous analyses of target reproducibility in extracranial stereotactic radiotherapy have revealed standard security margins for planning target volume (PTV) definition of 5mm in axial and 5-10mm in longitudinal direction. In this study the reproducibility of the clinical target volume (CTV) of lung and liver tumors within the PTV over the complete course of hypofractionated treatment is evaluated. The impact of target mobility on dose to the CTV is assessed by dose-volume histograms (DVH). MATERIALS AND METHODS Twenty-two pulmonary and 21 hepatic targets were treated with three stereotactic fractions of 10 Gy to the PTV-enclosing 100%-isodose with normalization to 150% at the isocenter. A conformal dose distribution was related to the PTV, which was defined by margins of 5-10mm added to the CTV. Prior to each fraction a computed tomography (CT)-simulation over the complete target volume was performed resulting in a total of 60 CT-simulations for lung and 58 CT-simulations for hepatic targets. The CTV from each CT-simulation was segmented and matched with the CT-study used for treatment planning. A DVH of the simulated CTV was calculated for each fraction. The target coverage (TC) of dose to the simulated CTV was defined as the proportion of the CTV receiving at least the reference dose (100%). RESULTS A decrease of TC to <95% was found in 3/60 simulations (5%) of pulmonary and 7/58 simulations (12%) of hepatic targets. In two of 22 pulmonary targets (9%) and in four of 21 hepatic targets (19%) a TC of <95% occurred in at least one fraction. At risk for a decreased TC <95% were pulmonary targets with increased breathing mobility and hepatic targets with a CTV exceeding 100 cm(3). CONCLUSIONS Target reproducibility was precise within the reference isodose in 91% of lung and 81% of liver tumors with a TC of the complete CTV >or=95% at each fraction of treatment. Pulmonary targets with increased breathing mobility and liver tumors >100 cm(3) are at risk for target deviation exceeding the standard security margins for PTV-definition at least for one fraction and require individual evaluation of sufficient margins.

Response to X-Irradiation of Fanconi Anemia Homozygous and Heterozygous Cells Assessed by the Single-Cell Gel Electrophoresis (Comet) Assay

Fanconi anemia (FA) is an autosomal recessive disorder characterized by bone marrow failure and cancer susceptibility. Patient cells are sensitive to a variety of clastogens, most prominently cross-linking agents. Although there is the long-standing clinical impression of radiosensitivity, in vitro studies have yielded conflicting results. We exposed peripheral blood mononuclear cells from FA patients and carriers to x-rays and determined their DNA damage and repair profiles using the alkaline single-cell gel electrophoresis (comet) assay. Studies were carried out in two independent series of experiments by two laboratories using different protocols. The cells of both FA patients and carriers showed uniformly high initial DNA damage rates as assessed by the total initial tail moment. In addition, the average residual tail moment at 30 to 50 minutes and the repair half-time parameters were significantly elevated. These findings suggest an increased release of fragmented DNA following x-ray exposure in cells that carry one or two mutations in one of the FA genes. The comet assay may be a useful adjunct for heterozygote detection in families of FA patients.

In vitro radiosensitivity measured in lymphocytes and fibroblasts by colony formation and comet assay: comparison with clinical acute reactions to radiotherapy in breast cancer patients.

Purpose : To compare colony-forming and comet assays on fibroblasts and lymphocytes of 32 breast cancer patients irradiated after breast-conserving operations and to correlate the results with acute clinical radiation reactions in the skin. Material and methods : Skin fibroblasts were isolated and cultivated before radiotherapy and lymphocytes were drawn prior to the first and directly after the final external irradiation. The colony-forming assay was performed with fibroblasts and the comet assay with lymphocytes and fibroblasts of breast cancer patients according to standard protocols. The clinical radiation reactions of the patients were graded according to the RTOG system. Results : No significant correlation (p =0.09) was detected between clinical acute skin reactions and the in vitro clonogenic data in fibroblasts. Results of the comet assay in lymphocytes, however, showed a significant correlation (p <0.05) with the clinical data when patients were divided into two groups with average and elevated acute reactions. Apart from initial damage, fibroblasts did not show significant differences between the two patient groups. Repeated comet assays in lymphocytes of the same patient drawn before treatment and before and after external radiotherapy demonstrated good reproducibility of the test and no significant impact of preceding radiation treatment. There was a good correlation (r =0.65) between the comet assay results in fibroblasts and lymphocytes of the same individual. Conclusions : In this cohort of patients, a significant correlation between the in vitro results of the comet assay in lymphocytes and clinical acute reactions was detected. The results of the comet assay and of fibroblast colony formation did not correlate with in vitro radiosensitivity.

The in vitro colony assay: a predictor of clinical outcome.

Purpose : To determine the predictive power of an in vitro colony assay on the clinical normal-tissue complication rate. Material and methods : Primary skin fibroblasts from 88 individuals were generated from the skin biopsies of patients who received a standardized radiotherapy. Tissue was cultured for three to six passages, irradiated with doses between 1 and 8 Gy under defined conditions, seeded and finally the colonies were stained and counted after 10-14 days. The survival curves were fitted by the L-Q model and the SF2, α / β and plating efficiency were calculated. Results : The parameters SF2 and plating efficiency were stable throughout the 4-year test period. Intra-individual differences between repeated experiments were significantly lower than inter-individual test results. For the observed acute skin and late normal-tissue reactions other than skin the in vitro parameter SF2 correlated significantly (p < 0.005). For late skin reactions this correlation was not found. Discussion : In contrast to other publications, a clear correlation was found between the in vitro test results and clinically observed early reactions. The lack of correlation for late skin reactions suggests that the combination of intrinsic radiation sensitivity and exogenous factors may alter the clinically observed reaction of certain tissues to a different extent.

Sequence analysis of the ATM gene in 20 patients with RTOG grade 3 or 4 acute and/or late tissue radiation side effects

PURPOSE Patients with ataxia-telangiectasia (A-T) show greatly increased radiation sensitivity and cancer predisposition. Family studies imply that the otherwise clinically silent heterozygotes of this autosomal recessive disease run a 3.5 to 3.8 higher risk of developing cancer. In vitro studies suggest moderately increased cellular radiation sensitivity of A-T carriers. They may also show elevated clinical radiosensitivity. We retrospectively examined patients who presented with severe adverse reactions during or after standard radiation treatment for mutations in the gene responsible for A-T, ATM, considering a potential means of future identification of radiosensitive individuals prospectively to adjust dosage schedules. MATERIAL AND METHODS We selected 20 cancer patients (breast, 11; rectum, 2; ENT, 2; bladder, 1; prostate, 1; anus, 1; astrocytoma, 1; Hodgkins lymphoma, 1) with Grade 3 to 4 (RTOG) acute and/or late tissue radiation side effects by reaction severity. DNA from the peripheral blood of patients was isolated. All 66 exons and adjacent intron regions of the ATM gene were PCR-amplified and examined for mutations by a combination of agarose gel electrophoresis, single-stranded conformational polymorphism (SSCP) analysis, and exon-scanning direct sequencing. RESULTS Only 2 of the patients revealed altogether four heteroallelic sequence variants. The latter included two single-base deletions in different introns, a single-base change causing an amino acid substitution in an exon, and a large insertion in another intron. Both the single-base deletions and the single-base change represent known polymorphisms. The large insertion was an Alu repeat, shown not to give rise to altered gene product. CONCLUSIONS Despite high technical efforts, no unequivocal ATM mutation was detected. Nevertheless, extension of similar studies to larger and differently composed cohorts of patients suffering severe adverse effects of radiotherapy, and application of new technologies for mutation detection may be worthwhile to assess the definite prevalence of significant ATM mutations within the group of radiotherapy patients with adverse reactions. To date, it must be recognized that our present results do not suggest that heterozygous ATM mutations are involved in clinically observed radiosensitivity but, rather, invoke different genetic predisposition or so far unknown exogenous factors.

Radiation-induced micronucleus formation in human skin fibroblasts of patients showing severe and normal tissue damage after radiotherapy

PURPOSE Treatment schedule and total dosage in radiation therapy is based on the tumoricidal doses and the tolerance dose of the perifocal normal tissue. Since large-scale variations occur between the patients concerning the side effects, one of the major goals of radiation research recently has been the development of a predictive in vitro assay. This paper is a contribution to that effort. MATERIALS AND METHODS Skin fibroblasts of patients with normal-tissue reactions or acute and/or late increased side effects and cell lines of four individuals carrying the heritable disease ataxia telangiectasia were irradiated in vitro. The formation of micronuclei was chosen as biological endpoint and the results were compared with the clinically observed side effects. RESULTS In general, a radiation dose-dependent increase in micronucleus frequency was found. The cells of the majority of the sensitive patients, as well as those of homozygous and heterozygous ataxia telangiectasia individuals, showed a higher micronucleus induction than the average of the donors with normal sensitivity. CONCLUSIONS The micronucleus test seems to be a very promising tool in the evaluation of radiation sensitivity prior to therapy. However, larger studies are needed to confirm these findings and to optimize the methodology, and it is presumed that a final predictive assay will consist of a combination with other test systems.