Optimizing patient selection for stereotactic ablative radiotherapy in patients with locally advanced pancreatic cancer after initial chemotherapy - a single center prospective cohort

Background

The role of stereotactic ablative radiation therapy (SABR) as local treatment option after chemotherapy for locally advanced pancreatic cancer (LAPC) is evolving. However adequate patient selection criteria for SABR in patients with LAPC are lacking.

Methods

A prospective institutional database collected data of patients with LAPC treated with chemotherapy, mainly FOLFIRINOX, followed by SABR, which was delivered using magnetic resonance guided radiotherapy, 40 Gy in 5 fractions within two weeks. Primary endpoint was overall survival (OS). Cox regression analyses were performed to identify predictors for OS.

Results

Overall, 74 patients were included, median age 66 years, 45.9% had a KPS score of ≥90. Median OS was 19.6 months from diagnosis and 12.1 months from start of SABR. Local control was 90% at one year. Multivariable Cox regression analyses identified KPS ≥90, age <70, and absence of pain prior to SABR as independent favorable predictors for OS. The rate of grade ≥3 fatigue and late gastro-intestinal toxicity was 2.7%.

Conclusions

SABR is a well-tolerated treatment in patients with unresectable LAPC following chemotherapy, with better outcomes when applied in patients with higher performance score, age <70 years and absence of pain. Future randomized trials will have to confirm these findings.

Stereotactic ablative radiotherapy or best supportive care in patients with localized pancreatic cancer not receiving chemotherapy and surgery (PANCOSAR): a nationwide multicenter randomized controlled trial according to a TwiCs design

BACKGROUND

Significant comorbidities, advanced age, and a poor performance status prevent surgery and systemic treatment for many patients with localized (non-metastatic) pancreatic ductal adenocarcinoma (PDAC). These patients are currently treated with 'best supportive care'. Therefore, it is desirable to find a treatment option which could improve both disease control and quality of life in these patients. A brief course of high-dose high-precision radiotherapy i.e. stereotactic ablative body radiotherapy (SABR) may be feasible.

METHODS

A nationwide multicenter trial performed within a previously established large prospective cohort (the Dutch Pancreatic cancer project; PACAP) according to the 'Trial within cohorts' (TwiCs) design. Patients enrolled in the PACAP cohort routinely provide informed consent to answer quality of life questionnaires and to be randomized according to the TwiCs design when eligible for a study. Patients with localized PDAC who are unfit for chemotherapy and surgery or those who refrain from these treatments are eligible. Patients will be randomized between SABR (5 fractions of 8 Gy) with 'best supportive care' and 'best supportive care' only. The primary endpoint is overall survival from randomization. Secondary endpoints include preservation of quality of life (EORTC-QLQ-C30 and -PAN26), NRS pain score response and WHO performance scores at baseline, and, 3, 6 and 12 months. Acute and late toxicity will be scored using CTCAE criteria version 5.0: assessed at baseline, day of last fraction, at 3 and 6 weeks, and 3, 6 and 12 months following SABR.

DISCUSSION

The PANCOSAR trial studies the added value of SBRT as compared to 'best supportive care' in patients with localized PDAC who are medically unfit to receive chemotherapy and surgery, or refrain from these treatments. This study will assess whether SABR, in comparison to best supportive care, can relieve or delay tumor-related symptoms, enhance quality of life, and extend survival in these patients.

TRIAL REGISTRATION

Clinical trials, NCT05265663 , Registered March 3 2022, Retrospectively registered.

P14.40 Trends in distribution of glioblastoma care and patient’s travel distance; results from the Dutch Brain Tumor Registry

BACKGROUND

Over the past years, increasing worldwide attention towards centralization of complex cancer care has been pursued as higher volume centers have shown improved outcomes. Changes in distribution of care and the impact on travel distance in glioblastoma patients have not been determined yet. In this study, we determine trends in distribution of glioblastoma care in the Netherlands over the last three decades and assess whether the observed trends affected travel distance for individual patients.

MATERIAL AND METHODS

Data were obtained from the Dutch Brain Tumor Registry from 1989 to 2018. All glioblastoma patients (≥18 years) were included for analysis. Patients, neurosurgical centers and radiotherapy centers were geocoded. Data were analyzed in six time intervals of 5 years. High volume hospitals were defined as &gt;50 cases per year. Travel distance was examined in two categories, ≤60km and &gt;60km respectively. Trend analyses for proportions were used to analyze hospital volume changes and travel distances.

RESULTS

A total of 16.477 glioblastoma patients were registered, with an annual increase from 203 patients in 1989 to 917 patients in 2018. Neurosurgical centers increased from 16 to 17 and for radiotherapy from 19 to 22 centers between 1989–1993 and 2014–2018. Mean neurosurgical- and radiotherapy center volumes increased from 12 to 39 (P=0.025) and 7 to 27 (P=0.025) patients per hospital per year from 1989–1993 to 2014–2018. High volume neurosurgical centers were observed since 2004, and an increased number of patients were treated in these centers, 27.8%, 52.6% and 64.1% in the time periods 2004–2008, 2009–2013, and 2014–2018 (P&lt;0.001). High volume radiology centers were observed since 2009, and 15.0% and 27.3% of patients were treated in these centers in the time periods 2009–2013 and 2014–2018 (P&lt;0.001). Patients with a travel distance &gt;60km to the neurosurgical center reduced from 15.8% to 13.2% (P=0.033). Travel distance &gt;60km to the radiotherapy center did not reduce significantly (10.4% to 8.8%, P=0.601).

CONCLUSION

An increasing number of glioblastoma patients were differentially treated in high volume neurosurgery and radiotherapy centers. The observation that this did not translate into increased travel distances, indicates accessible specialized Neuro-Oncology care for glioblastoma patients in The Netherlands.

P14.31 Between hospital variation in timings to multidisciplinary glioblastoma care in the Dutch Brain Tumor Registry

BACKGROUND

Delay in cancer care may adversely affect emotional distress, treatment outcome and survival. Optimal timings in multidisciplinary glioblastoma care are a matter of debate and clear national guidelines only exist for time to neurosurgery. We evaluated the between-hospital variation in timings to neurosurgery and adjuvant radiotherapy and chemotherapy in newly diagnosed glioblastoma patients in the Netherlands.

MATERIAL AND METHODS

Data were obtained from the nation-wide Dutch Brain Tumor Registry between 2014 and 2018. All adult patients with glioblastoma were included, covering all 18 neurosurgical hospitals, 28 radiotherapy hospitals, and 33 oncology hospitals. Long time-to-surgery (TTS) was defined as &gt;3 weeks from the date of first brain tumor diagnosis to surgery, long time-to-radiotherapy (TTR) as either &gt;4 or &gt;6 weeks after surgery, and long time-to-chemotherapy (TTC) as either &gt;4 or &gt;6 weeks after completion of radiotherapy. Between-hospital variation in standardized rate of long timings was analyzed in funnel plots after case-mix correction.

RESULTS

A total of 4203 patients were included. Median TTS was 20 days and 52.4% of patients underwent surgery within 3 weeks. Median TTR was 20 days and 24.6% of patients started radiotherapy within 4 weeks and 84.2% within 6 weeks after surgery. Median TTC was 28 days and 62.6% of patients received chemotherapy within 4 weeks and 91.8% within 6 weeks after radiotherapy. After case-mix correction, three (16.7%) neurosurgical hospitals had significantly more patients with longer than expected TTS. Three (10.7%) and one (3.6%) radiotherapy hospitals had significantly more patients with longer than expected TTR for &gt;4 and &gt;6 weeks, respectively. In seven (21.2%) chemotherapy hospitals, significantly less patients with TTC &gt;4 weeks were observed than expected. In four (12.1%) chemotherapy hospitals, significantly more patients with TTC &gt;4 weeks were observed than expected.

CONCLUSION

Between-hospital variation in timings to multidisciplinary treatment was observed in glioblastoma care in the Netherlands. A substantial percentage of patients experienced timings longer than anticipated.

OS09.4.A Health-related quality of life in low-grade glioma survivors 26 years after diagnosis

BACKGROUND

Many patients with low-grade gliomas (LGGs) continue to survive for many years, yet little is known about patients’ health-related quality of life (HRQOL) in long-term survivorship. We previously investigated HRQOL in LGG patients diagnosed on average 6 years prior to assessment (T1, N=195) with a follow-up in stable patients on average 12 years after diagnosis (T2, N=65). We present a final follow-up of LGG survivors (T3), now decades after diagnosis.

MATERIAL AND METHODS

We invited patients who participated in our previous assessment (N=65), regardless of disease status. Patients completed questionnaires to assess HRQOL, fatigue, and depressive symptoms: Short Form-36 Health Survey (SF-36), European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Brain Tumour Module (EORTC BN20), Checklist Individual Strength (CIS), and the Center for Epidemiological Studies Depression Scale (CES-D). Changes over time (T1-T2-T3) on group level and participant level were assessed.

RESULTS

Of the 65 patients, 18 (27.7%) were deceased, 3 (4.6%) experienced tumour progression to WHO III, 7 (10.8%) declined, and 3 (4.6%) could not be contacted. Thirty-four patients (52.3%) participated. Of these, 2 had missing HRQOL data, with 32 patients included in analysis. Survivors were M=52.0 (sd=11.3) years old and diagnosed M=26.2 (sd=3.7, range 19–35) years prior. On group level, a statistically significant (but not clinically relevant) improvement in mental health (p=0.049), and a clinically relevant (but not statistically significant) decline in emotional role functioning was found. No other group-level changes over time in HRQOL were found. Minimal detectable change in HRQOL scale scores over time was observed in individual participants (28.1% only improvement; 25.0% only decline; 21.9% both improvement and decline) with 25.0% remaining completely stable. At T3, 25.0% of survivors scored above the cut-off for high risk of clinical depression (≥16 CES-D), and 53.1% of survivors classed as severely fatigued (≥35 CIS).

CONCLUSION

In this cohort of LGG survivors, assessed decades after diagnosis and treatment, HRQOL does not appear to be greatly impacted during survivorship. However, depressive symptoms and fatigue remain relatively common. Findings can help inform patients, their families, and clinicians and can serve as a benchmark for treatment trials evaluating interventions that can have very long-term effects.

MR-guidance in clinical reality: current treatment challenges and future perspectives

Magnetic Resonance-guided radiotherapy (MRgRT) marks the beginning of a new era. MR is a versatile and suitable imaging modality for radiotherapy, as it enables direct visualization of the tumor and the surrounding organs at risk. Moreover, MRgRT provides real-time imaging to characterize and eventually track anatomical motion. Nevertheless, the successful translation of new technologies into clinical practice remains challenging. To date, the initial availability of next-generation hybrid MR-linac (MRL) systems is still limited and therefore, the focus of the present preview was on the initial applicability in current clinical practice and on future perspectives of this new technology for different treatment sites.MRgRT can be considered a groundbreaking new technology that is capable of creating new perspectives towards an individualized, patient-oriented planning and treatment approach, especially due to the ability to use daily online adaptation strategies. Furthermore, MRL systems overcome the limitations of conventional image-guided radiotherapy, especially in soft tissue, where target and organs at risk need accurate definition. Nevertheless, some concerns remain regarding the additional time needed to re-optimize dose distributions online, the reliability of the gating and tracking procedures and the interpretation of functional MR imaging markers and their potential changes during the course of treatment. Due to its continuous technological improvement and rapid clinical large-scale application in several anatomical settings, further studies may confirm the potential disruptive role of MRgRT in the evolving oncological environment.

Central neurotoxicity of standard treatment in patients with newly-diagnosed high-grade glioma: a prospective longitudinal study

Following tumor resection, the majority of high-grade glioma (HGG) patients are treated with a combined modality regimen of radiotherapy and temozolomide. As a result of the tumor itself or as treatment-related neurotoxic side-effects, these patients may experience cognitive deficits. Additionally, radiological abnormalities expressed as white matter hyperintensities (WMH) and cerebral atrophy (CA) can develop. In this study, these functional and morphological parameters are evaluated, and their relation is investigated. After surgery, HGG patients underwent chemo-irradiation for six weeks, followed by six cycles of temozolomide. Assessments were performed before chemo-irradiation, post-concomitantly, after the third and sixth adjuvant cycle, and 3 and 7 months after treatment. Degree of WMH and CA was scored on MRI. Patients' neuropsychological performance was compared to healthy matched controls, yielding six cognitive domain z-scores. Development or progression of pre-existing WMH and CA during follow-up was observed in 36 and 45 % of the patients (n = 39) respectively. Cognitive functioning remained stable or improved in 70 % of the patients and deteriorated in 30 % of the patients (n = 33). Of the cognitive decliners, 80 % had tumor progression within 4 months thereafter. No clear association between cognitive functioning and WMH or CA was found. Central neurotoxic effects of combined modality treatment in HGG patients expressed by radiological abnormalities are encountered in approximately 40 % of patients. However, functional impact as indexed by cognitive functioning was found to be limited. Furthermore, development or progression of pre-existing WMH and CA does not consistently result in functional impairment as measured by cognitive tests.

Developments in early-stage NSCLC: advances in radiotherapy

An increase in the number of predominantly elderly patients with early-stage non-small-cell lung cancer is anticipated in many Western populations. Patients often have major co-morbidities and are at increased risk for surgical morbidity and mortality. In the past decade, the use of stereotactic ablative radiotherapy (SABR) has achieved excellent results, with only mild toxicity in such vulnerable patient groups, leading to SABR becoming accepted as a standard of care for unfit patients in several countries. The planning and delivery of SABR has rapidly improved in recent years, particularly with the use of 'on-board' imaging at treatment units, and shortened treatment delivery times. Increasingly, more central tumors are being treated using lower doses per fraction (so-called risk-adapted schemes). It is also becoming clear that long-term follow-up should take place at specialist centers in order to distinguish the evolving fibrosis that is frequently observed from the relatively infrequent local recurrences. Given the high local control rates and limited toxicity, increasing attention is being paid to the use of SABR in the subgroup of so-called borderline operable patients, and clinical trials comparing surgery and SABR in these patients are ongoing.

Stage I-II non-small-cell lung cancer treated using either stereotactic ablative radiotherapy (SABR) or lobectomy by video-assisted thoracoscopic surgery (VATS): outcomes of a propensity score-matched analysis

BACKGROUND

Video-assisted thoracoscopic surgery (VATS) lobectomy and stereotactic ablative radiotherapy (SABR) are both used for early-stage non-small-cell lung cancer. We carried out a propensity score-matched analysis to compare locoregional control (LRC).

PATIENTS AND METHODS

VATS lobectomy data from six hospitals were retrospectively accessed; SABR data were obtained from a single institution database. Patients were matched using propensity scores based on cTNM stage, age, gender, Charlson comorbidity score, lung function and performance score. Eighty-six VATS and 527 SABR patients were matched blinded to outcome (1:1 ratio, caliper distance 0.025). Locoregional failure was defined as recurrence in/adjacent to the planning target volume/surgical margins, ipsilateral hilum or mediastinum. Recurrences were either biopsy-confirmed or had to be PET-positive and reviewed by a tumor board.

RESULTS

The matched cohort consisted of 64 SABR and 64 VATS patients with the median follow-up of 30 and 16 months, respectively. Post-SABR LRC rates were superior at 1 and 3 years (96.8% and 93.3% versus 86.9% and 82.6%, respectively, P = 0.04). Distant recurrences and overall survival (OS) were not significantly different.

CONCLUSION

This retrospective analysis found a superior LRC after SABR compared with VATS lobectomy, but OS did not differ. Our findings support the need to compare both treatments in a randomized, controlled trial.

The predictive value of 3D time-of-flight MR angiography in assessment of brain arteriovenous malformation obliteration after radiosurgery

BACKGROUND AND PURPOSE

The purpose of radiosurgery of bAVMs is complete angiographic obliteration of its nidus. We assessed the diagnostic accuracy of 1.5T T2-weighted MR imaging and TOF-MRA images for detecting nidus obliteration after radiosurgery.

MATERIALS AND METHODS

The pre- and postradiosurgery MR images and DSA images from 120 patients who were radiosurgically treated for a bAVM were re-evaluated by 2 observers for patency of the nidus (preradiosurgery) and obliteration (postradiosurgery: final follow-up MR imaging), by using a 3-point scale of confidence. Consensus reading of the DSA after radiosurgery was considered the criterion standard for obliteration. Sensitivity, specificity, PPVs, and NPVs, and overall diagnostic performance by using ROC were determined.

RESULTS

Mean bAVM volume during radiosurgery was 3.4 mL (95% CI, 2.6-4.3 mL). Sixty-six patients (55%) had undergone previous endovascular embolization. The mean intervals between radiosurgery and follow-up MR imaging and for DSA, respectively, were 35.6 months (95% CI, 32.3-38.9 months) and 42.1 months (95% CI, 40.3-44.0 months). With ROC, an area under curve of 0.81-0.83 was found. PPVs of final follow-up MR-imaging for definitive obliteration varied between 0.89 [corrected] and 0.95. NPV was 0.52 [corrected] . An average false-positive rate, meaning overestimation of nidus obliteration of 0.10 [corrected] and an average false-negative rate, meaning underestimation of nidus obliteration of 0.42 [corrected] were found.

CONCLUSIONS

MRA is insufficient to diagnose obliteration in the follow-up of bAVMs after radiosurgery. A remaining nidus diameter <10 mm seems to be the major limiting factor for reliable assessment of obliteration. We highly recommend follow-up DSA for definitive diagnosis of complete obliteration.

Brain arteriovenous malformations: from diagnosis to treatment

Brain arteriovenous malformations (bAVM) are a major cause of morbidity in young people. The main mode of presentation is with a cerebral bleeding or seizures, although nowadays, due to the increased use of MRI, more asymptomatic bAVMs are encountered. The clinical course of asymptomatic bAVMs seems to be mild in comparison to bAVMs that presented with a cerebral hemorrhage. This finding may lead to a paradigm shift regarding treatment of asymptomatic bAVMs. This review discusses the latest findings in bAVM epidemiology and natural history, and compares the optimal imaging modalities and best treatment options.

Intracranial Radiosurgery in the Netherlands. A Planning Comparison of Available Systems with Regard to Physical Aspects and Workload

Different planning and treatment systems for intracranial stereotactic radiosurgery available in the Netherlands are compared. The systems for intracranial radiosurgery include: Gamma Knife, Cyberknife, Novalis, and Tomotherapy. Electronic data of 5 patients was transferred to all participating centres and treatment plans were generated according to 2 different prescription protocols. For this study, plans were also generated for a conventional linac. Even systems with a high resolution (Gammaknife and Novalis) have conformity indices in violation with RTOG guidelines (CI > 2.5) when target volumes of <0.5 cc are treated. For medium sized targets (0.5–1 cc) all systems performed reasonably well, but for the different systems a large range of conformity indices was seen (1.1 to 3.7). The differences are partly system dependent but depend also on specific planning choices made. For larger target volumes (>1 cc), all systems perform well. The workload of the different techniques was comparable although the treatment times were usually longer for Gamma Knife radiosurgery. We conclude that small targets should be treated by dedicated systems, larger volumes (>0.5–1 cc) can also be treated using conventional treatment systems equipped with a MLC.

Impact of extent of resection of glioblastoma multiforme (GBM) in the era of chemoradiation

e13029

Background: Controversy remains regarding the impact of the extent of resection (EOR) on survival in patients with GBM (Sanai 2008). The main reason for this is the fact that most studies were based on the surgeon's estimate of the EOR, which is known to be unreliable, rather than early postoperative MRI scans (po-MRI). Data for the current standard of postoperative chemo-radiotherapy (CTRT) have recently been reported, but suffer from the same limitation (Gorlia 2008). We studied the prognostic impact of the EOR using early (<72 hours) po-MRI scans in a cohort of GBM patients treated with CTRT in a single center. Methods: The results of 48 consecutive patients (35 male, 13 female; age 18–73 yrs) treated with surgery, followed by concurrent CTRT (60 Gy plus temozolomide) and adjuvant temozolomide were assessed with respect to survival and relapse patterns. EOR was determined by both the surgeon's estimation and early po-MRI scans that were available in all but two patients. EOR was categorized as biopsy (N = 3), partial resection (N = 24), major resection (N = 11; i.e., total resection according to the surgeon's report, but residual tumor on po-MRI), and total resection (N = 10; i.e. no residual tumor on po-MRI). Results: Median overall survival of the entire cohort was 18.9 months, and EOR was the only significant prognostic factor (p = 0.02) on multivariate analysis, which also included age, gender, performance, and radiotherapy target volume. 2-year survival rates improved significantly with increasing EOR, with 0%, 18.9%, 68.6%, and 100% for biopsy, partial-, major-, and total resection, respectively. In-field progression was the predominant pattern of failure in 27 out of 30 patients (90%) with a recurrence. Time to neurological progression (TNP) was significantly correlated with EOR (p < 0.001). Median TNP was 3.0 months for biopsy, 7.0 months for partial resection, 20.5 months for major resection, and was not reached for total resection. Conclusions: With the use of more effective local therapy in the form of surgery and CTRT, the prognostic impact of the EOR on survival appears to be higher than previously reported. This should be accounted for in future trials.

No significant financial relationships to disclose.

Outcomes of stereotactic body radiotherapy (SBRT) in 175 patients with stage I NSCLC aged 75 years and older

9545

Background: Patients aged 75 years or older comprise more than 40% of all new cases of lung cancer. SEER data show lower compliance rates with guideline-recommended therapy in such patients. The elderly have increased post-surgical mortality and morbidity, and frequently require convalescence at extended-care facilities. SBRT is an image-guided technique used to deliver high biological doses of radiation in 3–8 fractions, in an outpatient setting. We report on clinical outcomes of SBRT in patients aged 75 years or older. Methods: Since 2003, 175 consecutive patients (67% male; 32% female) were treated with SBRT at a single center. The median age was 79 years, with 47% of patients aged 80 years or older. 56% of patients had T1 lesions and 44% T2 tumors. 79% of patients were considered medically inoperable and 21% declined to undergo surgery. Eligible tumors measured 6cm or less in maximal diameter, and all underwent an 18FDG-PET scan that revealed no metastases. The median age-adjusted Charlson co-morbidity score was 7 (range 2–12), and 25% had GOLD Class III or higher chronic obstructive pulmonary disease. Risk-adapted SBRT schemes were used with the same total dose of 60 Gy in 3 (31%), 5 (53%) or 8 fractions (16%) depending upon risk for toxicity. Quality of life was scored prospectively using validated EORTC instruments. Results: All patients completed planned SBRT and survival rates at 1 and 3 years were 85% and 46%. Survival rates correlated with performance score (p<0.01) and pre-SBRT lung function (p<0.01). Actuarial local-, regional- and distant failure rates at 3 years were 11%, 8% and 21%, respectively. 60% of patients reported no early side effects, and fatigue (31%), cough (6%), dyspnea (5%), local chest wall pain (3%) and chest wall erythema (2%) were observed in others. Severe late toxicity was uncommon, with RTOG Grade 3 or higher radiation pneumonitis observed in 2%, radiation-induced rib fractures in 2%, chronic chest wall pain in 3%, and non-malignant pleural effusion in 2% of cases. Conclusions: In a population consisting of frail elderly patients with stage I NSCLC, SBRT achieved high local control rates with minimal toxicity. This indicates that active diagnostic and therapeutic approaches are justified in elderly patients who may be unfit for surgery.

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Radiosurgery of brain arteriovenous malformations in children

OBJECTIVE

The authors describe their experience in treating 22 children with a single brain arteriovenous malformation (bAVM) using a dedicated LINAC stereotactic radiosurgery unit.

METHODS

The findings of 22 consecutive patients < or = 18 years of age who underwent radiosurgery for a single bAVM and with at least 24 months of follow-up, or earlier proven obliteration,were reviewed. The median age at radiosurgery was 13.8 years,with a hemorrhagic presentation in 86%. Median bAVM-volume was 1.8 ml, with a median prescribed marginal dose of 19.0 Gy.

RESULTS

The crude complete obliteration-rate was 68% (n = 15) after a median follow-up of 24 months. The actuarial obliteration- rate was 45 % after two years and 64 % after three years. Patients with a radiosurgery-based AVM score < or = 1 more frequently had an excellent outcome than patients with a bAVM score > 1 (71% vs. 20%, P = 0.12), as well as an increased obliteration rate (P = 0.03) One patient died from a bAVM-related hemorrhage 27 months after radiosurgery, representing a postradiosurgery hemorrhage rate of 1.3%/year for the complete followup interval. Overall outcome was good to excellent in 68% (n = 15). Radiation-induced changes on MR imaging were seen in 36% (n = 8) after a median interval of 12.5 months, resulting in deterioration of pre-existing neurological symptoms in one patient.

CONCLUSIONS

Radiosurgery is a relatively effective, minimally invasive treatment for small bAVMs in children. The rebleeding rate is low, provided that known predilection places for bleeding had been endovascularly eliminated.Our overall results compare unfavourably to recent pediatric microsurgical series, although comparison between series remains imprecise. Nevertheless, when treatment is indicated in a child with a bAVM that is amenable to both microsurgery or radiosurgery, microsurgery should carefully be advocated over radiosurgery, because of its immediate risk reduction.

Multiple "slow" CT scans for incorporating lung tumor mobility in radiotherapy planning

PURPOSE

The high local recurrence rates after radiotherapy in early-stage lung cancer may be due to geometric errors that arise when target volumes are generated using fast spiral CT scanners. A "slow" CT technique that generates more representative target volumes was evaluated.

METHODS AND MATERIALS

Planning CT scans (slice thickness 3 mm, reconstruction index 2.5 mm) were performed during quiet respiration in 10 patients with peripheral lung lesions. Planning CT scans were repeated twice, followed by three slow CT scans (slice thickness 4 mm, index 3 mm, revolution time 4 s/slice). All, except the first scan, were limited to the tumor region. Three-dimensional registration of all scans was performed. The reproducibility of the imaged volumes was evaluated with each technique using (1) the common overlapping volume (COM), the component of the clinical target volume (CTV) covered by all three CT scans, and (2) the encompassing volume (SUM), which is the volume enveloped by all CTVs.

RESULTS

In all patients, the target volumes generated using slow CT scans were larger than those derived using planning scans (mean ratio of planning-CTV:slow-CTV of 88.8% +/- 5.6%), and also more reproducible. The mean ratio of the respective COM:SUM volumes was 62.6% +/- 10.8% and 54.9% +/- 12.9%.

CONCLUSIONS

Larger, and more reproducible, target volumes are generated for peripheral lung tumors with the use of slow CT scans, thereby indicating that slow scans can better capture tumor movement.

Dosimetric consequences of tumor mobility in radiotherapy of stage I non-small cell lung cancer--an analysis of data generated using 'slow' CT scans

BACKGROUND

The target coverage for radiotherapy of early-stage lung cancer was evaluated using two different CT techniques.

MATERIALS AND METHODS

A conventional planning CT scan and two limited scans of the tumor region were performed in seven patients with peripheral tumors. Three 'slow' scans (slice thickness 4mm, index 3mm, revolution time 4s/slice) were then performed, followed by three-dimensional image registration. Planning target volumes (PTV) were generated using these GTV-PTV margins: (a) 1cm (PTV1.0); (b) 1.5 cm (PTV1.5); and (c) 0.9, 1.0, and 0.9 cm ('PTV(clinical)') when set-up errors are avoided.

RESULTS

PTVs derived from three 'slow' scans missed 1.9% of the volume derived from three planning scans for an immobile tumor and 9.3% in the case of a mobile tumor. For an immobile tumor, PTV1.5 achieved comparable coverage to that achieved using PTVclinical, which was generated from three 'slow' scans and a planning scan. For a mobile tumor, PTV(1.5) covered only 89% of the volume captured by PTVclinical. PTV1.0 resulted in inadequate target coverage in all the patients. Reductions in potential lung toxicity (V20) were achievable in six patients despite the larger GTVclinical when treatment set-up errors were minimized.

CONCLUSIONS

PTVs derived using 'slow' CT scans consistently produce superior target coverage than that using conventional scans. This may account for the poor local control observed in stage I lung cancer.

Characterization of the frequency distribution for human hematogenous metastases: evidence for clustering and a power variance function

When groups of mice are injected with cells from a metastasizing tumor, a minority of individuals within a given group tends to sustain disproportionately larger numbers of metastases relative to the remaining group members. This clustering of metastases obeys a power function relationship, sigma2 = amub, between the variance sigma2 and the mean number of lung metastases per animal mu (a and b constant). To see whether such clustering occurs with human lung, brain, and liver metastases, a meta-analysis of clinical and pathological series was performed. Thirty-three published series were identified that provided data regarding the numbers of organ metastases sustained by 5582 people. The data were grouped according to the primary tumor, site of metastasis and method of detection of metastases. Clustering of metastases within individuals of each subgroup (similar to the murine systems) was demonstrated by variance to mean ratios greater than 1, and by a strong correlation to the variance to mean power function (a approximately 0.49, b approximately 2.24, r2 = 96%, p < 10(-6)). The cause of this clustering remains unclear, but it may in part relate to heterogeneities in regional blood flow. As a consequence of this clustering, limited metastases would be expected to occur more frequently than predicted from random chance-providing for some optimism in the management of limited metastasis. As well, the frequency distribution for metastases revealed certain scaling symmetries, likely reflective of the underlying mechanisms of metastasis, that could be of interest to both clinicians and experimentalists working with metastasis.

Prognostic factors in patients with brain metastases

Management of patients with brain metastases (BrM) has been evolving over time, with a general tendency towards a more aggressive treatment approach. Although whole brain radiotherapy (WBRT) remains the mainstay of treatment for the majority of patients, the indications for stereotactic radiosurgery (SRS) with or without WBRT have been expanding rapidly. In order to select patients who would benefit from the improved intracranial control rates obtained with advanced radiation therapy techniques, knowledge of prognostic factors is essential. Literature findings indicate that performance status, age and systemic tumour activity (extracranial metastases and primary tumour status) are the major determinants of survival for patients with BrM. Based on recursive partitioning analysis (RPA) of these factors, the Radiation Therapy Oncology Group has developed a prognostic classification system for patients with BrM. RPA Class 1 represents the most favourable subset of patients with Karnofsky performance status of > or = 70, age under 65 years, controlled primary tumour and no extracranial metastases. RPA Class 3 patients have KPS < 70, associated with poor median survival rates. RPA Class 2 contains the remainder of patients, a rather heterogeneous subset of patients with intermediate survival rates. This RPA classification system, which has been validated for patients treated with WBRT, surgery and SRS, respectively, appears to be a valuable tool for assessment of prognosis in patients with BrM.

A CT-assisted method of dosimetry in brachytherapy of lung cancer. Rotterdam Oncological Thoracic Study Group

BACKGROUND

The toxicity of endobronchial brachytherapy (EB), in particular fatal haemoptysis and bronchial wall necrosis, has been correlated with the total dose, fraction size, volume encompassed by the 100% isodose, and a proximal tumor location. We describe a CT-based planning method which, by improving target volume definition and volumetric dose information, can improve the therapeutic ratio of EB.

MATERIALS AND METHODS

Sixteen CT-assisted EB procedures were performed in patients who were treated with palliative high-dose rate EB. The CT data were used to analyze applicator position in relation to anatomy. An example of a three-dimensional optimized treatment plan was generated and analyzed using different types of dose-volume histograms.

RESULTS

The procedure was well tolerated by patients and no post-procedure complications were observed. The bronchial applicator was eccentrically positioned at the level of the carina/mainstem bronchus in 12 (of 14) CT scans. A planning CT prior to EB was not found to be useful as the final target volume and/or the final applicator position were not reliably predicted before the therapeutic bronchoscopy. CT-scans performed with the applicator in situ allowed the bronchial segments in the target volume to be identified and enabled dose prescription to the bronchial mucosa.

CONCLUSIONS

CT-assisted EB is feasible and underlines the need for using centered applicators for proximally located tumors. By enabling accurate mucosal dose prescription, CT-assisted EB may reduce the toxicity of fractionated EB in the curative setting. However, faster on-line EB treatment planning is needed for the routine clinical application of this technique.

Mucosal dose prescription in endobronchial brachytherapy: a study based on CT-dosimetry

PURPOSE

To investigate the consequences of using different dose prescription methods for endobronchial brachytherapy (EB), both with and without the use of a centered applicator.

MATERIALS AND METHODS

A CT scan was performed during EB procedures in 13 patients after insertion of the lung applicator. A dosimetric analysis was subsequently performed in five of these patients using a 3D-brachytherapy treatment planning system (PLATO v13.3, Nucletron).

RESULTS

Dose prescription to the mucosa yields uniform dose distributions to the bronchial mucosa when a centrally positioned applicator is used. When non-centrally positioned applicators are used, mucosal dosing results in a significant underdosage to parts of the target volume. Due to the rapid dose fall-off in EB, dose prescription to the mucosa resulted in inadequate coverage of the outer portion of the bronchial wall and adjacent peribronchial space. When compared to mucosal dose prescription, prescription to the outer aspect of the bronchial wall appears to improve target coverage while limiting the hyperdose (i.e., 200%) volume. The diameters of the different bronchial segments, as determined by CT measurements in 13 patients, correlated well with calculated values based upon the tracheal diameter.

CONCLUSIONS

Mucosal dose prescription should only be used in combination with centered EB applicators. Given the rapid dose fall-off in EB mucosal dose prescription should be used with caution in curative treatments where EB, without additional external radiotherapy, is used as the sole treatment modality. In curative EB, both improved target coverage and a limited hyperdose volume can be achieved by dose prescription to the outer aspect of the bronchial wall.

Evaluation of a target contouring protocol for 3D conformal radiotherapy in non-small cell lung cancer

BACKGROUND

A protocol for the contouring of target volumes in lung cancer was implemented. Subsequently, a study was performed in order to determine the intra and inter-clinician variations in contoured volumes.

MATERIALS AND METHODS

Six radiation oncologists (RO) contoured the gross tumour volume (GTV) and/or clinical target volume (CTV), and planning target volume (PTV) for three patients with non-small cell lung cancer (NSCLC), on two separate occasions. These were, respectively, a well-circumscribed T1N0M0 lesion, an irregularly shaped T2N0M0 lesion, and a T2N2M0 tumour. Detailed diagnostic radiology reports were provided and contours were entered into a 3D planning system. The target volumes were calculated and beams-eye view (BEV) plots were generated to visualise differences in contouring. A software tool was used to expand the GTV and CTV in three dimensions for an automatically derived PTV.

RESULTS

Significant inter-RO variations in contoured target volumes were observed for all patients, and these were greater than intra-RO differences. The ratio of the largest to smallest contoured volume ranged from 1.6 for the GTV in the T1N0 lesion, to 2.0 for the PTV in the T2N2 lesion. The BEV plots revealed significant inter-RO variations in contouring the mediastinal CTV. The PTV's derived using a 3D margin programme were larger than manually contoured PTV's. These variations did not correlate with the experience of ROs.

CONCLUSIONS

Despite the use of an institutional contouring protocol, significant interclinician variations persist in contouring target volumes in NSCLC. Additional measures to decrease such variations should be incorporated into clinical trials.

A three-dimensional CT-based target definition for elective irradiation of the neck

INTRODUCTION

Elective treatment of the clinically node-negative neck by radiation results in excellent control rates. However, radiation therapy with its organ-preserving properties is not without morbidity. Side effects of elective neck irradiation are mainly due to damage of the major and minor salivary glands, resulting in the dry mouth syndrome. Given that RT is the preferred treatment modality in case of elective treatment of the neck in many institutions, it is of utmost importance to try and reduce the associated sequelae of RT.

MATERIAL AND METHODS

With the introduction of CT-planning systems and the development of 3D conformal radiation therapy (3D CRT) techniques, it has become feasible to deliver adequate doses of radiation to the target (neck) and at the same time saving (parts of) the salivary glands from doses beyond tolerance. A prerequisite for these techniques is that they require a precise knowledge of the target (i.e., of the elective neck) on CT. To be able to correlate borders of the surgical levels in the neck (I-VI) with structures seen on CT, an anatomical study, using two fixed (phenol, formaldehyde) human cadavers, was performed. Subsequently, the 6 potential lymph node regions in the neck on CT were defined.

RESULTS AND DISCUSSION

The reference for the current 3D CT-based definition of the lymph node regions in the neck is the official report of the American Academy of Otolaryngology, describing, based on surgical anatomy, the lymph node groups in the neck by Levels I-VI. The present investigation depicts reproducible landmarks on transversal CT images, corresponding to anatomical reference structures known from surgical levels (I-VI) and, this way, CT-based lymph node regions (1-6) were constructed.

Identification of prognostic factors in patients with brain metastases: a review of 1292 patients

PURPOSE

Prognostic factors in 1292 patients with brain metastases, treated in a single institution were identified in order to determine subgroups of patients suitable for selection in future trials.

MATERIALS AND METHODS

From January 1981 through December 1990, 1292 patients with CT-diagnosed brain metastases were referred to the Department of Radiation Oncology, Daniel den Hoed Cancer Center, Rotterdam. The majority of patients were treated with whole brain radiotherapy (84%), the remainder were treated with steroids only or surgery and radiotherapy. Information on potential prognostic factors (age, sex, performance status, number and distribution of brain metastases, site of primary tumor, histology, interval between primary tumor and brain metastases, systemic tumor activity, serum lactate dehydrogenase, response to steroid treatment, and treatment modality) was collected. Univariate and multivariate analyses were performed to determine significant prognostic factors. Results were compared with literature findings using a review of prognostic factors in 18 published reports.

RESULTS

Overall median survival was 3.4 months, with 6-month, 1-year, and 2-year survival percentages of 36%, 12%, and 4% respectively. Survival was statistically significantly different between treatment modalities, with median survival of 1.3 months in patients treated with steroids only, 3.6 months in patients treated with radiotherapy, and 8.9 months in patients treated with neurosurgery followed by radiotherapy (p < 0.0001). Multivariate analysis confirmed literature findings of the major prognostic value of treatment modality on survival of patients with brain metastases. Performance status, response to steroid treatment, systemic tumor activity, and serum lactate dehydrogenase were independent prognostic factors with the strongest impact on survival, second only to treatment modality. Site of primary tumor, age, and number of brain metastases were also identified as prognostic factors in our material, although with lesser importance. In patients with lung primaries, sex was found to have significant impact on survival. In patients with breast primaries, interval between primary tumor and development of brain metastases appeared to be a statistically significant prognostic factor. Histology in patients with lung primaries and distribution of brain metastases were not found to be statistically significant in multivariate analysis.

CONCLUSIONS

In this large database, the value of established prognostic factors was confirmed and, furthermore, some less well-recognized parameters such as response to steroid treatment, serum lactate dehydrogenase, age, sex in lung primaries, and site of primary tumor were established. From the three strongest prognostic factors--performance status, response to steroids, and evidence of systemic disease--simple identification of favorable and unfavorable subgroups of patients with brain metastases can be constructed.

Principles of radiotherapy of neoplastic meningosis

Neoplastic meningosis can be a complication of a tumor originating in the brain or the meninges, or it can be a complication of a solid tumor elsewhere that has metastasized to the leptomeninges. The therapeutic dilemma for a radiation oncologist is that neoplastic meningosis involves the entire neuraxis and, as a consequence, ideally, the entire neuraxis should be radiated. However, delivering the necessary radiation dose to the entire neuraxis may be associated with considerable neurologic or bone marrow toxicity. Radiotherapy of neoplastic meningosis can be performed by external beam radiation or by intrathecal injection of radioactive nuclides or radiolabeled monoclonal antibodies. Intrathecal radiation has the theoretical advantage that treatment is directed towards the entire neuraxis with limited irradiation outside the neuraxis. In practice, intrathecal radiation is still under investigation and subject to some limitations and toxicities. Indications and techniques for external beam radiation may range from either therapeutic or elective cranial or craniospinal radiation to palliative involved-field radiation. Patients with neoplastic meningosis are frequently treated with a combination of radiation and chemotherapy, and/or may have been irradiated to the nervous system in the past. Both are well known risk factors for radiation damage to the nervous system. In general, current treatment protocols focus on the development of combination chemotherapy programs and reduction of the radiation dose to minimize toxicity and/or to improve tumor control.

Gallstone size and the risk of gallbladder cancer

The relation between gallstone size and gallbladder cancer was investigated in a matched hospital-based case-control study of surgical patients in a predominantly white population. Stone size was considered to be an indicator of the damaging effects of gallstones on gallbladder mucosa, which may enhance carcinogenesis. A radiologist determined the size of the largest gallstone within the gallbladder by reviewing hard copies of the ultrasonographic examinations of cases and controls. Between 1983 and 1989, 83 surgical patients with gallbladder cancer were identified in 18 participating hospitals. Hard copies were available for 72 patients and 208 matched controls. For 43 cancer patients and 98 matched controls stone size could be determined. In contrast to two other studies, no relation was found between stone size and gallbladder cancer. The reasons for this discrepancy are discussed.