Impact of improved local control on survival

Direct Administration of Chemotherapy and Other Agents into the Fourth Ventricle to Treat Recurrent Malignant Brain Tumors in Children

Direct administration of chemotherapy and other agents into the fourth ventricle of the brain is a novel approach to treating recurrent malignant posterior fossa brain tumors in children. Candidates for this treatment approach include patients with recurrent medulloblastoma, ependymoma, atypical teratoid/rhabdoid tumor, and potentially other neoplasms that originate in the fourth ventricle or elsewhere in the posterior fossa. In this chapter, the authors first explain the rationale for considering fourth ventricular drug infusions in patients with recurrent malignant posterior fossa tumors. We then summarize the results of translational experiments conducted in piglets and non-human primates that demonstrated safety and favorable pharmacokinetics. These translational experiments led to several pilot human clinical trials, and the results of these trials are reviewed. Finally, currently open clinical trials testing infusion of various agents into the fourth ventricle are discussed, and thoughts about potential future directions are shared.

Postoperative Radiotherapy in Locally Advanced Head and Neck Cancer

This retrospective study was conducted on 255 consecutive patients with locally advanced squamous-cell carcinoma of the oral cavity, oropharynx, larynx or hypopharynx, treated at the Radiotherapy Department of Pordenone General Hospital between January 1975 and December 1985. All patients underwent radical surgery followed, after an interval ranging from 10 days to 2.9 months, by radiotherapy given either through a 6 MeV linear accelerator or a cobalt-60 unit. Field extension and dose delivered were comparable in relation to stage and involvement of the surgical resection margins. The aims of the study were to evaluate the survival rate and to analyze the clinical parameters which can influence the disease-free survival. The adjusted overall 5-year survival rate was 71%; stage, performance status at diagnosis, and site of the primary tumor were significant factors in determining patient prognosis, whereas Infiltration of resection margins was not significant in determining locoregional control of disease. Seventy-five patients relapsed and 67 died of cancer-related diseases whereas death in 52 patients was not related to the head and neck cancer. The combined modality treatment consisting of surgery followed by radiotherapy was well tolerated and proved to be effective in the treatment of locally advanced head and neck tumors.

Methotrexate administration directly into the fourth ventricle in children with malignant fourth ventricular brain tumors: a pilot clinical trial

We hypothesize that chemotherapy can be safely administered directly into the fourth ventricle to treat recurrent malignant brain tumors in children. For the first time in humans, methotrexate was infused into the fourth ventricle in children with recurrent, malignant brain tumors. A catheter was surgically placed into the fourth ventricle and attached to a ventricular access device. Cerebrospinal fluid (CSF) flow was confirmed by CINE MRI postoperatively. Each cycle consisted of 4 consecutive daily methotrexate infusions (2 milligrams). Disease response was monitored with serial MRI scans and CSF cytologic analysis. Trough CSF methotrexate levels were sampled. Five patients (3 with medulloblastoma and 2 with ependymoma) received 18, 18, 12, 9, and 3 cycles, respectively. There were no serious adverse events or new neurological deficits attributed to methotrexate. Two additional enrolled patients were withdrawn prior to planned infusions due to rapid disease progression. Median serum methotrexate level 4 h after infusion was 0.04 µmol/L. Range was 0.02–0.13 µmol/L. Median trough CSF methotrexate level 24 h after infusion was 3.18 µmol/L (range 0.53–212.36 µmol/L). All three patients with medulloblastoma had partial response or stable disease until one patient had progressive disease after cycle 18. Both patients with ependymoma had progressive disease after 9 and 3 cycles, respectively. Low-dose methotrexate can be infused into the fourth ventricle without causing neurological toxicity. Some patients with recurrent medulloblastoma experience a beneficial anti-tumor effect both within the fourth ventricle and at distant sites.

Ultrasound guided conformal brachytherapy of cervix cancer: survival, patterns of failure, and late complications

Objective

The aim of this study was to report on the long-term results of transabdominal ultrasound guided conformal brachytherapy in patients with cervical cancer with respect to patterns of failures, treatment related toxicities and survival.

Methods

Three hundred and nine patients with cervical cancer who presented to Institute between January 1999 and December 2008 were staged with magnetic resonance imaging and positron emission tomography and treated with external beam radiotherapy and high dose rate conformal image guided brachytherapy with curative intent. Follow-up data relating to sites of failure and toxicity was recorded prospectively.

Results

Two hundred and ninety-two patients were available for analyses. The median (interquantile range) follow-up time was 4.1 years (range, 2.4 to 6.1 years). Five-year failure free survival and overall survival (OS) were 66% and 65%, respectively. Primary, pelvic, para-aortic, and distant failure were observed in 12.5%, 16.4%, 22%, and 23% of patients, respectively. In multivariate analysis, tumor volume and nodal disease related to survival, whereas local disease control and point A dose did not.

Conclusion

Ultrasound guided conformal brachytherapy of cervix cancer has led to optimal local control and OS. The Melbourne protocol compares favorably to the more technically elaborate and expensive GEC-ESTRO recommendations. The Melbourne protocol's technical simplicity with real-time imaging and treatment planning makes this a method of choice for treating patients with cervical cancer.

MRI-based treatment of rectal cancer: is prognostication of the recurrence risk solid enough to render radiation redundant?

BACKGROUND

Most current guidelines recommend neoadjuvant short course radiotherapy (sRT) or radio-chemotherapy (nRCT) for rectal cancer stage II and III. After the introduction of total mesorectal excision (TME) and magnetic resonance imaging (MRI), this proceeding has been questioned and omission of neoadjuvant treatment according to preoperative MRI-criteria has been propagated. Aim of the present paper is to review the state of evidence regarding MRI-based treatment decision depending on the predicted width of the circumferential resection margin (CRM).

METHODS

A comprehensive survey of the literature was performed using the search terms "rectal cancer", "radiotherapy", "radio-chemotherapy", "MRI-based therapy", "circumferential resection margin". Data from lately published observational studies were compared to results from randomized trials and outcome analyses of the Norwegian national cancer registry.

RESULTS

Only one observational study using MRI-based treatment according to the anticipated CRM provided 5 year local recurrence data, however only for 65 patients. The second study did not yet evaluate recurrence rates. Two randomized trials comparing sRT to primary TME showed significantly worse outcome for non-irradiated patients. Data from the Norwegian rectal cancer registry demonstrate that TME alone is associated with higher LRR than achievable with preoperative RT.

CONCLUSIONS

Current evidence does not support the omission of neoadjuvant treatment for stage II-III rectal cancer on the basis of an MRI-predicted negative CRM. Randomized studies are warranted to clarify whether and for which subgroups TME alone is safe in terms of local recurrences.

A review of update clinical results of carbon ion radiotherapy

Among various types of ion species, carbon ions are considered to have the most balanced, optimal properties in terms of possessing physically and biologically effective dose localization in the body. This is due to the fact that when compared with photon beams, carbon ion beams offer improved dose distribution, leading to the concentration of the sufficient dose within a target volume while minimizing the dose in the surrounding normal tissues. In addition, carbon ions, being heavier than protons, provide a higher biological effectiveness, which increases with depth, reaching the maximum at the end of the beam's range. This is practically an ideal property from the standpoint of cancer radiotherapy. Clinical studies have been carried out in the world to confirm the efficacy of carbon ions against a variety of tumors as well as to develop effective techniques for delivering an efficient dose to the tumor. Through clinical experiences of carbon ion radiotherapy at the National Institute of Radiological Sciences and Gesellschaft für Schwerionenforschung, a significant reduction in the overall treatment time with acceptable toxicities has been obtained in almost all types of tumors. This means that carbon ion radiotherapy has meanwhile achieved for itself a solid place in general practice. This review describes clinical results of carbon ion radiotherapy together with physical, biological and technological aspects of carbon ions.

Safety and pharmacokinetic analysis of methotrexate administered directly into the fourth ventricle in a piglet model

We have developed a piglet model to assess chemotherapy administration directly into the fourth ventricle as a potential treatment for medulloblastoma and other malignant posterior fossa tumors. The objective of this study was to assess safety and pharmacokinetics after methotrexate infusions into the fourth ventricle. Catheters were inserted into the fourth ventricle and lumbar cistern in five piglets. Two milligrams of Methotrexate (MTX) was infused into the fourth ventricle on five consecutive days. Safety was assessed by neurological examination, 4.7 T MRI, and post-mortem pathological analysis. MTX levels in serum and cerebrospinal fluid (CSF) were measured, and area under the concentration-time curve (AUC) was calculated for CSF samples. No neurological deficits were caused by MTX infusions. One piglet died from complications of anesthesia induction for MRI scanning. MRI scans showed accurate catheter placement without signal changes in the brainstem or cerebellum. One piglet had asymptomatic ventriculomegaly. Pathological analysis demonstrated meningitis and choroid plexitis consisting predominantly of CD-3 positive T-lymphocytes in all piglets and a small focal area of subependymal necrosis in one. In all piglets, mean peak MTX level in fourth ventricular CSF exceeded that in lumbar CSF by greater than five-fold. Serum MTX levels were undetectable or negligible. Statistically significant differences between fourth ventricle and lumbar AUC were detected at peaks (P = 0.01) and at all collection time points (P = 0.01) but not at troughs (P = 0.36). MTX can be infused into the fourth ventricle without clinical or radiographic evidence of damage. An inflammatory response without clinical correlate is observed. Significantly higher peak MTX levels are observed in the fourth ventricle than in the lumbar cistern.

Pharmacokinetic analysis of etoposide distribution after administration directly into the fourth ventricle in a piglet model

We hypothesize that infusion of chemotherapeutic agents directly into the fourth ventricle potentially may play a role in treating malignant posterior fossa brain tumors. Accordingly, we used a piglet model developed in our laboratory to test the safety of etoposide infusions into the fourth ventricle and to study the pharmacokinetics associated with these infusions. In 5 piglets, closed-tip silicone catheters were inserted into the fourth ventricle and lumbar cistern. Five consecutive daily infusions of etoposide (0.5 mg) were administered via the fourth ventricle catheter. Serum and CSF from both catheters were sampled for measurement of etoposide level by reversed-phase high performance liquid chromatography (HPLC). For CSF samples, area under the concentration-time curve (AUC) was calculated. Piglets underwent daily neurological examinations, a 4.7 Tesla MRI scan, and then were sacrificed for post-mortem brain examination. No neurological deficits or signs of meningitis were caused by intraventricular chemotherapy infusions. MRI scans showed catheter placement within the fourth ventricle but no signal changes in the brain stem or cerebellum. In all piglets, the mean fourth ventricular CSF peak etoposide level exceeded the mean peak lumbar etoposide levels by greater than 10-fold. Statistically significant differences between fourth ventricle and lumbar AUC were noted at peaks (DeltaAUC = 3384196 ng h/ml with 95%CI: 1758625, 5009767, P = 0.0044) and at all collection time points (DeltaAUC = 1422977 ng h/ml with 95%CI: 732188, 2113766, P = 0.0046) but not at troughs (DeltaAUC = -29546 ng h/ml (95%CI: -147526, 88434.2, P = 0.5251). Serum etoposide was absent at two and four hours after intraventricular infusions in all animals. Pathological analysis demonstrated meningitis, choroid plexitis, and ependymitis in the fourth and occasionally lateral ventricles. Etoposide can be infused directly into the fourth ventricle without clinical or radiographic evidence of damage. Autopsy examination revealed ventriculitis and meningitis which did not have a clinical correlate. Etoposide does not distribute evenly throughout CSF spaces after administration into the fourth ventricle, and higher peak CSF levels are observed in the fourth ventricle than in the lumbar cistern.

Chemotherapy administration directly into the fourth ventricle in a new piglet model. Laboratory Investigation

OBJECT

The authors hypothesized that chemotherapy infusions directly into the fourth ventricle may potentially play a role in treating malignant posterior fossa tumors. In this study the safety and pharmacokinetics of etoposide administration into the fourth ventricle was tested using an indwelling catheter in piglets.

METHODS

A closed-tip silicone lumbar drain catheter was inserted into the fourth ventricle via a posterior fossa craniectomy and 5 daily infusions of etoposide (0.5 mg in 5 animals) or normal saline (in 2 animals) were instilled. Piglets (10-18 kg, 2-3 months of age) underwent daily neurological examinations and 4.7-T magnetic resonance (MR) imaging after the final infusion and were then killed for postmortem examination. Pharmacokinetics were studied using reversed-phase high-performance liquid chromatography on cerebrospinal fluid (CSF) samples at 0.25, 1, 2, 4, 8, 12, and 24 hours after etoposide infusion. Peak and trough CSF etoposide levels were measured for each subsequent infusion. Serum etoposide levels were obtained at 2 and 4 hours after infusion.

RESULTS

All piglets remained neurologically intact, and MR images demonstrated catheter placement within the fourth ventricle without signal changes in the brainstem or cerebellum. Serum etoposide was absent at 2 and 4 hours after intraventricular infusions. When adequate samples could be obtained for analysis, CSF etoposide levels peaked 15 minutes after infusion and progressively decreased. Cytotoxic levels (> 0.1 microg/ml) were maintained for 5 consecutive peak and trough measurements with 1 exception. Etoposide-related neuropathology included moderate-to-severe T-lymphocytic meningitis and fourth and lateral ventricular choroid plexitis with associated subependymal inflammation.

CONCLUSIONS

Etoposide can be infused directly into the fourth ventricle without clinical or imaging evidence of damage. Cytotoxic CSF etoposide levels can be maintained for 24 hours with a single daily infusion into the fourth ventricle using an indwelling catheter. Intraventricular etoposide elicits an inflammatory response, the long-term effects of which are as yet undetermined.

Patterns of failure and prognostic factor analyses in locally advanced cervical cancer patients staged by magnetic resonance imaging and treated with curative intent

Earlier we had shown that tumor volume and corpus invasion were important prognostic factors in cervical cancer and that corpus invasion was associated with nodal metastases. In view of these findings, we wanted to examine the factors associated with the patterns of relapse in cervical cancer patients who were staged by magnetic resonance imaging (MRI) and treated with curative intent. This was a retrospective study of locoregionally advanced cervical cancer patients treated with curative intent. All patients had examination under anesthesia and pretreatment MRI. Potential prognostics examined were FIGO stage, clinical diameter, histology, corpus invasion, tumor volume, and age. Outcome measures examined were times to failure, local failure, nodal failure, and distant failure. There were 249 eligible patients. The median age of the patients was 58 years, 85% had squamous histology, and 63% of tumors exhibited corpus invasion. Median tumor volume was 33.5 mL (range 1–628). The mean follow-up was 4.5 years. Eighty-five patients had relapsed and 89 died (70 following failure and 19 otherwise). At 5 years, for all patients, the failure-free rate was 62%, the local failure–free rate 88%, the nodal failure–free rate 69%, and the distant failure–free rate 74%. Corpus invasion, tumor volume, and age were all highly significantly and independently related to risk of failure at local, nodal, and distant (except tumor volume) sites. In the presence of these factors, clinical tumor diameter and FIGO stage were not significantly related to risk of any type of failure

Influence of low-dose daily cisplatin on the distant metastasis-free survival of patients with locally advanced nonmetastatic head and neck cancer treated with radiation therapy

We investigated the impact of low dose daily cisplatin on distant metastasis-free survival (DMFS) in locally advanced head and neck cancer treated with hyperfractionated radiotherapy (77Gy in 70 fractions in 35 treatment days). In locally controlled tumors cisplatin led to better DMFS (p=0.0272); Cisplatin may have acted independently of micrometastasis in locally advanced H&N cancer.

Kinetic modeling of tumor growth and dissemination in the craniospinal axis: implications for craniospinal irradiation

Background

Medulloblastoma and other types of tumors that gain access to the cerebrospinal fluid can spread throughout the craniospinal axis. The purpose of this study was to devise a simple multi-compartment kinetic model using established tumor cell growth and treatment sensitivity parameters to model the complications of this spread as well as the impact of treatment with craniospinal radiotherapy.

Methods

A two-compartment mathematical model was constructed. Rate constants were derived from previously published work and the model used to predict outcomes for various clinical scenarios.

Results

The model is simple and with the use of known and estimated clinical parameters is consistent with known clinical outcomes. Treatment outcomes are critically dependent upon the duration of the treatment break and the radiosensitivity of the tumor. Cross-plot analyses serve as an estimate of likelihood of cure as a function of these and other factors.

Conclusion

The model accurately describes known clinical outcomes for patients with medulloblastoma. It can help guide treatment decisions for radiation oncologists treating patients with this disease. Incorporation of other treatment modalities, such as chemotherapy, that enhance radiation sensitivity and/or reduce tumor burden, are predicted to significantly increase the probability of cure.

Introduction to clinical radiation biology

The authors have reviewed some of the most important and established factors that determine the effectiveness of IR in a wide variety of tumor types and normal tissues: the significance of increasing the dose of radiation, the importance of altered fractionation schemes, such as accelerated fractionation or hyperfractionation, and the need to address tumor hypoxia. Therapeutic gain can only be achieved when the increased tumor toxicity produced by these treatment modifications is balanced against injury to early-responding as well as late-responding normal tissues. In the not too distant future, therapeutic gain may be maximized by individualized therapies that are based on phenotypic and genotypic profiling of tumors and patients. For example, predicting which tumors respond to IR with accelerated tumor cell repopulation will allow us to apply more intense accelerated treatment regimens, while subjecting patients with slowly proliferating tumors to less toxic therapies. Similarly, the combination of radiation therapy with molecularly targeted pharmacologic agents will be a highly individualized treatment approach. However, to some degree, radiation therapy will always have to remain unselective and indiscriminant to inactivate the last surviving dormant and probably drug-resistant tumor clonogen. Although the field of radiation biology is rapidly evolving as a result of advances in molecular biology and genetics and the availability of new technologies, a thorough understanding of the established factors that determine radiation responses will remain an important prerequisite for the successful application of multimodal cancer therapies and molecularly targeted approaches in the future.

Radiation Therapy for Breast Cancer

Over the past five decades, radiotherapy (RT) has become an integral part in the combined modality management of breast cancer. Although its significant effect on local control has been long demonstrated, only recently has adjuvant RT been shown to have a significant effect on breast cancer mortality and overall survival. This article summarizes the adjuvant role of RT after mastectomy and lumpectomy, as well as the rationale and techniques for partial-breast irradiation.

FDG-PET/CT-guided intensity modulated head and neck radiotherapy: a pilot investigation

BACKGROUND

2-deoxy-2[(18)F]fluoro-D-glucose-positron emission tomography (FDG-PET) imaging can be registered with CT images and can potentially improve neck staging sensitivity and specificity in patients with head and neck squamous cell cancer. The intent of this study was to examine the use of registered FDG-PET/CT imaging to guide head and neck intensity modulated radiotherapy (IMRT) planning.

METHODS

Twenty patients with squamous cell carcinoma of the oral cavity, oropharynx, larynx, or hypopharynx underwent FDG-PET and contrast-enhanced CT imaging of the head and neck before neck dissection surgery. Combined FDG-PET/CT images were created by use of a nonrigid image registration algorithm. All IMRT plans were theoretical and were not used for treatment. We prescribed 66 Gy in 30 fractions to FDG-avid CT abnormalities and nodal zones directly involved with disease, without prophylactic coverage of uninvolved neck levels. Matched CT-guided IMRT plans designed according to the specifications of Radiation Therapy Oncology Group (RTOG) H-0022 were available for comparison. We investigated the feasibility of FDG-PET/CT-directed IMRT dose escalation in five patients with FDG-avid disease located away from critical normal structures. After 66 Gy, FDG-avid disease with 0.5-cm margins was boosted in 220 cGy increments until dose-limiting criteria were reached.

RESULTS

Elimination of prophylactic coverage to FDG-PET/CT-negative neck levels markedly reduced mean dose (Dmean) to the contralateral parotid gland (p < .001) and Dmean to the laryngeal cartilage (p = .001). No FDG-PET/CT-directed plan missed pathologically verified nodal disease. During the dose escalation exercise, we successfully increased the dose to 95% of the planning target volume (PTV95%) to a mean of 7490 cGy (range, 7153-8098 cGy).

CONCLUSIONS

We demonstrate early proof of the principle that FDG-PET/CT-guided IMRT planning can selectively target and intensify treatment of head and neck disease while reducing critical normal tissue doses. Routine clinical use of such planning should not be engaged until the accuracy of FDG-PET/CT is fully validated. Future directions, including refinement of treatment to gross disease and radiologically uninvolved neck nodal levels, are discussed.

The tumor bed effect: increased metastatic dissemination from hypoxia-induced up-regulation of metastasis-promoting gene products

Cancer patients with recurrent local disease after radiation therapy have increased probability of developing regional and distant metastases. The mechanisms behind this observation were studied in the present work by using D-12 and R-18 human melanoma xenografts growing in preirradiated beds in BALB/c-nu/nu mice as preclinical models of recurrent primary tumors in humans. D-12 tumors metastasize to the lungs, whereas R-18 tumors develop lymph node metastases. Based on earlier studies, we hypothesized that metastasis was governed primarily by the proangiogenic factor interleukin-8 (IL-8) in D-12 tumors and by the invasive growth-promoting receptor urokinase-type plasminogen activator receptor (uPAR) in R-18 tumors. Pimonidazole was used as a hypoxia marker, and hypoxia, microvascular hotspots, and the expression of IL-8 and uPAR were studied by immunohistochemistry. The metastatic frequency was significantly higher in tumors in preirradiated beds than in control tumors in unirradiated beds, and it increased with the preirradiation dose. D-12 tumors showed increased fraction of hypoxic cells, increased fraction of IL-8-positive cells, and increased density of microvascular hotspots in preirradiated beds, and R-18 tumors showed increased fraction of hypoxic cells and increased fraction of uPAR-positive cells in preirradiated beds. Strong correlations were found between these parameters and metastatic frequency. IL-8 was up-regulated in hypoxic regions of D-12 tumors, and uPAR was up-regulated in hypoxic regions of R-18 tumors. Daily treatment with anti-IL-8 antibody (D-12) or anti-uPAR antibody (R-18) suppressed metastasis significantly. Our preclinical study suggests that primary tumors recurring after inadequate radiation therapy may show increased metastatic propensity because of increased fraction of hypoxic cells and hypoxia-induced up-regulation of metastasis-promoting gene products. Two possible mechanisms were identified: hypoxia may enhance metastasis by inducing neoangiogenesis facilitating hematogenous spread and by promoting invasive growth facilitating lymphogenous spread. The aggressive behavior of postirradiation local recurrences suggests that they should be subjected to curative treatment as early as possible to prevent further metastatic dissemination. Moreover, the possibility that patients with a high probability of developing local recurrences after radiation therapy may benefit from postirradiation treatment with antiangiogenic and/or anti-invasive agents merits clinical investigation.

Conformal radiotherapy of urinary bladder cancer

Recent advances in radiotherapy (RT) are founded on the enhanced tumour visualisation capabilities of new imaging modalities and the precise deposition of individualised radiation dose distributions made possible with the new systems for RT planning and delivery. These techniques have a large potential to also improve the results of RT of urinary bladder cancer. Major challenges to take full advantage of these advances in the management of bladder cancer are to control, and, as far as possible, reduce bladder motion, and to reliably account for the related intestine and rectum motion. If these obstacles are overcome, it should be possible in the near future to offer selected patients with muscle invading bladder cancer an organ-sparing, yet effective combined-modality treatment as an alternative to radical surgery.

Investigation of relationship between change in locoregional control and change in overall survival in randomized controlled trials of modified radiotherapy in head-and-neck cancer

PURPOSE

To establish whether a relationship exists between improvement in locoregional control (LRC) and improvement in overall survival (OS) in trials of modified radiotherapy for head-and-neck cancer and to attempt to quantify the relationship.

METHODS AND MATERIALS

A systematic review of the literature was performed for randomized controlled trials of radiotherapy for head-and-neck cancer involving the use of altered fractionation or hypoxic sensitizers. The changes in LRC at 2 years and OS at 5 years were recorded for each trial. Regression analysis was used to investigate the relationship between the two variables.

RESULTS

Nineteen relevant trials were identified. Fourteen reported sufficient data for analysis. Linear regression analysis showed a statistically significant correlation between LRC and OS with a slope of 0.67 (95% confidence interval, 0.38-0.96, p = 0.00017).

CONCLUSIONS

We have demonstrated a relationship between a change in LRC and a change in OS in randomized trials of modified radiotherapy for head-and-neck cancer. A 10% improvement in the 2-year LRC is predicted to lead to a 6.7% improvement in the 5-year OS. This type of analysis may have applications in other tumor sites.

Role of postoperative radiotherapy after pelvic lymphadenectomy and radical retropubic prostatectomy: a single institute experience of 415 patients

PURPOSE

To evaluate the clinical benefit deriving from early (within 6 months) radiotherapy (ERT) after pelvic lymphadenectomy and radical retropubic prostatectomy for localized/locally advanced adenocarcinoma of the prostate in a single-institution series.

METHODS AND MATERIALS

We retrospectively analyzed 415 patients who underwent pelvic lymphadenectomy and radical retropubic prostatectomy between 1986 and 1998 for pT2b-pT4, pN0-pN1 prostate carcinoma. Of the 415 patients, 237 underwent ERT for adverse pathologic findings and 178 patients did not receive RT or underwent salvage RT < or =6 months (salvage or no RT [SNRT]).

RESULTS

After a median follow-up of 62 months, the 8-year actuarial freedom from biochemical, local and systemic failure, and cause-specific survival rate was 69% vs. 31% (p <0.0001, log-rank), 93% vs. 63% (p <0.0001), 88% vs. 75% (p = 0.04), and 93% vs. 80% (p = 0.02) in the ERT and SNRT group, respectively. A subgroup analysis indicated that an improvement in 8-year actuarial cause-specific survival was associated with ERT in patients with positive resection margins (91% vs. 67%, p = 0.007), extracapsular extension (92% vs. 75%, p = 0.002), Gleason score > or =7 (88% vs. 72%, p = 0.02), and lymph node metastases (88% vs. 68%, p = 0.04). This strong association between ERT and cause-specific survival persisted at multivariate analysis in the whole group of patients examined (hazard ratio, 4.3) and in the subgroups of patients with extracapsular extension (hazard ratio, 4.9), positive resection margins (hazard ratio, 4.7), Gleason score > or =7 (hazard ratio, 4.4), and lymph node metastases (hazard ratio, 7.4).

CONCLUSION

The results of this retrospective analysis indicate that ERT after pelvic lymphadenectomy and radical retropubic prostatectomy improved the 5-year and actuarial 8-year cause-specific survival of patients with adverse pathologic findings such as extracapsular extension, positive resection margins, Gleason score > or =7, and/or positive lymph nodes.

Organ motion, set-up variation and treatment margins in radical radiotherapy of urinary bladder cancer

BACKGROUND AND PURPOSE

A major challenge in conformal radiotherapy of bladder cancer is to determine adequate treatment margins. For this purpose, we therefore quantified the internal motion of the urinary bladder as well as the external patient set-up variation during a course of fractionated radiotherapy. In the light of the recently introduced ICRU-62 concept, the planning organ at risk volume, we also studied the internal motion of nearby organs at risk, the rectum and intestine.

MATERIAL AND METHODS

Weekly CT scans and electronic portal images (EPIs) were sampled from 20 patients during radical, conformal bladder irradiation (60-64 Gy/2 Gy in five fractions weekly). The planning scans were acquired with 70 ml of bladder contrast instilled, and patients were instructed to void before the treatment/repeat scanning sessions. Internal motion of the bladder, rectum and intestine was measured by 3-D image matching of the repeat scans to the patients' planning scans. Internal margins (CTV-to-ITV) were determined using both a direct empirical approach and an analytically derived margin recipe. The external patient set-up variability was determined by 2-D matching of front and lateral EPIs to corresponding digitally reconstructed radiographs.

RESULTS

A total of 149 CT scans (20 for planning, 129 during the treatment course) and 133 sets of EPIs were analysed. Bladder volumes were smaller during treatment than in the planning situation in 85% of the repeat scans. Nevertheless, we found the repeat scan bladder volumes to extend outside the planning scan bladder contours in 89% of the scans, on average with 9% of the volume (range: 0-47%). Eight patients (40%) had at least one repeat scan (25 scans in total) where displacements >15 mm were observed at one or more sides of the bladder. CTV-to-ITV margins of 10 mm inferior, 20 mm superior, 11 mm left, 8 mm right, 20 mm anterior and 14 mm posterior were required to simultaneously encompass all bladder deflections except for the largest outward deflection in all directions in 84% of the patients. Including patient set-up variation (CTV-to-PTV), we found that an additional safety margin of 2-6 mm had to be added in the various directions. The rectum expanded outside the planning contours in all repeat scans, on average with 24% of the volume (range: 2-69%). The volume of intestine found close to the bladder were significantly and negatively correlated to the bladder volume in almost half of the patients.

CONCLUSION

This study documented both a large internal motion of the bladder and a substantial patient set-up variation. Our current treatment margins have been adjusted according to the findings of this study. Considerable variation in position and volume of the rectum and intestine was also documented.

(Non)-migration of radiopaque markers used for on-line localization of the prostate with an electronic portal imaging device

PURPOSE

Radiopaque gold markers can be implanted in the prostate to visualize its position on portal images during radiation therapy. This procedure assumes that the markers do not move within the prostate. In this work we test this assumptiom.

METHODS AND MATERIALS

Three markers were implanted transrectally in the prostate of patients undergoing external radiation therapy. An orthogonal pair of portal images was acquired periodically throughout the course of radiation therapy with an a-Si electronic portal imaging device (EPID). The marker coordinates were determined, and the distances between the implanted markers were recorded. The distance time trend is used to evaluate the magnitude of marker migration.

RESULTS

The average standard deviation (SD) of the distances between markers was 1.3 mm (range 0.44 to 3.04 mm). Three of the 11 patients show a SD larger than 2 mm. For these patients, all three distances show a simultaneous reduction with time, compatible with a shrinking of the prostate. All had been treated with neoadjuvant hormone therapy. For 1 of the 3 patients, this reduction in volume was confirmed with a repeat computed tomographic scan.

CONCLUSION

None of the 33 markers studied migrated significantly. The implantation of three radiopaque gold markers enables accurate and precise on-line verification of the prostate position during external beam radiation therapy. The use of three markers provides a tool to monitor prostate position and volume changes that can occur over time due to hormone or radiation therapy.

Impact of treatment interruptions due to toxicity on outcome of patients with early stage (I/II) non-small-cell lung cancer (NSCLC) treated with hyperfractionated radiation therapy alone

We investigated the effect of treatment interruptions due to high-grade (> or =3) toxicity on outcome of patients with early stage (I/II) non-small-cell lung cancer treated with hyperfractionated radiation therapy (Hfx RT). Of 116 patients treated with total tumour doses of 69.6 Gy, 1.2 Gy b.i.d. fractionation, 44 patients refused surgery while 72 patients were medically inoperable due to existing co-morbid states. Patients who were medically inoperable had worse KPS (P=0.0059) and more pronounced weight loss (P=0.0005). Among them, 12 patients experienced high-grade toxicity and 11 of them with either acute (n=6) or "consequential" late (n=5) high-grade toxicity requested interruption in the Hfx RT course (range, 12-25 days; median, 17 days). Superior survival (OS) was observed in patients who refused surgery when compared to those who were medically inoperable (P=0.0041), as well as superior local recurrence-free survival (LRFS) (P=0.011), but not different distant metastasis-free survival (P=0.14). Cause-specific survival (CSS) also favoured patients who refused surgery (P=0.004). Multivariate analysis showed independent influence of the reason for not undergoing surgery on OS (P=0.035), but not on LRFS (P=0.084) or CSS (P=0.068). Patients who refused surgery did not experience high-grade toxicity (0/44), whereas 11 of 72 patients with medical inoperability and co-morbid states experienced high-grade toxicity and had treatment interruptions to manage toxicity (P=0.0064). Patients without treatment interruptions had significantly better OS (P=0.00000), LRFS (P=0.00000) and CSS (P=0.00000) than those with treatment interruptions. When corrected for treatment interruptions, the reason for not undergoing surgery independently influenced OS (P=0.040), but not LRFS (P=0.092) or CSS (P=0.068). In contrast to this, treatment interruption was independent prognosticator of all three endpoints used (P=0.00031, P=0.0075 and P=0.00033, respectively). When 11 patients with treatment interruptions were excluded, the reason for not undergoing surgery still affected OS (P=0.037) and CSS (P=0.039) but not LRFS (P=0.11). Multivariate analyses using OS, CSS and LRFS showed that the reason for not undergoing surgery affected OS (P=0.0436), but neither CSS (P=0.083) nor LRFS (P=0.080).

Radical radiation for localized prostate cancer: local persistence of disease results in a late wave of metastases

PURPOSE

To assess whether failure to maintain local control (LC) of prostate cancer after radiation therapy results in a higher incidence of distant metastasis (DM).

PATIENTS AND METHODS

From 1972 to 1999, 1,469 patients with clinically localized prostate cancer were treated with radical radiation therapy. Disease outcome was retrospectively reviewed for all patients with more than 2 years of follow-up.

RESULTS

The actuarial 10-year LC rate was 79%. Gleason score > or = 7, prostate-specific antigen (PSA) more than 15, and T3 to T4 tumors predicted a higher incidence of local failure (LF) (palpable recurrence or positive rebiopsy). The 10-year distant metastasis-free survival (DMFS) was 74%. Gleason score > or = 7, PSA more than 15, and T3 to T4 tumors predicted a higher incidence of distant failure. LF was the strongest predictor for DM in a multivariate model. The 10-year DMFS for LC and LF patients was 77% and 61%, respectively. Median time to distant failure was prolonged in patients with LF compared with patients with locally controlled disease (54 v 34 months). Hazard rate analysis of the time to DM revealed that patients who maintain LC have a lower rate of DM, which remains constant over time. Patients who ultimately develop LF have a higher initial rate of DM, which increases with time.

CONCLUSION

Patients with locally persistent prostate cancer are at greater risk of DM. The higher initial hazard of DM is consistent either with an increased likelihood of subclinical micrometastases before treatment or with posttreatment tumor embolization. The prolonged time to appearance of DM in locally failing patients and the increasing hazard of DM over time is most consistent with a late wave of metastases from a locally persistent tumor.

Clinical implementation of intensity-modulated arc therapy

PURPOSE

Intensity-modulated arc therapy (IMAT) is a method for delivering intensity-modulated radiation therapy (IMRT) using rotational beams. During delivery, the field shape, formed by a multileaf collimator (MLC), changes constantly. The objectives of this study were to (1) clinically implement the IMAT technique, and (2) evaluate the dosimetry in comparison with conventional three-dimensional (3D) conformal techniques.

METHODS AND MATERIALS

Forward planning with a commercial system (RenderPlan 3D, Precision Therapy International, Inc., Norcross, GA) was used for IMAT planning. Arcs were approximated as multiple shaped fields spaced every 5-10 degrees around the patient. The number and ranges of the arcs were chosen manually. Multiple coplanar, superimposing arcs or noncoplanar arcs with or without a wedge were allowed. For comparison, conventional 3D conformal treatment plans were generated with the same commercial forward planning system as for IMAT. Intensity-modulated treatment plans were also created with a commercial inverse planning system (CORVUS, Nomos Corporation). A leaf-sequencing program was developed to generate the dynamic MLC prescriptions. IMAT treatment delivery was accomplished by programming the linear accelerator (linac) to deliver an arc and the MLC to step through a sequence of fields. Both gantry rotation and leaf motion were enslaved to the delivered MUs. Dosimetric accuracy of the entire process was verified with phantoms before IMAT was used clinically. For each IMAT treatment, a dry run was performed to assess the geometric and dosimetric accuracy. Both the central axis dose and dose distributions were measured and compared with predictions by the planning system.

RESULTS

By the end of May 2001, 50 patients had completed their treatments with the IMAT technique. Two to five arcs were needed to achieve highly conformal dose distributions. The IMAT plans provided better dose uniformity in the target and lower doses to normal structures than 3D conformal plans. The results varied when the comparison was made with fixed gantry IMRT. In general, IMAT plans provided more uniform dose distributions in the target, whereas the inverse-planned fixed gantry treatments had greater flexibility in controlling dose to the critical structures. Because the field sizes and shapes used in the IMAT were similar to those used in conventional treatments, the dosimetric uncertainty was very small. Of the first 32 patients treated, the average difference between the measured and predicted doses was -0.54 +/- 1.72% at isocenter. The 80%-95% isodose contours measured with film dosimetry matched those predicted by the planning system to within 2 mm. The planning time for IMAT was slightly longer than for generating conventional 3D conformal plans. However, because of the need to create phantom plans for the dry run, the overall planning time was doubled. The average time a patient spent on the table for IMAT treatment was similar to conventional treatments.

CONCLUSION

Initial results demonstrated the feasibility and accuracy of IMAT for achieving highly conformal dose distributions for different sites. If treatment plans can be optimized for IMAT cone beam delivery, we expect IMAT to achieve dose distributions that rival both slice-based and fixed-field IMRT techniques. The efficient delivery with existing linac and MLC makes IMAT a practical choice.

Implementing multiple static field delivery for intensity modulated beams

A clinically oriented two-dimensional intensity-modulated beam delivery method is implemented using multiple static segmented fields, i.e., the "step-and-shoot" approach. Starting with a desired al" intensity distribution, it creates a multiple-level intensity approximation, and then constructs a sequence of segmented fields to deliver the multiple-level intensities using multileaf collimator (MLC) and independent backup jaws. The approach starts with a simple grouping of all the nonzero intensity values into a minimum number of clusters for a user specified deviation tolerance for the ideal plan. The k-means clustering algorithm is then employed to find the optimal levels of intensity that minimize the discrepancies between the ideal and the approximated intensities, without violating the user specified deviation tolerance. The multiple-level intensities are then decomposed into a sequence of machine deliverable segments. Apart from the first segment for each gantry angle, all the other segments are arranged to minimize the total travel distance of the leaves. The first segment covers the entire irradiated area and is used for treatment verification by electronic portal imaging. The implementation issues due to the physical constraints of the MLCs are also addressed.

Maximizing local tumor control and survival after proton beam radiotherapy of uveal melanoma

PURPOSE

This study reports local tumor control and survival after proton beam radiotherapy (PBRT) of uveal melanoma. It identifies the risk factors for local tumor-control failure and for ocular tumor-related death. It presents the improvements implemented to increase the rate of local tumor control, and compares the survival rate of patients with locally controlled tumors to those of patients who had to receive a second treatment.

PATIENTS AND METHODS

We have treated 2,435 uveal melanomas with PBRT between March 1984 and December 1998. Data were analyzed as of September 1999. Patients' age ranged from 9 to 89 years; there were 1,188 men and 1,247 women. The largest tumor diameter ranged from 4 to 26 mm, and tumor thickness from 0.9 to 15.6 mm. Median follow-up time was 40 months.

RESULTS

Local tumor control probability at 5 years was improved from 90.6 +/- 1.7% for patients treated before 1988, to 96.3 +/- 0.6% for patients treated between 1989 and 1993, and became 98.9 +/- 0.6% for patients treated after 1993. Among 2,435 treated patients, 73 (3%) had to receive a second treatment because of tumor regrowth. Cause-specific survival at 10 years was calculated to 72.6 +/- 1.9% for patients with controlled tumors compared to 47.5 +/- 6.5% for those with recurrent tumors.

CONCLUSION

Reduced safety margins, large ciliary body tumors, eyelids within the treatment field, inadequate positioning of tantalum clips, and male gender were identified to be the main factors impairing local tumor control. The improvement of local tumor control rate after 1993 is attributed to changes implemented in the treatment procedure. Our data strongly support that the rate of death by metastases is influenced by local tumor control failure: improvement of the local tumor control rate results in a better survival rate.

A novel approach to overcome hypoxic tumor resistance: Cu-ATSM-guided intensity-modulated radiation therapy

PURPOSE

Locoregional tumor control for locally advanced cancers with radiation therapy has been unsatisfactory. This is in part associated with the phenomenon of tumor hypoxia. Assessing hypoxia in human tumors has been difficult due to the lack of clinically noninvasive and reproducible methods. A recently developed positron emission tomography (PET) imaging-based hypoxia measurement technique which employs a Cu(II)-diacetyl-bis(N(4)-methylthiosemicarbazone) (Cu-ATSM) tracer is of great interest. Oxygen electrode measurements in animal experiments have demonstrated a strong correlation between low tumor pO(2) and excess (60)Cu-ATSM accumulation. Intensity-modulated radiation therapy (IMRT) allows selective targeting of tumor and sparing of normal tissues. In this study, we examined the feasibility of combining these novel technologies to develop hypoxia imaging (Cu-ATSM)-guided IMRT, which may potentially deliver higher dose of radiation to the hypoxic tumor subvolume to overcome inherent hypoxia-induced radioresistance without compromising normal tissue sparing.

METHODS AND MATERIALS

A custom-designed anthropomorphic head phantom containing computed tomography (CT) and positron emitting tomography (PET) visible targets consisting of plastic balls and rods distributed throughout the "cranium" was fabricated to assess the spatial accuracy of target volume mapping after multimodality image coregistration. For head-and-neck cancer patients, a CT and PET imaging fiducial marker coregistration system was integrated into the thermoplastic immobilization head mask with four CT and PET compatible markers to assist image fusion on a Voxel-Q treatment-planning computer. This system was implemented on head-and-neck cancer patients, and the gross tumor volume (GTV) was delineated based on physical and radiologic findings. Within GTV, regions with a (60)Cu-ATSM uptake twice that of contralateral normal neck muscle were operationally designated as ATSM-avid or hypoxic tumor volume (hGTV) for this feasibility study. These target volumes along with other normal organs contours were defined and transferred to an inverse planning computer (Corvus, NOMOS) to create a hypoxia imaging-guided IMRT treatment plan.

RESULTS

A study of the accuracy of target volume mapping showed that the spatial fidelity and imaging distortion after CT and PET image coregistration and fusion were within 2 mm in phantom study. Using fiducial markers to assist CT/PET imaging fusion in patients with carcinoma of the head-and-neck area, a heterogeneous distribution of (60)Cu-ATSM within the GTV illustrated the success of (60)Cu-ATSM PET to select an ATSM-avid or hypoxic tumor subvolume (hGTV). We further demonstrated the feasibility of Cu-ATSM-guided IMRT by showing an example in which radiation dose to the hGTV could be escalated without compromising normal tissue (parotid glands and spinal cord) sparing. The plan delivers 80 Gy in 35 fractions to the ATSM-avid tumor subvolume and the GTV simultaneously receives 70 Gy in 35 fractions while more than one-half of the parotid glands are spared to less than 30 Gy.

CONCLUSION

We demonstrated the feasibility of a novel Cu-ATSM-guided IMRT approach through coregistering hypoxia (60)Cu-ATSM PET to the corresponding CT images for IMRT planning. Future investigation is needed to establish a clinical-pathologic correlation between (60)Cu-ATSM retention and radiation curability, to understand tumor re-oxygenation kinetics, and tumor target uncertainty during a course of radiation therapy before implementing this therapeutic approach to patients with locally advanced tumor.

a controlled trial of intratumoral ONYX-015, a selectively-replicating adenovirus, in combination with cisplatin and 5-fluorouracil in patients with recurrent head and neck cancer

ONYX-015 is an adenovirus with the E1B 55-kDa gene deleted, engineered to selectively replicate in and lyse p53-deficient cancer cells while sparing normal cells. Although ONYX-015 and chemotherapy have demonstrated anti-tumoral activity in patients with recurrent head and neck cancer, disease recurs rapidly with either therapy alone. We undertook a phase II trial of a combination of intratumoral ONYX-015 injection with cisplatin and 5-fluorouracil in patients with recurrent squamous cell cancer of the head and neck. There were substantial objective responses, including a high proportion of complete responses. By 6 months, none of the responding tumors had progressed, whereas all non-injected tumors treated with chemotherapy alone had progressed. The toxic effects that occurred were acceptable. Tumor biopsies obtained after treatment showed tumor-selective viral replication and necrosis induction.

Dosimetric effects of patient displacement and collimator and gantry angle misalignment on intensity modulated radiation therapy

PURPOSE AND OBJECTIVE

The primary goal of this study was to examine systematically the dosimetric effect of small patient movements and linear accelerator angular setting misalignments in the delivery of intensity modulated radiation therapy. We will also provide a method for estimating dosimetric errors for an arbitrary combination of these uncertainties.

MATERIALS AND METHODS

Sites in two patients (lumbar-vertebra and nasopharynx) were studied. Optimized intensity modulated radiation therapy treatment plans were computed for each patient using a commercially available inverse planning system (CORVUS, NOMOS Corporation, Sewickley, PA). The plans used nine coplanar beams. For each patient the dose distributions and relevant dosimetric quantities were calculated, including the maximum, minimum, and average doses in targets and sensitive structures. The corresponding dose volumetric information was recalculated by purposely varying the collimator angle or gantry angle of an incident beam while keeping other beams unchanged. Similar calculations were carried out by varying the couch indices in either horizontal or vertical directions. The intensity maps of all the beams were kept the same as those in the optimized plan. The change of a dosimetric quantity, Q, for a combination of collimator and gantry angle misalignments and patient displacements was estimated using Delta=Sigma(DeltaQ/Deltax(i))Deltax(i). Here DeltaQ is the variation of Q due to Deltax(i), which is the change of the i-th variable (collimator angle, gantry angle, or couch indices), and DeltaQ/Deltax(i) is a quantity equivalent to the partial derivative of the dosimetric quantity Q with respect to x(i).

RESULTS

While the change in dosimetric quantities was case dependent, it was found that the results were much more sensitive to small changes in the couch indices than to changes in the accelerator angular setting. For instance, in the first example in the paper, a 3-mm movement of the couch in the anterior-posterior direction can cause a 38% decrease in the minimum target dose or a 41% increase in the maximum cord dose, whereas a 5 degrees change in the &theta;(1)=20 degrees beam only gave rise to a 1.5% decrease in the target minimum or 5.1% in the cord maximum. The effect of systematic positioning uncertainties of the machine settings was more serious than random uncertainties, which tended to smear out the errors in dose distributions.

CONCLUSIONS

The dose distribution of an intensity modulated radiation therapy (IMRT) plan changes with patient displacement and angular misalignment in a complex way. A method was proposed to estimate dosimetric errors for an arbitrary combination of uncertainties in these quantities. While it is important to eliminate the angular misalignment, it was found that the couch indices (or patient positioning) played a much more important role. Accurate patient set-up and patient immobilization is crucial in order to take advantage fully of the technological advances of IMRT. In practice, a sensitivity check should be useful to foresee potential IMRT treatment complications and a warning should be given if the sensitivity exceeds an empirical value. Quality assurance action levels for a given plan can be established out of the sensitivity calculation.

Hyperfractionated radiation therapy with or without concurrent low-dose daily cisplatin in locally advanced squamous cell carcinoma of the head and neck: a prospective randomized trial

PURPOSE

To investigate whether the addition of cisplatin (CDDP) to hyperfractionation (Hfx) radiation therapy (RT) offers an advantage over the same Hfx RT given alone in locally advanced (stages III and IV) squamous cell carcinoma of the head and neck.

PATIENTS AND METHODS

One hundred thirty patients were randomized to receive either Hfx RT alone to a tumor dose of 77 Gy in 70 fractions in 35 treatment days over 7 weeks (group I, n = 65) or the same Hfx RT and concurrent low-dose (6 mg/m(2)) daily CDDP (group II, n = 65).

RESULTS

Hfx RT/chemotherapy offered significantly higher survival rates than Hfx RT alone (68% v 49% at 2 years and 46% v 25% at 5 years; P =.0075). It also offered higher progression-free survival (46% v 25% at 5 years; P =.0068), higher locoregional progression-free survival (LRPFS) (50% v 36% at 5 years; P =.041), and higher distant metastasis-free survival (DMFS) (86% v 57% at 5 years; P =.0013). However, there was no difference between the two treatment groups in the incidence of either acute or late high-grade RT-induced toxicity. Hematologic high-grade toxicity was more frequent in group II patients.

CONCLUSION

As compared with Hfx RT alone, Hfx RT and concurrent low-dose daily CDDP offered a survival advantage, as well as improved LRPFS and DMFS.

Diode-light transillumination for ophthalmic plaque localization around juxtapapillary choroidal melanomas

PURPOSE

An evaluation of plaque-mounted diode-light transillumination (DLT) for localization of episcleral plaques beneath juxtapapillary tumors.

METHODS AND MATERIALS

Two patients scheduled for radiotherapy for juxtapapillary melanomas were offered DLT as an additional method of ophthalmic plaque localization. Plaques were constructed by affixing 4 non-heat producing, light-emitting diodes with their apertures flush with the episcleral outer surface of the plaque's rim. Bio-implantable epoxy was used to encapsulate the electronic components. Then the plaques were loaded with 103Pd seeds. After the eye-plaques were sewn to the episclera covering the base of the intraocular tumors; the diode-lights were illuminated, viewed and recorded. Photodocumentation of the relative position of the 4 lights around tumor's base was obtained in both cases.

RESULTS

Digital images of plaque-mounted diode retro-transillumination were obtained. No evidence of diode-light toxicity was noted. Both tumors were found to be covered by the ophthalmic plaques.

CONCLUSION

Juxtapapillary tumors are often difficult or impossible to visualize with standard transillumination techniques and have been associated with poor local control rates. We have developed plaque-mounted DLT in an effort to improve ophthalmic plaque localization. Retrobulbar transillumination was viewed by indirect ophthalmoscopy and recorded with video-imaging. This technique provides unique photographic documentation of episcleral plaque localization beneath juxtapapillary tumors.

Determination of tumor kinetics: strategies for the delivery of radiotherapy and chemotherapy

Both clinical and laboratory evidence indicates that local control rates for many experimental and clinical human tumors decrease with protraction of the overall duration of radiation therapy and that a likely basis for this decrease is tumor cell repopulation during treatment. Such observations have stimulated interest in tumor kinetics, and a number of techniques have been developed that increase the potential for meaningful clinical study of the proliferative behavior of tumors. This review discusses the clinical and experimental evidence for proliferation during treatment, describes two potential approaches-accelerated fractionation and concurrent chemotherapy and radiotherapy-that can be employed to counteract such intratreatment proliferation, explores methods available for measuring tumor cell kinetics, and discusses how kinetics information may be used in the future to tailor therapy to a tumor's individual characteristics.

Intensity-modulated radiation therapy with dynamic multileaf collimators

Intensity-modulated radiotherapy (IMRT) has been considered as a means of providing dose distributions that conform to concave target volumes. For computer-controlled multileaf collimators (MLCs) to be used to modulate x-ray beams, some procedure must be used to determine the sequence of leaf positions used to produce the desired modulation. This article derives and compares four leaf-sequencing algorithms. MLC leaf sequencing can be accomplished by representing the areal intensity modulation of a beam with a series of beam profiles. A velocity-modulation equation for computing the modulation required for a one-dimensional profile, described originally using more extensive algebra, is derived using a graphic approach. The velocity-modulation approach is compared with an equal incremental step-and-shoot approach derived by Bortfeld and Boyer. An areal step-and-shoot technique derived by Xia and Verhey is introduced and compared with the profile-by-profile methods. Finally, an approach is considered using multiple repeated arcs developed by Yu. This wide variety of methods can yield an approach to IMRT that conforms to the engineering constraints imposed by the design of a particular linear accelerator.

[Practical determination of volume and doses in conformal radiotherapy]

The determination of the target volumes and the dose to be delivered are critical medical steps in order to locally control the disease and to limit the risks of normal tissues injury. While many clinical situations are compatible with standardised technique and beam arrangements, the tools provided by modern medical diagnostic imaging procedures and tridimensional dosimetry allow an improved conformation of the irradiated volume and the administered dose to the clinical target volume. However, this approach requires an increased precision in tumour and normal tissues delineation, based on patient immobilisation devices, standardisation of mobile organs repletion status and image acquisition procedures, explicit definition of the biological and physical safety margins, definition of acceptable levels of dose heterogeneity in the planning target volume and appropriate quality assurance procedures.

An image registration scheme applied to verification of radiation therapy

The introduction of modern conformal radiation therapy techniques requires high geometric precision in treatment delivery which must be verified. For that purpose we have developed an automated system based on registration of portal and simulation (or planning) image pairs. The image registration is performed on anatomical features which are automatically extracted from the portal image. The portal image is then registered with a planning or simulation radiographic image which represents the geometric prescription for the treatment, using an optimized version of the chamfer matching algorithm. Subsequently, the magnitude of the radiation field displacement during treatment is measured by registering the prescribed and treated field boundaries. Algorithms based on chamfer matching and polygon matching have been used for the field boundary registration. Performance of the entire scheme was evaluated on a series of 15 portal images of a pelvic phantom representing various known degrees of the radiation field displacement. The measurements of the radiation field displacements performed by the automated system proved very reliable and after correction for systematic bias agreed to within 1.5 mm or 1 degree with the displacements applied. Second test series involved comparisons between the automated registrations and those performed manually/visually by an experienced human observer, on 31 portal images acquired during treatments of 18 pelvic patients. These tests showed close agreement (in 80% of cases discrepancies were smaller than 1.5 mm or 1.5 degrees) between the automated scheme and the human observer. It is concluded that the developed scheme would be suitable for online geometric verification of radiation therapy treatments.

Particle beam radiation therapy in prostate cancer: is there an advantage?

Hadron therapy uses heavy particles to deliver therapeutic ionizing energy. Each particle's inherent attributes determine the pattern of energy deposited by its beam, expressed in macro (conformability to a three-dimensional target volume) and micro (radiobiologic properties) distributions. Mass and charge regulate the inherent properties; beam energy provides a controllable, variable characteristic. Generally, heavy charged particles provide superior macrodosimetric properties; heavy particles (charged or not) have microdosimetric characteristics that produce high linear energy transfer (LET). Neutron macrodosimetry is similar to that of photons. Protons and helium ions possess superior macrodosimetric properties, plus microdosimetric characteristics resulting in low LET, yielding beam characteristics that approach the ideal for clinical radiotherapy. Hadron therapy for prostate cancer has been limited by the availability of appropriate treatment facilities. Nonetheless, encouraging results have been obtained. Neutron therapy demonstrated improved overall survival in a multi-institutional randomized trial, and improved local disease control in a subsequent trial. Proton radiation forms the boost component of several conformal dose-escalation studies. A Loma Linda University study demonstrated low treatment-related morbidity despite a prostate dose of 75 CGE; late-morbidity data were superior to published reports from multi-field, conformal photon therapy. A Phase III dose-escalation study of protons for early prostate cancer is proceeding.

The effects of intra-fraction organ motion on the delivery of dynamic intensity modulation

Computer-optimized treatment plans, aimed to enhance tumour control and reduce normal tissue complication, generally require non-uniform beam intensities. One of the techniques for delivering intensity-modulated beams is the use of dynamic multileaf collimation, where the beam aperture moves and the field shape changes during irradiation. When intensity-modulated beams are delivered with dynamic collimation, the problem of intra-fraction organ motion can cause distortions to the desired beam intensities. Unlike static field treatments, where intra-fraction organ motion only affects the boundaries creating broad dose penumbra, the interplay of the movement of the beam aperture and the movement of the patient anatomy can create 'hot' and 'cold' spots throughout the field. The mechanism for creating these effects is not well understood. This paper provides a simple analytical model which illustrates the fundamental mechanism for creating the dosimetric variations in the target when both the beam aperture and the target move during irradiation. Numerical analysis was carried out which calculates the cumulative primary photon fluence, or beam intensity, received by each point in the target, for a given pattern of motion. The results show that, for clinically realistic parameters, the magnitude of intensity variations in the target can be greater than 100% of the desired beam intensity. The magnitude of the photon intensity variations is strongly dependent on the speed of the beam aperture relative to the speed of the target motion, and the width of the scanning beam relative to the amplitude of target motion. The effects of fractionation as well as methods of minimizing and eliminating the dosimetric effects of intra-fraction organ motion are discussed.

The impact of adjuvant radiotherapy on carcinosarcoma of the uterus

BACKGROUND

The role of adjuvant radiotherapy in the setting of uterine carcinosarcoma has not been clearly established.

METHODS

A retrospective review of 60 patients receiving definitive therapy for carcinosarcoma of the uterus was undertaken at a single institution. Twenty-nine of 60 patients were treated with adjuvant radiotherapy.

RESULTS

The addition of radiotherapy significantly reduced the local recurrence rate from 55% (17 patients) to 3% (1 patient). Adjuvant radiotherapy reduced the risk of distant failure and death in patients with disease confined to the uterus but did not impact distant recurrence or survival in stage III patients. Increasing stage and depth of myometrial tumor invasion were negatively associated with overall survival and disease-free survival but had no impact on local recurrence rates. The nuclear grade of the epithelial component was predictive of local recurrence (P = 0.0592), but epithelial architectural grade, grade of stromal component, and stromal versus epithelial predominance did not provide prognostic information. The relative risk of local recurrence of unirradiated patients versus irradiated patients was 17.54 (P = 0.0055) after adjusting for nuclear grade of the epithelial component.

CONCLUSIONS

Local failure represents a significant site of failure in the absence of adjuvant radiotherapy. The improvement in local failure rates with the addition of radiotherapy translates into an improvement in distant failure rates and survival only for patients with stage I/II disease. Epithelial nuclear grade, in addition to depth of myometrial invasion and stage, provides important prognostic information. Epithelial architectural grade, stromal grade, type of stromal component (homologous versus heterologous), and predominance of either stromal or epithelial component were not found to be significant prognostic factors.

Radiation therapy for choroidal melanoma

Radiotherapy offers patients with malignant melanoma of the choroid an eye and a vision-sparing alternative to enucleation. The most commonly used forms of radiotherapy are ophthalmic plaque brachytherapy and charged-particle (external beam) radiotherapy. Unfortunately, after all forms of radiotherapy for choroidal melanoma many patients experience sight-limiting side effects, and an average of 16.3% of patients treated with radiotherapy subsequently require enucleation because of tumor regrowth or uncontrollable neovascular glaucoma. The severity, location, and incidence of radiation-induced complications are related to the type of radiation used, its method of delivery, amount of radiation delivered to normal ocular structures, the size and location of the tumor, as well as its response to irradiation. Current research is directed toward developing methods to reduce the amount of radiation delivered to normal structures, e.g., adding heat to radiotherapy. The true viability and metastatic potential of irradiated uveal melanoma cells has not been established, although clinical studies have reported local control of choroidal melanoma in 81-100% (mean = 92.8%) of cases. The purpose of this review is to present the world's experience with radiotherapy for choroidal melanoma, information that will contribute to patient education and informed consent.