Detection of recurrence in childhood solid tumors

Relapsing pediatric non-rhabdomyosarcoma soft tissue sarcomas: The impact of routine imaging surveillance on early detection and post-relapse survival

PURPOSE

The chances of patients with relapsing pediatric non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) being cured are limited. This retrospective single-institutional study examines the potential role of routine surveillance imaging for detecting recurrent tumor, and its impact on post-relapse survival.

METHODS

The analysis concerned 86 patients < 21 years old with relapsing NRSTS treated from 1985 to 2020. Clinical findings, treatment modalities and survival were analyzed, comparing patients whose relapse was first suspected from symptoms (symptomatic group) with those whose relapse was detected by radiological surveillance (imaging group).

RESULTS

Tumor relapses were identified from clinical symptoms in 49 cases and on routine imaging in 37. Time to relapse was similar in the two groups. Routine imaging detected 6/32 local relapses and 31/48 distant relapses (and 79% of the cases of lung metastases). Overall survival (OS) at 5 years was 34.3% for the symptomatic group, and 24.0% for the imaging group (p-value 0.270). In patients with lung metastases at relapse, the 5-year OS was statistically better for the imaging group, that is, 25.8% versus 0% for the symptomatic group (p-value 0.044).

CONCLUSION

This is the first study to explore the role of surveillance imaging in pediatric NRSTS. Judging from our findings, the value of routine scanning of primary sites seems limited, while radiological surveillance may help to detect lung metastases, improving survival for this patient category. The potentially negative effects of periodic radiological exams should be considered in deciding the optimal follow-up for patients off therapy.

Is Detection of Relapse by Surveillance Imaging Associated With Longer Survival in Patients With Rhabdomyosarcoma?

BACKGROUND

We investigated whether surveillance imaging had an impact on post-relapse survival in patients with rhabdomyosarcoma (RMS). We hypothesized that relapse detected by imaging (group IM) would be associated with longer survival compared with relapse detected with a clinical sign or symptom (group SS).

MATERIALS AND METHODS

We performed an observational multi-institutional study in 127 patients with relapsed RMS comparing overall survival (OS) after relapse using Kaplan-Meier and Cox proportional hazards analyses.

RESULTS

Relapse was detected in 60 (47%) group IM and 67 (53%) SS patients. Median follow-up in survivors was 4 years (range 1.0 to 16.7 y). Four-year OS rates were similar between group IM (28%, 95% confidence interval [CI]: 14%-40%) and SS (21%, 95% CI: 11%-31%) ( P =0.14). In multivariable analyses accounting for institution, age at diagnosis, time to relapse, risk group at diagnosis, and primary site, not receiving chemotherapy (hazard ratio [HR]: 6.8, 95% CI: 2.8-16.6), radiation (HR: 3, 95% CI: 1.7-5.3), or surgery (HR: 2.8, 95% CI: 1.6-4.8) after relapse were independently associated with poor OS.

CONCLUSION

These results on whether surveillance imaging provides survival benefit in patients with relapsed RMS are inconclusive. Larger studies are needed to justify current surveillance recommendations. Chemotherapy, radiotherapy and surgery to treat recurrence prolong OS.

Role of surveillance screening in detecting tumor recurrence after treatment of childhood cancers

Objective

As the survival rates in children with cancer reach up to 80%, this improvement in survival increases the number of patients under follow-up. After cancer treatment is completed, patients are taken to follow-up surveillance to ensure the early detection of recurrence and the late effects of treatments. The frequency and necessity of surveillance screening tests are controversial. This study aimed to assess the efficacy of surveillance screening in the detection of recurrence.

Material and methods

The files of 533 children who were diagnosed as having cancer at our pediatric oncology clinic between 2004 and 2013 were retrospectively evaluated. We looked at outcomes after recurrence, the timing and pattern of recurrence, the presence of symptoms during recurrence, physical examination findings, tumor marker levels, laboratory findings, and radiologic tests.

Results

Of the 63 patients with recurrence, 23 were symptomatic and 40 were asymptomatic at the time of the recurrence. Tumor location and time of the recurrence did not affect the post recurrence survival. The median post-recurrence survival for patients was 13 (range, 1-98) months. The median post-relapse survival was 10 (range, 1-73) months in patients with symptomatic recurrence, and 16 (range, 1-98) months in patients with asymptomatic recurrence. It was determined that patients in whom recurrence was identified with surveillance tests had longer post-relapse survival time. The 5-year survival rate of 23 patients with symptomatic recurrence was 12.2%; this rate was 49.5% in asymptomatic patients (p<0.05).

Conclusions

It should be considered that surveillance testing offers the benefit of prolonging post recurrence survival.

A systematic review of evidence for and against routine surveillance imaging after completing treatment for childhood extracranial solid tumors

BACKGROUND

Regular off-treatment imaging is often used to assess for recurrence of disease after childhood cancer treatment. It is unclear if this increases survival, or what burden surveillance places on patients, families, or health-care services. This systematic review examines the impact of routine surveillance imaging after treatment of pediatric extracranial solid tumors.

METHODS

Collaborative patient and public involvement informed the design and interpretation of this work. Thirteen electronic databases, conference proceedings, and trial registries were searched alongside reference list checking and forward citation searching from 1990 onwards. Studies were screened and data were extracted by two researchers. Risk of bias was assessed using a modified ROBINS-I tool. Relevant outcomes were overall survival, psychological distress indicators, number of imaging tests, cost-effectiveness, and qualitative data regarding experiences of surveillance programs. PROSPERO (CRD42018103764).

RESULTS

Of 17 727 records identified, 55 studies of 10 207 patients were included. All studies used observational methods. Risk of bias for all except one study was moderate, serious, or critical. Data were too few to conduct meta-analysis; however, narrative synthesis was performed. Surveillance strategies varied, and poorly reported, involving many scans and substantial radiation exposure (eg, neuroblastoma, median 133.5 mSv). For most diseases, surveillance imaging was not associated with increased overall survival, with the probable exception of Wilms tumor. No qualitative or psychological distress data were identified.

CONCLUSIONS

At present, there is insufficient evidence to evaluate the effects of routine surveillance imaging on survival in most pediatric extracranial solid tumors. More high-quality data are required, preferably through randomized controlled trials with well-conducted qualitative elements.

Is surveillance imaging in pediatric patients treated for localized rhabdomyosarcoma useful? The European experience

Background

After the completion of therapy, patients with localized rhabdomyosarcoma (RMS) are subjected to intensive radiological tumor surveillance. However, the clinical benefit of this surveillance is unclear. This study retrospectively analyzed the value of off‐therapy surveillance by comparing the survival of patients in whom relapse was detected by routine imaging (the imaging group) and patients in whom relapse was first suspected by symptoms (the symptom group).

Methods

This study included patients with relapsed RMS after the completion of therapy for localized RMS who were treated in large pediatric oncology hospitals in France, the United Kingdom, Italy, and the Netherlands and who were enrolled in the International Society of Paediatric Oncology Malignant Mesenchymal Tumor 95 (1995‐2004) study, the Italian Paediatric Soft Tissue Sarcoma Committee Rhabdomyosarcoma 96 (1996‐2004) study, or the European Paediatric Soft Tissue Sarcoma Study Group Rhabdomyosarcoma 2005 (2005‐2013) study. The survival times after relapse were compared with a log‐rank test between patients in the imaging group and patients in the symptom group.

Results

In total, 199 patients with relapsed RMS were included: 78 patients (39.2%) in the imaging group and 121 patients (60.8%) in the symptom group. The median follow‐up time after relapse was 7.4 years (interquartile range, 3.9‐11.5 years) for survivors (n = 86); the 3‐year postrelapse survival rate was 50% (95% confidence interval [CI], 38%‐61%) for the imaging group and 46% (95% CI, 37%‐55%) for the symptom group (P = .7).

Conclusions

Although systematic routine imaging is the standard of care after RMS therapy, the majority of relapses were detected as a result of clinical symptoms. This study found no survival advantage for patients whose relapse was detected before the emergence of clinical symptoms. These results show that the value of off‐therapy surveillance is controversial, particularly because repeated imaging may also entail potential harm.

This study assesses the clinical value of radiological surveillance imaging in pediatric patients with rhabdomyosarcoma, which is routinely performed after the completion of therapy. In the majority of patients, relapse is detected because of symptoms, and there is no evidence that early detection by imaging results in improved survival.

Surveillance imaging in pediatric lymphoma

Current therapies used in treating children with Hodgkin lymphoma and many histological subtypes of non-Hodgkin lymphoma have resulted in overall survival rates exceeding 90% in many instances. With increasing concerns related to the cost of radiologic imaging, exposure to ionizing radiation, and potential false-positive results, the role of routine off-therapy surveillance imaging has been called into question. Although radiologic imaging plays an important role in diagnosing and assessing treatment response, in these children - the majority of whom have an excellent outcome following completion of therapy - there is an opportunity to dramatically reduce the number of off-therapy imaging evaluations. This review summarizes several recent studies in both Hodgkin and non-Hodgkin lymphoma providing evidence to support these efforts. In addition, we propose a surveillance imaging strategy that uses a novel risk-adapted and response-based approach to determine which children would most benefit from off-therapy imaging surveillance.

Does routine surveillance imaging after completing treatment for childhood solid tumours cause more harm than good? A systematic review and meta-analysis protocol

BACKGROUND

This systemic review aims to synthesise the current literature surrounding off-therapy surveillance imaging in children and young people with extra-cranial solid tumours, with a view to establishing if routine imaging studies after treatment for childhood cancer increase overall survival, increase the psychological distress caused to patients and families, result in other harms to patients and are cost-effective strategies. Within this manuscript, we also describe how patient and public involvement has impacted upon the protocol.

METHODS

The search will cover thirteen different databases, key conference proceedings and trial registers, as well as reference lists and forward citations of included papers. Prominent authors/clinicians in the field will be contacted. A full search strategy is provided. The study designs to be included in the review will be added in an iterative way (RCTs, quasi-randomised trials, prospective cohorts and retrospective cohorts). Qualitative studies will also be eligible for inclusion. We will include studies which examine a programme of surveillance imaging that aims to detect relapse in children or young people up to age 25 years who have completed treatment for a malignant extracranial solid tumour and have no evidence of active and ongoing disease at end of treatment. The primary outcome is overall survival, with secondary outcomes including psychological distress indicators, number of imaging tests performed, other harms of imaging and cost-effectiveness measures. Studies will be screened and data extracted by two researchers. Studies will be critically appraised using a stratified version of the ROBINS-I tool. Where appropriate, data will be synthesised using a random effects meta-analysis. A detailed analysis plan, including assessment of heterogeneity and publication bias, is provided.

DISCUSSION

The aim of routine surveillance imaging is to detect recurrence of disease before clinical symptoms and signs develop. Some studies have suggested that most relapses of childhood cancer are detected due to clinical symptoms or signs, particularly in those with extra-cranial solid tumours, and when these relapses are detected by imaging, there is no increase in survival. This review aims to establish whether routine surveillance imaging is beneficial, as well as evaluating the potential negative impacts of surveillance programmes.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018103764.

Staging and following common pediatric malignancies: MRI versus CT versus functional imaging

Most pediatric malignancies require some form of cross-sectional imaging, either for staging or response assessment. The majority of these are solid tumors and this review addresses the role of MRI, as well as other cross-sectional and functional imaging techniques, for evaluating the most common pediatric solid tumors. The primary emphasis is on neuroblastoma, hepatoblastoma and Wilms tumor, three of the most common non-central-nervous-system (CNS) pediatric solid tumors encountered in young children. The initial focus will be a review of the imaging techniques and approaches used for diagnosis, staging and early post-treatment response assessment, followed by a discussion of the role surveillance imaging plays in pediatric oncology and a brief review of other emerging imaging techniques. The lessons learned here can be applied to most other pediatric tumors, including rhabdomyosarcoma, Ewing sarcoma and osteosarcoma, as well as germ cell tumors, neurofibromatosis and other rare tumors. Although lymphoma, in particular Hodgkin lymphoma, represents one of the more common pediatric malignancies, this is not discussed in detail here. Rather, many of the lessons that we have learned from lymphoma, specifically with regard to how we integrate both anatomical imaging and functional imaging techniques, is applied to the discussion of the other pediatric solid tumors.

Routine surveillance imaging after end of therapy for pediatric extracranial tumors: A retrospective analysis

Frequent surveillance imaging is routine practice for pediatric patients after cancer therapy. This retrospective study evaluated the follow-up of 301 children with extracranial tumors diagnosed between 2002 and 2012, at a tertiary pediatric cancer center in Beirut, Lebanon. Recurrence occurred in 15% of patients, at a median of 12 months after end of primary therapy. Outcome was not different comparing patients with recurrence detected via imaging surveillance versus clinically. False positive findings in 55 patients led to further interventions. These results raise important questions regarding benefit of current surveillance practices as standard care, especially in countries with limited resources.

[Relapse after rhabdomyosarcoma in childhood and adolescence: Impact of an early detection on survival]

SUBJECT

Prognostic values of an early detection of a relapse after treatment of a localized rhabdomyosarcoma and the interest of performing systematic radiologic assessment after treatment have not yet been evaluated in Europe.

MATERIAL AND METHODS

Modalities of relapse of 99 patients under 20 years of age, after an initially localized rhabdomyosarcoma, treated in 9 French centers ("Société française des cancers de l'enfant" consortium) have been analyzed. Prognostic value of the protocol compliance during the observation period after therapy has been evaluated.

RESULTS

Relapses have been diagnosed in 59 cases by a "symptom" the child was complaining of, in 12 cases because of "physical signs" detected during the clinical examination of a systematic consultation and in 27 cases thanks to "systematic follow-up imaging" (missing data: 1 case). Survival after relapse at 3 years was 47.5 % (IC95 %: 37.1 %-57.1 %). Diagnosis of the relapse is established earlier in the group "systematic imaging" rather than with other methods of detection ("symptom", "physical signs"), (P= 0.025), with detection of smaller tumors (≤ 5 cm ; 100.0 % vs. 60.9 % vs. 77.8 %, P= 0.007) but without possibility of reaching a second remission (70.4 % vs. 50.8 % vs. 50.0 % P= 0.37), nor significant impact on 5-year overall survival (47.1 % vs. 47.1 % vs. 48.6 % P= 0.94).

CONCLUSION

Current methods of systematic surveillance after a first-line treatment of an initially localized rhabdomyosarcoma seem to improve the earliness of the diagnosis, but not the prognosis of the relapse.

Surveillance imaging and radiation exposure in the detection of relapsed neuroblastoma

BACKGROUND

More than half of children with high-risk neuroblastoma (NB) will experience recurrence. Radiologic imaging is used for initial staging and during therapy to assess response. However, the role of surveillance imaging in the detection of relapse has not been well studied. Surveillance potentially results in high cumulative exposure to ionizing radiation, which may be associated with an increased risk of developing second malignancies.

PROCEDURE

We reviewed NB cases at our institution between 2000 and 2011. We calculated radiation exposure due to imaging (during diagnosis, treatment, and posttherapy surveillance) using cumulative effective dose (CED) estimates and determined whether cross-sectional imaging identified recurrences.

RESULTS

Fifty of 183 patients with NB experienced a recurrence. The median time from diagnosis to relapse was 1.20 years (range: 0.18-6.66 years). Most patients had evidence of metastases and only 4 of 50 patients presented with isolated primary tumor site recurrences. The mean CED prior to relapse was 125.2 mSv (range: 24.5-259.7), 64% of which was from computed tomography (CT) scans. Thirty-seven of 50 patients had clinically evident or measurable disease detected by X-ray (XR), ultrasound (US), or urinary catecholamines (UCats), and the addition of metaiodobenzylguanidine (MIBG) scans identified eight additional recurrences. Thus, cross-sectional imaging (CT/MRI, where MRI is magnetic resonance imaging) was only required to identify 10% (5/50) of cases.

CONCLUSION

Relapsed disease was detected in most patients by symptoms/exam, MIBG scan, UCats, and/or XR/US, supporting reduced use of CT imaging in posttherapy surveillance, thereby decreasing cumulative radiation dose. Refinement of surveillance imaging may be further guided by risk stratification, disease sites, and potentially biomolecular markers.

Does Routine Imaging of Patients for Progression or Relapse Improve Survival in Rhabdomyosarcoma?

BACKGROUND

Patients with rhabdomyosarcoma (RMS) who complete therapy typically undergo 4 years of surveillance imaging despite lack of evidence that this improves outcomes. We compared overall survival (OS) between patients in whom progression or relapse was detected by routine clinical evaluation or by imaging.

PROCEDURE

Children with progressive or relapsed RMS treated at Texas Children's Hospital between 1992 and 2012 were identified and their records were reviewed. Survival time after progression or relapse was compared between two groups: (1) patients in whom progression or relapse was suspected on the basis of clinical history, symptoms, laboratory evaluation, or physical exam; and (2) patients whose progression or relapse was initially detected by imaging.

RESULTS

Of the 43 children with progressive or relapsed RMS, 26 (60%) had metastatic disease at diagnosis and 19 (44%) had alveolar histology. With a median follow up time of 5 years in six survivors, there was no difference in OS between patients in whom progression or relapse was diagnosed based on imaging (n = 15) or by clinical evaluation (n = 28) (3-year OS 20% vs. 11%, respectively, P = 0.38). Disease extent, primary site, and risk group at diagnosis were associated with survival after progression or relapse.

CONCLUSIONS

Routine surveillance imaging practice should be critically reviewed for children with RMS. Although our findings must be validated by larger studies, they do have substantive implications. Reduced imaging tailored to the risk and pattern of recurrence, associated risks and cost could improve patient quality of life and decrease health-care expenditure without compromising outcome.

Post-treatment surveillance abdominopelvic computed tomography in children with Wilms tumour: Is it worth the risk?

Background: Wilms tumour is a comparatively common paediatric malignancy with a relatively good prognosis. Routine post-treatment surveillance at our institution currently includes regular abdominopelvic computed tomography (CT) over a two-year period for the early detection of disease recurrence. The rationale is that early salvage therapy may improve overall patient survival, and thus justifies the exposure to potentially harmful ionising radiation. Objective: To critically evaluate the routine use of post-treatment abdominopelvic CT by determining the detection rate of disease recurrence and associated clinical outcomes.Methods: Sixty-four patients in remission following initial treatment for Wilms tumour were included in this retrospective study. Variables obtained from patient records included gender, age, histological grading and tumour stage at presentation, number of abdominopelvic CT scans, site(s) of relapse, method of recurrence detection and confirmation, time to recurrence and clinical outcome. Results: The patients received a total of 334 surveillance abdominopelvic CT scans. Nine (14%) patients developed disease recurrence during the follow-up period. In three cases, the initial detection method was abdominopelvic CT. All three of these patients subsequently died despite salvage therapy (22 months median survival). Five false-positive diagnoses of recurrence occurred, with two being made on abdominopelvic CT. Conclusion: Routine post-treatment abdominopelvic CT showed a low detection rate of disease recurrence in children treated for Wilms tumour, while subjecting patients to a large radiation burden. The recommendation is that current practice be changed in line with the ultrasound-based Société Internationale d’Oncologie Pédiatrique (SIOP) imaging guidelines.

The role of chest computed tomography (CT) as a surveillance tool in children with high-risk neuroblastoma

BACKGROUND

Standardization of imaging obtained in children with neuroblastoma is not well established. This study examines chest CT in pediatric patients with high-risk neuroblastoma.

PROCEDURE

Medical records and imaging from 88 patients with high-risk neuroblastoma, diagnosed at St. Jude Children's Research Hospital between January, 2002 and December, 2009, were reviewed. Surveillance imaging was conducted through 2013. Ten patients with thoracic disease at diagnosis were excluded. Event free survival (EFS) and overall survival (OS) were estimated. Size specific dose estimates for CT scans of the chest, abdomen, and pelvis were used to estimate absolute organ doses to 23 organs. Organ dosimetry was used to calculate cohort effective dose.

RESULTS

The 5 year OS and EFS were 51.9% ± 6.5% and 42.6% ± 6.5%, respectively. Forty-six (58.9%) patients progressed/recurred and 41 (52.6%) died of disease. Eleven patients (14%) developed thoracic disease progression/recurrence identified by chest CT (1 paraspinal mass, 1 pulmonary nodules, and 9 nodal). MIBG (metaiodobenzylguanidine) scans identified thoracic disease in six patients. Five of the 11 had normal chest MIBG scans; three were symptomatic and two were asymptomatic with normal chest MIBG scans but avid bone disease. The estimated radiation dose savings from surveillance without CT chest imaging was 42%, 34% when accounting for modern CT acquisition (2011-2013).

CONCLUSIONS

Neuroblastoma progression/recurrence in the chest is rare and often presents with symptoms or is identified using standard non-CT imaging modalities. For patients with non-thoracic high-risk neuroblastoma at diagnosis, omission of surveillance chest CT imaging can save 35-42% of the radiation burden without compromising disease detection.

Pediatric oncology surveillance imaging: two recommendations. Abandon CT scanning, and randomize to imaging or solely clinical follow-up

Radiologic assessments in children with cancer provide information crucial to patient management at diagnosis and during follow-up. Many studies have now been published, however, questioning the usefulness of off-therapy surveillance imaging. There is growing concern regarding the hazards from diagnostic irradiation to young patients, most notably from CT scanning. In this paper we advocate abandoning repeated CT surveillance in young patients with a previously treated solid malignancy not arising in the central nervous system. In addition, randomized studies of imaging surveillance versus no imaging surveillance strategies are needed to determine whether earlier detection of recurrence results in improved survival.

Isolation of tumor spheres and mesenchymal stem-like cells from a single primitive neuroectodermal tumor specimen

PURPOSE

It has been reported that cancer stem cells (CSCs) can be isolated from primitive neuroectodermal tumor (PNET) specimens. Moreover, mesenchymal stem-like cells (MSLCs) have been isolated from Korean glioma specimens. Here, we tested whether tumor spheres and MSLCs can be simultaneously isolated from a single PNET specimen, a question that has not been addressed.

METHODS

We isolated single-cell suspensions from PNET specimens, then cultured these cells using methods for MSLCs or CSCs. Cultured cells were analyzed for surface markers of CSCs using immunocytochemistry and for surface markers of bone marrow-derived mesenchymal stem cells (BM-MSCs) using fluorescence-activated cell sorting (FACS). Tumor spheres were exposed to neural differentiation conditions, and MSLCs were exposed to mesenchymal differentiation conditions. Possible locations of MSLCs within PNET specimens were determined by immunofluorescence analysis of tumor sections.

RESULTS

Cells similar to tumor spheres and MSLCs were independently isolated from one of two PNET specimens. Spheroid cells, termed PNET spheres, were positive for CD133 and nestin, and negative for musashi and podoplanin. PNET spheres were capable of differentiation into immature neural cells and astrocytes, but not oligodendrocytes or mature neural cells. FACS analysis revealed that adherent cells isolated from the same PNET specimen, termed PNET-MSLCs, had surface markers similar to BM-MSCs. These cells were capable of mesenchymal differentiation. Immunofluorescence labeling indicated that some CD105(+) cells might be closely related to endothelial cells and pericytes.

CONCLUSION

We showed that both tumor spheres and MSLCs can be isolated from the same PNET specimen. PNET-MSLCs occupied a niche in the vicinity of the vasculature and could be a source of stroma for PNETs.

Is routine pelvic surveillance imaging necessary in patients with Wilms tumor?

BACKGROUND

It is unclear whether routine pelvic imaging is needed in patients with Wilms tumor. Thus, the primary objective of the current study was to examine the role of routine pelvic computed tomography (CT) in a cohort of pediatric patients with Wilms tumor.

METHODS

With institutional review board approval, the authors retrospectively identified 110 patients who had Wilms tumor diagnosed between January 1999 and December 2009 with surveillance imaging that continued through March 2011. The authors estimated overall survival (OS), event-free survival (EFS), and dosimetry from dose length product (DLP) conversion to the effective dose (ED) for every CT in a subgroup of 80 patients who had CT studies obtained using contemporary scanners (2002-2011). Metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters were placed within organs of anthropomorphic phantoms to directly calculate the truncal ED. ED(DLP) was correlated with ED(MOSFET) to calculate potential pelvic dose savings.

RESULTS

Eighty patients underwent 605 CT examinations that contained DLP information, including 352 CT scans of the chest, abdomen, and pelvis; 123 CT scans of the chest and abdomen; 102 CT scans of the chest only; 18 CT scans of the abdomen and pelvis; 9 CT scans of the abdomen only; and 1 CT that was limited to the pelvis. The respective 5-year OS and EFS estimates were 92.8% ± 3% and 2.6% ± 4.3%. Sixteen of 110 patients (15%) developed a relapse a median of 11.3 months (range, 5.0 months to 7.3 years) after diagnosis, and 4 patients died of disease recurrence. Three patients developed pelvic relapses, all 3 of which were symptomatic. The estimated ED savings from sex-neutral CT surveillance performed at a 120-kilovolt peak without pelvic imaging was calculated as 30.5% for the average patient aged 1 year, 30.4% for the average patient aged 5 years, 39.4% for the average patient aged 10 years, and 44.9% for the average patient aged 15 years.

CONCLUSIONS

Omitting pelvic CT from the routine, off-therapy follow-up of patients with Wilms tumor saved an average 30% to 45% of the ED without compromising disease detection.

Oncological imaging: tumor surveillance in children

As the need for accurate diagnostic imaging often continues throughout a cancer survivor's life, imaging methods with the least toxicity must be used so as to provide needed information without contributing to long-term sequelae that might compound toxicities inherent with the primary disease and its treatment. In this regard, the costs, benefits and potential risks of post-therapy monitoring for disease recurrence warrant periodic review. Unfortunately, few analyses are available regarding the impact of surveillance imaging on the detection of disease recurrence, salvage rates of relapse disease and long-term survival outcomes for pediatric cancer survivors. This review will examine the role and limitations of surveillance imaging in pediatric oncology.

Pediatric brain tumor cancer stem cells: cell cycle dynamics, DNA repair, and etoposide extrusion

Reliable model systems are needed to elucidate the role cancer stem cells (CSCs) play in pediatric brain tumor drug resistance. The majority of studies to date have focused on clinically distinct adult tumors and restricted tumor types. Here, the CSC component of 7 newly established primary pediatric cell lines (2 ependymomas, 2 medulloblastomas, 2 gliomas, and a CNS primitive neuroectodermal tumor) was thoroughly characterized. Comparison of DNA copy number with the original corresponding tumor demonstrated that genomic changes present in the original tumor, typical of that particular tumor type, were retained in culture. In each case, the CSC component was approximately 3–4-fold enriched in neurosphere culture compared with monolayer culture, and a higher capacity for multilineage differentiation was observed for neurosphere-derived cells. DNA content profiles of neurosphere-derived cells expressing the CSC marker nestin demonstrated the presence of cells in all phases of the cell cycle, indicating that not all CSCs are quiescent. Furthermore, neurosphere-derived cells demonstrated an increased resistance to etoposide compared with monolayer-derived cells, having lower initial DNA damage, potentially due to a combination of increased drug extrusion by ATP-binding cassette multidrug transporters and enhanced rates of DNA repair. Finally, orthotopic xenograft models reflecting the tumor of origin were established from these cell lines. In summary, these cell lines and the approach taken provide a robust model system that can be used to develop our understanding of the biology of CSCs in pediatric brain tumors and other cancer types and to preclinically test therapeutic agents.

Initial Patient Characteristics Can Predict Pattern and Risk of Relapse in Localized Rhabdomyosarcoma

Purpose

Evaluation of primary tumor-, treatment-, and patient-related factors predicting relapse pattern, risk, and survival after relapse with the aim to design a risk-adapted, tumor-directed surveillance program for patients with localized rhabdomyosarcoma (RMS).

Patients and Methods

One thousand one hundred sixty-four patients with nonmetastatic RMS achieved complete remission at the end of multimodal therapy in the consecutive trials of the Cooperative Weichteilsarkom Studiengruppe (CWS)-81, CWS-86, CWS-91, and CWS-96 between 1980 and 2002 (median follow-up, 5 years). Three hundred thirty-seven of these individuals developed either locoregional, metastatic, or combined relapses. Predictive factors for relapse, its pattern, and postrelapse survival were analyzed.

Results

Age, histology, tumor size, tumor site, postsurgical stage, and omission of radiotherapy were identified as factors associated with an increased relapse risk in multivariate analyses. Relapse rates did not differ among the CWS trials. Median time to relapse was 1.43 years from first diagnosis (range, 0.13 to 13.5 years). There were 217 locoregional, 72 metastatic, and 48 combined recurrences. Only two patients developed metastases more than 4 years after diagnosis, and both had combined recurrences. Five-year postrelapse survival was 24%. Patient subsets with consistent relapse pattern, risk, and postrelapse survival rates were identified on the basis of histologic subtype and tumor size.

Conclusion

Initial patient and tumor characteristics predict pattern and risk of relapse and also correlate with postrelapse survival probabilities. In localized RMS, tumor-directed follow-up should focus on the primary site. Screening for metastatic relapse may not be necessary more than 4 years after diagnosis. The identification of subgroups with distinctive pattern and risk of relapse may be used to develop risk-adapted, tumor-directed guidance for detection of recurrent disease in localized RMS.