Patients with testicular cancer undergoing CT surveillance demonstrate a pitfall of radiation-induced cancer risk estimates: the timing paradox

Split-bolus single-phase versus single-bolus split-phase CT acquisition protocols for staging in patients with testicular cancer: A retrospective study

INTRODUCTION

Computed tomography (CT) imaging has become indispensable in the management of medical oncology patients. Risks associated with high cumulative effective dose (CED) are relevant in testicular cancer patients. Split-bolus protocols, whereby the contrast medium injection is divided into two, followed by combining the required phase images in a single scan acquisition has been shown to provide images of comparable image quality and less radiation dose compared to single-bolus split-phase CT for various indications. We retrospectively evaluated the performance of split-bolus and single-bolus protocols in patients having follow-up CT imaging for testicular cancer surveillance.

METHODS

45 patients with testicular cancer undergoing surveillance CT imaging of the thorax, abdomen, and pelvis who underwent split-bolus and single-bolus protocols were included. Quantitative image quality analysis was conducted by placing region of interests in pre-defined anatomical sub-structures within the abdominal cavity. The signal-to-noise ratio (SNR) and radiation dose in the form of dose length product (DLP) and effective dose (ED) were recorded.

RESULTS

The DLP and ED for the single-bolus, split-phase acquisition was 506 ± 89 mGy cm and 7.59 ± 1.3 mSv, respectively. For the split-bolus, single-phase acquisition, 397 ± 94 mGy∗cm and 5.95 ± 1.4 mSv, respectively (p < 0.000). This represented a 21.5 % reduction in radiation dose exposure. The SNR for liver, muscle and fat for the single-bolus were 7.4, 4.7 and 8, respectively, compared to 5.5, 3.8 and 7.4 in the split-bolus protocol (p < 0.001).

CONCLUSION

In a testicular cancer patient cohort undergoing surveillance CT imaging, utilization of a split-bolus single-phase acquisition CT protocol enabled a significant reduction in radiation dose whilst maintaining subjective diagnostic acceptability.

IMPLICATIONS FOR PRACTICE

Use of split-bolus, single-phase acquisition has the potential to reduce CED in surveillance of testicular cancer patients.

Can whole-body MRI replace CT in management of metastatic testicular cancer? A prospective, non-inferiority study

PURPOSE

Concerns of imaging-related radiation exposure in young patients with high survival rates have increased the use of magnetic resonance imaging (MRI) in testicular cancer (TC) stage I. However, computed tomography (CT) is still preferred for metastatic TC. The purpose of this study was to compare whole-body MRI incl. diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) with contrast-enhanced, thoracoabdominal CT in metastatic TC.

METHODS

A prospective, non-inferiority study of 84 consecutive patients (median age 33 years) with newly diagnosed metastatic TC (February 2018-January 2021). Patients had both MRI and CT before and after treatment. Anonymised images were reviewed by experienced radiologists. Lesion malignancy was evaluated on a Likert scale (1 benign-4 malignant). Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated on patient and lesion level. The primary outcome was demonstrating non-inferiority regarding sensitivity of MRI compared to CT. The non-inferiority margin was set at 5%. ROC curves and interobserver agreement were calculated.

RESULTS

On patient level, MRI had 98% sensitivity and 75% specificity compared to CT. On lesion level within each modality, MRI had 99% sensitivity and 78% specificity, whereas CT had 98% sensitivity and 88% specificity. MRI sensitivity was non-inferior to CT (difference 0.57% (95% CI - 1.4-2.5%)). The interobserver agreement was substantial between CT and MRI.

CONCLUSION

MRI with DWIBS was non-inferior to contrast-enhanced CT in detecting metastatic TC disease.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov NCT03436901, finished July 1st 2021.

Late adverse effects and quality of life in survivors of testicular germ cell tumour

Currently, ~95% of patients with testicular germ cell tumour (TGCT) are cured, resulting in an increasing number of TGCT survivors. Although cured, these men face potential late adverse effects and reduced quality of life. Survivors face a twofold increased risk of second malignant neoplasms after chemotherapy and radiotherapy, with evidence of dose-dependent associations. For survivors managed with surveillance or treated with radiotherapy, the risk of cardiovascular disease (CVD) is comparable to the risk in the general population, whereas treatment with chemotherapy increases the risk of life-threatening CVD, especially during treatment and after 10 years of follow-up. Other adverse effects are organ-related toxicities such as neuropathy and ototoxicity. Pulmonary and renal impairment in patients with TGCT treated with chemotherapy is limited. Survivors of TGCT might experience psychosocial distress including anxiety disorders, fear of cancer recurrence and TGCT-specific issues, such as sexual dysfunction. Late adverse effects can be avoided in most patients with stage I disease if followed on a surveillance programme. However, patients with disseminated disease can experience toxicities associated with radiotherapy and chemotherapy, and/or adverse effects related to surgery for residual disease. The severity of adverse effects increases with dose of both chemotherapy and radiotherapy. This Review discusses the most recent data concerning the late adverse effects of today's standard treatments for TGCT.

Unenhanced MRI of the abdomen and pelvis for surveillance of patients with stage 1 testicular cancer post-radical orchiectomy

OBJECTIVE

To evaluate the ability of unenhanced magnetic resonance imaging (MRI) to detect metastatic lymphadenopathy in men with stage 1 testicular cancer on surveillance.

MATERIALS AND METHODS

With IRB approval, we identified 23 consecutive men with stage 1 testicular cancer (diagnosed after orchiectomy) undergoing surveillance with unenhanced MRI of the abdomen and pelvis. Three blinded radiologists (2 inexperienced R1/R2 and 1 experienced R3) independently assessed MRI for: presence, location and size of abnormal lymph nodes and degree of confidence (5-point Likert scale) in diagnosis. Diagnostic accuracy was tabulated and compared between groups using ROC. Inter-observer agreement was assessed using Cohen's kappa statistic.

RESULTS

17.4% (4/23) men developed 6 metastatic lymph nodes (reference standard: interval development from baseline, size > 1.0 cm short axis). R1 and R2 detected 75% (3/4) patients with abnormal lymph nodes, compared to R3 who detected all four cases. False positive interpretations occurred in: 5.2% (1/19) R1, 10.5% (2/19) R2 and no patients for R3. Sensitivity, specificity and area under the ROC curve (AUC) were: R1: 75% (95% CI 19.4-99.4%), 94.7% (74.0-99.9%) and 0.85 (0.59-1.00), R2: 75% (19.4-99.4%), 89.5% (66.9-98.7%) and 0.82 (0.57-1.00) and, R3: 100% (95% 39.8-100.0%), 100% (82.4-100%) and 1.00 (1.00-1.00) with no difference in AUC between readers (p = 0.383). Comparison in accuracy between readers is limited due to the small sample size. Inter-observer agreement was substantial (K = 0.62). Median (range) degree of confidence scores were rated: R1 5 (5-5), R2 4 (3-5) and, R3 5 (5-5).

CONCLUSION

In this study, unenhanced MRI was adequate for surveillance of stage 1 testicular cancer; however, radiologist inexperience may lead to errors.

An institutional review of hospital resource utilization and patient radiation exposure in shunted idiopathic intracranial hypertension

Patients with idiopathic intracranial hypertension (IIH) frequently utilize healthcare services and undergo radiological studies to assess refractory headache symptoms despite cerebrospinal fluid diversion. To delineate the clinical utility of different imaging modalities and to estimate cumulative patient radiation exposure in shunted patients with IIH, we retrospectively reviewed 100 randomly selected patients with IIH and a prior cerebrospinal fluid diversion procedure treated at our institution between July 2010 and August 2018. Patients had an average of 16.3 office (SD ± 13.8), 12.4 emergency department (± 21.0), and 4.6 inpatient (± 5.1) encounters over an average 4.8 years of follow-up. Patients underwent an average of 9.0 head CTs (± 8.1), 10.3 shunt series x-rays (± 11.2), and 4.3 MRIs (± 3.7). Approximated radiation exposure per patient was 21.4 mSv (± 18.7). Radiological studies performed for acute symptoms usually demonstrated no actionable findings (82.5% CTs, 97.5% shunt series x-rays, and 79.6% MRIs). Shunted IIH patients undergo numerous radiological studies and are subject to considerable levels of radiation, yet imaging shows actionable findings in less than 10% percent of radiographic studies. IIH patients may benefit from radiation-reducing protocols and the use of alternative imaging to assess symptoms.

Ten years of experience with MRI follow-up of testicular cancer stage I: a retrospective study and an MRI protocol with DWI

INTRODUCTION

Patients with testicular cancer (TC) are mainly young and survival rates are high. MRI has several times been proposed to replace CT in follow-up of this patient group to reduce image-related radiation exposure. However, current evidence is scarce for the use of MRI in this context.

AIMS

First, to retrospectively evaluate the ability of MRI of the retroperitoneum and pelvis to detect relapse in patients with TC stage I. Second, to present a relevant MRI protocol of the retroperitoneum and pelvis with diffusion weighted imaging (DWI).

MATERIAL AND METHODS

A retrospective analysis of written radiology reports compared to clinical data from clinical practice from 2010 to 2018. The cohort consists of 2487 MRIs of the retroperitoneum and pelvis in 759 patients with TC stage I (524 seminoma (69.0%), 235 non-seminoma (31.0%)), including 102 patients (13.4%) with confirmed relapse. Confirmed relapse was defined when treatment was initiated for metastatic TC.

RESULTS

Ninety-five patients had a relapse in the MRI scan field during follow-up. MRI of the retroperitoneum and pelvis showed a high sensitivity of 93.8% and a high specificity of 97.4% for detecting TC relapse. The sensitivity for detecting relapse ≥10 mm in short axis lymph node diameter was 100%. The negative predictive value was 99.7%, the positive predictive value was 59.9% and the accuracy was 97.3%.

CONCLUSIONS

MRI of the retroperitoneum and pelvis constitutes a safe alternative to CT in follow-up of patients with TC stage I with both a high sensitivity and a high specificity. We present a robust MRI protocol with DWI and estimate that MRI follow-up of TC stage I can be easily implemented in most modern radiology departments. Registration: Conducted with permission from the Danish Data Protection Agency (1-16-02-323-16) and the Danish Health Authority.

Understanding, justifying, and optimizing radiation exposure for CT imaging in nephrourology

An estimated 4-5 million CT scans are performed in the USA every year to investigate nephrourological diseases such as urinary stones and renal masses. Despite the clinical benefits of CT imaging, concerns remain regarding the potential risks associated with exposure to ionizing radiation. To assess the potential risk of harmful biological effects from exposure to ionizing radiation, understanding the mechanisms by which radiation damage and repair occur is essential. Although radiation level and cancer risk follow a linear association at high doses, no strong relationship is apparent below 100 mSv, the doses used in diagnostic imaging. Furthermore, the small theoretical increase in risk of cancer incidence must be considered in the context of the clinical benefit derived from a medically indicated CT and the likelihood of cancer occurrence in the general population. Elimination of unnecessary imaging is the most important method to reduce imaging-related radiation; however, technical aspects of medically justified imaging should also be optimized, such that the required diagnostic information is retained while minimizing the dose of radiation. Despite intensive study, evidence to prove an increased cancer risk associated with radiation doses below ~100 mSv is lacking; however, concerns about ionizing radiation in medical imaging remain and can affect patient care. Overall, the principles of justification and optimization must remain the basis of clinical decision-making regarding the use of ionizing radiation in medicine.

Detection of Relapse by Low-dose Computed Tomography During Surveillance in Stage I Testicular Germ Cell Tumours

BACKGROUND

Standard-dose computed tomography (SDCT) scans are associated with radiation exposure during stage I testicular cancer surveillance.

OBJECTIVE

To evaluate low-dose CT (LDCT) for clinical use.

DESIGN, SETTING, AND PARTICIPANTS

In this single-arm prospective study, patients on surveillance for stage I testicular germ cell tumour underwent SDCT and LDCT scans on their first visit after enrolment. The adequacy of LDCT image quality was assessed for subsequent use. Patients were followed with LDCT only and suspected relapse was confirmed by SDCT.

OUTCOME MEASURES AND STATISTICAL ANALYSIS

We assessed whether initial LDCT scans were of sufficient quality for routine clinical use. We compared mean differences in nodal size at relapse between LDCT and SDCT using a one-sample paired t test. The relapse free-rate was calculated using the Kaplan-Meier method.

RESULTS AND LIMITATIONS

Of 257 patients, one was excluded because of inadequate image quality. At median follow-up of 5.25 yr, 35 patients had relapsed, 33 with retroperitoneal lymphadenopathy. The 2- and 5-yr relapse-free rates were 89.5% and 85.3%, respectively. The mean size of retroperitoneal nodal relapse was 17.3 and 17.5mm on the short axis, 23.2 and 22.7mm on the long axis, and 26.1 and 26.7mm on craniocaudal length for LDCT and SDCT, respectively. The mean difference between LDCT and SDCT was 0.14mm (p=0.55) short axis, -0.54mm (p=0.092) long axis, and -0.51mm (p=0.086) length. A limitation was the lack of a control arm.

CONCLUSIONS

LDCT image quality was adequate for clinical use, and retroperitoneal nodal relapse was detected with minimal differences seen between LD and SDCT. LDCT can be safely adopted and will decrease overall radiation exposure in stage I germ cell tumour surveillance.

PATIENT SUMMARY

We studied the use of low-dose computed tomography scans for detecting testicular cancer recurrence in lymph nodes of the abdomen and pelvis and found that they were safe, effective and would potentially reduce overall X-ray exposure. This trial is registered at ClinicalTrials.gov as NCT03142802.

Radiation Dose and Risk Estimates of CT-Guided Percutaneous Liver Ablations and Factors Associated with Dose Reduction

PURPOSE

To determine the radiation dose associated with CT-guided percutaneous liver ablations and identify potential risk factors that result in higher radiation doses.

MATERIALS AND METHODS

Between June 2011 and June 2015, 245 consecutive patients underwent 304 CT-guided liver ablation treatments. Patient demographics, tumor characteristics and procedural parameters were identified and analyzed. The peak skin dose and effective dose were assessed for each procedure. Excess relative risk related to radiation effects was calculated. A logistic regression model was prepared by means of stepwise logistic regression to identify variables predictive of increased radiation exposure.

RESULTS

Tumor ablations were performed with microwave (n = 220), radiofrequency (n = 74) or irreversible electroporation (IRE) (n = 10). The mean peak skin dose for ablations was 239.2 ± 136.4 mGy, and the mean effective dose was 36.6 ± 22.3 mSv. Of the patient and procedural parameters that were analyzed, increasing weight, use of intravenous contrast and/or hydrodissection during the procedure, together with treatment of multiple lesions in the same sitting were all associated with higher radiation exposure. The mean increase in the absolute risk of fatal malignancy from a single procedure was 0.18% (range 0.02-0.9%). No deterministic skin changes were identified in the patient cohort.

CONCLUSION

The overall risk of stochastic and deterministic effects from radiation associated with CT-guided ablations is low compared with other inherent procedural complications. This study identifies several factors that are associated with higher radiation dose in percutaneous liver ablation procedures.

Optimizing Communication With Parents on Benefits and Radiation Risks in Pediatric Imaging

Effective radiation risk communication is a core competency for radiology care providers and can prevent and resolve potential conflicts while helping achieve effective public health safeguards. The authors present a synopsis of the challenges to holding such dialogue and review published methods for strengthening and maintaining this discourse. Twelve strategies are discussed in this article that can help alleviate concerns about the iatrogenic risk associated with medical imaging using radiation exposure.

Management of stage I testicular germ cell tumours

Clinical stage I testicular germ cell tumours (TGCT) are highly curable neoplasms. The treatment of stage I testicular cancer is complex and requires a multidisciplinary approach. Standard options after radical orchiectomy for seminoma include active surveillance, radiation therapy or 1-2 cycles of carboplatin, and options for nonseminoma include active surveillance, retroperitoneal lymph node dissection (RPLND) or 1-2 cycles of bleomycin plus etoposide plus cisplatin (BEP). All the options should be discussed with each patient and treatment choices should be made by shared decision making as virtually all patients with clinical stage I TGCT can be cured of their disease. Long-term survival of men with stage I disease is ∼99% and care must be taken to limit the long-term risks of treatment. Orchiectomy is curative in the majority of patients. The management of clinical stage I TGCT remains controversial among experts at high-volume centres throughout the world. The main controversy is whether to overtreat a substantial number of patients with stage I disease to prevent relapse, or to observe and treat only patients who experience disease relapse as adjuvant treatment and surveillance strategy both bring curative outcome. Thus, a summary of the available evidence in stage I disease and recommendations for disease management from a high-volume centre such as Indiana University might be of interest to treating clinicians.

CT restaging of testicular germ cell tumors: The incidence of isolated pelvic metastases

PURPOSE

We determined the incidence of isolated pelvic metastases at restaging computed tomography (CT) in patients with testicular germ cell tumors to consider if imaging the pelvis could be omitted.

METHODS

After receiving IRB approval for this HIPAA-compliant retrospective study, medical records of 560 men (mean age 32.8) with 583 testicular germ cell tumors who underwent 3683 restaging CT scans of the abdomen and pelvis were reviewed to determine the proportion of patients with metastatic disease in the pelvis alone, as verified by histology or by resolution after therapy. Chi-square statistical analysis tested the association between factors currently thought to predispose patients to pelvic metastases. Patients were also categorized by clinical stage, tumor histology, and initial treatment.

RESULTS

Isolated pelvic metastases were detected in nine (1.6%) of 560 men. Neither bulky abdominal disease (p=0.85) nor extratesticular invasion by the primary tumor (p=0.37) were statistically significant in predicting which patients were more likely to have isolated pelvic metastases. Among the nine patients with isolated pelvic recurrence, only three (0.7%) of 408 men with no known pelvic disease at initial staging and no tumor marker elevation at restaging had isolated pelvic metastases. Isolated pelvic recurrence was not statistically different when analyzed by initial stage and treatment.

CONCLUSION

The incidence of isolated pelvic metastases in testicular germ cell tumors at restaging CT is low, but no group of patients was found to be without risk. Therefore, given the small, if any, risk of radiation-induced harm, the decision about whether to include routine pelvic CT in surveillance protocols should be individualized.

Answers to Common Questions About the Use and Safety of CT Scans

Articles in the scientific literature and lay press over the past several years have implied that computed tomography (CT) may cause cancer and that physicians and patients must exercise caution in its use. Although there is broad agreement on the latter point--unnecessary medical tests of any type should always be avoided--there is considerable controversy surrounding the question of whether, or to what extent, CT scans can lead to future cancers. Although the doses used in CT are higher than those used in conventional radiographic examinations, they are still 10 to 100 times lower than the dose levels that have been reported to increase the risk of cancer. Despite the fact that at the low doses associated with a CT scan the risk either is too low to be convincingly demonstrated or does not exist, the magnitude of the concern among patients and some medical professionals that CT scans increase cancer risk remains unreasonably high. In this article, common questions about CT scanning and radiation are answered to provide physicians with accurate information on which to base their medical decisions and respond to patient questions.

Role of imaging in testicular cancer: current and future practice

The article provides a summary of the epidemiologic and clinical aspects of testicular malignancy. Current standard imaging and novel techniques are reviewed. Present data and clinical treatment trends have favored surveillance protocols over adjuvant radiation or chemotherapy for low-stage testicular malignancy. This has resulted in increasing numbers of imaging studies and the potential for increased long-term exposure risks. Understanding imaging associated risks as well as strategies to minimize these risks is of increasing importance. The development, validation and incorporation of alternative lower risk highly efficacious and cost-effective imaging techniques is essential.

Radiation exposure from CT-guided ablation of renal masses: effects on life expectancy

OBJECTIVE. The purpose of this article is to project the effects of radiation exposure on life expectancy (LE) in patients who opt for CT-guided radiofrequency ablation (RFA) instead of surgery for renal cell carcinoma (RCC). MATERIALS AND METHODS. We developed a decision-analytic Markov model to compare LE losses attributable to radiation exposure in hypothetical 65-year-old patients who undergo CT-guided RFA versus surgery for small (≤ 4 cm) RCC. We incorporated mortality risks from RCC, radiation-induced cancers (for procedural and follow-up CT scans), and all other causes; institutional data informed the RFA procedural effective dose. Radiation-induced cancer risks were generated using an organ-specific approach. Effects of varying model parameters and of dose-reduction strategies were evaluated in sensitivity analysis. RESULTS. Cumulative RFA exposures (up to 305.2 mSv for one session plus surveillance) exceeded those from surgery (up to 87.2 mSv). In 65-year-old men, excess LE loss from radiation-induced cancers, comparing RFA to surgery, was 11.7 days (14.6 days for RFA vs 2.9 days for surgery). Results varied with sex and age; this difference increased to 14.6 days in 65-year-old women and to 21.5 days in 55-year-old men. Dose-reduction strategies that addressed follow-up rather than procedural exposure had a greater impact. In 65-year-old men, this difference decreased to 3.8 days if post-RFA follow-up scans were restricted to a single phase; even elimination of RFA procedural exposure could not achieve equivalent benefits. CONCLUSION. CT-guided RFA remains a safe alternative to surgery, but with decreasing age, the higher burden of radiation exposure merits explicit consideration. Dose-reduction strategies that target follow-up rather than procedural exposure will have a greater impact.

Radiographic screening of infants and young children with genetic predisposition for rare malignancies: DICER1 mutations and pleuropulmonary blastoma

OBJECTIVE

The purpose of this study was to compare the risks of radiation in screening strategies using chest radiographs and CT to detect a rare cancer in a genetically predisposed population against the risks of undetected disease.

MATERIALS AND METHODS

A decision analytic model of diagnostic imaging screening strategies was built to predict outcomes and cumulative radiation doses for children with DICER1 mutations screened for pleuropulmonary blastoma. Screening strategies compared were chest radiographs followed by chest CT for a positive radiographic result and CT alone. Screening frequencies ranged from once in 3 years to once every 3 months. BEIR VII (model VII proposed by the Committee on the Biological Effects of Ionizing Radiation) risk tables were used to predict excess cancer mortality for each strategy, and the corresponding loss of life expectancy was calculated using Surveillance Epidemiologic and End Results (SEER) statistics. Loss of life expectancy owing to undetected progressive pleuropulmonary blastoma was estimated on the basis of data from the International Pleuropulmonary Blastoma Registry. Sensitivity analysis was performed for all model parameters.

RESULTS

Loss of life expectancy owing to undetected disease in an unscreened population exceeded that owing to radiation-induced cancer for all screening scenarios investigated. Increases in imaging frequency decreased loss of life expectancy for the combined (chest radiographs and CT) screening strategy but increased that for the CT-only strategy. This was because loss of life expectancy for combined screening is dominated by undetected disease, whereas loss of life expectancy for CT screening is dominated by radiation-induced cancers.

CONCLUSION

Even for a rare disease such as pleuropulmonary blastoma, radiographic screening of infants and young children with cancer-predisposing mutations may result in improved life expectancy compared with the unscreened population. The benefit of screening will be greater for diseases with a higher screening yield.

A refined risk stratification scheme for clinical stage 1 NSGCT based on evaluation of both embryonal predominance and lymphovascular invasion

BACKGROUND

Active surveillance is an increasingly accepted approach for managing patients with germ-cell tumors (GCTs) after an orchiectomy. Here we investigate a time-to-relapse stratification scheme for clinical stage 1 (CS1) nonseminoma GCT (NSGCT) patients according to factors associated with relapse and identify a group of patients with a lower frequency and longer time-to-relapse who may require an alternative surveillance strategy.

PATIENTS AND METHODS

We analyzed 266 CS1 GCT patients from the IRB-approved DFCI GCT database that exclusively underwent surveillance following orchiectomy from 1997 to 2013. We stratified NSGCT patients according to predominance of embryonal carcinoma (EmbP) and lymphovascular invasion (LVI), using a 0, 1, and 2 scoring system. Cox regression and conditional risk analysis were used to compare each NSGCT group to patients in the seminomatous germ-cell tumor (SGCT) category. Median time-to-relapse values were then calculated among those patients who underwent relapse. Relapse-free survival curves were generated using the Kaplan-Meier method.

RESULTS

Fifty (37%) NSGCT and 20 (15%) SGCT patients relapsed. The median time-to-relapse was 11.5 versus 6.3 months for the SGCT and NSGCT groups, respectively. For NSGCT patients, relapse rates were higher and median time-to-relapse faster with increasing number of risk factors (RFs). Relapse rates (%) and median time-to-relapse (months) were 25%/8.5 months, 41%/6.8 months and 78%/3.8 months for RF0, RF1 and RF2, respectively. We found a statistically significant difference between SGCT and patients with one or two RFs (P < 0.001) but not between SGCT and NSGCT RF0 (P = 0.108).

CONCLUSION

NSGCT patients grouped by a risk score system based on EmbP and LVI yielded three groups with distinct relapse patterns -and patients with neither EmbP nor LVI appear to behave similar to SGCT.

Microsimulation model of CT versus MRI surveillance of Bosniak IIF renal cystic lesions: should effects of radiation exposure affect selection of imaging strategy?

OBJECTIVE

The objective of this study was to quantify the effects of radiation-induced cancer risks in patients with Bosniak category IIF lesions undergoing CT versus MRI surveillance.

MATERIALS AND METHODS

We developed a Markov-Monte Carlo model to determine life expectancy losses attributable to radiation-induced cancers in hypothetical patients undergoing CT versus MRI surveillance of Bosniak IIF lesions. Our model tracked hypothetical patients as they underwent imaging surveillance for up to 5 years, accounting for potential lesion progression and treatment. Estimates of radiation-induced cancer mortality were generated using a published organ-specific radiation-risk model based on Biological Effects of Ionizing Radiation VII methods. The model also incorporated surgical mortality and renal cancer-specific mortality. Our primary outcome was life expectancy loss attributable to radiation-induced cancers. A sensitivity analysis was performed to assess the stability of the results with variability in key parameters.

RESULTS

The mean number of examinations per patient was 6.3. In the base case, assuming 13 mSv per multiphase CT examination, 64-year-old men experienced an average life expectancy decrease of 5.5 days attributable to radiation-induced cancers from CT; 64-year-old women experienced a corresponding life expectancy loss of 6.9 days. The results were most sensitive to patient age: Life expectancy loss attributable to radiation-induced cancers increased to 21.6 days in 20-year-old women and 20.0 days in 20-year-old men. Varied assumptions of each modality's (CT vs MRI) depiction of lesion complexity also impacted life expectancy losses.

CONCLUSION

Microsimulation modeling shows that radiation-induced cancer risks from CT surveillance for Bosniak IIF lesions minimally affect life expectancy. However, as progressively younger patients are considered, increasing radiation risks merit stronger consideration of MRI surveillance.

Imaging-based screening: understanding the controversies

OBJECTIVE

The goals of this article are to provide an overview of controversial aspects of imaging-based screening and to elucidate potential risks that may offset anticipated benefits.

CONCLUSION

Current controversial topics associated with imaging-based screening include false-positive results, incidental findings, overdiagnosis, radiation risks, and costs. Alongside the benefits of screening, radiologists should be prepared to discuss these additional diagnostic consequences with providers and patients to better guide shared decision making regarding imaging-based screening.

Cost analysis of adjuvant management strategies in early stage (stage I) testicular seminoma

BACKGROUND

Acceptable post-orchiectomy adjuvant therapy strategies for stage I seminoma patients include surveillance, para-aortic radiation therapy (RT), dog-leg RT, and a single cycle of carboplatin. The required follow-up recommendations were amended by the National Comprehensive Cancer Network (NCCN) in 2012. Given a cause-specific survival of nearly 100%, a closer analysis of the reimbursement for each treatment strategy is warranted.

METHODS

NCCN guidelines were used to design treatment plans for each acceptable adjuvant treatment strategy. Follow-up charges were generated for 10 years based on 2012 (version 1.2012; unchanged in current version 1.2013) and 2011 NCCN (version 2.2011) surveillance recommendations. The 2012 Medicare reimbursement rates were used to calculate each treatment strategy and incremental cost-effectiveness ratios to compare the treatment options.

RESULTS

Under the current NCCN follow-up recommendations, the total reimbursements generated over 10 years of surveillance, para-aortic RT, dog-leg RT, and carboplatin were $10,643, $11,678, $9,662, and $10,405, respectively. This is compared with the reimbursements as per the 2011 NCCN recommendations: $20,986, $11,517, $9,394, and $20,365 respectively. Factoring the rates of relapse into a salvage model, observation was found to be more costly and less effective ($-1,831, $-7,318, $-7,010) in the adjuvant management of stage I seminoma patients.

CONCLUSION

Based on incremental cost-effectiveness ratios, para-aortic RT, dog-leg RT, and carboplatin are cost-effective options for the treatment of stage I seminoma when compared with observation; however, surveillance could potentially spare as many as 80%-85% of men diagnosed with stage I seminoma from additional therapy after radical inguinal orchiectomy. Such cost and reimbursement analyses are becoming increasingly relevant, but are not meant to usurp sound clinical judgment. Further studies are required to validate these findings.

Radiation exposure from diagnostic imaging in young patients with testicular cancer

OBJECTIVES

Risks associated with high cumulative effective dose (CED) from radiation are greater when imaging is performed on younger patients. Testicular cancer affects young patients and has a good prognosis. Regular imaging is standard for follow-up. This study quantifies CED from diagnostic imaging in these patients.

METHODS

Radiological imaging of patients aged 18-39 years, diagnosed with testicular cancer between 2001 and 2011 in two tertiary care centres was examined. Age at diagnosis, cancer type, dose-length product (DLP), imaging type, and frequency were recorded. CED was calculated from DLP using conversion factors. Statistical analysis was performed with SPSS.

RESULTS

In total, 120 patients with a mean age of 30.7 ± 5.2 years at diagnosis had 1,410 radiological investigations. Median (IQR) surveillance was 4.37 years (2.0-5.5). Median (IQR) CED was 125.1 mSv (81.3-177.5). Computed tomography accounted for 65.3 % of imaging studies and 98.3 % of CED. We found that 77.5 % (93/120) of patients received high CED (>75 mSv). Surveillance time was associated with high CED (OR 2.1, CI 1.5-2.8).

CONCLUSIONS

Survivors of testicular cancer frequently receive high CED from diagnostic imaging, mainly CT. Dose management software for accurate real-time monitoring of CED and low-dose CT protocols with maintained image quality should be used by specialist centres for surveillance imaging.

KEY POINTS

• CT accounted for 98.3 % of CED in patients with testicular cancer. • Median CED in patients with testicular cancer was 125.1 mSv • High CED (>75 mSv) was observed in 77.5 % (93/120) of patients. • Dose tracking and development of low-dose CT protocols are recommended.

Surveillance for Stage I Nonseminoma Testicular Cancer: Outcomes and Long-Term Follow-Up in a Population-Based Cohort

Purpose

To describe treatment results in a large cohort with stage I nonseminoma germ cell cancer (NSGCC) treated in a surveillance program.

Patients and Methods

From January 1, 1984, to December 31, 2007, 1,226 patients with stage I NSGCC, including high-risk patients with vascular invasion, were observed in a surveillance program.

Results

The relapse rate after orchiectomy alone was 30.6% at 5 years. Presence of vascular invasion together with embryonal carcinoma and rete testis invasion in the testicular primary identified a group with a relapse risk of 50%. Without risk factors, the relapse risk was 12%. Eighty percent of relapses were diagnosed within the first year after orchiectomy. The median time to relapse was 5 months (range, 1 to 308 months). Early relapses were mainly detected by increase in tumor markers, and late relapses were detected by computed tomography scans. Relapses after 5 years were seen in 0.5% of the whole cohort or in 1.6% of relapsing patients. The majority of relapses (94.4%) belonged to the good prognostic group according to the International Germ Cell Cancer Collaborative Group classification. The disease-specific survival at 15 years was 99.1%.

Conclusion

A surveillance policy for patients with stage I NSGCC is a safe approach associated with an excellent cure rate and an overall low treatment burden despite a high relapse rate in a small group of patients. We recommend surveillance for patients with stage I NSGCC with immediate systemic treatment at relapse. Clearly defined risk factors for relapse are presented if an option of risk-adapted treatment is preferred.

Imaging for appendicitis: should radiation-induced cancer risks affect modality selection?

PURPOSE

To compare life expectancy (LE) losses attributable to three imaging strategies for appendicitis in adults-computed tomography (CT), ultrasonography (US) followed by CT for negative or indeterminate US results, and magnetic resonance (MR) imaging-by using a decision-analytic model.

MATERIALS AND METHODS

In this model, for each imaging strategy, LE losses for 20-, 40-, and 65-year-old men and women were computed as a function of five key variables: baseline cohort LE, test performance, surgical mortality, risk of death from delayed diagnosis (missed appendicitis), and LE loss attributable to radiation-induced cancer death. Appendicitis prevalence, test performance, mortality rates from surgery and missed appendicitis, and radiation doses from CT were elicited from the published literature and institutional data. LE loss attributable to radiation exposure was projected by using a separate organ-specific model that accounted for anatomic coverage during a typical abdominopelvic CT examination. One- and two-way sensitivity analyses were performed to evaluate effects of model input variability on results.

RESULTS

Outcomes across imaging strategies differed minimally-for example, for 20-year-old men, corresponding LE losses were 5.8 days (MR imaging), 6.8 days (combined US and CT), and 8.2 days (CT). This order was sensitive to differences in test performance but was insensitive to variation in radiation-induced cancer deaths. For example, in the same cohort, MR imaging sensitivity had to be 91% at minimum (if specificity were 100%), and MR imaging specificity had to be 62% at minimum (if sensitivity were 100%) to incur the least LE loss. Conversely, LE loss attributable to radiation exposure would need to decrease by 74-fold for combined US and CT, instead of MR imaging, to incur the least LE loss.

CONCLUSION

The specific imaging strategy used to diagnose appendicitis minimally affects outcomes. Paradigm shifts to MR imaging owing to concerns over radiation should be considered only if MR imaging test performance is very high.

Prioritizing examination-centered over patient-centered dose reduction: a hazard of institutional "benchmarking"

OBJECTIVE

The purpose of this article is to evaluate whether examination-specific radiation dose metrics reliably measure an institution's success in reducing cancer risks.

MATERIALS AND METHODS

We projected health benefits from dose-reduction programs in a hypothetical institution that sought to decrease exposures from abdominopelvic CT. Using modeling techniques to project radiation-induced cancer risks and tertiary center data to inform the institution's abdominopelvic CT age distribution, we compared a program in which effective doses were reduced equally (from 10 to 7 mSv) across all scans with programs in which dose reduction was age dependent. For each program, we projected lethal cancers averted, life expectancy gained, and average institutional dose achieved. Markov Chain Monte Carlo methods were used to estimate uncertainty in projections.

RESULTS

The analysis's age distribution drew from 20,979 CT scans; 39% were from patients 65 years old and older. To illustrate trends yielded, if all patients in the hypothetical institution underwent 7-mSv (instead of 10-mSv) scans, we projected the maximum number of lethal cancers averted to be seven per 100,000 patients, and maximum life expectancy gained to be 0.26 days per patient, when averaged over the institution's population. When restricting dose reduction (from 10 to 7 mSv) to patients younger than 65 years, benefits were slightly lower (five lethal cancers averted per 100,000 patients and 0.22 days per patient gained); however, the average institutional dose was substantially higher (8.2 mSv). Although dose reduction in patients 65 years old and older accounted for only 16% of possible institutional life expectancy gains, this patient group contributed disproportionately (39%) to the institution's average dose.

CONCLUSION

Institutional examination-specific dose metrics can be misleading, because the least-benefited patients may contribute disproportionately toward "improved" averages.

The time has arrived for national reimbursement of screening CT colonography

OBJECTIVE

CT colonography (CTC) has been fully validated as an accurate screening test for colorectal carcinoma and is being disseminated globally. There is an abundance of new literature addressing the prior concerns of the U.S. Preventive Services Task Force and the Centers for Medicare & Medicaid Services. Specific areas related to radiation dose, extracolonic findings, and generalizability of CTC to senior patients are discussed.

CONCLUSION

The time has arrived for national reimbursement of CTC in the United States.