Retinopathy, Optic Neuropathy, and Cataract in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

PURPOSE

Few reports describe the risks of late ocular toxicities after radiation therapy (RT) for childhood cancers despite their effect on quality of life. The Pediatric Normal Tissue Effects in the Clinic (PENTEC) ocular task force aims to quantify the radiation dose dependence of select late ocular adverse effects. Here, we report results concerning retinopathy, optic neuropathy, and cataract in childhood cancer survivors who received cranial RT.

METHODS AND MATERIALS

A systematic literature search was performed using the PubMed, MEDLINE, and Cochrane Library databases for peer-reviewed studies published from 1980 to 2021 related to childhood cancer, RT, and ocular endpoints including dry eye, keratitis/corneal injury, conjunctival injury, cataract, retinopathy, and optic neuropathy. This initial search yielded abstracts for 2947 references, 269 of which were selected as potentially having useful outcomes and RT data. Data permitting, treatment and outcome data were used to generate normal tissue complication probability models.

RESULTS

We identified sufficient RT data to generate normal tissue complication probability models for 3 endpoints: retinopathy, optic neuropathy, and cataract formation. Based on limited data, the model for development of retinopathy suggests 5% and 50% risk of toxicity at 42 and 62 Gy, respectively. The model for development of optic neuropathy suggests 5% and 50% risk of toxicity at 57 and 64 Gy, respectively. More extensive data were available to evaluate the risk of cataract, separated into self-reported versus ophthalmologist-diagnosed cataract. The models suggest 5% and 50% risk of self-reported cataract at 12 and >40 Gy, respectively, and 50% risk of ophthalmologist-diagnosed cataract at 9 Gy (>5% long-term risk at 0 Gy in patients treated with chemotherapy only).

CONCLUSIONS

Radiation dose effects in the eye are inadequately studied in the pediatric population. Based on limited published data, this PENTEC comprehensive review establishes relationships between RT dose and subsequent risks of retinopathy, optic neuropathy, and cataract formation.

Adolescent and Young Adult Oncology, Version 2.2018, NCCN Clinical Practice Guidelines in Oncology

This selection from the NCCN Guidelines for Adolescent and Young Adult (AYA) Oncology focuses on treatment and management considerations for AYA patients with cancer. Compared with older adults with cancer, AYA patients have unique needs regarding treatment, fertility counseling, psychosocial and behavioral issues, and supportive care services. The complete version of the NCCN Guidelines for AYA Oncology addresses additional aspects of caring for AYA patients, including risk factors, screening, diagnosis, and survivorship.

The effects of focal adhesion kinase and platelet-derived growth factor receptor beta inhibition in a patient-derived xenograft model of primary and metastatic Wilms tumor

Aggressive therapies for patients with metastatic Wilms tumor (WT) with subsequent severe late effects warrant the search for novel therapies. The role of focal adhesion kinase (FAK), a non-receptor tyrosine kinase important in pediatric solid tumor development and progression, has not been examined in metastatic WT. Using a novel patient-derived xenograft (PDX) of a primary and matched, isogenic, metastatic WT, the hypothesis of the current study was that FAK would contribute to metastatic WT and small molecule inhibition would decrease tumor growth. Immunohistochemical staining, immunoblotting, cell viability and proliferation assays, cell cycle analysis, and cellular motility and attachment-independent growth assays were performed. FAK was present and phosphorylated in both WT PDXs and in the human samples from which they were derived. FAK inhibition decreased cellular survival, proliferation, and cell cycle progression in both PDXs but only significantly decreased migration, invasion, and attachment-independent growth in the primary WT PDX. Kinomic profiling revealed that platelet-derived growth factor receptor beta (PDGFRβ) may be affected by FAK inhibition in WT. Pharmacologic inhibition of FAK and PDGFRβ was synergistic in primary WT PDX cells. These findings broaden the knowledge of metastatic WT and support further investigations on the potential use of FAK and PDGFRβ inhibitors.

Predictors of colorectal cancer surveillance among survivors of childhood cancer treated with radiation: a report from the Childhood Cancer Survivor Study

BACKGROUND

Childhood cancer survivors treated with radiotherapy to a field including the colon or rectum have an elevated risk of developing radiation-induced colorectal cancer (CRC). The Children's Oncology Group recommends colonoscopy every 5 years beginning at age 35 years for at-risk survivors.

METHODS

Analyses included 702 five-year survivors (Childhood Cancer Survivor Study) aged ≥36 years who received ≥30 gray of abdominal, pelvic, or spinal radiotherapy. Multivariate generalized linear models were used to calculate relative risks (RR) with 95% confidence intervals (95% CI) for adherence to the Children's Oncology Group's CRC surveillance recommendations.

RESULTS

With a median age of 43 years (range, 36-58 years), 29.5% of the survivors (207 of 702 survivors) met surveillance recommendations. In multivariate analyses, age ≥50 years versus age 36 to 49 years (RR, 2.6; 95% CI, 2.0-3.4), reporting a routine cancer follow-up visit within 1 year before the study (RR, 1.5; 95% CI, 1.0-2.2), reporting ≥10 physician visits within the past year versus 0 to 9 visits (RR, 1.4; 95% CI, 1.1-1.7), and discussing future cancer risk with a physician at the time of the most recent follow-up visit (RR, 1.4; 95% CI, 1.1-1.7) were found to be associated with adherence to CRC surveillance recommendations.

CONCLUSIONS

Greater than 70% of survivors at an increased risk of CRC were not screened as recommended. Regular physician contact and discussion of screening were associated with a 60% increase in CRC surveillance. Educational interventions targeted at survivors and their primary care physicians are needed to heighten knowledge of CRC risk after radiotherapy and the importance of appropriate surveillance.

Barriers to the Use of Psychosocial Support Services Among Adolescent and Young Adult Survivors of Pediatric Cancer

Purpose: Adolescent and young adult (AYA) survivors of pediatric cancer commonly report both functional and emotional difficulties, yet many of their mental health needs are not met. Given the unique needs of these survivors, this study examined barriers to psychosocial support service utilization in this population, including accessibility, personal preferences, and practical barriers such as insurance and transportation. Methods: Thirty-six adolescent and young adult survivors of pediatric cancer (aged 15-29) with mental health difficulties (i.e., anxiety or depression) completed surveys assessing access and utilization of services and barriers to utilization. Services assessed included the use of mental health professionals, a pastor or someone in a place of worship, and support groups. Results: Half of the participants utilized a mental health professional, but other forms of support were used less frequently. Utilization of services was related to insurance status and use of prescription medication. Greater time since completion of treatment was a barrier to utilizing psychosocial support services. Conclusion: Use of psychosocial support services is linked closely with use of other healthcare services, including taking prescription medication for mood difficulties. Results have implications for how primary care and oncology providers address barriers to these services among AYA survivors of pediatric cancer.

Adolescent and young adult oncology. Clinical practice guidelines in oncology

Cancer is the leading cause of death among the adolescent and young adult (AYA) population, excluding homicide, suicide, or unintentional injury. AYA patients should be managed by a multidisciplinary team of health care professionals who are well-versed in the specific developmental issues relevant to this patient population. The recommendations for age-appropriate care outlined in these NCCN Guidelines include psychosocial assessment, a discussion of infertility risks associated with treatment and options for fertility preservation, genetic and familial risk assessment for all patients after diagnosis, screening and monitoring of late effects in AYA cancer survivors after successful completion of therapy, and palliative care and end-of-life considerations for patients for whom curative therapy fails.

Anisakid larvae in Atlantic salmon (Salmo salar L.) grilse and post-smolts: molecular identification and histopathology

The molecular identification and histopathology are described for the parasitic larvae of a nematode species present in the abdominal cavity of Atlantic salmon ( Salmo salar ) grilse caught in fish traps on their natal river in the west of Ireland and post-smolts collected during experimental trawls on the continental shelf edge of the northeast Atlantic Ocean. Larvae in the adult and juvenile salmon were identified as Anisakis simplex sensu stricto by PCR amplification and RFLP and sequencing of the ITS gene and PCR amplification and sequencing of the cox2 gene. Parasitic nematode larvae in the grilse were either encapsulated in the abdominal mesentery associated with the pyloric ceca or on the serosal surface of the liver and in the vent region. In some fish, larvae were found in the parenchyma of the liver and muscularis circularis of the intestine. In general, the larvae induced a limited cellular response apart from the occurrence of focal melanin macrophage aggregates and individual eosinophilic granular cells in the connective tissue capsule. Melanin macrophage aggregates were also present among the hepatocytes adjacent to encapsulated larvae in the liver. The reaction to the parasites was more severe in the wall of the intestine. Encapsulated nematode larvae caused displacement, vacuolation, and necrosis of the circular muscle fibers. The stratum compactum was also disrupted with focal areas of degeneration. Overall, the intestinal wall had a hypercellular appearance with extensive cellular infiltration comprising eosinophilic granular cells, macrophages, lymphocytes, and fibrocytes. The post-smolts were caught in May during the early oceanic phase of their life cycle. In these fish, A. simplex sensu stricto larvae were found lying free on the serosal surface of the intestine and liver without any apparent histologic changes. This is the earliest in the marine migration of Atlantic salmon that A. simplex sensu stricto infection has been recorded.

Ocular late effects in childhood and adolescent cancer survivors: a report from the childhood cancer survivor study

INTRODUCTION

Approximately 80% of children currently survive 5 years following diagnosis of their cancer. Studies based on limited data have implicated certain cancer therapies in the development of ocular sequelae in these survivors.

PROCEDURE

The Childhood Cancer Survivor Study (CCSS) is a retrospective cohort study investigating health outcomes of 5+ year survivors diagnosed and treated between 1970 and 1986 compared to a sibling cohort. The baseline questionnaire included questions about the first occurrence of six ocular conditions. Relative risks (RR) and 95% confidence intervals (CI) were calculated from responses of 14,362 survivors and 3,901 siblings.

RESULTS

Five or more years from the diagnosis, survivors were at increased risk of cataracts (RR: 10.8; 95% CI: 6.2-18.9), glaucoma (RR: 2.5; 95% CI: 1.1-5.7), legal blindness (RR: 2.6; 95% CI: 1.7-4.0), double vision (RR: 4.1; 95% CI: 2.7-6.1), and dry eyes (RR: 1.9; 95% CI: 1.6-2.4), when compared to siblings. Dose of radiation to the eye was significantly associated with risk of cataracts, legal blindness, double vision, and dry eyes, in a dose-dependent manner. Risk of cataracts were also associated with radiation 3,000+ cGy to the posterior fossa (RR: 8.4; 95% CI: 5.0-14.3), temporal lobe (RR: 9.4; 95% CI: 5.6-15.6), and exposure to prednisone (RR: 2.3; 95% CI: 1.6-3.4).

CONCLUSIONS

Childhood cancer survivors are at risk of developing late occurring ocular complications, with exposure to glucocorticoids and cranial radiation being important determinants of increased risk. Long-term follow-up is needed to evaluate potential progression of ocular deficits and impact on quality of life.

Mapping studies and genetic analysis of transfer genes of the multi-resistant IncHI2 plasmid, R478

A bank of transfer-defective Tn7 insertion mutants of the multi-resistant IncHI2 megaplasmid, R478, was generated. Complementation analysis of these mutations identified a large 144-kb transfer-associated region of R478. A 6.8-kb segment from the transfer region was sequenced. The precise locations of Tn7 insertion within four distinct R478::Tn7 transfer-defective mutants were mapped and each insertion was found to disrupt a specific open reading frame. These transfer-associated determinants of R478 were designated htdB (H transfer determinant), htdD, htdT and htdC. Both htdB and htdC encoded amino acid sequences that showed a low homology with pilus biosynthetic proteins encoded by the F plasmid.

Spatial and temporal variation in the infestation of sea trout (Salmo trutta L.) by the caligid copepod Lepeophtheirus salmonis (Krøyer) in relation to sources of infection in Ireland

Infestations of post-smolt sea trout (Salmo trutta L.) by the salmon louse (Lepeophtheirus salmonis Krøyer) were characterized in 42 estuaries over a 5 year period in Ireland. Spatial variation in infestation was more significant than temporal trends and existed at 3 levels; between regions (regions > 100 km of coastline), between bays within regions (bays < 50 km in length) and between estuaries within bays (distance between estuaries < 10 km). The observed spatial structure in infestations inferred that production of the infective larvae varied between regions and bays and that there was limited movement of fish and infective larvae between regions and bays. In addition the different levels of infestation recorded between estuaries in the same bay indicated short spatial scale variability in parasite transmission. Significantly higher infestations occurred in bays that contained lice-infested farmed salmon. Lice-infested wild spring salmon, which were present in estuaries of some systems, did not have a significant positive impact on infestations.

Displacement of OmpF loop 3 is not required for the membrane translocation of colicins N and A in vivo

The pore-forming colicins N and A require the porin, OmpF, in order to translocate across the outer membrane of Escherichia coli. We investigated the hypothesis that in vivo, colicins N and A may traverse the outer membrane through the OmpF channel. In order to accommodate a polypeptide in the pore, the mid-channel constriction loop of OmpF, L3, would need to undergo a conformational change. We used five OmpF cystine mutants, which fix L3 in the conformation determined by X-ray crystallography, to investigate L3 movement during colicin activity in vivo. Sensitivity to colicins N and A of E. coli cells expressing these OmpF cystine mutants was determined using cell survival and in vivo potassium efflux and fluorescence assays. Results indicate that gross movement of L3 is not required for colicin N or A activity and that neither of these colicins crosses the outer membrane of E. coli through the lumen of the OmpF pore.

Characterization of a region of the IncHI2 plasmid R478 which protects Escherichia coli from toxic effects specified by components of the tellurite, phage, and colicin resistance cluster

The IncHI2 plasmid R478 specifies resistance to potassium tellurite (Te(r)), to some bacteriophages (Phi), and to pore-forming colicins (PacB). The genes encoding the three phenotypes are linked, and an 8.4-kb fragment of R478 DNA encoding them cannot be subcloned unless cocloned with a second section of the plasmid. Subclone pKFW4A contains a 5.9-kb BamHI-EcoRI fragment which caused some toxicity when present in Escherichia coli cells. Bacterial cells containing freshly transformed pKFW4A, examined by light microscopy and electron microscopy, had a filamentous morphology consistent with a block in septation. Insertion of transposon Tn1000 into terZ, -A, -B, and -C genes of pKFW4A resulted in the loss of the filamentation phenotype. Deletion of several regions of the clone confirmed that these latter components are involved in the filamentation phenotype. The region specifying protection from toxicity caused by the larger 8.4-kb fragment (encompassing this cluster and the entire 5.9-kb section of pKFW4A) was sequenced and analyzed by T7 polymerase expression and Tn1000 mutagenesis. Three open reading frames, terW, terY, and terX, were identified in a 2.6-kb region. Two polypeptides with approximate molecular masses of 18 and 28 kDa were expressed in CSRDE3 cells and were consistent with TerW (17.1 kDa; 155 amino acids [aa]) and TerY (26.9 kDa; 248 aa), whereas a protein of 213 aa deduced from terX was not observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The terX gene product shows strong identity with the previously identified TerE, TerD, and TerZ polypeptides, and there is a conserved motif of 13 residues, GDN(R/L)TG(E/A)GDGDDE, within this group of polypeptides. Complementation analysis indicated that terW, located approximately 6.0 kb upstream of terZ, brings about protection of cells from toxic effects of components of the Te(r), Phi, and PacB cluster.

Phage inhibition, colicin resistance, and tellurite resistance are encoded by a single cluster of genes on the IncHI2 plasmid R478

A region of the IncHI2 plasmid R478, encoding the phenotypes of tellurite resistance (Ter), phage inhibition (Phi), and colicin resistance (PacB), was cloned and sequenced. Analysis indicated seven open reading frames (ORFs), whose genes were designated terZ, -A, -B, -C, -D, -E, and -F. Five of these predicted ORFs (A to E) had extensive amino acid homology with the previously reported ORFs of the IncHI2 Ter operon from plasmid pMER610. There were domains of highly conserved amino acid residues within the group TerA, -D, -E, and -F and within TerD, -E, and -Z, but no consensus could be found among all five putative polypeptides. There were also regions of good identity and similarity between individual pairs of ORFs which was not reflected in the multiple alignments. The three phenotypes were expressed in Escherichia coli DH5 alpha by an 8.4-kb EcoRI insert subcloned from a cosmid of R478. The latter insert was clonable only as a double insertion with a 4.5-kb fragment, and forced deletion of the smaller fragment was lethal to cells. This lethality was not dependent on the cloned orientation of either fragment, suggesting that there is a trans-acting element in the 4.5-kb fragment. Tn1000 mutagenesis of one of the double-insert clones, pDT2575, showed that the phenotypes, including multiple colicin resistance, were genetically linked. Transpositions into terD, terC, and terZ reduced or abolished all phenotypes, while inserts into terE and terF had no effect on the phenotypes. Insertions in terA reduced phage inhibition levels only. The presence of the terZ and terF ORFs in pMER610 was confirmed, and derivatives of this plasmid mediated Phi, PacB, and Ter.

Genetic and nucleotide sequence analysis of the gene htdA, which regulates conjugal transfer of IncHI plasmids

IncHI plasmids are naturally repressed for conjugative transfer and do not allow efficient propagation of the IncH pilus-specific phage Hgal. Transposons Tn7, Tn5, and TnlacZ were inserted into IncHI plasmids R478, R477-1, and R27, respectively, leading to the isolation of several plasmid mutants which exhibited increased levels of transfer and also permitted good lysis with phage Hgal. A 4.3-kb HindIII fragment from R478 reversed both phenotypic effects of derepression for the R477-1::Tn5 and the R478::Tn7 derivatives, pKFW99 and pKFW100, respectively. Exonuclease III deletions of this fragment and nucleotide sequence analysis indicated that the gene responsible for transfer repression, named here htdA, encoded a polypeptide of 150 amino acids. Cloning and sequence analysis of pDT2454 (R27::TnlacZ) revealed that the transposon had inserted into an open reading frame (ORF) which had an 83% amino acid identity with the R478 htdA gene. Maxicell analysis showed both the R27 and R478 HtdA products had molecular masses of 19.9 kDa. Conjugation experiments showed that the cloned htdA determinants caused a significant reduction of the transfer frequencies of wild-type R478 and R27 plasmids. Examination of both R478 derepressed mutants, pKFW100 and pKFW101, indicated that both transposon insertions occurred upstream of the htdA ORF. The results suggest that HtdA is a regulatory component of IncH plasmid transfer and also show that the region upstream of the htdA ORF is involved in transfer repression. The locations of the htdA determinants were identified on the plasmid maps of R27 and R478.

Restriction endonuclease mapping of the HI2 incompatibility group plasmid R478

A restriction map of the 272-kb IncHI2 plasmid R478 was constructed by using the enzymes ApaI, XbaI, SalI, and XhoI. The map was derived from cloned restriction fragments from R478 inserted into cosmid and plasmid vectors as well as from double-digestion analysis of R478 and R478 miniplasmids. All previously known resistance determinants were cloned from R478, and their positions were located on the restriction map. A region involved in incompatibility was cloned and mapped. The location of a previously unreported arsenite resistance gene was also determined. The genes encoding tellurite resistance, colicin B resistance, and phage inhibition were found to be associated with a 6.7-kb SalI fragment of R478.