Dose and fractionation regimen for brachytherapy boost in cervical cancer in the US.

PURPOSE: Curative-intent radiotherapy for locally advanced and select early stage cervical cancer in the US includes external beam radiotherapy (EBRT) with brachytherapy. Although there are guidelines for brachytherapy dose and fractionation regimens, there are limited data on practice patterns. This study aims to evaluate the contemporary utilization of cervical cancer brachytherapy in the US and its association with patient demographics and facility characteristics. METHODS: We retrospectively analyzed clinical covariates of cervical cancer patients diagnosed and treated in 2018-2020 with curative-intent radiotherapy from the 2020 National Cancer Database. Associations between patient and institutional factors with the number of brachytherapy fractions were identified with logistic regression. Factors with association (p < 0.10) were then included in a multivariable logistic regression model. All tests were two-sided with significance <0.05 unless specified otherwise. RESULTS: Among the eligible 2517 patients, 97.3% received HDR or LDR and is further analyzed. More patients received HDR than LDR brachytherapy (98.9% vs 1.1%) and intracavitary than interstitial brachytherapy (86.4% vs 13.6%). The most common number of HDR fractions prescribed were 5 (51.0%), 4 (32.9%), and 3 (8.6%). After adjusting for the other variables in the model, ethnicity, private insurance status, overall insurance status, and facility type were the only factors that were significantly associated with the number of brachytherapy factions (p < 0.0001, p = 0.028, p = 0.001, and p < 0.0001, respectively, n = 2184). CONCLUSIONS: In the US, various HDR brachytherapy regimens are utilized depending on patient and institutional factors. Future research may optimize cervical cancer brachytherapy by correlating specific dose and fractionation regimens with patient outcomes.

Reduced hepatic stellate cell expression of Kruppel-like factor 6 tumor suppressor isoforms amplifies fibrosis during acute and chronic rodent liver injury.

UNLABELLED: Kruppel-like factor 6 (KLF6), a zinc finger transcription factor and tumor suppressor, is induced as an immediate-early gene during hepatic stellate cell (HSC) activation. The paradoxical induction of a tumor suppressor in HSCs during proliferation led us to explore the biology of wildtype KLF6 (KLF6(WT) ) and its antagonistic, alternatively spliced isoform KLF6(SV1) in cultured HSCs and animal models. The animal models generated include a global heterozygous KLF6 mouse (Klf6+/-), and transgenic mice expressing either hKLF6(WT) or hKLF6(SV1) under the control of the Collagen α2 (I) promoter to drive HSC-specific gene expression following injury. The rat Klf6 transcript has multiple splice forms that are homologous to those of the human KLF6 gene. Following a transient increase, all rat Klf6 isoforms decreased in response to acute carbon tetrachloride (CCl(4)) liver injury and culture-induced activation. After acute CCl(4), Klf6+/- mice developed significantly increased fibrosis and enhanced fibrogenic messenger RNA (mRNA) and protein expression. In contrast, HSC-specific transgenic mice overexpressing KLF6(WT) or KLF6(SV1) developed significantly diminished fibrosis with reduced expression of fibrogenic genes. Chromatin IP and quantitative reverse-transcription polymerase chain reaction in mouse HSCs overexpressing KLF6(WT) demonstrated KLF6(WT) binding to GC boxes in promoters of Colα1 (I), Colα2 (I), and beta-platelet-derived growth factor receptor (ß-Pdgfr) with reduced gene expression, consistent with transcriptional repression by KLF6. Stellate cells overexpressing either KLF6(WT) or KLF6(SV1) were more susceptible to apoptotic stress based on poly (ADP-ribose) polymerase (PARP) cleavage. CONCLUSION: KLF6 reduces fibrogenic activity of HSCs by way of two distinct mechanisms, direct transcriptional repression of target fibrogenic genes and increased apoptosis of activated HSCs. These results suggest that following its initial induction, sustained down-regulation of KLF6 in liver injury may allow de-repression of fibrogenic genes and decreased stellate cell clearance by inhibiting apoptosis.

Autophagy releases lipid that promotes fibrogenesis by activated hepatic stellate cells in mice and in human tissues.

BACKGROUND & AIMS: The pathogenesis of liver fibrosis involves activation of hepatic stellate cells, which is associated with depletion of intracellular lipid droplets. When hepatocytes undergo autophagy, intracellular lipids are degraded in lysosomes. We investigated whether autophagy also promotes loss of lipids in hepatic stellate cells to provide energy for their activation and extended these findings to other fibrogenic cells. METHODS: We analyzed hepatic stellate cells from C57BL/6 wild-type, Atg7(F/F), and Atg7(F/F)-GFAP-Cre mice, as well as the mouse stellate cell line JS1. Fibrosis was induced in mice using CCl(4) or thioacetamide (TAA); liver tissues and stellate cells were analyzed. Autophagy was blocked in fibrogenic cells from liver and other tissues using small interfering RNAs against Atg5 or Atg7 and chemical antagonists. Human pulmonary fibroblasts were isolated from samples of lung tissue from patients with idiopathic pulmonary fibrosis or from healthy donors. RESULTS: In mice, induction of liver injury with CCl(4) or TAA increased levels of autophagy. We also observed features of autophagy in activated stellate cells within injured human liver tissue. Loss of autophagic function in cultured mouse stellate cells and in mice following injury reduced fibrogenesis and matrix accumulation; this effect was partially overcome by providing oleic acid as an energy substrate. Autophagy also regulated expression of fibrogenic genes in embryonic, lung, and renal fibroblasts. CONCLUSIONS: Autophagy of activated stellate cells is required for hepatic fibrogenesis in mice. Selective reduction of autophagic activity in fibrogenic cells in liver and other tissues might be used to treat patients with fibrotic diseases.

Dendritic cell regulation of carbon tetrachloride-induced murine liver fibrosis regression.

UNLABELLED: Although hepatic fibrosis typically follows chronic inflammation, fibrosis will often regress after cessation of liver injury. In this study, we examined whether liver dendritic cells (DCs) play a role in liver fibrosis regression using carbon tetrachloride to induce liver injury. We examined DC dynamics during fibrosis regression and their capacity to modulate liver fibrosis regression upon cessation of injury. We show that conditional DC depletion soon after discontinuation of the liver insult leads to delayed fibrosis regression and reduced clearance of activated hepatic stellate cells, the key fibrogenic cell in the liver. Conversely, DC expansion induced either by Flt3L (fms-like tyrosine kinase-3 ligand) or adoptive transfer of purified DCs accelerates liver fibrosis regression. DC modulation of fibrosis was partially dependent on matrix metalloproteinase (MMP)-9, because MMP-9 inhibition abolished the Flt3L-mediated effect and the ability of transferred DCs to accelerate fibrosis regression. In contrast, transfer of DCs from MMP-9-deficient mice failed to improve fibrosis regression. CONCLUSION: Taken together, these results suggest that DCs increase fibrosis regression and that the effect is correlated with their production of MMP-9. The results also suggest that Flt3L treatment during fibrosis resolution merits evaluation to accelerate regression of advanced liver fibrosis.

A polymorphism that delays fibrosis in hepatitis C promotes alternative splicing of AZIN1, reducing fibrogenesis.

UNLABELLED: Among several single-nucleotide polymorphisms (SNPs) that correlate with fibrosis progression in chronic HCV, an SNP in the antizyme inhibitor (AzI) gene is most strongly associated with slow fibrosis progression. Our aim was to identify the mechanism(s) underlying this observation by exploring the impact of the AzI SNP on hepatic stellate cell (HSC) activity. Seven novel AZIN1 splice variants ("SV2-8") were cloned by polymerase chain reaction from the LX2 human HSC line. Expression of a minigene in LX2 containing the AZIN1 slow-fibrosis SNP yielded a 1.67-fold increase in AZIN1 splice variant 2 (AZIN1 SV2) messenger RNA (mRNA) (P = 0.05). In healthy human leukocytes, the SNP variant also correlated with significantly increased SV2 mRNA. Cells (293T) transfected with short hairpin RNA (shRNA) complementary to the exonic splicing chaperone SRp40 expressed 30% less SRp40 (P = 0.044) and 43% more AzI SV2 (P = 0.021) than control shRNA-expressing cells, mimicking the effect of the sequence variant. LX2 cells transfected with AZIN1 full-length complementary DNA expressed 35% less collagen I mRNA (P = 0.09) and 18% less α-smooth muscle actin mRNA (P = 0.09). Transient transfection of AZIN1 SV2 complementary DNA into LX2 cells reduced collagen I gene expression by 64% (P = 0.001) and α-smooth muscle actin by 43% (P = 0.005) compared to vector-transfected controls, paralleling changes in protein expression. Both AZIN1 and AZIN-SV2 mRNAs are detectable in normal human liver and reduced in HCV cirrhotic livers. The AZIN1-SV2 acts via a polyamine-independent pathway, as it neither interacts with antizyme nor affects the ability of AZIN1 lacking this variant to neutralize antizyme. CONCLUSION: An SNP variant in the AZIN1 gene leads to enhanced generation of a novel alternative splice form that modifies the fibrogenic potential of HSCs.

Dosimetric comparison of two afterloaders and treatment planning systems in vaginal high-dose-rate brachytherapy.

Purpose: In treatment planning for high-dose-rate (HDR) single-channel vaginal cylinder brachytherapy, dose distribution along the cylinder is influenced by the anisotropy of the source. Differences in anisotropy are due to differences in source dimensions and characteristics. In this study, we compared HDR vaginal cylinder brachytherapy treatment plans from two afterloader/treatment planning systems. Material and methods: Seventy-five plans with prescription to the surface were generated for cylinders in Varian BrachyVision and Elekta Oncentra. To understand the impact of source anisotropy on dose distribution to the surface of the cylinder, potential effect caused by differences in cylinder geometry between systems was eliminated by re-planning Varian cylinder using Elekta source model. Mean relative dose was calculated for each point as well as the dome and length of the cylinder. Related-samples Wilcoxon signed-rank tests were performed to compare the mean relative dose between systems. Results: Treatment plans with VariSource iX source and cylinder demonstrated 16.2% lower (p < 0.001) dose at the tip compared to Elekta v.3. Average dose to the points along the dome of cylinder was 128.4% ±17.9% prescription dose with VariSource iX source and cylinder, and 99.9% ±4.3% with Elekta v.3 source and cylinder. For the same cylinder geometry, the effect of source characteristics produced up to 36.8% difference in dose homogeneity. When cylinder types were planned with the same source, there was no significant difference in dose distribution. Conclusions: This study demonstrates that the effect of source characteristics produced up to 37% difference in dose homogeneity when comparing two afterloader/treatment planning systems, independent of cylinder geometry. This insight on variation in dose surrounding source system is imperative for dosimetry considerations. Depending on the choice of afterloader, the extent of EQD2 for tumor control versus normal tissue toxicity can vary.

A first radiotherapy application of functional bulboclitoris anatomy, a novel female sexual organ-at-risk, and organ-sparing feasibility study.

OBJECTIVE: The bulboclitoris (clitoris and vestibular bulbs) is the primary organ responsible for female sexual arousal and orgasm. Effects of radiotherapy on the bulboclitoris are unknown, as its structure/function has yet to be described in radiotherapy, and it overlaps only partially with the external genitalia structure. Our aim was to: describe bulboclitoris structure, function and delineation; compare volume of and dose delivered to the bulboclitoris vs external genitalia; and, compare bulboclitoris-sparing IMRT (BCS-IMRT) to standard IMRT (S-IMRT) to determine reoptimization feasibility. METHODS: Our expert team (anatomist, pelvic radiologist, radiation oncologist) reviewed bulboclitoris anatomy and developed contouring guidance for radiotherapy. 20 female patients with anal cancer treated with chemoradiation were analyzed. Sexual organs at risk (OARs) included the external genitalia and the bulboclitoris. Volumes, dice similarity coefficients (DSCs) and dose received using S-IMRT were compared. Plans were reoptimized using BCS-IMRT. Dose-volume histograms (DVHs) for PTVs and all OARs were compared for BCS-IMRT vs S-IMRT. RESULTS: Bulboclitoris structure, function and delineation are described herein. The bulboclitoris occupies 20cc (IQR:12-24), largely distinct from the external genitalia (DSC <0.05). BCS-IMRT was superior to S-IMRT in reducing the dose to the bulboclitoris, with the greatest reductions in V30 and V40, with no significant changes in dose to other OARs or PTV 1/V95. CONCLUSION: The bulboclitoris can be contoured on planning imaging, largely distinct from the external genitalia. Compared with S-IMRT, BCS-IMRT dramatically reduced dose to the bulboclitoris in anal cancer planning. BCS-IMRT might safely reduce sexual toxicity compared with standard approaches. ADVANCES IN KNOWLEDGE: The structure and function of the bulboclitoris, the critical primary organ responsible for female sexual arousal and orgasm, has yet to be described in the radiotherapy literature. Structure, function and delineation of the bulboclitoris are detailed, delineation and bulboclitoris-sparing IMRT were feasible, and sparing reduces the dose to the bulboclitoris nearly in half in female patients receiving IMRT for anal cancer, warranting further clinical study.

Factors associated with the receipt and completion of whole brain radiation therapy among older adults in the United States from 2010-2013.

INTRODUCTION: Whole brain radiation therapy (WBRT) is widely used to treat patients with brain metastases. However, there is debate regarding its utility in patients with poor prognoses. In this study, we sought to characterize the use of WBRT in the United States, especially in adults aged 55 and above. MATERIAL AND METHODS: Patients with brain metastases were identified using the National Cancer Database between 2010 and 2013. The receipt and completion of WBRT with various patient factors were correlated using multivariable logistic regression. RESULTS: 28,422 patients with brain metastases were identified, 23,362 of whom were aged 55 or above. 14,845 patients received WBRT and 12,310 patients completed treatment. Among adults aged 55 and above, 11,945 patients received WBRT, and 9812 patients completed treatment. Patients aged 60 and above were less likely to receive WBRT, while those aged 65 and above were less likely to complete WBRT. DISCUSSION: These results suggest that WBRT may be over-utilized in the United States, especially among older adults. Better interventions to improve pre-WBRT decision-making in this population are needed to select patients who might derive benefit.

Overall Survival Trends and Clinical Characteristics of Plasmacytoma in the United States: A National Cancer Database Analysis.

BACKGROUND: Given the rarity of plasmacytoma, large-scale database analysis can provide useful information regarding the clinical presentation and patient-related factors impacting overall survival (OS). MATERIALS AND METHODS: The National Cancer Data Base was queried for patients with plasmacytoma between 2004 and 2013, excluding patients with systemic disease. Plasmacytomas were classified as originating in bone (P-bone), in extramedullary tissue (P-EM), or unspecified. Survival was estimated using the Kaplan-Meier and log-rank test method. We used Cox regression to determine specific outcomes adjusting for demographic, socioeconomic, geographic, facility type, year of diagnosis, and comorbid factors. RESULTS: In total, 6225 patients were identified, of which 61.5% were men. The median age at diagnosis was 64 years (range, 18-90 years), and the median follow-up was 58 months. The primary site of disease was P-bone in 4056 (65.1%) patients and P-EM in 1468 (23.6%), and the remaining 701 patients were P-unspecified. The unadjusted median survival for solitary P-bone was 89 months (95% confidence interval, 82.9-95.0 months), and for solitary P-EM was 117.3 months (95% confidence interval, 108.8 months to not reached). Factors associated with improved OS include younger age, private insurance, higher income, solitary lesion, and lower comorbidity score. Patients with P-bone disease treated at academic facilities had improved OS. Only 65% of patients with solitary plasmacytoma lesions received radiation treatment. Age greater than 75 years and increased distance to treatment facility was associated with a decreased likelihood of receiving radiation. CONCLUSIONS: This is the largest study examining outcomes of patients with plasmacytoma using a large database analysis, revealing unique aspects of P-EM versus P-bone and underutilization of radiation treatment.

Utilization Patterns of Single Fraction Radiation Therapy for Multiple Myeloma.

BACKGROUND: Patients with multiple myeloma (MM) are living longer than ever before thanks to new therapies. As a consequence, radiation therapy (RT) is increasingly important in the management of bone lesions from MM. Current American Society for Radiation Oncology guidelines recommend greater usage of 8 Gy in 1 fraction for treatment of these lesions. The objective of this study is to analyze utilization of 8 Gy in 1 fraction for treatment of MM bone lesions in the United States utilizing the National Cancer Data Base (NCDB). MATERIALS AND METHODS: The NCDB was used to identify patients with MM treated with palliative RT for painful bony lesions in the period between 2004 and 2014. Utilization rate of RT in this patient population as well as single-fraction (SFRT) versus multiple-fraction RT (MFRT) was compared according to demographic, socioeconomic, and logistic details. RESULTS: A total of 95,190 patients met our inclusion criteria. Of these, 10,261 (10.8%) patients received RT, and a total of 243 (2.4%) of these patients received SFRT over the 10-year period. There was an 11.73% annual increase (P = .0001) in SFRT utilization from 2004 to 2014. Older age, black race, longer distance from the treatment facility, lower degree of education, treatment at an academic or integrated healthcare network, worse comorbidities, and more recent diagnoses were all associated with increased usage of SFRT. CONCLUSION: SFRT for the management of MM painful bony metastases remains underutilized. Trends show that radiation oncologists do not appear to be changing their approach to treating this disease.

Premature discontinuation of curative radiation therapy: Insights from head and neck irradiation.

PURPOSE: Factors related to premature discontinuation of curative radiation therapy (PDCRT) are understudied. This study aimed to examine causes and clinical outcomes of PDCRT at our institution by investigating the most common anatomical site associated with PDCRT. METHODS AND MATERIALS: Among the 161 patients with PDCRT of various anatomic sites at our institution between 2010 and 2017, 36% received radiation to the head and neck region. Pertinent demographic, clinical, and treatment-related data on these 58 patients were collected. Survival was examined using the life-table method and log-rank test. RESULTS: The majority of patients were male (81%), white (67%), ≥60 years old (59%), living ≥10 miles away from the hospital (60%), single (57%), with Eastern Cooperative Oncology Group score ≥1 (86%), experiencing significant pain issues (67%), and had treatment interruptions in radiation therapy (RT; 66%). The most common reasons for PDCRT were discontinuation against medical advice (33%), medical comorbidity (24%), and RT toxicity (17%). Of the comorbidities leading to PDCRT, 50% was acute cardiopulmonary issues and 43% was infection. The mean follow-up time was 15.9 months, and the 2-year overall survival and disease-specific survival rates were 61% and 78%, respectively. Patients with illicit substance abuse, cardiovascular disease, and Eastern Cooperative Oncology Group score ≥2 had worse survival. A trend toward improved survival with total completed dose ≥50 Gy versus <50 Gy existed (74% versus 44%, respectively; P = .07). CONCLUSIONS: In this largest-to-date, modern analysis of PDCRT, the most common cause of discontinuation was discontinuation against medical advice, which underscores the importance of patient education, optimization of RT symptoms, involvement of social work, and integration of other supportive services early in treatment. Survival remains suboptimal after PDCRT for H&N tumors, with a 2-year overall survival rate of 61%. Completing >50 Gy appears to confer a relative therapeutic benefit.

Prognostic Factors and Patterns of Locoregional Failure After Surgical Resection in Patients With Cholangiocarcinoma Without Adjuvant Radiation Therapy: Optimal Field Design for Adjuvant Radiation Therapy.

PURPOSE: To identify prognostic factors and patterns of local failure in patients with cholangiocarcinoma (CCA), after surgical resection in the absence of adjuvant radiation, for optimal definition of target volumes encompassing the majority of local recurrences. METHODS AND MATERIALS: A chart review was performed in patients who underwent resection for primary CCA (intrahepatic, hilar, and distal) between 1999 and 2014. Local failure was defined as recurrence in a theoretical reasonable postoperative radiation volume. This includes the cut surface of liver, biliary anastomosis, hilum, portal nodes, celiac nodes, peri-pancreatic nodes, gastro-hepatic nodes, and retroperitoneal nodes. Patients who received adjuvant radiation were excluded. RESULTS: A total of 189 patients underwent surgical resection for CCA, of whom 145 patients had sufficient follow-up. Median follow-up was 41.6 months (95% confidence interval 35.4-48.7 months). Of the 145 cases, 102 were intrahepatic and 43 were hilar/distal CCA. Adjuvant chemotherapy was given in 38 cases (26%), of which 20 (54%) were gemcitabine-based. Eighty-six patients (59%) had a documented recurrence, of whom 44 (51%) had a locoregional component. Among patients who had a recurrence, 23 (27%) had a recurrence at the biliary anastomosis and/or cut liver surface. Twenty-eight patients (32.6%) had a recurrence in the regional lymph nodes, most prevalent in the portal (16.3%) and retroperitoneal (17.4%) lymph nodes. Univariable analysis identified tumor size, any vascular invasion, presence of satellites, stage/nodal status, and receipt of chemotherapy as significant prognostic factors of overall recurrence among intrahepatic patients. Presence of satellites, and stage 3/Nx status remained statistically significant in multivariable modeling. CONCLUSIONS: The areas at highest risk for locoregional recurrence after surgical resection for primary CCA are the biliary anastomosis/cut liver surface, portal lymph nodes, and retroperitoneal lymph nodes. Although these results need to be validated, adjuvant radiation should possibly cover these areas to maximize locoregional control.

Tumor suppressor activity of KLF6 mediated by downregulation of the PTTG1 oncogene.

The tumor suppressor Kruppel-like factor 6 (KLF6) is frequently inactivated in hepatocellular carcinoma (HCC). To unearth downstream transcriptional targets of KLF6, cDNA microarray analysis of whole liver was compared between KLF6+/+ and KLF6+/- mice. Pituitary tumor transforming gene 1 (PTTG1), an oncogene, was the most up-regulated transcript in KLF6+/- liver. In human HCCs, KLF6 mRNA was significantly decreased, associated with increased PTTG1. In HepG2, KLF6 transcriptionally repressed PTTG1 by direct promoter interaction. Whereas KLF6 downregulation by siRNA increased HepG2 proliferation, siRNA to PTTG1 was anti-proliferative. PTTG1 downregulation represents a novel tumor suppressor pathway of KLF6.

Advances in antifibrotic therapy.

Sustained progress in defining the molecular pathophysiology of hepatic fibrosis has led to a comprehensive framework for developing antifibrotic therapies. Indeed, the single greatest limitation in bringing new drugs to the clinical setting is a lack of clarity regarding clinical trial and treatment end points, not a lack of promising agents. A range of treatments, including those developed for other indications, as well as those specifically developed for hepatic fibrosis, are nearing or in clinical trials. Most are focused on attacking features of either hepatic injury and/or activated stellate cells and myofibroblasts, which are the primary sources of extracellular matrix (scar) proteins. Thus, features of injury and stellate cell activation provide a useful template for classifying these emerging agents and point to a new class of therapies for patients with fibrosing liver disease.