Lifestyle Factors and Breast Cancer in Females with PTEN Hamartoma Tumor Syndrome (PHTS)

Females with PTEN Hamartoma Tumor Syndrome (PHTS) have breast cancer risks up to 76%. This study assessed associations between breast cancer and lifestyle in European female adult PHTS patients. Data were collected via patient questionnaires (July 2020-March 2023) and genetic diagnoses from medical files. Associations between lifestyle and breast cancer were calculated using logistic regression corrected for age. Index patients with breast cancer before PHTS diagnosis (breast cancer index) were excluded for ascertainment bias correction. In total, 125 patients were included who completed the questionnaire at a mean age of 44 years (SD = 13). This included 21 breast cancer indexes (17%) and 39 females who developed breast cancer at 43 years (SD = 9). Breast cancer patients performed about 1.1 times less often 0-1 times/week physical activity than ≥2 times (ORtotal-adj = 0.9 (95%CI 0.3-2.6); consumed daily about 1.2-1.8 times more often ≥1 than 0-1 glasses of alcohol (ORtotal-adj = 1.2 (95%CI 0.4-4.0); ORnon-breastcancer-index-adj = 1.8 (95%CI 0.4-6.9); were about 1.04-1.3 times more often smokers than non-smokers (ORtotal-adj = 1.04 (95%CI 0.4-2.8); ORnon-breastcancer-index-adj = 1.3 (95%CI 0.4-4.2)); and overweight or obesity (72%) was about 1.02-1.3 times less common (ORtotal-adj = 0.98 (95%CI 0.4-2.6); ORnon-breastcancer-index-adj = 0.8 (95%CI 0.3-2.7)). Similar associations between lifestyle and breast cancer are suggested for PHTS and the general population. Despite not being statistically significant, results are clinically relevant and suggest that awareness of the effects of lifestyle on patients' breast cancer risk is important.

Cancer risks by sex and variant type in PTEN hamartoma tumor syndrome

BACKGROUND

PTEN Hamartoma Tumor Syndrome (PHTS) is a rare syndrome with a broad phenotypic spectrum, including increased risks of breast (BC, 67%-78% at age 60 years), endometrial (EC, 19%-28%), and thyroid cancer (TC, 6%-38%). Current risks are likely overestimated due to ascertainment bias. We aimed to provide more accurate and personalized cancer risks.

METHODS

This was a European, adult PHTS cohort study with data from medical files, registries, and/or questionnaires. Cancer risks and hazard ratios were assessed with Kaplan-Meier and Cox regression analyses, and standardized incidence ratios were calculated. Bias correction consisted of excluding cancer index cases and incident case analyses.

RESULTS

A total of 455 patients were included, including 50.5% index cases, 372 with prospective follow-up (median 6 years, interquartile range = 3-10 years), and 159 of 281 females and 39 of 174 males with cancer. By age 60 years, PHTS-related cancer risk was higher in females (68.4% to 86.3%) than males (16.4% to 20.8%). Female BC risks ranged from 54.3% (95% confidence interval [CI] = 43.0% to 66.4%) to 75.8% (95% CI = 60.7% to 88.4%), with two- to threefold increased risks for PTEN truncating and approximately twofold for phosphatase domain variants. EC risks ranged from 6.4% (95% CI = 2.1% to 18.6%) to 22.1% (95% CI = 11.6% to 39.6%) and TC risks from 8.9% (95% CI = 5.1% to 15.3%) to 20.5% (95% CI = 11.3% to 35.4%). Colorectal cancer, renal cancer, and melanoma risks were each less than 10.0%.

CONCLUSIONS

Females have a different BC risk depending on their PTEN germline variant. PHTS patients are predominantly at risk of BC (females), EC, and TC. This should be the main focus of surveillance. These lower, more unbiased and personalized risks provide guidance for optimized cancer risk management.

Universal Tumor DNA BRCA1/2 Testing of Ovarian Cancer: Prescreening PARPi Treatment and Genetic Predisposition

Background

Women with epithelial ovarian cancer (OC) have a higher chance to benefit from poly (ADP-ribose) polymerase inhibitor (PARPi) therapy if their tumor has a somatic or hereditary BRCA1/2 pathogenic variant. Current guidelines advise BRCA1/2 genetic predisposition testing for all OC patients, though this does not detect somatic variants. We assessed the feasibility of a workflow for universal tumor DNA BRCA1/2 testing of all newly diagnosed OC patients as a prescreen for PARPi treatment and cancer predisposition testing.

Methods

Formalin-fixed paraffin-embedded tissue was obtained from OC patients in seven hospitals immediately after diagnosis or primary surgery. DNA was extracted, and universal tumor BRCA1/2 testing was then performed in a single site. Diagnostic yield, uptake, referral rates for genetic predisposition testing, and experiences of patients and gynecologists were evaluated.

Results

Tumor BRCA1/2 testing was performed for 315 (77.6%) of the 406 eligible OC samples, of which 305 (96.8%) were successful. In 51 of these patients, pathogenic variants were detected (16.7%). Most patients (88.2%) went on to have a genetic predisposition test. BRCA1/2 pathogenic variants were shown to be hereditary in 56.8% and somatic in 43.2% of patients. Participating gynecologists and patients were overwhelmingly positive about the workflow.

Conclusions

Universal tumor BRCA1/2 testing in all newly diagnosed OC patients is feasible, effective, and appreciated by patients and gynecologists. Because many variants cannot be detected in DNA from blood, testing tumor DNA as the first step can double the identification rate of patients who stand to benefit most from PARP inhibitors.

Evaluation of yield and experiences of age-related molecular investigation for heritable and nonheritable causes of mismatch repair deficient colorectal cancer to identify Lynch syndrome

Universal mismatch repair deficiency (dMMR) testing of colorectal cancer (CRC) is promoted as routine diagnostics to prescreen for Lynch syndrome. We evaluated the yield and experience of age-related molecular investigation for heritable and nonheritable causes of dMMR in CRC below age 70 to identify Lynch Syndrome. In a prospective cohort of 3602 newly diagnosed CRCs below age 70 from 19 hospitals, dMMR, MLH1 promoter hypermethylation, germline MMR gene and somatic MMR gene testing was assessed in daily practice. Yield was evaluated using data from the Dutch Pathology Registry (PALGA) and two regional genetic centers. Experiences of clinicians were evaluated through questionnaires. Participating clinicians were overwhelmingly positive about the clinical workflow. Pathologists routinely applied dMMR-testing in 84% CRCs and determined 10% was dMMR, largely due to somatic MLH1 hypermethylation (66%). Of those, 69% with dMMR CRC below age 70 without hypermethylation were referred for genetic testing, of which 55% was due to Lynch syndrome (hereditary) and 43% to somatic biallelic pathogenic MMR (nonhereditary). The prevalence of Lynch syndrome was 18% in CRC < 40, 1.7% in CRC age 40-64 and 0.7% in CRC age 65-69. Age 65-69 represents most cases with dMMR, in which dMMR due to somatic causes (13%) is 20 times more prevalent than Lynch syndrome. In conclusion, up to age 65 routine diagnostics of (non-)heritable causes of dMMR CRCs effectively identifies Lynch syndrome and reduces Lynch-like diagnoses. Above age 64, the effort to detect one Lynch syndrome patient in dMMR CRC is high and germline testing rarely needed.

New mutations and an updated database for the patched-1 (PTCH1) gene

BACKGROUND

Basal cell nevus syndrome (BCNS) is an autosomal dominant disorder characterized by multiple basal cell carcinomas (BCCs), maxillary keratocysts, and cerebral calcifications. BCNS most commonly is caused by a germline mutation in the patched-1 (PTCH1) gene. PTCH1 mutations are also described in patients with holoprosencephaly.

METHODS

We have established a locus-specific database for the PTCH1 gene using the Leiden Open Variation Database (LOVD). We included 117 new PTCH1 variations, in addition to 331 previously published unique PTCH1 mutations. These new mutations were found in 141 patients who had a positive PTCH1 mutation analysis in either the VU University Medical Centre (VUMC) or Maastricht University Medical Centre (MUMC) between 1995 and 2015.

RESULTS

The database contains 331 previously published unique PTCH1 mutations and 117 new PTCH1 variations.

CONCLUSION

We have established a locus-specific database for the PTCH1 gene using the Leiden Open Variation Database (LOVD). The database provides an open collection for both clinicians and researchers and is accessible online at http://www.lovd.nl/PTCH1.

Clinical Aspects of SDHA-Related Pheochromocytoma and Paraganglioma: A Nationwide Study

CONTEXT

Paraganglioma (PGL) has the highest degree of heritability among human neoplasms. Current clinical understanding of germline SDHA mutation carriers is limited.

OBJECTIVE

To estimate the contribution of SDHA mutations in PGL and to assess clinical manifestations and age-related penetrance.

DESIGN

Nationwide retrospective cohort study.

SETTING

Tertiary referral centers in the Netherlands (multicenter).

PATIENTS

Germline SDHA analysis was performed in 393 patients with genetically unexplained PGL. Subsequently, 30 index SDHA mutation carriers and 56 nonindex carriers were studied.

MAIN OUTCOME MEASURES

SDHA mutation detection yield, clinical manifestations, and SDHA-related disease penetrance.

RESULTS

Pathogenic germline SDHA variants were identified in 30 of the 393 referred patients with PGL (7.6%), who had head and neck PGL (21 of 174 [12%]), pheochromocytoma (4 of 191 [2%]), or sympathetic PGL (5 of 28 [18%]). The median age at diagnosis was 43 years (range, 17 to 81 years) in index SDHA mutation carriers compared with 52 years (range, 7 to 90 years) in nonmutation carriers (P = 0.002). The estimated penetrance of any SDHA-related manifestation was 10% at age 70 years (95% confidence interval, 0% to 21%) in nonindex mutation carriers.

CONCLUSION

Germline SDHA mutations are relatively common (7.6%) in patients with genetically unexplained PGL. Most index patients presented with apparently sporadic PGL. In this SDHA series, the largest assembled so far, we found the lowest penetrance of all major PGL predisposition genes. This suggests that recommendations for genetic counseling of at-risk relatives and stringency of surveillance for SDHA mutation carriers might need to be reassessed.

Postzygotic mosaicism in basal cell naevus syndrome

Basal cell naevus syndrome (BCNS) is an autosomal dominant disorder most commonly caused by a germline mutation in the Drosophila homologue of patched-1 gene (PTCH1). Here we describe a patient with clinical signs of BCNS, caused by postzygotic mosaicism of a PTCH1 mutation. We performed restriction fragment length polymorphism analysis and Droplet Digital polymerase chain reaction to determine the degree of mosaicism in different tissues of this patient. Our case shows that a relatively low-grade mosaicism can lead to clinical signs reminiscent of those caused by a germline mutation. This finding has important implications for genetic counselling and therefore is pivotal to recognize for dermatologists, as well as for clinical geneticists and clinical laboratory geneticists.

A de novo FLCN mutation in a patient with spontaneous pneumothorax and renal cancer; a clinical and molecular evaluation

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant condition due to germline FLCN (folliculin) mutations, characterized by skin fibrofolliculomas, lung cysts, pneumothorax and renal cancer. We identified a de novo FLCN mutation, c.499C>T (p.Gln167X), in a patient who presented with spontaneous pneumothorax. Subsequently, typical skin features and asymptomatic renal cancer were diagnosed. Probably, de novo FLCN mutations are rare. However, they may be under-diagnosed if BHD is not considered in sporadic patients who present with one or more of the syndromic features. Genetic and immunohistochemical analysis of the renal tumour indicated features compatible with a tumour suppressor role of FLCN. The finding that mutant FLCN was expressed in the tumour might indicate residual functionality of mutant FLCN, a notion which will be explored in future studies.

Severely reduced diffusion capacity in idiopathic pulmonary arterial hypertension: patient characteristics and treatment responses

A subgroup of patients with idiopathic pulmonary arterial hypertension (IPAH) has severely reduced diffusing capacity of the lung for carbon monoxide (DLCO) and poor prognosis. Their characteristics are currently unknown. The aim of this study is to contrast clinical characteristics and treatment responses of IPAH-patients with a severely reduced and more preserved DLCO. Retrospectively, 166 IPAH patients were included and grouped based on a DLCO cut-off value of 45% pred (IPAH(<45%) and IPAH(≥45%)). Clinical characteristics, treatment responses and survival were compared. IPAH(<45%) were older, more often male, had a more frequent history of coronary disease and a higher tobacco exposure. Forced expiratory volume in 1 s (FEV1), FEV1/forced vital capacity, total lung capacity and alveolar volume values were slightly lower and computed tomography scan abnormalities more prevalent in patients with a low DLCO. Age and number of pack years were independently associated with DLCO < 45% pred. IPAH(<45%) showed no different haemodynamic profile, yet worse exercise performance and a worse survival rate, which were both related to age, sex and the presence of coronary disease. To conclude, a severely reduced DLCO in IPAH is associated with advanced age and a greater tobacco exposure. These patients have a worse exercise performance despite a similar hemodynamic profile. We confirm the decreased survival in this patient group and now show that this poor outcome is related to age, sex and the presence of coronary disease.

Genetic counselling for pulmonary arterial hypertension: a matter of variable variability

We report three cases which highlight the complex considerations surrounding genetic counselling for pulmonary arterial hypertension (PAH). The first counselee developed PAH symptoms shortly after his daughter's death from PAH and was diagnosed with a delay of 1 year. An early diagnosis of familial PAH was established in the second counselee. Oral therapy was initiated immediately, and her functional status has since remained stable. The third counselee was a healthy woman who struggled to cope with her risk for familial PAH, having lost two siblings from the disease. These cases show that incomplete penetrance and variable expression need particular attention during clinical assessment and genetic counselling of heritable PAH patients and family members.

TBX4 mutations (small patella syndrome) are associated with childhood-onset pulmonary arterial hypertension

Background

Childhood-onset pulmonary arterial hypertension (PAH) is rare and differs from adult-onset disease in clinical presentation, with often unexplained mental retardation and dysmorphic features (MR/DF). Mutations in the major PAH gene, BMPR2, were reported to cause PAH in only 10–16% of childhood-onset patients. We aimed to identify more genes associated with childhood-onset PAH.

Methods

We studied 20 consecutive cases with idiopathic or heritable PAH. In patients with accompanying MR/DF (n=6) array-comparative genomic hybridisation analysis was performed, with the aim of finding common deletion regions containing candidate genes for PAH. Three patients had overlapping deletions of 17q23.2. TBX2 and TBX4 were selected from this area as candidate genes and sequenced in all 20 children. After identifying TBX4 mutations in these children, we subsequently sequenced TBX4 in a cohort of 49 adults with PAH. Because TBX4 mutations are known to cause small patella syndrome (SPS), all patients with newly detected TBX4 mutations were screened for features of SPS. We also screened a third cohort of 23 patients with SPS for PAH.

Results

TBX4 mutations (n=3) or TBX4-containing deletions (n=3) were detected in 6 out of 20 children with PAH (30%). All living patients and two parents with TBX4 mutations appeared to have previously unrecognised SPS. In the adult PAH-cohort, one TBX4 mutation (2%) was detected. Screening in the cohort of (predominantly adult) SPS patients revealed no PAH.

Conclusions

These data indicate that TBX4 mutations are associated with childhood-onset PAH, but that the prevalence of PAH in adult TBX4 mutation carriers is low.

Renal cancer and pneumothorax risk in Birt-Hogg-Dubé syndrome; an analysis of 115 FLCN mutation carriers from 35 BHD families

Background:

Birt–Hogg–Dubé (BHD) syndrome is an autosomal dominant condition caused by germline FLCN mutations, and characterised by fibrofolliculomas, pneumothorax and renal cancer. The renal cancer risk, cancer phenotype and pneumothorax risk of BHD have not yet been fully clarified. The main focus of this study was to assess the risk of renal cancer, the histological subtypes of renal tumours and the pneumothorax risk in BHD.

Methods:

In this study we present the clinical data of 115 FLCN mutation carriers from 35 BHD families.

Results:

Among 14 FLCN mutation carriers who developed renal cancer 7 were <50 years at onset and/or had multifocal/bilateral tumours. Five symptomatic patients developed metastatic disease. Two early-stage cases were diagnosed by surveillance. The majority of tumours showed characteristics of both eosinophilic variants of clear cell and chromophobe carcinoma. The estimated penetrance for renal cancer and pneumothorax was 16% (95% minimal confidence interval: 6–26%) and 29% (95% minimal confidence interval: 9–49%) at 70 years of age, respectively. The most frequent diagnosis in families without identified FLCN mutations was familial multiple discoid fibromas.

Conclusion:

We confirmed a high yield of FLCN mutations in clinically defined BHD families, we found a substantially increased lifetime risk of renal cancer of 16% for FLCN mutation carriers. The tumours were metastatic in 5 out of 14 patients and tumour histology was not specific for BHD. We found a pneumothorax risk of 29%. We discuss the implications of our findings for diagnosis and management of BHD.

Familial multiple discoid fibromas: a look-alike of Birt-Hogg-Dubé syndrome not linked to the FLCN locus

BACKGROUND

Previously, we proposed that familial multiple trichodiscomas (OMIM 190340) is distinct from Birt-Hogg-Dubé syndrome (BHD) (OMIM #135150). BHD is characterized by multiple fibrofolliculomas/trichodiscomas, lung cysts, pneumothorax, and renal cell cancer. Germline FLCN mutations can be detected in most but not all BHD families.

OBJECTIVE

We sought to evaluate familial multiple trichodiscomas at a clinical and genetic level. We now renamed this condition "familial multiple discoid fibromas" (FMDF) to emphasize the distinction from BHD.

METHODS

In 8 additional families with an autosomal dominant pattern of multiple discoid fibromas we assessed the clinical findings and the histopathological features of skin lesions. FLCN germline mutation analysis was completed in 7 families. In two of these families segregation analysis was performed using polymorphic DNA markers in and around the FLCN locus.

RESULTS

The clinical findings in FMDF are different from those in BHD with early onset of skin lesions, prominent involvement of the pinnae, and discoid fibromas without the follicular epithelial component characteristic of the fibrofolliculoma/trichodiscoma spectrum of BHD. In addition, there were no evident pulmonary or renal complications. In none of the families were pathogenic FLCN germline mutations identified. Using segregation analysis we could exclude involvement of the FLCN locus in the two kindreds tested.

LIMITATIONS

The prevalence of FMDF is presently unknown. The underlying gene defect has not yet been identified.

CONCLUSIONS

FMDF is clinically distinct from BHD and is not linked to the FLCN locus.

Birt-Hogg-Dubé Syndrome: Clinical and Genetic Studies of 20 Families

Birt-Hogg-Dubé syndrome (BHD) is an autosomal-dominant genodermatosis characterized by skin fibrofolliculomas and an increased risk of spontaneous pneumothorax, renal and possibly other tumors. A causative gene (FLCN) on chromosome 17p has recently been identified. We here report clinical and genetic studies of 20 BHD families ascertained by the presence of multiple fibrofolliculomas or trichodiscomas in the proband. Pathogenic FLCN germline mutations were found in 11 (69%) of 16 probands tested and in 14 family members. Six different FLCN germline mutations were detected, four of which have not been reported previously. The clinical features were variable. None and less than 10 skin lesions were observed in two mutation carriers at the age of 67 and 29 years, respectively. Spontaneous pneumothorax was reported in four and renal carcinoma of mixed histological types in two of 36 BHD-affected individuals and/or FLCN mutation carriers. Both the prevalence of spontaneous pneumothorax and renal tumors appeared to be relatively low compared with previously reported data. Various other extracutaneous tumors were observed in 11 of 36 BHD-affected individuals and/or FLCN mutation carriers. This study of the second largest cohort to date contributes to the expanding data on the variable phenotype and underlying gene defects in BHD.

Four-dimensional multislice computed tomography for determination of respiratory lung tumor motion in conformal radiotherapy

PURPOSE

We used four-dimensional multislice spiral computed tomography (MSCT) to determine respiratory lung-tumor motion and compared this strategy to common clinical practice in conformal radiotherapy treatment-planning imaging.

METHODS AND MATERIALS

The entire lung volume of 10 consecutive patients with 14 lung metastases were scanned by a 16-slice MSCT. During the scans, patients were instructed to breathe through a spirometer that was connected to a laptop computer. For each patient, 10 stacks of 1.5-mm slices, equally distributed throughout the respiratory cycle, were reconstructed from the acquired MSCT data. The lung tumors were manually contoured in each data set. For each patient, the tumor-volume contours of all data sets were copied to 1 data set, which allowed determination of the volume that encompassed all 10 lung-tumor positions (i.e., the tumor-traversed volume [TTV]) during the respiratory cycle. The TTV was compared with the 10 tumor volumes contoured for each patient, to which an empiric respiratory-motion margin was added. The latter target volumes were designated internal-motion included tumor volume (IMITV).

RESULTS

The TTV measurements were significantly smaller than the reference IMITV measurements (5.2 +/- 10.2 cm(3) and 10.1 +/- 13.7 cm(3), respectively). All 10 IMITVs for 2 of the 4 tumors in 1 subject completely encompassed the TTV. All 10 IMITVs for 3 tumors in 2 patients did not show overlap with up to 35% of the corresponding TTV. The 10 IMITVs for the remaining tumors either completely encompassed the corresponding TTV or did not show overlap with up to 26% of the corresponding TTV.

CONCLUSIONS

We found that individualized determination of respiratory lung-tumor motion by four-dimensional respiratory-gated MSCT represents a better and simple strategy to incorporate periodic physiologic motion compared with a generalized approach. The former strategy can, therefore, improve common and state-of-the-art clinical practice in conformal radiotherapy.

A biplane angiographic study on cardiac motion of coronary artery stents: options to minimize the target volume for high-precision external beam radiotherapy of coronary artery in-stent restenosis

PURPOSE

High-precision external beam radiotherapy (EBRT) has been suggested as a potential alternative to endovascular brachytherapy for the treatment of coronary artery in-stent restenosis. The purpose of our study was to investigate and compare different options to define a smallest feasible target volume.

METHODS AND MATERIALS

The cardiac motion of 17 coronary artery stents in 17 patients was studied by use of biplane conventional angiography, recorded during breath-hold. Each stent was reconstructed in three dimensions by use of biplane sets of frames covering an entire cardiac cycle. The volume traversed by the stent during the entire or part of the cardiac cycle was determined. Four options to define the stent-traversed volume (STV) as a target for high-precision EBRT were investigated.

RESULTS

The mean STV during the entire cardiac cycle was 3.5 cm3; the STV represented less than 1% of the heart volume in all patients. The STV during the diastolic and systolic phase resulted in a mean reduction of 26.6% and 29.1%, respectively, compared with the STV during the entire cardiac cycle. The smallest STV, measured during a 160-ms interval within the cardiac cycle, resulted in a mean maximal reduction of 75.9% compared with the STV during the entire cardiac cycle.

CONCLUSIONS

The STV during the entire cardiac cycle represents a small potential target volume for high-precision EBRT. A significant reduction of this target volume is possible in case of definition during a selected interval within the cardiac cycle.

Dosimetric comparison between high-precision external beam radiotherapy and endovascular brachytherapy for coronary artery in-stent restenosis

PURPOSE

Several drawbacks of endovascular brachytherapy for the treatment of coronary artery in-stent restenosis may be addressed by high-precision external beam radiotherapy (EBRT). The dosimetric characteristics of both treatment techniques were compared.

METHODS AND MATERIALS

The traversed volume of 10 coronary artery stents during the cardiac cycle was determined by electrocardiographically gated multislice spiral CT in 10 patients. By use of this traversed volume, high-precision EBRT treatment plans were generated for stents in the left circumflex (LCx), left anterior descending (LAD), and right coronary artery (RCA). The maximum dose to the nontargeted major coronary arteries was determined and compared to similar data calculated for endovascular brachytherapy.

RESULTS

High-precision EBRT targeted at LCx stents contributed a mean maximum dose (D(max)) of 83.5% (range: 71.6-95.3%) and 16.3% to the LAD and RCA, respectively. Targeted LAD stents contributed a mean D(max) of 39.3% (range: 14.5-94.8%) and 5.2% (range: 0-13.4%) to the LCx and RCA, respectively. Targeted RCA stents contributed a mean D(max) of 6.2% (range: 0-12.4%) and 5.8% (range: 0-11.5%) to the LCx and LAD, respectively. Endovascular brachytherapy targeted at LCx stents contributed a mean D(max) of 1.7% (range: 0.7-2.7%) and 1.0% (range: 0.6-1.4%) to the LAD and RCA, respectively. Targeted LAD stents contributed a mean D(max) of 5.2% (range: 0.5-11.4%) and 0.7% (range: 0.4-1.1%) to the LCx and RCA, respectively; targeted RCA stents contributed a mean D(max) of 0.3% (range: 0.2-0.5%) and 0.2% (range: 0.1-0.3%) to the LCx and LAD, respectively.

CONCLUSIONS

Although the doses distributed throughout the heart were higher for high-precision EBRT compared to endovascular brachytherapy, they are expected to be clinically irrelevant when nontargeted major coronary arteries are not closely situated to the targeted vessel segment. These encouraging results warrant further investigation of high-precision EBRT as a potential alternative to endovascular brachytherapy for the treatment of coronary artery in-stent restenosis.

Coronary stent traversed volume during the cardiac cycle defined as a target for high-precision radiotherapy by using biplane angiograms

Three-dimensional reconstructions of 19 coronary artery stents from biplane angiograms were used for measurement of the volume through which the stents traversed during the cardiac cycle. This volume, less than 0.8% of the whole heart volume in all patients, represents a target volume for high-precision radiotherapy to treat coronary artery in-stent restenosis.

Definition of a moving gross target volume for stereotactic radiation therapy of stented coronary arteries

PURPOSE

To measure the effect of cardiac motion on coronary artery stent position during the cardiac cycle as a first step toward exploring the feasibility of stereotactic external beam radiation therapy targeted at restenotic stented coronary arteries.

METHODS AND MATERIALS

The three-dimensional (3D) position of eight coronary artery stents in 8 patients immobilized in a stereotactic body frame was studied noninvasively by single-breathhold ECG-gated multislice spiral computed tomography (MSCT) during 10 retrospectively selected phases, equally distributed throughout the R-R interval of consecutive cardiac cycles. The volume encompassing all measured 3D positions of the stent was measured.

RESULTS

Stent volumes measured by MSCT closely agreed with measurements by quantitative coronary angiography (r > 0.99). The mean of the maximum 3D stent center of mass displacement between any two phases during the cardiac cycle for all eight coronary arteries was 7.5 mm (range 3.3-20.5 mm) in the lateral direction, 8.6 mm (range 2.7-21.6 mm) in the ventrodorsal direction, and 8.2 mm (range 2.5-19.7 mm) in the craniocaudal direction. As was anticipated, the volume encompassing all measured 3D positions of the stent represented only a fraction of the whole heart volume in all patients, i.e., less than 0.6%.

CONCLUSIONS

ECG-gated MSCT allowed the measurement of the volume encompassing multiphase 3D positions of coronary artery stents during the cardiac cycle. This volume, a measure of the cardiac motion effect on coronary artery stent position during the cardiac cycle, represents a moving gross target for stereotactic external beam radiation therapy.

Comparison of different methods to define a target volume for external beam radiation therapy of restenotic coronary arteries

PURPOSE

Different methods have been described to define a target volume for the treatment of restenotic (stented) coronary arteries by external beam radiation therapy (EBRT). The purpose of this study was to explore two methods to define a target for such therapy, and to compare these with previously investigated methods.

MATERIALS AND METHODS

The 3-D position of a stent throughout the cardiac cycle in the three major epicardial coronary arteries was measured in three patients by single-breathhold multislice spiral CT and breathhold biplane conventional X-ray angiography, both indexed in time with the ECG. The volume through which the stent traversed (STV) during the cardiac cycle was determined by use of displacement measurements.

RESULTS

For multislice CT and biplane angiography, respectively, the mean STV was 1.23 cm(3) (range 0.65-2.22 cm(3)) and 2.81 cm(3) (range 1.60-4.99 cm(3)). The STV represented only a fraction of the whole heart volume in all patients, that is, equal to or less than 0.4%.

CONCLUSIONS

Multislice CT and biplane angiography allowed the measurement of a relatively small potential target, that is the STV, for EBRT of restenotic stented coronary arteries. Both studied imaging modalities are instrumental for targeting the STV by highly conformal radiation therapy in case of restenotic stented coronary arteries.