Common genetic variants and modification of penetrance of BRCA2-associated breast cancer

The considerable uncertainty regarding cancer risks associated with inherited mutations of BRCA2 is due to unknown factors. To investigate whether common genetic variants modify penetrance for BRCA2 mutation carriers, we undertook a two-staged genome-wide association study in BRCA2 mutation carriers. In stage 1 using the Affymetrix 6.0 platform, 592,163 filtered SNPs genotyped were available on 899 young (<40 years) affected and 804 unaffected carriers of European ancestry. Associations were evaluated using a survival-based score test adjusted for familial correlations and stratified by country of the study and BRCA2*6174delT mutation status. The genomic inflation factor (λ) was 1.011. The stage 1 association analysis revealed multiple variants associated with breast cancer risk: 3 SNPs had p-values<10(-5) and 39 SNPs had p-values<10(-4). These variants included several previously associated with sporadic breast cancer risk and two novel loci on chromosome 20 (rs311499) and chromosome 10 (rs16917302). The chromosome 10 locus was in ZNF365, which contains another variant that has recently been associated with breast cancer in an independent study of unselected cases. In stage 2, the top 85 loci from stage 1 were genotyped in 1,264 cases and 1,222 controls. Hazard ratios (HR) and 95% confidence intervals (CI) for stage 1 and 2 were combined and estimated using a retrospective likelihood approach, stratified by country of residence and the most common mutation, BRCA2*6174delT. The combined per allele HR of the minor allele for the novel loci rs16917302 was 0.75 (95% CI 0.66-0.86, ) and for rs311499 was 0.72 (95% CI 0.61-0.85, ). FGFR2 rs2981575 had the strongest association with breast cancer risk (per allele HR = 1.28, 95% CI 1.18-1.39, ). These results indicate that SNPs that modify BRCA2 penetrance identified by an agnostic approach thus far are limited to variants that also modify risk of sporadic BRCA2 wild-type breast cancer.

Prognostic time dependence of deletions affecting codons 557 and/or 558 of KIT gene for relapse-free survival (RFS) in localized GIST: a Spanish Group for Sarcoma Research (GEIS) Study

BACKGROUND

To assess whether deletions involving codons 557 and/or 558 (critical deletions) of exon 11 of KIT are relevant in the prognosis of relapse-free survival (RFS) in gastrointestinal stromal tumor (GIST) patients with a long follow-up.

PATIENTS AND METHODS

A univariate and multivariate analysis for RFS were carried out on 162 localized GIST patients over the entire follow-up period and over the intervals 0-4 years and >4 years. Factors assessed among others were Fletcher/National Institutes of Health and Miettinen-Lasota/Armed Forces Institute of Pathology (M-L/AFIP) risk categories, critical deletions and non-deletion-type mutation (NDTM) within exon 11 of KIT.

RESULTS

Multivariate analyses revealed that M-L/AFIP [relative risk (RR) 11.45, confidence interval (CI) 4.40-29.76, for the high-risk subgroup and RR 5.97, CI 2.09-17.06, for the intermediate subgroup] and critical deletions (RR 3.05, CI 1.59-5.85) were independent prognostic factors for RFS for the first 4 years and for the entire follow-up period. Beyond 4 years, the high-risk M-L/AFIP subgroup (RR 8.12, CI 1.48-44.4) and NDTM (RR 6.42, CI 1.17-35.12) were independent prognostic factors for RFS. The median follow-up was 84 months.

CONCLUSION

Critical deletions represent a time-dependent prognostic factor limited to the first 4 years after surgery, which could help identify a subset with higher and earlier risk for relapse in GIST patients.

Sequence variants at the TERT-CLPTM1L locus associate with many cancer types

The common sequence variants that have recently been associated with cancer risk are particular to a single cancer type or at most two. Following up on our genome-wide scan of basal cell carcinoma, we found that rs401681[C] on chromosome 5p15.33 satisfied our threshold for genome-wide significance (OR = 1.25, P = 3.7 x 10(-12)). We tested rs401681 for association with 16 additional cancer types in over 30,000 cancer cases and 45,000 controls and found association with lung cancer (OR = 1.15, P = 7.2 x 10(-8)) and urinary bladder, prostate and cervix cancer (ORs = 1.07-1.31, all P < 4 x 10(-4)). However, rs401681[C] seems to confer protection against cutaneous melanoma (OR = 0.88, P = 8.0 x 10(-4)). Notably, most of these cancer types have a strong environmental component to their risk. Investigation of the region led us to rs2736098[A], which showed stronger association with some cancer types. However, neither variant could fully account for the association of the other. rs2736098 corresponds to A305A in the telomerase reverse transcriptase (TERT) protein and rs401681 is in an intron of the CLPTM1L gene.

[DPOAE and lateral inhibition in chronic tinnitus]

INTRODUCTION

According to our audiological data, 90% of tinnitus patients have deficits in inner ear function as a generator of tinnitus, mainly in the outer hair cells (OHC). This can be verified by registration of distortion products of otoacoustic emissions (DPOAE). Thus, the main origin of tinnitus is peripheral, and most patients suffer from accompanying hearing loss, even though it is sometimes mild or subjectively not even felt. Whether or not the tinnitus is disturbing, however, is determined through further auditory processing of the "signal" tinnitus and its psychological validation. With almost 50% of our tinnitus and hyperacusis patients, we find hyperfunctioning of the OHC, possibly originating from reduced or ineffective efferent control in the auditory pathway. Efferent activity can be measured by acoustic stimulation of the contralateral ear, which normally reduces the DPOAE amplitudes via efferent inhibition.

METHOD AND PATIENTS

DPOAE were recorded with 67 tinnitus patients (127 ears) with and without contralateral acoustic stimulation. Twenty-one persons (41 ears) served as controls.

RESULTS

With 64% of the tinnitus patients, DPOAE amplitudes were not reduced significantly, compared with 34% of the controls. The medium amplitude reduction for controls was 1.76 dB, whereas for the tinnitus patients it was significantly less (0.91 dB).

CONCLUSION

For a considerable number of tinnitus patients, efferent control of OHC activity is restricted, but this seems to be confined to a certain type of tinnitus only.

Prognostic role of circulating melanoma cells detected by reverse transcriptase-polymerase chain reaction for tyrosinase mRNA in patients with melanoma

A need for factors predictive of prognosis is present in patients who are diagnosed with malignant melanoma. The detection of circulating melanoma cells by reverse transcriptase-polymerase chain reaction for tyrosinase mRNA is a possible negative prognostic factor. The aim of this study was to assess the prognostic value of reverse transcriptase-PCR for tyrosinase mRNA in peripheral blood samples. From January 2000 to February 2003, duplicate blood samples were drawn from 114 melanoma patients following surgery and informed consent, and were tested with reverse transcriptase-PCR, for tyrosinase mRNA. Outer primers for the first PCR were R1 (sense): TTGGCAGATTGTCTGTAGCC and R2 (antisense): AGGCATTGTGCATGCTGCT. For the second round of PCR, nested primers were R3 (sense): GTCTTTATGCAATGGAACGC and R4 (antisense): GCTATCCCAGTAAGTGGACT. Threshold for detection of the technique was determined by adding serially diluted MelJuSo cells to healthy volunteer blood samples. Overall, 91 (79.1%) patients tested negative for tyrosinase mRNA and 24 (20.9%) tested positive. The number of patients who tested positive by stage was 3/38 (7.9%) for stage I, 3/22 (13.6%) for stage II, 5/30 (16.7%) for stage III and 13/24 (54.2%) for stage IV (P< 0.0001). 11/90 (12.2%) patients with no evidence of disease (stage I, II and III) tested positive and 13/24 (54.2%) patients with clinically confirmed distant metastases (stage IV) tested positive (P<0.00001). With median follow-up of 372 days or to death (range: 0-1303 days), median progression-free survival has not been reached for tyrosinase-negative patients and was 265 days for tyrosinase-positive patients (P<0.00001, log-rank test=21.07). Median overall survival was 344 days for tyrosinase-positive patients and has not been reached for tyrosinase-negative patients (P=0.0001, log-rank test=21.38). Stage, Breslow thickness and result of RT-PCR were significant prognostic factors for disease-free survival in a multivariate analysis, and stage was the only significant prognostic factor for overall survival. In conclusion, detection of circulating melanoma cells by reverse transcriptase-PCR for tyrosinase mRNA is a significant adverse prognostic factor for disease-free survival in patients with malignant melanoma.

Pathological significance of deletions involving codons 557 and 558 of KIT gene in localized resected gastrointestinal stromal tumors (GIST) of intermediate and high risk: A study by the Spanish Group for Sarcoma Research (GEIS)

10051

Background: Approximately 60 to 85% of GISTs harbour activating mutations of the KIT or PDGFRA tyrosine kinase genes. Deletions affecting codons 557–558 of KIT are relevant to prognosis of resected GIST (Martin J, et al. J Clin Oncol. 2005, 23:6190). Methods: GIST of high or intermediate malignant risk according to Fletcher classification (Hum Pathol. 2002;33; 459) with a complete (R0) or microscopic residual (R1) resection were prospectively evaluated. Central pathology review was carried out. The mutational analysis of exons 9, 11, 13 and 17 of KIT and exons 12 and 18 of PDGFRA was undertaken from DNA extracted from paraffin-embedded tissue. The purpose of this study was to explore the correlation between deletion mutation involving 557–558 codons within KIT gene and known prognostic factors in GIST: mitotic count and size. Results: Of the 33 GIST, 19 were gastric, 13 of small bowell and one of other location. Median tumor size was 10.4 cm (1.9–22 cm), and median mitotic count was 2 (1–32). All cases showed an immunostaining with diffuse cytoplasmic pattern of c-kit (CD117). An 82% (27) presented either a KIT (23) or a PDGFRA (4) mutation. Eleven deletions affecting codons 557–558 of KIT were observed. KIT mutations were associated to spindle type histology and PDGFRA mutations to epithelioid histology. No statistical association between tumor size and KIT mutations, including patients with deletions 557–558, was found. Tumors carrying a deletion of codons 557–558 of KIT presented a different median of mitotic count (8 mit × 50 hpf) than the rest (2 mit × 50 hpf), this difference was statistically significant (p = 0,029) in the Mann-Whitney U test. Conclusions: Deletions affecting codons 557–558 of KIT define a group of cases with a high proliferative potential. The prognostic and predictive significance of these findings are waiting for a longer follow-up.

No significant financial relationships to disclose.

Common variants on chromosomes 2q35 and 16q12 confer susceptibility to estrogen receptor-positive breast cancer

Familial clustering studies indicate that breast cancer risk has a substantial genetic component. To identify new breast cancer risk variants, we genotyped approximately 300,000 SNPs in 1,600 Icelandic individuals with breast cancer and 11,563 controls using the Illumina Hap300 platform. We then tested selected SNPs in five replication sample sets. Overall, we studied 4,554 affected individuals and 17,577 controls. Two SNPs consistently associated with breast cancer: approximately 25% of individuals of European descent are homozygous for allele A of rs13387042 on chromosome 2q35 and have an estimated 1.44-fold greater risk than noncarriers, and for allele T of rs3803662 on 16q12, about 7% are homozygous and have a 1.64-fold greater risk. Risk from both alleles was confined to estrogen receptor-positive tumors. At present, no genes have been identified in the linkage disequilibrium block containing rs13387042. rs3803662 is near the 5' end of TNRC9 , a high mobility group chromatin-associated protein whose expression is implicated in breast cancer metastasis to bone.

Cerebral revascularization model in a swine

The purpose of this study was to analyze the suitability of the cerebral vasculature of the pig regarding a revascularization procedure. In two 60 kg pigs the femoral artery was exposed and canulated for selective angiography and interventional procedures. After the angiography, the pigs were brought to the animal OR for craniotomy and analysis of the intracranial cerebral arteries and the surgical exposure of the carotid arteries under the microscope. Angiography demonstrated the presence of a true internal-, external carotid artery and vertebral arteries. Both the vertebral and internal carotid arteries are feeding a rete mirabilis both at the cranial base and the cranio-cervical junction. At these sites further advancement of the angiography catheter was not possible. Out of these rete mirabilis, an intracranial carotid artery and an intracranial vertebral artery were formed, respectively. The intracranial cerebral vessels were of the dimension of 1 mm and less. The extracranial portion of the internal carotid artery was 2.5 mm of diameter. From these findings, we conclude that a direct cerebral revascularization procedure of the intracranial vessels is not possible in the swine. However, a global revascularization procedure on the extracranial portion of the internal carotid artery is thus feasible, both using a low- and high-flow anastamosis technique.

Gemcitabine/capecitabine in patients with metastatic breast cancer pretreated with anthracyclines and taxanes

PURPOSE

Gemcitabine and capecitabine are 2 anticancer drugs with a mechanism of action involving metabolism of pyrimidine nucleotides. Both are among the few agents active in patients with metastatic breast cancer (MBC) progressing after therapy with anthracyclines and taxanes. We have conducted a phase II trial of gemcitabine/capecitabine in patients with disease progression after treatment with anthracyclines and taxanes.

PATIENTS AND METHODS

Treatment included gemcitabine 2000 mg/m2 on day 1 every 3 weeks and capecitabine 2500 mg/m2 daily (divided into 2 doses) on days 1-14 every 3 weeks; treatment was administered until disease progression or unacceptable toxicity was documented. All patients received concomitant oral pyridoxine 300 mg twice daily to prevent hand-foot syndrome (HFS). Of 39 patients treated, 33 had received previous treatment with anthracyclines, 6 had medical contraindication to anthracyclines, 35 had previously received taxanes, and 23 had received vinorelbine. Fourteen patients had previous high-dose chemotherapy with stem cell rescue and 5 had previously received trastuzumab. Patients were 31-79 years of age (median, 55 years) and, altogether, were given 386 courses of therapy (range, 1-36 courses per patient; median, 6 courses).

RESULTS

Grade 3/4 toxicities included HFS (11 courses, 6 patients), stomatitis (6 courses, 2 patients), diarrhea (5 courses, 4 patients), anemia (5 courses, 2 patients), thrombocytopenia (5 courses, 2 patients), and neutropenia (1 course, 1 patient). Response rate (all 39 patients were evaluable) was 48.7% (partial response, n = 19; stable disease, n = 7; progressive disease, n = 13). Thirty-six patients died because of disease progression, and 3 are alive with progressive disease. Median follow-up was 26 months or until death. Median duration of response was 15 months (range, 3-26 months). Median time to disease progression was 5 months (range, 1-26 months). Median overall survival duration was 10 months (range, 1-37 months).

CONCLUSION

In this cohort of patients heavily pretreated with anthracyclines and taxanes, the response rate to gemcitabine/capecitabine is encouraging, although response duration is limited.

Insulin control of glucose metabolism in man: a new kinetic analysis

Analyses of the control of glucose metabolism by insulin have been hampered by changes in bloog glucose concentration induced by insulin administration with resultant activation of hypoglycemic counterregulatory mechanisms. To eliminate such mechanisms, we have employed the glucose clamp technique which allows maintenance of fasting blood glucose concentration during and after the administration of insulin. Analyses of six studies performed in young healthy men in the postabsorptive state utilizing the concurrent administration of [14C]glucose and 1 mU/kg per min (40 mU/m2 per min) porcine insulin led to the development of kinetic models for insulin and for glucose. These models account quantitatively for the control of insulin on glucose utilization and on endogenous glucose production during nonsteady states. The glucose model, a parallel three-compartment model, has a central compartment (mass = 68 +/- 7 mg/kg; space of distribution = blood water volume) in rapid equilibrium with a smaller compartment (50 +/- 17 mg/kg) and in slow equilibrium with a larger compartment (96 +/-21 mg/kg). The total plasma equivalent space for the glucose system averaged 15.8 liters or 20.3% body weight. Two modes of glucose loss are introduced in the model. One is a zero-order loss (insulin and glucose independent) from blood to the central nervous system; its magnitude was estimated from published data. The other is an insulin-dependent loss, occurring from the rapidly equilibrating compartment and, in the basal period, is smaller than the insulin-independent loss. Endogenous glucose production averaged 1.74 mg/kg per min in the basal state and enters the central compartment directly. During the glucose clamp experiments plasma insulin levels reached a plateau of 95 +/-8 microU/ml. Over the entire range of insulin levels studied, glucose losses were best correlated with levels of insulin in a slowly equilibrating insulin compartment of a three-compartment insulin model. A proportional control by this compartment on glucose utilization was adequate to satisfy the observed data. Insulin also rapidly decreased the endogenous glucose production to 33% of its basal level (0.58 mg/kg per min), this suppression being maintained for at least 40 min after exogenous insulin infusion was terminated and after plasma insulin concentrations had returned to basal levels. The change in glucose utilization per unit change in insulin in the slowly equilibrating insulin compartment is proposed as a new measure for insulin sensitivity. This defines insulin effects more precisely than previously used measures, such as plasma glucose/plasma insulin concentration ratios. Glucose clamp studies and the modeling of the coupled kinetics of glucose and insulin offers a new and potentially valuable tool to the study of altered states of carbohydrate metabolism.

Differences in the relationship between lipid CHD risk factors and body composition in Caucasians and Japanese

OBJECTIVES

To examine differences in the relationship between fat distribution and lipid coronary risk factors in Caucasian and Japanese population and further to determine whether the cut-points for body mass index (BMI) and waist circumference (WC) proposed by WHO and NHLBI are applicable to Japanese population as a predictor of a lipid risk factor abnormality or not.

RESEARCH METHODS AND PROCEDURES

Subjects were 895 participants of the Baltimore Longitudinal Study of Aging in the US (BLSA) and 1705 participants of the Longitudinal Study of Aging by the National Institutes for Longevity Science in Japan (NILS-LSA). Subjects were divided into four demographic groups as younger (age<65 y) men and women, and older (age> or =65 y) men and women. Blood total cholesterol, triglycerides, LDL- and HDL-cholesterol and anthropometry were measured. Regression coefficients of BMI and WC on risk factors, sensitivity and specificity of the BMI and WC cut-points for blood lipid abnormality, and mean values of blood lipids at BMI or WC cut-points were computed in both populations.

RESULTS

Height, weight, WC and BMI were significantly greater in the BLSA than those in the NILS-LSA subjects. Total cholesterol, HDL- and LDL-cholesterol were significantly greater in the NILS-LSA than in the BLSA subjects. Sensitivities of BMI and WC cut-points were much lower in the NILS-LSA than in the BLSA subjects. Specificities of BMI and WC cut-points were higher in the NILS-LSA than in the BLSA subjects. Mean values of triglycerides, total cholesterol, HDL- and LDL-cholesterol at BMI=25 were significantly greater in the NILS-LSA than in the BLSA subjects. At the WC cut-point (94 cm for men, 80 cm for women), mean values of all lipids were significantly greater in the NILS-LSA than in the BLSA subjects with the exception of triglycerides in younger women.

CONCLUSIONS

The Japanese subjects have smaller BMI and WC, worse total and LDL-cholesterol levels and better HDL-cholesterol levels compared to Caucasians. Sensitivities of BMI and WC for predicting lipid risk factor abnormality are much lower in Japanese. The cut-points for BMI and WC proposed by WHO and NHLBI may be too high for predicting an abnormality in triglycerides, total and LDL-cholesterol in Japanese. For detecting an abnormal HDL-cholesterol level, the BMI and WC cut-points may not be as beneficial for the Japanese population as for Caucasians.