Roope A. Kallionpää

Distinctive Cancer Associations in Patients With Neurofibromatosis Type 1

PURPOSE The current study was designed to determine the risk of cancer in patients with neurofibromatosis type 1 (NF1) by cancer type, age, and sex with unprecedented accuracy to be achieved by combining two total population-based registers. PATIENTS AND METHODS A population-based series of patients with NF1 (N = 1,404; 19,076 person-years) was linked to incident cancers recorded in the Finnish Cancer Registry and deaths recorded in the national Population Register Centre between 1987 and 2012. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) were calculated for selected cancer types. Survival of the patients with cancer with and without NF1 was compared. RESULTS In malignant peripheral nerve sheath tumors and CNS tumors, the cancers traditionally associated with NF1, we observed SIRs of 2,056 (95% CI, 1,561 to 2,658), and 37.5 (95% CI, 30.2 to 46.0), respectively, and SMRs of 2,301 (95% CI, 1,652 to 3,122) and 30.2 (95% CI, 19.1 to 45.2), respectively. We found an unequivocally increased risk for breast cancer. In particular, SIR was 11.1 (95% CI, 5.56 to 19.5) for breast cancer in women with NF1 age < 40 years; the overall SMR for breast cancer was 5.20 (95% CI, 2.38 to 9.88). Particularly high overall SIRs were observed in patients with NF1 age < 15 years: women, 87.6 (95% CI, 58.6 to 125); men, 45.6 (95% CI, 28.4 to 68.5). An estimated lifetime cancer risk for patients with NF1 was 59.6%. The 5-year survival of patients with cancer and NF1, excluding nervous tissue cancers, was worse than that of comparable patients with cancers without NF1 (54.0% v 67.5%; P = .01). CONCLUSION Our results emphasize the general cancer proclivity of patients with NF1. These findings should translate to clinical practices to determine clinical interventions and focused follow-up of patients with NF1.

Breast cancer in neurofibromatosis type 1: overrepresentation of unfavourable prognostic factors

Background:An increased breast cancer incidence and poor survival have been reported for women with neurofibromatosis 1 (NF1). To explain the poor survival, we aimed to link the histopathology and clinical characteristics of NF1-associated breast cancers.Methods:The Finnish Cancer Registry and the Finnish NF Registry were cross-referenced to identify the NF1 patients with breast cancer. Archival NF1 breast cancer specimens were retrieved for histopathological typing and compared with matched controls.Results:A total of 32 breast cancers were diagnosed in 1404 NF1 patients during the follow-up. Women with NF1 had an estimated lifetime risk of 18.0% for breast cancer, and this is nearly two-fold compared with that of the general Finnish female population (9.74%). The 26 successfully retrieved archival NF1 breast tumours were more often associated with unfavourable prognostic factors, such as oestrogen and progesterone receptor negativity and HER2 amplification. However, survival was worse in the NF1 group (P=0.053) even when compared with the control group matched for age, diagnosis year, gender and oestrogen receptor status. Scrutiny of The Cancer Genome Atlas data set showed that NF1 mutations and deletions were associated with similar characteristics in the breast cancers of the general population.Conclusions:These results emphasise the role of the NF1 gene in the pathogenesis of breast cancer and a need for active follow-up for breast cancer in women with NF1.

Neurofibromatosis Type 1 Gene Mutation Analysis Using Sequence Capture and High-throughput Sequencing

Neurofibromatosis type 1 syndrome (NF1) is caused by mutations in the NF1 gene. Availability of new sequencing technology prompted us to search for an alternative method for NF1 mutation analysis. Genomic DNA was isolated from saliva avoiding invasive sampling. The NF1 exons with an additional 50bp of flanking intronic sequences were captured and enriched using the SeqCap EZ Choice Library protocol. The captured DNA was sequenced with the Roche/454 GS Junior system. The mean coverages of the targeted regions were 41x and 74x in 2 separate sets of samples. An NF1 mutation was discovered in 10 out of 16 separate patient samples. Our study provides proof of principle that the sequence capture methodology combined with high-throughput sequencing is applicable to NF1 mutation analysis. Deep intronic mutations may however remain undetectable, and change at the DNA level may not predict the outcome at the mRNA or protein levels.

Neurofibromatosis type 1 (NF1) gene: Beyond café au lait spots and dermal neurofibromas.

Neurofibromatosis 1 (NF1) occurs in 1:2000 births. The main diagnostic signs are visible on the skin, and this opens several interesting aspects for dermatological point of view. The NF1 syndrome is caused by mutations in the NF1 gene which encodes the tumor suppressor protein neurofibromin. Neurofibromin functions as a Ras‐GTPase‐activating protein (RasGAP), and NF1 mutations lead to overactivation of the Ras signalling pathway. The NF1 gene and neurofibromin have intriguing functions in keratinocytes and melanocytes. Neurofibromin regulates melanin synthesis and keratinocyte differentiation in a currently unknown manner. The NF1 gene has also an important but poorly understood role in tumorigenesis and cancer. Compared to the general population, NF1 patients have a fivefold risk for cancer and a more than 2000‐fold risk for neurogenic malignancies. Mutations of the NF1 gene are common in numerous cancer types in patients without NF1, and this suggests a more general role for the NF1 gene in oncogenesis. In melanoma, NF1 mutations seem to drive tumorigenesis and contribute to drug resistance. In this article, we review the literature on neurofibromin with special attention to keratinocytes, melanocytes, NF1‐related tumors and melanoma.

The pregnancy in neurofibromatosis 1: A retrospective register‐based total population study

The objective of this retrospective total population study was to form a view of the pregnancies of the patients with neurofibromatosis type 1 (NF1). A cohort of 1,410 Finnish patients with NF1 was acquired by searching NF1‐related inpatient and outpatient hospital visits and confirming the diagnoses by reviewing the medical records. Ten matched control persons per patient with NF1 were collected from Population Register Centre. Study persons were linked to data from Medical Birth Register and Care Register for Health Care through the personal identity code. Cesarean deliveries, hypertension/preeclampsia, and placental abruptions were more common among mothers with NF1 with adjusted odds ratios of 2.24 (95%CI 1.63–3.07), 1.96 (95%CI 1.18–3.24), and 13.40 (95%CI 4.26–42.13), respectively. The adjusted mean pregnancy duration was 0.65 (95%CI 0.42–0.88) weeks shorter among the mothers with NF1 than in the control group consisting of non‐NF1 mothers giving birth to a non‐NF1 child. The pregnancies of non‐NF1 mothers giving birth to a NF1 child were 0.43 (95%CI 0.24–0.62) weeks shorter than in the control group. In summary, NF1 of the mother was associated with a shortened pregnancy and increased pregnancy complications. Also, the NF1 of the fetus slightly shortened pregnancy. Since mothers with NF1 are at increased risk for pregnancy complications, careful evaluation of their pregnancies is warranted.

Prevalence of neurofibromatosis type 1 in the Finnish population

PurposeThe incidence of neurofibromatosis 1 (NF1) is ~1/2,000 live births, but the current estimates of prevalence vary greatly. This retrospective total-population study was aimed at determining the prevalence of NF1 in Finland.MethodsAll secondary and tertiary referral centers of Finland were searched for NF1 patients. Patient records were manually reviewed and patients fulfilling the National Institutes of Health diagnostic criteria for NF1 were included. Prevalence on 31 December 2005 was determined. Data on incidence and survival were combined to refine the prevalence estimation.ResultsA total of 1,279 patients with NF1 were alive on 31 December 2005, yielding a prevalence of 1/4,088 (95% confidence interval (CI) 1/4,320–1/3,869). The survival of patients with NF1 was inferior compared with the general population (hazard ratio 3.10, 95% CI 2.73–3.53, P < 0.001). When the survival rates of NF1 patients and the Finnish population were combined with an estimate of NF1 incidence, a prevalence of 1/2,052 (95% CI 1/2,176–1/1,941) was estimated for NF1 in a population aged 0–74 years.ConclusionNF1 is a much more common disorder than previously thought. A large proportion of NF1 patients may not be correctly identified by health-care systems or they do not seek secondary health care for their NF1.

Neurofibromatosis type 1 is not associated with subarachnoid haemorrhage

Background The prevalence of intracranial aneurysms (IAs) has been proposed to be elevated in the patients with neurofibromatosis type 1 (NF1). Our aims were to determine the prevalence of NF1 in a large Finnish population based cohort of IA patients and, on the other hand, the occurrences of subarachnoid haemorrhage and unruptured intracranial aneurysms in a nationwide population-based cohort of NF1 patients and its matched ten-fold control cohort. Methods The Kuopio IA Database (www.kuopioneurosurgery.fi) includes all ruptured and unruptured IA cases admitted to the Kuopio University Hospital (KUH) from its defined Eastern Finnish catchment population since 1980. In this registry-based study, we cross-linked the Kuopio IA database with the Finnish national registry covering all hospital diagnoses. The NF1 diagnoses of the 4543 patients with either saccular of fusiform IA were identified from 1969 to 2015 and verified from patient records. Our second approach was to analyze the occurrence of aneurysmal subarachnoid haemorrhage (aSAH) and unruptured IAs in a nationwide population-based database of 1410 NF1 patients and its ten-fold matched control cohort (n = 14030) using national registry of hospital diagnoses between 1987 and 2014. Results One NF1 patient was identified among the 4543 IA patients. Three verified IA cases (one unruptured IA and two aSAH cases) were identified in the cohort of 1410 NF1 patients, with similar occurrences in the control cohort. Conclusions We found no evidence in our population-based cohorts to support the conception that NF1 is associated with IAs. Our results indicate that the incidence of aSAH is not elevated in patients with NF1. Further studies are required to confirm that there is no association between NF1 and unruptured IAs.

Association of Catechol-O-methyltransferase polymorphism Val158Met and mammographic density: A meta-analysis

OBJECTIVES The Val158Met polymorphism in catechol-O-methyltransferase (COMT) enzyme reduces the methylation of catechol estrogens, which may affect mammographic density. High mammographic density is a known risk factor of breast cancer. Our aim was to perform meta-analysis of the effect of COMT Val158Met polymorphism on mammographic density. METHODS Original studies reporting data on mammographic density, stratified by the presence of COMT Val158Met polymorphism, were identified and combined using genetic models Met/Val vs. Val/Val, Met/Met vs. Val/Val, Val/Met+Met/Met vs. Val/Val (dominant model) and Met/Met vs. Val/Met+Val/Val (recessive model). Subgroup analyses by breast cancer status, menopausal status and use of hormone replacement therapy (HRT) were also performed. RESULTS Eight studies were included in the meta-analysis. The overall effect in percent mammographic density was -1.41 (CI -2.86 to 0.05; P=0.06) in the recessive model. Exclusion of breast cancer patients increased the effect size to -1.93 (CI -3.49 to -0.37; P=0.02). The results suggested opposite effect of COMT Val158Met for postmenopausal users of HRT versus premenopausal women or postmenopausal non-users of HRT. CONCLUSIONS COMT Val158Met polymorphism may be associated with mammographic density at least in healthy women. Menopausal status and HRT should be taken into account in future studies to avoid masking of the underlying effects.

The effect of estradiol, testosterone, and human chorionic gonadotropin on the proliferation of Schwann cells with NF1 +/− or NF1 −/− genotype derived from human cutaneous neurofibromas

Dermal neurofibromas are the hallmarks of neurofibromatosis type 1 (NF1). Neurofibromas harbor Schwann cells with two different genotypes: Schwann cells which carry the germline mutation and a healthy NF1 allele (NF1+/−), and a subpopulation of Schwann cells which harbor the so-called second hit leading to inactivation of both NF1 alleles (NF1−/−). The second hit in the NF1 gene of Schwann cells is considered to be the initial step in the development of neurofibromas. Dermal neurofibromas typically start to grow in puberty, and their number and size increase during pregnancy, indicating hormone responsiveness. This is the first study to address the effect of human chorionic gonadotropin (hCG) on the proliferation of human NF1+/− and NF1−/− Schwann cells in vitro. In addition, the effects of estradiol and testosterone were also investigated. The results showed that NF1−/− Schwann cells were more sensitive to estradiol, testosterone, and human chorionic gonadotropin than NF1+/− cells. Specifically, the proliferation of NF1−/− Schwann cells was increased by up to 99, 110, and 170% compared to vehicle control when treated with estradiol, testosterone, and hCG, respectively. Interestingly, no effect of estradiol, testosterone, or hCG on the proliferation of the cells with NF1+/− genotype was observed. To conclude, the somatic second hit in the NF1 gene sensitizes Schwann cells to sex hormones resulting in a highly increased proliferation. Our results highlight the significance of sex hormones in the regulation of neurofibroma growth.

Germline and Somatic NF1 Alterations Are Linked to Increased HER2 Expression in Breast Cancer

NF1 germline mutation predisposes to breast cancer. NF1 mutations have also been proposed as oncogenic drivers in sporadic breast cancers. To understand the genomic and histologic characteristics of these breast cancers, we analyzed the tumors with NF1 germline mutations and also examined the genomic and proteomic profiles of unselected tumors. Among 14 breast cancer specimens from 13 women affected with neurofibromatosis type 1 (NF1), 9 samples (NF + BrCa) underwent genomic copy number (CN) and targeted sequencing analysis. Mutations of NF1 were identified in two samples and TP53 were in three. No mutation was detected in ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, NBN, PALB2, PTEN, RAD50, and STK11. HER2 (ErbB2) overexpression was detected by IHC in 69.2% (9/13) of the tumors. CN gain/amplification of ERBB2 was detected in 4 of 9 with DNA analysis. By evaluating HER2 expression and NF1 alterations in unselected invasive breast cancers in TCGA datasets, we discovered that among samples with ERBB2 CN gain/amplification, the HER2 mRNA and protein expression were much more pronounced in NF1-mutated/deleted samples in comparison with NF1-unaltered samples. This finding suggests a synergistic interplay between these two genes, potentially driving the development of breast cancer harboring NF1 mutation and ERBB2 CN gain/amplification. NF1 gene loss of heterozygosity was observed in 4 of 9 NF + BrCa samples. CDK4 appeared to have more CN gain in NF + BrCa and exhibited increased mRNA expression in TCGA NF1--altered samples. Cancer Prev Res; 11(10); 655–64. ©2018 AACR.