Johannes Bjornsson

Cancer as a Complex Phenotype: Pattern of Cancer Distribution within and beyond the Nuclear Family

Background The contribution of low-penetrant susceptibility variants to cancer is not clear. With the aim of searching for genetic factors that contribute to cancer at one or more sites in the body, we have analyzed familial aggregation of cancer in extended families based on all cancer cases diagnosed in Iceland over almost half a century. Methods and Findings We have estimated risk ratios (RRs) of cancer for first- and up to fifth-degree relatives both within and between all types of cancers diagnosed in Iceland from 1955 to 2002 by linking patient information from the Icelandic Cancer Registry to an extensive genealogical database, containing all living Icelanders and most of their ancestors since the settlement of Iceland. We evaluated the significance of the familial clustering for each relationship separately, all relationships combined (first- to fifth-degree relatives) and for close (first- and second-degree) and distant (third- to fifth-degree) relatives. Most cancer sites demonstrate a significantly increased RR for the same cancer, beyond the nuclear family. Significantly increased familial clustering between different cancer sites is also documented in both close and distant relatives. Some of these associations have been suggested previously but others not. Conclusion We conclude that genetic factors are involved in the etiology of many cancers and that these factors are in some cases shared by different cancer sites. However, a significantly increased RR conferred upon mates of patients with cancer at some sites indicates that shared environment or nonrandom mating for certain risk factors also play a role in the familial clustering of cancer. Our results indicate that cancer is a complex, often non-site-specific disease for which increased risk extends beyond the nuclear family.

Primary chondrosarcoma of long bones and limb girdles

Chondrosarcomas are common solid malignant tumors of bone, second in incidence only to osteosarcomas. The biologic evolution of chondrosarcomas is slow, requiring long follow‐up intervals for meaningful survival analysis.

Mutations in BRIP1 confer high risk of ovarian cancer

Ovarian cancer causes more deaths than any other gynecologic malignancy in developed countries. Sixteen million sequence variants, identified through whole-genome sequencing of 457 Icelanders, were imputed to 41,675 Icelanders genotyped using SNP chips, as well as to their relatives. Sequence variants were tested for association with ovarian cancer (N of affected individuals = 656). We discovered a rare (0.41% allelic frequency) frameshift mutation, c.2040_2041insTT, in the BRIP1 (FANCJ) gene that confers an increase in ovarian cancer risk (odds ratio (OR) = 8.13, P = 2.8 × 10−14). The mutation was also associated with increased risk of cancer in general and reduced lifespan by 3.6 years. In a Spanish population, another frameshift mutation in BRIP1, c.1702_1703del, was seen in 2 out of 144 subjects with ovarian cancer and 1 out of 1,780 control subjects (P = 0.016). This allele was also associated with breast cancer (seen in 6/927 cases; P = 0.0079). Ovarian tumors from heterozygous carriers of the Icelandic mutation show loss of the wild-type allele, indicating that BRIP1 behaves like a classical tumor suppressor gene in ovarian cancer.

Formation of New Vasa Vasorum in Vasculitis Production of Angiogenic Cytokines by Multinucleated Giant Cells

Inflammation of the arterial wall in giant cell arteritis induces a series of structural changes, including the formation of new vasa vasorum. To study the regulation of neoangiogenesis in giant cell arteritis, temporal arteries were examined for the extent and localization of microvessel generation and for the production of angiogenic factors. In normal arteries, vasa vasorum were restricted to the adventitia, but in inflamed arteries, capillaries emerged in the media and the intima. These capillaries displayed a distinct topography with a circumferential arrangement in the external one-third of the intima. Neovascularization was closely correlated with the formation of lumen-obstructing intima, the fragmentation of the internal elastic lamina, and the presence of multinucleated giant cells. Comparison of tissue cytokine transcription in temporal arteries of giant cell arteritis patients with and without up-regulated neoangiogenesis identified interferon-gamma and vascular endothelial growth factor but not fibroblast growth factor-2 as mediators associated with vasa vasorum proliferation. Giant cells and CD68-positive macrophages at the media-intima junction were found to be the major cellular sources of vascular endothelial growth factor. These data demonstrate that formation of new vasa vasorum in vasculitis is regulated by inflammatory cells and not by arterial wall cells, raising the possibility that it represents a primary disease mechanism and not a secondary hypoxia-induced event. Increased neovascularization in interferon-gamma-rich arteries suggests that the formation of new vasa vasorum is determined by the nature of the immune response in the arterial wall, possibly resulting from the generation and functional activity of multinucleated giant cells.

Intracranial germ cell tumors: pathobiological and immunohistochemical aspects of 70 cases.

Seventy cases of histologically verified intracranial germ cell tumor were reviewed: 43 germinomas, 16 immature teratomas, seven mature teratomas, two embryonal carcinomas, one choriocarcinoma, and one yolk sac tumor. The male-to-female ratio was 2.6:1. The average age was 19 years in patients with germinoma, 11 years in patients with immature teratoma, and 17 years in patients with mature teratoma. Duration of symptoms averaged 19 months for germinoma, three months for immature teratoma, and 11 months for mature teratoma. Sixty-six lesions were located in the midline. Fifty-eight percent of the germinomas arose anterior to the pineal gland, whereas 29% of the immature and 14% of the mature teratomas were located anteriorly. The histologic appearance of the germinomas was indistinguishable from that of the usual testicular seminoma. The immature teratomas contained tissue from all three germ layers and exhibited morphologic features of fetal tissue. Of 14 immature teratomas, seven contained, in addition, foci of other malignant germ cell elements; thus, there were two teratocarcinomas, two lesions with germinoma and immature teratoma, two lesions with extensive rhabdomyoblastic differentiation in an immature teratoma, and one lesion with both germinoma and embryonal carcinoma in addition to immature teratoma. The seven mature teratomas consisted of fully differentiated epithelial and mesenchymal tissues. In 23 cases, immunoperoxidase stains for human chorionic gonadotropin (HCG), α-fetoprotein (AFP), and carcino-embryonic antigen (CEA) revealed patterns which, with minor exceptions, were essentially identical to those found in genital germ cell lesions. Survival was longest for patients with germinomas. In classifying germ cell tumors of the central nervous system, the World Health Organizations (WHO) classification of testicular germ cell tumors is preferable to its present classification of intracranial germ cell tumors.

Correlation of the topographical arrangement and the functional pattern of tissue-infiltrating macrophages in giant cell arteritis.

End organ ischemia, fragmentation of elastic membranes, and aneurysm formation in patients with giant cell vasculitis results from an inflammation destroying the mural layers of large and medium sized arteries. Although the inflammatory infiltrate extends through all layers of the affected blood vessel, the most pronounced changes involve the intima and the internal elastic lamina. Analysis of the functional profile of tissue infiltrating CD68+ cells demonstrates that different subsets of macrophages can be distinguished. TGFbeta1-expressing CD68+ cells coproduce IL-1beta and IL-6, are negative for inducible nitric oxide synthase (iNOS), and exhibit a strong preference for localization in the adventitia. The adventitial homing of TGFbeta1+ CD68+ cells places them in the vicinity of IFN-gamma secreting CD4+ T cells which also accumulate in the exterior layer of the artery. Conversely, iNOS expressing CD68+ cells are negative for TGFbeta and are almost exclusively found in the intimal layer of the inflamed artery. The intimal-medial junction is the preferred site for 72-kD collagenase expressing CD68+ cells. Thus, TGFbeta1-producing macrophages colocalize with activated CD4+ T cells and home to an area of inflammation which is distant from the site of tissue damage but critical in regulating cellular influx, suggesting that TGFbeta1 functions as a proinflammatory mediator in this disease. iNOS- and 72-kD collagenase-producing macrophages accumulate at the center of pathology implying a role of these products in tissue destruction. These data indicate that the microenvironment controls the topographical arrangement as well as the functional commitment of macrophages.

Clear cell chondrosarcoma of bone: observations in 47 cases

Clear cell chondrosarcoma of bone, a lowgrade malignant tumor, frequently presents diagnostic difficulties. Its clinical, roentgenographic, and pathologic characteristics separate it from conventional chondrosarcoma and, more importantly, from several benign bone tumors with which it is often confused. This report analyzes 47 cases seen at the Mayo Clinic and in consultation. The lesion is more common in males than females (2.6:1) and has a predilection for the end of long bones, particularly the proximal femur. The age range is wide; most patients are in the third and fourth decades of life. Roentgenographically, the lesion most often is purely lytic and slightly expansile, with a sharp margin between the tumor and the adjacent normal bone. Pathologically, clear cells arranged in an indistinct lobular pattern characterize the tumor. Frequently, areas mimicking other primary bone tumors, benign and malignant, are present, often to such an extent as to obscure the true identity of the process. The overall mortality in the present series was 15%. En bloc resection, including a margin of normal bone and soft tissue, appears to be the treatment of choice.

Cancer of unknown primary: clinicopathologic correlations.

Cancer of unknown primary origin (CUP) accounts for 5–10% of all malignant tumors at presentation and remains the death certificate diagnosis in 0.5–5% of patients. We investigated CUP patients whose primary site remained unknown throughout the entire clinical course. We reviewed 9,436 consecutive autopsies performed between 1984 and 1999 at the Mayo Clinic, matched with 177,167 cancer patients treated in the same time period. Sixty‐four patients who died of CUP underwent postmortem examination. Antemortem pathologic diagnoses were obtained in 57 patients, agreed with postmortem diagnoses in 98%, and included adenocarcinoma (n=44), undifferentiated carcinoma (n=7), squamous cell carcinoma (n=3), and others (n=3). Autopsy located the primary site in 35 patients (55%). Common primary sites were lung (n=8), the pancreaticobiliary (n=13) and GI tracts (n=9). Of 43 patients evaluated for tumor‐specific therapy, only six received no further oncologic treatment and untreated patients survived a median of 57 (range 10–280) days, compared with 225 (range 19–1,129) days for patients treated with chemotherapy and/or radiotherapy (n=37). Our findings show that ( 1 ) autopsy studies provide a valuable tool for quality control in the setting of CUP, and ( 2 ) treated patients have a small but significant survival benefit.

The accuracy of death certificates. Implications for health statistics.

The death certificate is an important source of data on disease incidence, prevalence and mortality. It should therefore be as accurate and complete as possible. Death certificates from 433 autopsied hospital patients were reviewed and matched against the results of post-mortem examinations. Significant discrepancies between the two documents were observed in 50% of patients. In 25%, the immediate cause of death was incorrectly stated on the certificate, having been assigned to a different organ system in the majority of those cases. In 33%, there was disagreement on major disease other than the immediate cause of death. In 9%, the death certificate was signed before the autopsy was performed. The extent of disagreement was largely independent of whether the certificate was signed before or after the autopsy. We conclude that: (1) there is a significant discrepancy between autopsy diagnoses and entries on death certificates; (2) disagreement is not due to unavailability of autopsy data at the time of completion of the certificate; (3) death certificates should be completed or amended utilizing data gained at autopsy.

Death from pulmonary thromboembolism in severe obesity: lack of association with established genetic and clinical risk factors.

Abstract Several clinical and environmental conditions are causally related to sudden death from acute pulmonary thromboembolism (APT). Morbid obesity, despite its frequency and association with adverse health effects, is usually considered at most only an additive risk factor for APT. We reviewed protocols and histories from 7227 consecutive autopsies performed between 1985 and 1996 at the Mayo Clinic, including all deaths from APT where no clinical or environmental risk factor could be identified in the study. Body mass indices (BMI) were calculated and compared with those of age- and sex-matched controls who had died suddenly and naturally without evidence of APT. Resistance to activated protein C is the most common molecular clotting defect predisposing to APT, and it is caused by a point mutation in the factor V gene (R506Q). Genomic DNA was extracted from archival tissues of all cases and controls, and the R506Q status was determined by polymerase chain reaction amplification, restriction endonuclease digestion, and direct sequencing. APT was found as the immediate cause of death in 433 patients, with 36 (8%) having no previously established risk factors. Twenty-four of these persons (67%) were morbidly obese (BMI >30 kg/m2), compared with only five controls (14%, P<0.0001). Four patients in both groups, each with a BMI <30 kg/m2, had at least one allele positive for R506Q. Morbid obesity is an independent risk factor in cases of sudden death from APT after the exclusion of previously established clinical, environmental, and molecular risk factors.