Invasive and in situ squamous cell carcinoma of the skin: a nationwide study in Iceland.

BACKGROUND: The worldwide incidence of cutaneous squamous cell carcinoma (cSCC) is increasing. OBJECTIVES: To evaluate the tumour burden of in situ and invasive cSCC in Iceland, where the population is exposed to limited ultraviolet radiation. METHODS: This whole-population study used the Icelandic Cancer Registry, which contains records of all in situ and invasive cSCC cases from 1981 to 2017. Incidence of cSCC was evaluated according to age, anatomical location, residence and multiplicity, and trends were assessed using joinpoint analysis. Age-standardized rates (WSR) and age-specific incidence rates per 100 000 person-years were calculated, along with cumulative and lifetime risks. RESULTS: Between 1981 and 2017, in situ cSCC WSR increased from 1·2 to 19·1 for men and from 2·0 to 22·3 for women. Invasive cSCC WSR rose from 4·6 to 14 for men and from 0·3 to 13·2 for women. The average number of in situ cSCC lesions was 1·71 per woman and 1·39 per man. Women developed more in situ cSCCs than invasive cSCCs in almost all anatomical locations, whereas men developed more invasive cSCCs, mostly on the head and neck. The rates of in situ cSCC were higher in Reykjavik compared with rural areas. Furthermore, women more commonly developed multiple in situ lesions. For lip cSCCs, invasive lesions occurred more frequently than in situ lesions among both sexes. Joinpoint analysis showed that in situ cSCC in women exhibited the most rapid incidence increase. CONCLUSIONS: cSCC has become an increasingly significant public health problem in Iceland. Tanning bed use and travelling abroad may contribute to skin cancer development. Public health efforts are needed to stem the behaviours leading to this rapid rise in cSCC.

Basal cell carcinoma: an emerging epidemic in women in Iceland.

BACKGROUND: An epidemic of basal cell carcinoma (BCC) has led to a significant healthcare burden in white populations. OBJECTIVES: To provide an update on incidence rates and tumour burden in an unselected, geographically isolated population that is exposed to a low level of ultraviolet radiation. METHODS: This was a whole-population study using a cancer registry containing records of all cases of BCC in 1981-2017. We assessed BCC incidence according to age, residence and multiplicity and assessed trends using join-point analysis. Age-standardized and age-specific incidence rates were calculated along with cumulative and lifetime risks. RESULTS: During the study period, the age-standardized incidence rates increased from 25·7 to 59·9 for men, and from 22·2 to 83·1 for women (per 100 000). Compared with the single-tumour burden, the total tumour burden in the population was 1·72 times higher when accounting for multiplicity. At the beginning of the study period, the world-standardized rates in men and women were similar, but by the end of the study period the rates were 39% higher in women (83·1 per 100 000, 95% confidence interval 77·9-88·3) than in men (59·9 per 100 000, 95% confidence interval 55·6-64·2). This increase was most prominent in women on sites that are normally not exposed to ultraviolet radiation in Iceland: the trunk and legs. CONCLUSIONS: This is the only reported population in which the incidence of BCC is significantly higher in women than in men. The period of notable increase in BCC lesions correlates with the period of an increase in tanning beds and travel popularity. The high multiplicity rates suggest that the total tumour burden worldwide might be higher than previously thought. What is already known about this topic? Basal cell carcinoma (BCC) is becoming an increasing healthcare burden worldwide, especially in white populations. Recent population studies have reported a rapid increase in incidence among younger individuals, especially women. What does this study add? Iceland is the only reported population in which the incidence of BCC is significantly higher in women than in men, and there does not seem to be a clear relationship between latitude and BCC incidence in Europe. Men might be comparatively protected in the northern low-ultraviolet environment, with tanning beds and travel abroad likely playing important roles in the observed incidence increase, especially in women. The high multiplicity rates suggest that the total tumour burden worldwide might be higher than previously thought. Linked Comment: Pandeya. Br J Dermatol 2020; 183:799-800.

Autopsy rates in Iceland.

A clinical as well as forensic autopsy is a uniform medical investigation of the deceased, which mainly serves to verify the plausibility of information on the cause, mode and mechanism of death provided by the police and/or medical personnel. Despite its importance in the context of a conclusive assessment of a person's medical history and in detecting any criminal correlation or malpractice, a significant decline in autopsies is evident in Iceland. This article gives an overview on autopsy rates in Iceland and compares the situation with European countries.

The incidence and outcome of ischemic colitis in a population-based setting.

OBJECTIVE: Population-based studies on patients with ischemic colitis (IC) are limited. We aimed to determine the incidence, risk factors and outcome of patients with IC. METHODS: A retrospective nationwide study was conducted on adult patients with histologically confirmed IC in 2009-2013 in Iceland. IC patients were matched for age and gender with patients hospitalized with lower gastrointestinal bleeding. Data were collected on clinical presentation, comorbidities, smoking habits, management and outcome. RESULTS: Eighty-nine patients, 61 (69%) females and mean age of 65 years (±17), fulfilled the predetermined criteria. Females were older than males, 68 years (±14) vs. 59 years (±20) (p = .0170). The mean cumulative incidence was 7.3 cases per 100,000 inhabitants. A total of 57 (64%) patients presented with abdominal pain, hematochezia and diarrhea. IC was localized in the left colon in 78 (88%) patients. Overall, 62 (70%) patients had cardiovascular disease vs. 53 (60%) of control group (NS) and 55 (62%) had a history of smoking vs. 53 (60%) in control group (NS). Ten (11%) patients required surgery and/or died within 30-days from hospital admission. At the end of follow-up, 7 (9%) patients had experienced recurrence of IC with an estimated 3-year recurrence rate of 15%. CONCLUSIONS: IC is a common clinical phenomenon that affects a wide range of age groups, but is most prominent among elderly women. It typically presents with a clinical triad of abdominal pain, hematochezia and diarrhea. Most cases are mild and self-limiting with a good prognosis.

Cutaneous melanoma in Iceland: changing Breslow's tumour thickness.

BACKGROUND: The incidence of cutaneous melanoma increased dramatically in Iceland during the last two decades of the 20th century. OBJECTIVE: The aim of this study was to investigate the trend in Breslow's tumour thickness during the years 1980-2009. METHODS: The population-based Icelandic Cancer Registry provided information on all cutaneous melanomas diagnosed in the country during the study period, a total of 854 cases. Incidence rates were stratified according to gender, age at diagnosis, year of diagnosis and Breslow's tumour thickness. RESULTS: When stratified by gender and age, the incidence of thin (≤1.0 mm) melanomas increased dramatically in all subgroups. The increase in thin (≤1.0 mm) melanomas was more apparent in women or 2.6 per 100,000 in 1980-1989 to 13.3 in 2000-2009 and especially in young (<50 years) women or from 1.6 to 12.2 per 100,000 during the same period compared to an increase from 0.2 to 3.4 per 100,000 for young (<50 years) men (P < 0.05). In intermediate thickness (1.01-4.0 mm) tumours, the incidence increased only in men over the age of 50 from 2.1 in 1980-1989 to 11.3 per 100,000 in 2000-2009 (P < 0.05). The incidence of thick melanomas (>4 mm) did not increase. The median Breslow's thickness declined from 2.15 mm in 1980-1989 to 0.9 mm in 2000-2009 in males and from 1.0 to 0.6 mm in females for the same period (P < 0.001). CONCLUSION: The rise in melanoma incidence in individuals under 50 years and in women over 50 years was confined to thin tumours. However, among older males there was also an increased incidence of tumours of an intermediate thickness. This could indicate that future melanoma educational campaigns in Iceland should be directed at older individuals, and that older men may need special attention regarding suspicious nevi.

pT4 stage II and III colon cancers carry the worst prognosis in a nationwide survival analysis. Shepherd's local peritoneal involvement revisited.

The aim of this study is to clarify the prognostic importance of several well-known but still debated pathological variables related to the survival of colon cancer patients. The study focuses on the definition and survival carried by the pT4 category and stage II where the presence of high-risk variables may determine whether or not adjuvant chemotherapy is administered. A retrospective nationwide study was carried out including all colon cancer patients that underwent resection in Iceland between 1990 and 2004 (n = 889). All histopathology was reassessed. Cancer-specific survival (CSS) and overall survival were analysed using Kaplan-Meier and Cox regression analysis. In stage II, the five-year CSS for pT4 was 50% (95% CI, 32-69%), which was the lowest survival observed in that stage. In stage III the five-year CSS was 30% (95% CI, 18-41%) and 37% (95% CI, 26-48%) for pT4 and pN2 tumors, respectively. Lymphatic invasion and differentiation had no prognostic value in stage II. The survival associated with pT4a versus pT4b depends on how these categories are defined with regard to Shepherd's local peritoneal involvement (LPI). In the present series, pT4 is a major indicator of poor prognosis in patients with stage II and III colon carcinoma. Four-tiered TNM or Dukes staging systems are insufficient by not taking this variable into account. Only Shepherd's LPI4 and a subgroup of LPI3 (i.e., borderline LPI3/LPI4) should qualify for the pT4a subcategory. The results do not support lymphatic invasion or poor differentiation as high-risk stage II variables.

Trisomy 21 mosaicism: we may all have a touch of Down syndrome.

Ever increasing sophistication in the application of new analytical technology has revealed that our genomes are much more fluid than was contemplated only a few years ago. More specifically, this concerns interindividual variation in copy number (CNV) of structural chromosome aberrations, i.e. microdeletions and microduplications. It is important to recognize that in this context, we still lack basic knowledge on the impact of the CNV in normal cells from individual tissues, including that of whole chromosomes (aneuploidy). Here, we highlight this challenge by the example of the very first chromosome aberration identified in the human genome, i.e. an extra chromosome 21 (trisomy 21, T21), which is causative of Down syndrome (DS). We consider it likely that most, if not all, of us are T21 mosaics, i.e. everyone carries some cells with an extra chromosome 21, in some tissues. In other words, we may all have a touch of DS. We further propose that the occurrence of such tissue-specific T21 mosaicism may have important ramifications for the understanding of the pathogenesis, prognosis and treatment of medical problems shared between people with DS and those in the general non-DS population.

A single BRCA2 mutation in male and female breast cancer families from Iceland with varied cancer phenotypes.

The BRCA2 gene on chromosome 13 has been shown to be associated with familial male and female breast cancer. Here we describe a study on BRCA2 in 21 Icelandic families, including 9 with male breast cancer. We have previously reported linkage to the BRCA2 region in an Icelandic male breast cancer family and subsequently found a strong indication of linkage to BRCA2 and the same BRCA2 haplotype in breast cancer cases from 15 additional families, indicating a common origin. We describe a five base-pair deletion in exon 9 of BRCA2 in an affected male from the male breast cancer family. The same mutation occurs in all the families with the shared BRCA2 haplotype indicating a founder effect. Among mutation carriers there are 12 males with breast cancer, which accounts for 40% of all males diagnosed with breast cancer in Iceland over the past 40 years. Three of them have no family history of breast cancer indicating that this mutation may have variable penetrance. The same BRCA2 mutation appears to be associated with different cancer phenotypes in this population including male and female breast cancer, prostate cancer, pancreas cancer and ovarian cancer.

The frequency of advanced adenoma in consulting patients: a nationwide survey in Iceland (2003-2006).

AIM: To assess the frequency of advanced colorectal adenomas in consulting patients in Iceland. METHOD: The histological configuration of colorectal adenomas (CRA) found in 3603 patients was classified into tubular (TA), villous (VA) and serrated (SA) and the degree of neoplastic severity into low-grade dysplasia (LGD), high-grade dysplasia (HGD), carcinoma in situ (CIS), intramucosal carcinoma (IMC) and submucosal carcinoma (SMC). Advanced CRA were those showing HGD, CIS, IMC and/or SMCs. In patients with two or more adenomas, the adenoma with the highest degree of epithelial neoplasia was selected to record cases. RESULTS: Between 2003 and 2006 a total of 19424 endoscopic examinations (13572 colonoscopies and 5852 sigmoidoscopies) were performed in Iceland (mean, 4856 endoscopies per year). At histology a mean of 759.3 CRA per year were found. Thus, CRA were found in 15.6% of the colorectal endoscopies performed per year. Out of the 3037 CRA studied, 67% were TA, 29% VA and the remaining 4% SA. LGD was present in 79%, HGD in 15%, CIS in 2.4%, IMC in 1.9% and SMC in 1.9%. Consequently, out of 3037 CRA investigated, 652 (21.5%) were advanced CRA; 71% of these showed HGD, 11% CIS, 9% IMC and 9% SMC. Two-thirds of the 652 advanced CRA were advanced VA, and more than three-quarters of 58 advanced CRA with SMC, were advanced VA. CONCLUSION: Advanced VA displaying intraepithelial neoplasia (HGD and CIS) showed a propensity to evolve into invasive carcinoma. Accordingly, VA displaying HGD and CIS might be regarded as biological markers for predicting colorectal cancer risk. This is the first study in which the frequency of CRA and advanced CRA detected in consulting patients is reported on a nationwide basis.

Incidence and prognosis of patients with small intestinal neuroendocrine tumors in a population based nationwide study.

BACKGROUND & AIMS: Small intestinal neuroendocrine tumours (SI-NETs) are the most frequent malignant tumours of the small intestine. Population based studies on SI-NETs are scarce. We aimed to examine the incidence, presentation of disease and prognosis of SI-NET and to determine patient prognosis in those undergoing emergency or elective surgery. METHODS: This was a retrospective population-based study. Information on all patients diagnosed with neuroendocrine tumours of the small intestine (excluding duodenum) from the beginning of the Icelandic Cancer Registry and the pathology departments in the country (1966-2017). Detailed phenotypic information was obtained from medical records on symptoms at diagnosis, treatment, recurrence and survival. RESULTS: A total of 113 patients with SI-NETs were identified, 3 patients were excluded due to lack of data and/or diagnostic error, leaving 110 patients for final analysis. The incidence of SI-NET was 0.78/100,000 and did not increase during the study period. A total of 42 % (n = 46) of patients were diagnosed incidentally. Long-term prognosis, after a landmark of 12 months, was better in patients who were diagnosed incidentally (HR 0.52; p = 0.03). Overall 89 % (n = 98) of cases underwent surgical resection of the primary tumor, 31 % (n = 30) patients acute or semi-acute surgery and 69 % (n = 68) elective surgery. Emergency surgery was associated with a 6-fold risk of death in the first 12 months after surgery (HR: 5.99; p = 0.01) and associated with more severe surgical complications. However, there was no difference in the long-term risk of death after the first 12 months (HR: 1.39; p = 0.27). CONCLUSIONS: The incidence of SI-NETs has not changed significantly in the last decades. Incidentally diagnosed SI-NET was associated with a favorable long-term prognosis. Emergency surgery in patients with SI-NET was associated with a significantly worse short-term risk of mortality compared to those who underwent elective surgery.

Arrest-related death on the basis of a drug-induced excited delirium syndrome.

AIMS: In typical arrest-related death (ARD) scenarios, the victims often show signs of excited delirium syndrome (ExDS), intoxication, exhaustion and/or suffered from a preexisting physical or psychiatrical condition, all of which could have caused or at least triggered the person's death. Since autopsy findings are very rare in such cases, a clear clinicopathologic diagnosis and thus mechanism of death is rarely found. METHODS: We present a case of a 25-year old woman, who died while being arrested by the police. Based on the patient's medical history, autopsy findings, contradicting witness testimonies, and reliable clinical and toxicological blood parameters, the most probable diagnosis is discussed. RESULTS: The cause of death was determined as cardiac arrest subsequent to a combination of excited delirium syndrome, physical exhaustion and respiratory impairment. The manner of death was unnatural and juridically, the charges were dropped. CONCLUSIONS: In cases, where the cause and mechanism of death can only be diagnosed by exclusion, police collaboration, detailed clinical history (past and present) as well as clinical blood parameter analyses are necessary to help evaluating possible contributing factors and the most probable cause of death in ARD.

Risks of second primary cancer among patients with major histological types of lung cancers in both men and women.

BACKGROUND: Patterns of second primary cancers (SPCs) following first primary lung cancers (FPLCs) may provide aetiological insights into FPLC. METHODS: Cases of FPLCs in 13 cancer registries in Europe, Australia, Canada, and Singapore were followed up from the date of FPLC diagnosis to the date of SPC diagnosis, date of death, or end of follow-up. Standardised incidence ratios (SIRs) were calculated to estimate the magnitude of SPC development following squamous cell carcinoma (SCC), small cell lung carcinoma (SCLC), and adenocarcinoma (ADC). RESULTS: Among SCC patients, male SIR=1.58 (95% confidence interval (CI)=1.50-1.66) and female SIR=2.31 (1.94-2.72) for smoking-related SPC. Among SCLC patients, the respective ratios were 1.39 (1.20-1.60) and 2.28 (1.73-2.95), and among ADC patients, they were 1.73 (1.57-1.90) and 2.24 (1.91-2.61). We also observed associations between first primary lung ADC and second primary breast cancer in women (SIR=1.25, 95% CI=1.05-1.48) and prostate cancer (1.56, 1.39-1.79) in men. CONCLUSION: The FPLC patients carried excess risks of smoking-related SPCs. An association between first primary lung ADC and second primary breast and ovarian cancer in women at younger age and prostate cancers in men may reflect an aetiological role of hormones in lung ADC.

Pixel-based analysis of FRAP data with a general initial bleaching profile.

In Jonasson et al. (2008), we presented a new pixel-based maximum likelihood framework for the estimation of diffusion coefficients from data on fluorescence recovery after photobleaching (FRAP) with confocal laser scanning microscopy (CLSM). The main method there, called the Gaussian profile method below, is based on the assumption that the initial intensity profile after photobleaching is approximately Gaussian. In the present paper, we introduce a method, called the Monotone profile method, where the maximum likelihood framework is extended to a general initial bleaching profile only assuming that the profile is a non-decreasing function of the distance to the bleaching centre. The statistical distribution of the image noise is further assumed to be Poisson instead of normal, which should be a more realistic description of the noise in the detector. The new Monotone profile method and the Gaussian profile method are applied to FRAP data on swelling of super absorbent polymers (SAP) in water with a Fluorescein probe. The initial bleaching profile is close to a step function at low degrees of swelling and close to a Gaussian profile at high degrees of swelling. The results obtained from the analysis of the FRAP data are corroborated with NMR diffusometry analysis of SAP with a polyethylene glycol probe having size similar to the Fluorescein. The comparison of the Gaussian and Monotone profile methods is also performed by use of simulated data. It is found that the new Monotone profile method is accurate for all types of initial profiles studied, but it suffers from being computationally slow. The fast Gaussian profile method is sufficiently accurate for most of the profiles studied, but underestimates the diffusion coefficient for profiles close to a step function. We also provide a diagnostic plot, which indicates whether the Gaussian profile method is acceptable or not.

Insulin glargine use and short-term incidence of malignancies-a population-based follow-up study in Sweden.

AIMS/HYPOTHESIS: In the light of a report suggesting that insulin glargine may increase cancer occurrence, the EASD asked us to perform this study. METHODS: We followed 114,841 individuals who had a prescription dispensed for insulin between 1 July and 31 December 2005. From 1 January 2006 to 31 December 2007, we noted the occurrence of malignancies. Seven different nationwide registers were used to obtain information on insulin exposure, outcome and possible confounders; these were linked using the unique personal identity number assigned to every Swedish resident. RESULTS: After adjustment for age and, when appropriate, sex, users of insulin glargine alone (no other types of insulin), compared with users of types of insulin other than insulin glargine, had an RR of 1.99 (95% CI 1.31-3.03) for breast cancer, 0.93 (95% CI 0.61-1.40) for gastrointestinal cancer, 1.27 (95% CI 0.89-1.82) for prostate cancer and 1.07 (95% CI 0.91-1.27) for any type of malignancy. Adjustment for age, smoking, BMI, age at onset of diabetes, age at birth of first child, cardiovascular disease and oestrogen use gave an RR for breast cancer of 1.97 (95% CI 1.29-3.00). The 95% CIs crossed 1.0 for the RR calculated in all analyses of users of insulin glargine in combination with other types of insulin. CONCLUSIONS/INTERPRETATION: In Sweden, during 2006 and 2007, women using insulin glargine alone (no other types of insulin) had an increased incidence rate of breast cancer as compared with women using types of insulin other than insulin glargine. This result may be due to a random fluctuation; the possibilities for examining validity are limited, and no statistically significant results were obtained for any other individual cancer site or for the outcome 'all malignancies'. No definitive conclusions regarding a possible causal relationship between insulin glargine use and the occurrence of malignancies can be drawn from the results of this study.

Mitochondrial haplogroup is associated with the phenotype of familial amyloidosis with polyneuropathy in Swedish and French patients.

Familial amyloidotic polyneuropathy (FAP) is a monogenic disease caused by mutations in the transthyretin (TTR) gene. The phenotype of the most common TTR mutation, V30M, varies within and between populations. Oxidative stress and protein misfolding are cellular processes involved in the development of FAP. Because the mitochondria are important for both these processes, we investigated if mitochondrial haplogroups are related to age at onset of the disease in Swedish and French FAP patients. Mitochondrial haplogroup analysis was performed on 25 early-onset (below 40 years) and 29 late-onset (above 51 years) Swedish FAP patients. DNA from 249 Swedish individuals served as controls. In addition, 6 early-onset and 17 late-onset French FAP patients were examined with 25 French controls. The haplogroup distribution among late-onset Swedish and French cases was similar to that found in the general populations, whereas among early-onset cases a different haplogroup distribution was seen. The relatively rare haplogroup K was significantly more common among early-onset cases. Our findings substantiate the suggestion that a genetic component, still to be found, affecting mitochondrial function has an impact on the amyloid generating process in transthyretin amyloidosis.

Peri- and post mortem hemorrhages in the anterior neck after chin-collar application.

Intense blunt compression trauma to the neck can result in subcutaneous, intramuscular or laryngeal mucosa bleedings of different intensity. While these findings can easily be detected through a layer-wise dissection of the neck muscles and soft tissue during autopsy, it can be difficult to distinguish between peri-/post- and ante mortem hemorrhages solely based on macroscopic findings. Especially when an initial preliminary diagnosis is required, possible artifacts have to be excluded. The study at hand examines possible peri- and post mortem hemorrhages in the anterior neck after NorMors™ chin-collar application. In routine clinical and forensic autopsy cases, where such a chin-collar has been placed around the neck of the deceased in close proximity after death, focus was directed to the soft tissue and muscles of the neck. The results of our analysis could prove that the use of chin-collar shortly within the first 1 ½ hours after death applies just enough pressure to the neck to be able to cause superficial hemorrhages within the surface of the sternocleidomastoid muscles, which can mimic vital compression trauma injuries. Based on location, morphological outlines and intensity of the injuries, it is possible to correlate them with the position of the applied collar. Together with histological analyses, asphyxia by a second party involvement can be excluded. However, the application of chin-collars should be prohibited in any case, where an autopsy might be performed.

Risk of second malignant neoplasms after childhood central nervous system malignant tumours: an international study.

PURPOSE: The aim of this study was to assess the risk of second malignant neoplasms (SMNs) other than central nervous system (CNS) neoplasms after childhood CNS cancer in an international multicentre study. METHODS: Individual data on cases of CNS cancer in children (0-14 years) and on subsequent SMNs were obtained from 13 population-based cancer registries contributing data for different time periods in 1943-2000. Standardised incidence ratios (SIRs) with 95% confidence intervals (CI), absolute excess risk and cumulative incidence of SMNs were computed. RESULTS: We observed 43 SMNs in 8431 CNS cancer survivors. The SIR was 10.6 (4.85-20.1) for thyroid cancer (nine cases), 2.75 (1.01-5.99) for leukaemia (six cases) and 2.47 (0.90-5.37) for lymphoma (six cases). The SIRs were highest in the first 10 years after CNS cancer diagnosis. The cumulative incidence of non-CNS SMNs was 3.30% (0.95-5.65%) within 45 years after a CNS cancer diagnosis. Within 15 years, the cumulative incidence was highest for cases diagnosed after 1980 (0.56%, 95% CI: 0.29-0.82%). CONCLUSION: This population-based study indicates that about one every 180 survivors of a childhood CNS cancer will develop a non-CNS SMN within the following 15 years. The excess is higher after glioma and embryonal malignant tumour than after another CNS tumour.

A pixel-based likelihood framework for analysis of fluorescence recovery after photobleaching data.

A new framework for the estimation of diffusion coefficients from data on fluorescence recovery after photobleaching (FRAP) with confocal laser scanning microscopy (CLSM) is presented. It is a pixel-based statistical methodology that efficiently utilizes all information about the diffusion process in the available set of images. The likelihood function for a series of images is maximized which gives both an estimate of the diffusion coefficient and a corresponding error. This framework opens up possibilities (1) to obtain localized diffusion coefficient estimates in both homogeneous and heterogeneous materials, (2) to account for time differences between the registrations at the pixels within each image, and (3) to plan experiments optimized with respect to the number of replications, the number of bleached regions for each replicate, pixel size, the number of pixels, the number of images in each series etc. To demonstrate the use of the new framework, we have applied it to a simple system with polyethylene glycol (PEG) and water where we find good agreement with diffusion coefficient estimates from NMR diffusometry. In this experiment, it is also shown that the effect of the point spread function is negligible, and we find fluorochrome-concentration levels that give a linear response function for the fluorescence intensity.

BRCA2 and p53 mutations in primary breast cancer in relation to genetic instability.

The products of the BRCA breast cancer susceptibility genes have been implicated in cell cycle control and DNA repair. It has been suggested that mutations in the p53 gene are a necessary step in tumorigenesis in BRCA tumors. We tested samples from 402 breast cancer patients for germ-line BRCA2 and p53 mutations in tumors. p53 mutations are more frequent in BRCA2 mutation carriers than they are in controls. Tumors with mutations in either gene had multiple chromosomal abnormalities, as shown by cytogenetic analysis.

High incidence of loss of heterozygosity in breast tumors from carriers of the BRCA2 999del5 mutation.

Germ-line mutation in the BRCA2 gene confers an increased risk of breast cancer. An elevation of additional genetic defects in tumors of patients with germ-line mutation in the BRCA2 gene compared with sporadic breast tumors has been reported. To evaluate the nature of the difference, we did detailed mapping of chromosomes 1p, 3p, 6q, 11, 13q, 16q, 17, and 20q, using microsatellite markers. We found that the frequency of loss of heterozygosity was similar at some chromosomal regions in the BRCA2 999del5 and sporadic tumors but significantly different at others. These others include chromosomal arms 3p, 6q, 11p, 11q, 13q, and 17p. Loss of heterozygosity mapping suggests that the same chromosome regions are involved in both tumor groups but at elevated frequencies in BRCA2 999del5 tumors. This higher frequency of genetic aberrations could pinpoint genes that selectively promote tumor progression in individuals predisposed to breast cancer due to the BRCA2 999del5 germ-line mutation. Accumulation of somatic genetic changes during tumor progression may follow a specific and more aggressive pathway of chromosome damage in these individuals.