Biomedical subjects
Publications and source records attributed to T Bjørge.
We investigated relations between measured body mass index (BMI) and stature and thyroid cancer (3046 cases) in a large Norwegian cohort of more than two million individuals. The risk of thyroid cancer, especially of the papillary and follicular types, increased moderately with increasing BMI and height in both sexes.
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The present study aimed at exploring the relations between body mass index (BMI, (weight in kilograms)/(height in meters)(2)) and stature and cancer of the small intestine (1162 cases) in a large Norwegian cohort (of two million) with measured height and weight. Elevated BMI in males and increasing height in both sexes were associated with a moderately increased risk of cancer of the small intestine.
The aims of the present study were to find the frequency of the most common BRCA1 mutations in women with ovarian tumours identified from a population-based cancer registry and in the general population, to estimate the relative risk of ovarian tumours among the mutation carriers, and to explore the value of using CA125 as a prediagnostic test. The study was designed as a nested case-control study within a cohort mainly consisting of participants in population-based health examinations. The data files of The Cancer Registry of Norway and the Janus serum bank were linked to identify cases with ovarian cancer and borderline tumours. Hereditary BRCA1 mutations were determined using archived serum samples and capillary electrophoresis. Altogether 478 ovarian cancer patients and 190 patients with borderline tumours were identified, and 1421 and 568 matching controls were selected. Odds ratios (OR) of developing ovarian cancer and borderline tumours in the presence of BRCA1 mutations and CA125 level were derived from conditional logistic regression models. Among the 478 ovarian cancer patients, 19 BRCA1 mutations were identified (1675delA, 1135insA, 816delGT and 3347delAG), none among the patients with borderline tumours. Only two of the 1989 controls were BRCA1 mutation carriers (0.10%). The risk of ovarian cancer among the mutation carriers was strongly elevated (OR=29, 95% CI=6.6-120). CA125 was a marker for ovarian cancer, but the sensitivity was low. This study showed that BRCA1 mutation carriers have a very high risk of ovarian cancer. However, since the prevalence of BRCA1 mutations in the Norwegian population was low, the proportion of ovarian cancers due to BRCA1 mutations seemed to be low, about 4%. The sensitivity of using CA125 only as a screening test for ovarian cancer was low.
This case-control study based in Nordic serum banks evaluated the joint effects of infections with genital human papillomavirus (HPV) types, and Chlamydia trachomatis in the aetiology of cervical squamous cell carcinoma. Through a linkage with the cancer registries, 144 cases were identified and 420 controls matched to them. Exposure to past infections was defined by the presence of specific IgG antibodies. The odds ratio (OR) for the second-order interaction of HPV16, HPV6/11 and C. trachomatis was small (1.0) compared to the expected multiplicative OR, 57, and the additive OR, 11. The interactions were not materially different among HPV16 DNA-positive squamous cell carcinomas. When HPV16 was replaced with HPV18/33 in the analysis of second-order interactions with HPV6/11 and C. trachomatis, there was no evidence of interaction, the joint effect being close to the expected additive OR. Possible explanations for the observed antagonism include misclassification, selection bias or a true biological phenomenon with HPV6/11 and C. trachomatis exposures antagonizing the carcinogenic effects of HPV16.
The present study explored body mass index (BMI), height, and risk of prostate cancer in a large Norwegian cohort of 950000 men aged 20-74 years, whose height and weight were measured in a standardised way in the period 1963-1999. These were followed for an average of 21 years. The Cox proportional hazard models were used in the analyses. During follow-up, 33 300 histologically verified cases of prostate cancer were registered. The risk of prostate cancer increased by both BMI and height. The magnitude of the increase by BMI was modest, the relative risk (RR) of obese men (BMI>or=30) compared with normal weighted was 1.09 (95% CI: 1.04-1.15). However, the RR at age 50-59 years was 1.58 (95% CI: 1.29-1.94) in men being obese at about age 45 years compared with normal weighted men. The tallest men had an RR of 1.72 (95% CI: 1.46-2.04) compared with the shortest men. The overall effect of BMI on the incidence of prostate cancer was modest. The larger effect found in men aged 50-59 years might partly explain the previous inconsistent findings.
Human papillomavirus has emerged as the leading infectious cause of cervical and other anogenital cancers. We have studied the relation between human papillomavirus infection and the subsequent risk of anal and perianal skin cancer. A case-cohort study within two large Nordic serum banks to which about 760 000 individuals had donated serum samples was performed. Subjects who developed anal and perianal skin cancer during follow up (median time of 10 years) were identified by registry linkage with the nationwide cancer registries in Finland and Norway. Twenty-eight cases and 1500 controls were analysed for the presence of IgG antibodies to HPV 16, 18, 33 or 73, and odds ratios of developing anal and perianal skin cancer were calculated. There was an increased risk of developing anal and perianal skin cancer among subjects seropositive for HPV 16 (OR=3.0; 95%CI=1.1-8.2) and HPV 18 (OR=4.4; 95%CI=1.1-17). The highest risks were seen for HPV 16 seropositive patients above the age of 45 years at serum sampling and for patients with a lag time of less than 10 years. This study provides prospective epidemiological evidence of an association between infection with HPV 16 and 18 and anal and perianal skin cancer.
OBJECTIVES: The aim of this study was to give an overview of the Norwegian population of gestational trophoblastic tumors (GTT), diagnosed during 1968-1997 and treated with chemotherapy at the Norwegian Radium Hospital (NRH), with regard to patient characteristics, treatment, and prognosis. METHODS: The cases were grouped according to a modified version of the WHO scoring system. Staging was performed retrospectively according to the systems adopted by FIGO. Survival estimates were calculated by the method described by Kaplan and Meier. Cox regression models were used to find the best classification system with regard to prognosis (disease-free survival). RESULTS: A total of 141 cases, 106 invasive moles (IM) and 35 choriocarcinomas (CC), were diagnosed in Norway and treated with chemotherapy at the NRH in the period 1968-1997. Altogether, 56% of the patients were assigned to the low-risk category, 20% to the medium-risk category, and 15% to the high-risk category. Most cases were classified into the clinical stages I (69%) and III (23%). The overall 5-year survival rate was 96%. A more favorable prognosis was seen in patients diagnosed in the 1980s and 1990s compared with those diagnosed in the 1970s (P = 0.04). Five patients had progressive disease and died from the disease. Nine patients relapsed. The prognosis (disease-free survival) was more favorable for IM compared with CC (P < 0.01). The FIGO classification system seemed to be a better predictor of disease-free survival than the WHO scoring system. CONCLUSIONS: This study showed that the prognosis of patients with GTT improved in the 1980s and 1990s in Norway, and that the FIGO system might be the best predictor of disease-free survival.
BACKGROUND: Cervical cancer is the third most frequent cancer among women worldwide. Human papillomavirus (HPV) infection is a necessary risk factor and the first step in cervical carcinogenesis. MATERIAL AND METHODS: This article reviews the current literature concerning the possibility of preventing cervical cancer by HPV testing and vaccination. RESULTS: HPV testing cannot replace cytology, but will reduce false negative cytology and may improve the screening programme for cervical neoplasia. It has not yet been incorporated in any national cervical cancer screening program, but trials are ongoing in Scandinavia and in the Netherlands. The cost-effectiveness of HPV testing in screening has to be proven and whether it can affect the recommended screening-intervals. Therapeutic and prophylactic vaccines for HPV associated disease are in progress. Evaluating the clinical trials that are ongoing will take several years. Several anti-HPV vaccines are now in clinical trials; Norway will also participate. Therapeutic vaccines against cervical cancer have so far not been successful, but anogenital dysplasias and condylomas may be more susceptible. Prophylactic vaccines against HPV 6, 11, 16 and 18 have been evaluated in clinical phase I and II trials, and phase III trials are in progress. INTERPRETATION: HPV testing improves the specificity and sensitivity of cervical cytology and it can be used to clarify cases with atypical cells of undetermined significance (ASCUS) and low-grade intraepithelial neoplasia. In the near future it may also be included in the cervical cancer screening programme for women above the age of 30. The first results in clinical vaccine trials are encouraging, and final conclusions about the effectiveness of these vaccines may be achieved in five years' time.
Only within the last decade we have begun to fully appreciate the natural history and biologic behaviour of borderline tumours in the ovaries. In contradiction to invasive epithelial tumours, most borderline tumours are confined to the ovary(ies) (stage I). Because the prognosis of stage I serous borderline tumours is excellent, with five-year survival rates of almost 100%, some experts are advocating that this subset should be classified as benign. Although the standard treatment for older patients is abdominal hysterectomy and bilateral salpingo-oophorectomy, many young patients who have not completed childbearing can be safely treated with unilateral salpingo-oophorectomy coupled with comprehensive surgical staging, thereby preserving their fertility potential. Another major controversy associated with borderline tumours is the clinical management of patients with advanced-stage disease or peritoneal implants. Many experts strongly believe that surgery is the only effective treatment for borderline tumours. Others routinely employ postoperative chemotherapy for at least some subset of patients with peritoneal implants. Several investigators have focused on DNA ploidy as a predictor of recurrence and survival, but their findings are conflicting.
BACKGROUND: Ovarian cancer is a common malignant neoplasm in affluent societies. Although the prognosis has continuously improved since the 1950s, it is still poor, with five-year relative survival rates of about 40%. MATERIAL AND METHODS: The paper discusses the potential use of screening for early ovarian cancer detection. RESULTS: The disease is a suitable candidate for screening because the prognosis is strongly dependent on the stage of disease at the time of diagnosis. Ovarian cancer does not, however, meet all the prerequisites for successful screening; there is no preclinical stage that can be detected, and the tests are not sensitive and specific enough to be effective. Furthermore, there is so far no direct evidence that screening would decrease mortality from ovarian cancer, though recent data suggest that screening may increase survival. INTERPRETATION: Screening women at higher risk of developing ovarian cancer might be beneficial.
Cervical carcinoma is a sexually transmitted disease most strongly linked with human-papillomavirus (HPV) infection. We conducted a prospective sero-epidemiologic study to evaluate the role of Chlamydia trachomatis infection in the development of cervical carcinoma, with invasive cancer as an end point. A nested case-control study within a cohort of 530000 Nordic women was performed. Linking data files of 3 Nordic serum banks and the cancer registries of Finland, Norway and Sweden identified 182 women with invasive cervical carcinoma diagnosed during a mean follow-up of 5 years after serum sampling. The serum samples of the cases and matched cancer-free controls were analyzed for IgG antibodies to C. trachomatis, C. pneumoniae (a control microbe) and HPV types 16, 18 and 33, as well as for serum cotinine (an indicator of tobacco smoking). Serum antibodies to C. trachomatis were associated with an increased risk for cervical squamous-cell carcinoma (HPV- and smoking-adjusted OR, 2.2; 95% CI, 1.3-3.5). The association remained also after adjustment for smoking both in HPV16-seronegative and -seropositive cases (OR, 3.0; 95% CI, 1.8-5.1; OR, 2.3, 95% CI, 0. 8-7.0 respectively). No such association was found for C. pneumoniae. Our prospective study provides sero-epidemiologic evidence that infection with C. trachomatis confers an increased risk for subsequent development of invasive squamous-cell carcinoma of the uterine cervix.
Screening can be defined as the process of identifying preclinical disease in asymptomatic people. The main objective of screening is to reduce the incidence and the mortality from disease. There are several prerequisites for successful screening, and screening has both beneficial and adverse effects. In Norway only screening for cervical and breast cancer are recommended as nation-wide, organised programmes. Screening for colorectal cancer is planned as a pilot project. Also a study on screening for prostate cancer is planned. Screening for other cancers is not recommended.
Human papillomavirus (HPV) types 16 and 18 are the major risk factors for cervical carcinoma, whereas HPV types 6 and 11 cause benign genital lesions. We wanted to study the joint effect of simultaneous infections with the oncogenic and non-oncogenic HPV types on risk of subsequent development of cervical carcinoma. A cohort of 530,000 women who had donated blood samples to Nordic serum banks between 1973 and 1994 was followed up by linkage to national cancer registries. We identified 182 prospective cases with invasive cervical carcinoma and selected 538 matched controls at random. HPV 6, 11, 16, 18 and 33 seropositivity was used as a marker for the different HPV infections, and seropositivity for Chlamydia trachomatis and cotinine were used as markers for risk-taking sexual behavior and smoking respectively. The adjusted odds ratio (OR) of cervical squamous-cell carcinoma (SCC) was 2.2 for HPV6/11 among HPV16 seronegatives and 5.5 for HPV16 among HPV6/11 seronegatives. Assuming multiplicative joint effect, the expected OR for seropositivity to both HPV6/11 and HPV16 would have been 12, but the observed OR was 1.0. The antagonistic interaction was statistically significant (p = 0.001) and present also under deterministic considerations of possible misclassification bias. Antagonistic interactions were also detected for combinations of HPV16 and HPV18 and of HPV16 and HPV33. The results are in line with the concept that HPV-specific immunity protects against SCC and support primary prevention of SCC by vaccination against the HPVs.
Long-term trends in the incidence, prognosis, and mortality of patients with ovarian cancer and borderline tumours in Norway were examined based on data from the population-based Cancer Registry of Norway. The incidence of ovarian cancer rose continuously from the mid-1950s to the mid-1980s. There was also an increasing trend in the incidence of borderline tumours from the early 1970s to the early 1990s. The prognosis for patients with ovarian cancer has improved since the 1950s. In 1989-93 the five-year relative survival rate was 37%. The prognosis for patients with borderline tumours was very favourable, with a five-year relative survival rate of 93% (1970-93). The mortality from ovarian cancer has been almost constant since the 1960s.
During the last two decades there have been frequent discussions as to whether passive smoking causes cancer, or not. It is difficult to carry out satisfactory studies on this issue, partially because any increased risk of cancer seems modest. The tobacco industry has not only attempted to make the public aware of studies which conclude that passive smoking is harmless, but it has also tried to keep alive the discussion as to whether exposure to passive smoking is harmful, or not. A large number of studies has been carried out on the possible impact passive smoking may have on the risk of lung cancer, and it seems justifiable to conclude that passive smoking does increase the risk of this type of cancer. For other types of cancer too few studies have been performed to draw any firm conclusions.
The Scandinavian countries exhibit some of the highest incidence rates of ovarian cancer in the world. Prognosis is poor, and the crude 5-year relative survival was 36% in the Nordic countries in the 1980s. Histology-specific prognostic trends in 5-year relative survival of patients with ovarian cancer and borderline tumours were examined, based on data from the population-based Cancer Registry of Norway. Relative risks (RRs) of dying were derived from Cox regression models. Logistic regression analysis on the proportion of cases with a localised tumour was performed. The 5-year relative survival rate of patients with ovarian cancer increased steadily from 1954 to 1993, being most pronounced in women below the age of 65 at the time of diagnosis. No improvement was seen for women older than 75. For all patients with ovarian cancer, an RR of dying of 0.48 (95% CI = 0.44-0.53) was estimated in 1989-1993 compared with 1954-1958. For patients with epithelial cancer, an RR of 0.63 (95% CI = 0.57-0.69) was seen in 1989-1993 compared with 1970-1973. Patients with mucinous, endometrioid and clear cell tumours had the highest odds of having a localised tumour. The age-adjusted 5-year relative survival rate of patients with borderline tumours was almost constant between 1970 and 1993, at about 93%. The prognosis of patients with ovarian cancer in Norway has improved since the 1950s. The very favourable prognosis of patients with borderline tumours has remained unchanged since the 1970s.
Lung cancer is the most common cancer in the world today, and the prognosis for lung cancer patients is poor. In the Nordic countries, the five-year relative survival was only seven percent in patients diagnosed in 1983-87. In the present study, the survival of 36,010 lung cancer patients diagnosed in Norway in 1954-93 was examined, based on data from the population-based Cancer Registry of Norway. The variation in survival by gender, age, stage, period of diagnosis, and histologic group was explored. Relative survival rates were calculated and relative risks of dying were obtained from multivariate Cox proportional hazards regression analysis. Only a slight improvement in the prognosis of lung cancer patients was observed during the 40-year study period. More than half the patients died during the first six months after diagnosis. Patients with small cell carcinoma had the lowest frequency of localized tumors and also had the poorest prognosis, even after adjustment for stage. Patients with squamous cell carcinoma had the highest frequency of localized tumors. The patients with a localized tumor also have a poor prognosis, with a crude median survival time of nine months in males and 11 months in females in 1984-93.