The BOADICEA model of genetic susceptibility to breast and ovarian cancers: updates and extensions

Multiple genetic loci confer susceptibility to breast and ovarian cancers. We have previously developed a model (BOADICEA) under which susceptibility to breast cancer is explained by mutations in BRCA1 and BRCA2, as well as by the joint multiplicative effects of many genes (polygenic component). We have now updated BOADICEA using additional family data from two UK population-based studies of breast cancer and family data from BRCA1 and BRCA2 carriers identified by 22 population-based studies of breast or ovarian cancer. The combined data set includes 2785 families (301 BRCA1 positive and 236 BRCA2 positive). Incidences were smoothed using locally weighted regression techniques to avoid large variations between adjacent intervals. A birth cohort effect on the cancer risks was implemented, whereby each individual was assumed to develop cancer according to calendar period-specific incidences. The fitted model predicts that the average breast cancer risks in carriers increase in more recent birth cohorts. For example, the average cumulative breast cancer risk to age 70 years among BRCA1 carriers is 50% for women born in 1920-1929 and 58% among women born after 1950. The model was further extended to take into account the risks of male breast, prostate and pancreatic cancer, and to allow for the risk of multiple cancers. BOADICEA can be used to predict carrier probabilities and cancer risks to individuals with any family history, and has been implemented in a user-friendly Web-based program (http://www.srl.cam.ac.uk/genepi/boadicea/boadicea_home.html).

CYP17 genotype is associated with short menstrual cycles, early oral contraceptive use and BRCA mutation status in young healthy women

The CYP17 gene is involved in steroid hormone metabolism and has been proposed as a low penetrance gene for breast cancer. We aimed to investigate the associations between the CYP17 genotype and breast cancer risk factors, such as age at menarche, menstrual cycle length, oral contraceptive (OC) use, and BRCA mutation status among 258 healthy young women, aged < or =40, from 158 breast cancer high-risk families. Questionnaires including questions on reproductive factors and OC use were completed and blood samples were obtained from all women. CYP17 (rs743572) was genotyped with sequencing in 254 women. The main findings were that short menstrual cycles (<27 days) were significantly more common with increasing number of variant A2 alleles (8%, 17% and 32%; P(trend) = 0.002, adjusted for family clustering). Each A2 allele was associated with a 7 months earlier OC start (17.8, 17.0, and 16.6 years; P(trend) = 0.014, adjusted for age at menarche, ever-smoking and family clustering). Homozygosity for the A2 allele was more common among known non-carriers from BRCA1/2 families compared with other high-risk women OR 2.92 (95% CI 1.49-5.73; P = 0.002, adjusted for family clustering). We found no association between CYP17 genotype and age at menarche. In conclusion, this study suggests that short menstrual cycles, age at first OC use and BRCA mutation status may need to be considered in studies exploring the relationships between CYP17 and risk factors for early onset breast cancer.

Age at first birth and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

An early age at first full-term birth is associated with a reduction in the subsequent development of breast cancer among women in the general population. A similar effect has not yet been reported among women who carry an inherited BRCA1 or BRCA2 mutation. We conducted a matched case-control study on 1816 pairs of women with a BRCA1 (n = 1405) or BRCA2 (n = 411) mutation in an attempt to elucidate the relationship between age at first full-term pregnancy and the risk of developing breast cancer. Information about the age at first childbirth and other pregnancy-related variables was derived from a questionnaire administered to women during the course of genetic counselling. There was no difference in the mean age at first full-term birth in the cases and controls (24.9 years vs. 24.8 years; P = 0.81, respectively). Compared to women whose first child was born at or before 18 years of age, a later age at first full-term birth did not influence the risk of developing breast cancer (OR = 1.00 per year; 95% CI 0.98-1.03; P-trend = 0.67). Stratification by mutation status did not affect the results. These findings suggest that an early first full-term birth does not confer protection against breast cancer in BRCA mutation carriers. Nonetheless, BRCA mutation carriers opting for a prophylactic oophorectomy as a breast and/or ovarian cancer risk-reducing strategy should complete childbearing prior to age 40 when this prevention modality is most effective.

Increased risk of malignancies in a population-based study of 818 soft-tissue sarcoma patients

Soft-tissue sarcomas (STS) have been associated with various rare cancer syndromes and occur at increased frequencies in survivors of childhood cancer. Also adult patients with STS have been suggested to be at an increased risk of additional malignancies. After exclusion of syndrome-associated and radiation-induced sarcomas, we studied multiple primary malignancies in a population-based cohort of 818 patients with primary STS of the extremities and the trunk wall. In total, 203 other malignancies developed in 164 (20%) patients median 10 (0-32) years before and median 4 (0-35) years after the sarcoma diagnosis. Standardised morbidity ratios (SMRs) were determined for primary malignancies following a STS. Hereby individuals who had developed a STS were identified to be at increased risk of second primary malignancies (SMR for all malignant tumours=1.3; 95% CI=1.0-1.5; P=0.02) with STS being the only specific tumour type that occurred at an increased risk (SMR=17.6; 95% CI=8.1-33.5; P<0.001). Hence, this population-based series demonstrates a high frequency of second primary tumours among STS patients and indicates a particularly increased risk of developing a new STS.

Insulin-like growth factor-1 genotype predicts breast volume after pregnancy and hormonal contraception and is associated with circulating insulin-like growth factor-1 levels: implications for risk of early-onset breast cancer in young women from hereditary breast cancer families

BACKGROUND

BRCA1/2 mutations predispose to early-onset breast cancer, especially after oral contraceptive (OC) use and pregnancy. However, the majority of breast cancers might be due to more prevalent low penetrance genes that may also modify the risk in BRCA1/2 mutation carriers. The absence of the IGF1 19-CA repeat allele has been associated with high insulin-like growth factor-1 (IGF-1) levels during OC use in nulliparous women of four different ethnic groups. High IGF-1 levels are linked to an increased risk of early-onset breast cancer and to larger breast volumes in the general population. It has also been hypothesized that women whose breast size increases while exposed to OCs may be at increased risk of future breast cancer.

AIM

We explored the effect of the IGF1 genotype, specifically the absence of the common 19-CA repeat allele in the promoter region of the IGF1 gene, in combination with oral contraceptive (OC) use or parity on breast volume and IGF-1 levels.

MATERIALS AND METHODS

Two hundred fifty-eight healthy women, </=40 years old, from hereditary breast cancer families participated in this prospective study. Twenty-three women were known BRCA1 mutation carriers, 7 women were known BRCA2 mutation carriers, 54 women were noncarriers from BRCA1/2 families, 111 women belonged to breast cancer families where no BRCA1 or BRCA2 mutations were detected, and 63 women were untested from high-risk breast cancer families. All women completed a questionnaire including information on reproductive factors and OC use. We measured height, weight, breast volumes, and plasma IGF-1 levels once during menstrual cycle days 5-10 and once again during menstrual cycle days 18-23. The IGF1 genotype was successfully analyzed with polymerase chain reaction and fragment analyses in 254 women.

RESULTS

Thirteen percent had no IGF1 19-CA repeat allele. The absence of the 19-CA repeat allele was more common among women with known BRCA1 mutations compared to other women (26% versus 12%; P= 0.05). See updated and revised Table 1 from original publication. IGF-1 levels were similar among parous and nulliparous women not using OCs, which is in contrast to results from women in the general population, where parous women have lower IGF-1 levels than nulliparous women. Furthermore, OC use did not affect IGF-1 levels in parous women in our study. BRCA mutation status did not affect age-adjusted IGF-1 levels in either cycle phase among nonusers. Most of the nulliparous OC users had lower IGF-1 levels than nonusers. However, there was an interaction between IGF1 genotype and OC use on IGF-1 levels in nulliparous women (P= 0.026). Compared with nonusers, IGF-1 levels were highly suppressed in OC users with a 19-CA repeat allele (P < 0.001), but not among women lacking the 19-CA repeat allele (P= 0.81). We also observed an interaction between parity and IGF1 genotype on breast volume (P= 0.01). Absence of the 19-CA repeat allele was associated with larger breast volumes in parous versus nulliparous women and OC users, while parous women and OC users with the 19-CA repeat allele had smaller breast volumes than nulliparous women and nonusers adjusted for body weight. During follow-up, six incident breast cancers cases occurred, four in known BRCA1 mutation carriers and two in untested women. Incident breast cancers were associated with absence of the 19-CA repeat allele (log-rank; P= 0.002).

CONCLUSION

Our results suggest that absence of the IGF1 19-CA repeat allele modifies IGF-1 levels, breast volume, and possibly early-onset breast cancer risk after hormone exposure in young, high-risk women. These results warrant confirmation in a larger prospective cohort of high-risk women. If confirmed, the IGF1 genotype could be incorporated as an additional marker to improve risk estimates for early-onset breast cancer during genetic counseling of women from high-risk breast cancer families.

Testosterone levels in relation to oral contraceptive use and the androgen receptor CAG and GGC length polymorphisms in healthy young women

BACKGROUND

The combined effect from the androgen receptor (AR) CAG and GGC length polymorphisms on testosterone levels has not been studied in young women.

METHODS

Testosterone levels were measured in blood drawn on both menstrual cycle days 5-10 and 18-23 in 258 healthy women, aged < or =40 years, from high-risk breast cancer families. CAG and GGC length polymorphisms were analysed by PCR and fragment analyses. All women completed a questionnaire including information on oral contraceptive (OC) use and reproductive factors.

RESULTS

OC users had lower median testosterone levels than non-users during cycle days 5-10 and 18-23 (P < or = 0.005 for both). The BRCA mutation status was associated neither with testosterone levels nor with CAG or GGC length polymorphism. The CAG length polymorphism was not associated with testosterone levels. The cumulative number of long GGC alleles (> or =17 repeats) was significantly associated with lower testosterone levels in OC users during cycle days 5-10 (P(trend) =0.014), but not during cycle days 18-23 or in non-users. The interaction between the GGC length polymorphism and OC status was highly significant during cycle days 5-10 (P = 0.002) and near-significant during days 18-23 (P = 0.07). Incident breast cancer was more common in women with two short GGC alleles (log-rank P = 0.003).

CONCLUSION

The GGC repeat length was the only significant genetic factor modifying the testosterone levels in current OC users from high-risk families. Homozygosity for the short GGC allele may be linked to the increased risk of early-onset breast cancer after OC exposure in high-risk women.

Survival in women with breast cancer having children with pediatric tumors—-A nationwide cancer register study

20071

Background: Breast cancer is a heterogenous disease with a minoruty of cases having a hereditary background. Hereditary factors could affect disease prognosis and it has been postulated that breast cancer patients having p53 germline mutations have an especially bad prognosis. In the present study survival has been compared in women with breast cancer with and without having a child with a pediatric tumour. Methods: Using and linking the population based fertility registry and cancer registry the offspring of all women with breast cancer diagnosed between 1961–1999 was traced in Sweden. All women with breast cancer with a pregnancy were included. Further all childhood cancer cases < 21 years of age were identified among the offspring. Likewise using census data the women’s overall survival was followed. Results: Patients with breast cancer having a child with a childhood malignancy (n = 254) had a significant worse survival compared with other women with breast cancer (n = 74,781), RR = 1.25, 95% CI 1.02–1.55, p < 0.04, adjusted for age at diagnosis, year of diagnosis, parity and time since last pregnancy. Mothers with children with pediatric sarcomas or acute myeloid leukemias seemed to be strongest associated with a worse survival in the mother (RR = 1.38 and RR = 1.69). The worse survival of the mother was present regardless if the breast cancer diagnosis was before or after 50 years of age. Conclusion: The results suggest that genetic syndromes such as the Li-Fraumeni syndrome and possibly other childhood/adult cancer syndromes if present worsens the survival for breast cancer patients. This familial factor may be of importance for future treatment stratification. It is unknown whether other tumor diseases in the mother may be associated with a worse survival if their children have had cancer.

No significant financial relationships to disclose.

Formation of a hard tissue barrier after pulp cappings in humans. A systematic review

AIM

To evaluate the evidence on the formation of a hard tissue barrier after pulp capping in humans.

METHODOLOGY

A PubMed and CENTRAL literature search with specific indexing terms and a hand search were made. The authors assessed the level of evidence of each publication as high, moderate or low. Based on this, the evidence grade of the conclusions was rated as strong, moderately strong, limited or insufficient.

RESULTS

The initial search process resulted in a total of 171 publications. After reading the abstracts and hand searching the reference lists of the retrieved publications, 107 studies were retrieved in full-text and interpreted. After the interpretation, 21 studies remained and were included in the systematic review and given a level of evidence. No study had a high level of evidence, one study had moderate and 20 studies had a low level of evidence. There was heterogeneity between the studies; therefore, no meta-analysis was performed. The majority of studies on pulp capping using calcium hydroxide based materials reported formation of hard tissue bridging, studies on other pulp capping materials such as bonding agents presented inferior results. The evidence grade was insufficient.

CONCLUSIONS

Insufficient evidence grade does not necessarily imply that there is no effect of a pulp capping procedure or that it should not be used. Rather, the insufficient evidence underpins the need for high-quality studies.

Breast and ovarian cancer risks to carriers of the BRCA1 5382insC and 185delAG and BRCA2 6174delT mutations: a combined analysis of 22 population based studies

A recent report estimated the breast cancer risks in carriers of the three Ashkenazi founder mutations to be higher than previously published estimates derived from population based studies. In an attempt to confirm this, the breast and ovarian cancer risks associated with the three Ashkenazi founder mutations were estimated using families included in a previous meta-analysis of populatrion based studies. The estimated breast cancer risks for each of the founder BRCA1 and BRCA2 mutations were similar to the corresponding estimates based on all BRCA1 or BRCA2 mutations in the meta-analysis. These estimates appear to be consistent with the observed prevalence of the mutations in the Ashkenazi Jewish population.

Insulin-like growth factor-1 (IGF1) genotype predicts breast volume after pregnancy and hormonal contraception and is associated with circulating IGF-1 levels: implications for risk of early-onset breast cancer in young women from hereditary breast cancer families

BRCA1/2 mutations predispose to early-onset breast cancer, especially after oral contraceptive (OC) use and pregnancy. However, the majority of breast cancers might be due to more prevalent low-penetrance genes, which may also modify the risk in BRCA mutation carriers. The absence of the IGF1 19-repeat allele has been associated with high insulin-like growth factor-1 (IGF-1) levels during OC use. High IGF-1 levels are linked to early-onset breast cancer and larger breast volumes in the general population. The goal of this study was to elucidate the relationships between IGF1 genotype, early-onset breast cancer, breast volume, circulating IGF-1 levels and OC use in a prospective cohort of 258 healthy women ⩽40 years old from high-risk breast cancer families. All women completed a questionnaire including information on reproductive factors and OC use. We measured the height, weight, breast volumes and plasma IGF-1 levels. IGF-1 levels were similar among parous and nulliparous women not using OCs. In all, 13% had no IGF1 19-repeat allele. There was an interaction between IGF1 genotype and OC use on IGF-1 levels (P=0.026) in nulliparous women and another interaction between IGF1 genotype and parity on breast volume (P=0.01). Absence of the 19-repeat allele was associated with high IGF-1 levels in nulliparous OC users and with larger breast volumes in parous women and OC users. Incident breast cancers were also more common in women without the 19-repeat allele (log rank P=0.002). Our results suggest that lack of the IGF1 19-repeat allele modifies IGF-1 levels, breast volume and possibly early-onset breast cancer risk after hormone exposure in young high-risk women.

Dental pulp capping: effect of Emdogain Gel on experimentally exposed human pulps

AIM

To investigate the effect of Emdogain Gel (Biora AB, Malmo, Sweden), consisting of a enamel matrix derivative (EMD) in a propylene glycol alginate (PGA) vehicle, on experimentally exposed human pulps and to register postoperative symptoms.

METHODOLOGY

Nine pairs of contralateral premolars scheduled for extraction on orthodontic indications were included. Following a superficial pulp amputation performed with a small (016) diamond bur, either EMDgel or a mix of calcium hydroxide and sterile saline was placed at random in contact with the pulp wound. The subjects made records of symptoms and were also interviewed about pain/discomfort by a blinded examiner. After 12 weeks the teeth were extracted, prepared and subjected to light microscopic examination in which the inflammation and newly formed hard tissue in the pulp were analysed. Immunohistochemistry was performed using affinity-purified rabbit anti-EMD polyclonal antibodies.

RESULTS

Postoperative symptoms were less frequent in the EMDgel-treated than in the calcium hydroxide-treated teeth, especially during the first six weeks. In the EMDgel-treated teeth, new tissue partly filled the space initially occupied by the gel and hard tissue was formed alongside the exposed dentine surfaces and in patches in the adjacent pulp tissue. EMD was detected in the areas where new hard tissue had been formed. The wound area of the EMDgel-treated teeth exhibited inflammation in the majority of the teeth whereas less inflammation was seen in the calcium hydroxide-treated teeth where the hard tissue was formed as a bridge.

CONCLUSIONS

In the EMDgel-treated teeth, postoperative symptoms were less frequent and the amount and pattern of hard tissue formation were markedly different than in the teeth treated with calcium hydroxide. However, the operative procedure and the formulation with EMD in a PGA vehicle do not seem to be effective for the formation of a hard tissue barrier.

Tumour necrosis factor blockers do not increase overall tumour risk in patients with rheumatoid arthritis, but may be associated with an increased risk of lymphomas

OBJECTIVE

To determine whether TNF blockers increase tumour risk in patients with RA.

MATERIALS AND METHODS

The South Swedish Arthritis Treatment Group register (SSATG) comprises over 90% of anti-TNF treated patients with RA in the area. 757 patients treated with etanercept or infliximab included between 1 February 1999 and 31 December 2002 were identified. 800 patients with conventional antirheumatic treatment in a community based cohort served as a comparison cohort. Tumours and deaths were identified in the cancer registry and population census registers. Patients were followed up from initiation of anti-TNF treatment or 1 July 1997 for the comparison group, until death or 31 December 2002.

RESULTS

In the anti-TNF group, 16 tumours (5 lymphomas) were identified in 1603 person-years at risk, and in the comparison group 69 tumours (2 lymphomas) in 3948 person-years. Standardised incidence ratios (SIRs) for total tumour relative risk for the anti-TNF group and the comparison group were 1.1 (95% confidence interval (CI) 0.6 to 1.8) and 1.4 (95% CI 1.1 to 1.8), respectively. The lymphoma relative risk (RR) was 11.5 (95% CI 3.7 to 26.9) and 1.3 (95% CI 0.2 to 4.5), respectively The total tumour RR excluding lymphoma was 0.79 (95% CI 0.4 to 1.42) and 1.39 (95% CI 1.08 to 1.76), respectively. Proportional hazard analysis for lymphomas yielded RR 4.9 (95% CI 0.9 to 26.2) in anti-TNF treated versus untreated patients.

CONCLUSION

Community based patients with RA treated conventionally had an increased overall tumour risk compared with the background population. A possible additional increased risk for lymphoma associated with TNF blockers was based on few cases and needs confirmation.

Birth weight is associated with postmenopausal breast cancer risk in Swedish women

There is some evidence that birth weight is associated with breast cancer. Whether this association differs between premenopausal and postmenopausal ages is still unclear. The results from this study suggest that higher birth weight is a risk factor for postmenopausal breast cancer (OR 1.06, CI 1.00–1.12, per 100 g), independent of selected early-life and adult factors.

Familial risk of tumors associated with hereditary non-polyposis colorectal cancer: a Swedish population-based study

BACKGROUND

Familial clustering, which may be due to inherited predisposition, is seen in several common cancer types. The aim of this study was to assess the familial risk of tumors that are associated with hereditary non-polyposis colorectal cancer (HNPCC), a familial cancer syndrome that confers an increased risk of several cancer types, and is associated with a low age at onset.

METHODS

The National Swedish Cancer Registry and population registers were utilized to identify all tumors among the offspring of individuals who had developed any of the diagnoses included in the Amsterdam II criteria for HNPCC. In all, 204,358 offspring of 102,814 individuals with cancer of the colorectum, endometrium, upper urinary tract or small intestine were identified.

RESULTS

Significantly increased risks for several tumor types were demonstrated. If the parent was below age 50 at diagnosis, the offspring Standard Incidence Ratios (SIRs) were 3.6 for colon cancer, 3.8 for rectal cancer, 2.8 for gastric cancer, and 2.3 for ovarian cancer. Offspring who had both a parent and a sibling with HNPCC-associated cancer showed even higher SIRs for cancer of the colorectum, endometrium, ovary, and urinary tract. The highest values were observed in the subgroup whose parent had developed multiple primary tumors; SIR 34.0 for colon cancer, 17.9 for rectal cancer, 21.8 for endometrial cancer, and 5.8 for ovarian cancer.

CONCLUSIONS

The study demonstrates that there is an increased risk for several tumor types among individuals whose parents developed HNPCC-associated tumors, where a young age at diagnosis and development of multiple tumors in the parents lead to the highest SIRs.

Breast-feeding and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

BACKGROUND

Several studies have reported that the risk of breast cancer decreases with increasing duration of breast-feeding. Whether breast-feeding is associated with a reduced risk of hereditary breast cancer in women who carry deleterious BRCA1 and BRCA2 mutations is currently unknown.

METHODS

We conducted a case-control study of women with deleterious mutations in either the BRCA1 or the BRCA2 gene. Study participants, drawn from an international cohort, were matched on the basis of BRCA mutation (BRCA1 [n = 685] or BRCA2 [n = 280]), year of birth (+/-2 years), and country of residence. The study involved 965 case subjects diagnosed with breast cancer and 965 control subjects who had no history of breast or ovarian cancer. Information on pregnancies and breast-feeding practices was derived from a questionnaire administered to the women during the course of genetic counseling. Conditional logistic regression analyses were used to estimate odds ratios (ORs) for the risk of breast cancer. All statistical tests were two-sided.

RESULTS

Among women with BRCA1 mutations, the mean total duration of breast-feeding was statistically significantly shorter for case subjects than for control subjects (6.0 versus 8.7 months, respectively; mean difference = 2.7 months, 95% confidence interval [CI] = 1.4 to 4.0; P<.001). The total duration of breast-feeding was associated with a reduced risk of breast cancer (for each month of breast-feeding, OR = 0.98, 95% CI = 0.97 to 0.99; P(trend)<.001). Women with BRCA1 mutations who breast-fed for more than 1 year were less likely to have breast cancer than those who never breast-fed (OR = 0.55, 95% CI = 0.38 to 0.80; P =.001), although no such association was seen for BRCA2 (OR = 0.95, 95% CI = 0.56 to 1.59; P =.83).

CONCLUSIONS

Women with deleterious BRCA1 mutations who breast-fed for a cumulative total of more than 1 year had a statistically significantly reduced risk of breast cancer.

Melanoma and nonmelanoma skin cancer in patients with multiple tumours--evidence for new syndromes in a population-based study

BACKGROUND

The hypotheses that Swedish patients with four or more primary tumours [including at least one cutaneous malignant melanoma (CMM)] harbour an increased number of CDKN2A (formerly p16) germline mutations, and that this group of patients show a predisposition to other tumours, e.g. nonmelanoma skin cancer (NMSC), were studied descriptively. So far the mutation 113insArg explains all CDKN2A-associated CMM in ethnic Swedes.

OBJECTIVES

All patients with four or more primary tumours, of which at least one was a CMM, from the Southern Swedish Regional Tumour Registry, between 1958 and 1999, were included in this study.

METHODS

Forty-four patients were found and subdivided into three groups according to having multiple CMM (group A) or single CMM +/- NMSC (groups B and C). Screening for the presence of the Swedish founder mutation 113insArg in blood or in tissue blocks was performed.

RESULTS

Patients in group A were younger at the time of the first CMM diagnosis than patients in group B and group C. The 113insArg mutation was found in four of 44 patients (9%), three with multiple CMM. In group C (n = 14) no founder mutation was evident, while in group B (n = 15) one mutation carrier was found. Nonmutation carriers with multiple CMM (group A) also had a predilection for meningiomas and neurinomas (four patients) or multiple NMSC (three patients). In group B CMM were especially associated with adenocarcinomas but in group C CMM were associated with multiple NMSC.

CONCLUSION

The association between meningiomas and neurinomas (no acoustic neurinoma was seen) might indicate a new syndrome. Patients in groups B and C may harbour unknown genetic defects, which could interact with different environmental risk factors.

No relations between breast cancer risk and fatty acids of erythrocyte membranes in postmenopausal women of the Malmö Diet Cancer cohort (Sweden)

OBJECTIVE

To examine the fatty acid composition of erythrocyte membranes, in relation to obesity indexes and breast cancer risk.

DESIGN

A nested case-control study.

SETTING

The Malmö Diet Cancer cohort, Sweden.

SUBJECTS

Among women 50 y or older at baseline (n=12 803), incident breast cancer cases (n=237) were matched to controls (n=673) on age and screening date.

METHODS

A diet history method, a structured questionnaire, anthropometrics and blood samples provided data. Analysis included partial correlation coefficients between dietary fatty acids (DFA) and fatty acids of erythrocyte membranes (EFA), and Spearman's rank order correlations between EFA and four obesity indexes. Conditional logistic regression examined breast cancer risks related to EFA.

RESULTS

DFA and EFA from fish and milk, and DFA and EFA linoleic acid, show significant positive associations. Relations are negative between indexes of obesity and "milk" EFA, but positive between indexes of obesity and indexes of delta9- and delta6-desaturase enzyme activity. No significant relations were observed between EFA and breast cancer risk.

CONCLUSIONS

Similar to other studies, dietary fish and milk fatty acids, and linoleic acid, are related to the corresponding EFA. Breast cancer risk was not significantly related to EFA in this study. However, the findings suggest positive relations between body mass index, body fat per cent and indexes of desaturase activity, and negative relations between central obesity and milk EFA.

SPONSORSHIP

The Swedish Cancer Society, the Swedish Medical Research Council, the European Commission, the Swedish Dairy Association and the City of Malmö.