Change in the penetrance of founder BRCA1/2 mutations? A retrospective cohort study

Cancer Risks Associated With Germline PALB2 Pathogenic Variants: An International Study of 524 Families

PURPOSE

To estimate age-specific relative and absolute cancer risks of breast cancer and to estimate risks of ovarian, pancreatic, male breast, prostate, and colorectal cancers associated with germline PALB2 pathogenic variants (PVs) because these risks have not been extensively characterized.

METHODS

We analyzed data from 524 families with PALB2 PVs from 21 countries. Complex segregation analysis was used to estimate relative risks (RRs; relative to country-specific population incidences) and absolute risks of cancers. The models allowed for residual familial aggregation of breast and ovarian cancer and were adjusted for the family-specific ascertainment schemes.

RESULTS

We found associations between PALB2 PVs and risk of female breast cancer (RR, 7.18; 95% CI, 5.82 to 8.85; P = 6.5 × 10-76), ovarian cancer (RR, 2.91; 95% CI, 1.40 to 6.04; P = 4.1 × 10-3), pancreatic cancer (RR, 2.37; 95% CI, 1.24 to 4.50; P = 8.7 × 10-3), and male breast cancer (RR, 7.34; 95% CI, 1.28 to 42.18; P = 2.6 × 10-2). There was no evidence for increased risks of prostate or colorectal cancer. The breast cancer RRs declined with age (P for trend = 2.0 × 10-3). After adjusting for family ascertainment, breast cancer risk estimates on the basis of multiple case families were similar to the estimates from families ascertained through population-based studies (P for difference = .41). On the basis of the combined data, the estimated risks to age 80 years were 53% (95% CI, 44% to 63%) for female breast cancer, 5% (95% CI, 2% to 10%) for ovarian cancer, 2%-3% (95% CI females, 1% to 4%; 95% CI males, 2% to 5%) for pancreatic cancer, and 1% (95% CI, 0.2% to 5%) for male breast cancer.

CONCLUSION

These results confirm PALB2 as a major breast cancer susceptibility gene and establish substantial associations between germline PALB2 PVs and ovarian, pancreatic, and male breast cancers. These findings will facilitate incorporation of PALB2 into risk prediction models and optimize the clinical cancer risk management of PALB2 PV carriers.

The role of body size and physical activity on the risk of breast cancer in BRCA mutation carriers

Women who inherit a BRCA mutation face a high lifetime risk of developing breast cancer. Given the high penetrance of these mutations, prevention is of extreme importance. Here, we review the literature regarding the role of body size and of physical activity in the context of BRCA-associated breast cancer. There is some evidence to support a protective role of a healthy body size and of regular physical activity among mutation carriers, particularly during adolescence or early adulthood. Factors which increase the physiologic expression of the normal copy of the BRCA1 or BRCA2 gene and thereby normalize protein levels, contribute to stem cell homeostasis, and/or affect hormone levels, might mitigate the effects of an inherited BRCA mutation. Preliminary evidence from one in vivo study and from one epidemiologic report suggests that an increase in BRCA1 mRNA expression occurs with increasing levels of physical activity. The prospect of changing lifestyle for the purpose of preventing breast cancer in high-risk women, complemented by mechanistic evidence, warrants evaluation in large-scale prospective studies.

Breast-cancer risk in families with mutations in PALB2

BACKGROUND

Germline loss-of-function mutations in PALB2 are known to confer a predisposition to breast cancer. However, the lifetime risk of breast cancer that is conferred by such mutations remains unknown.

METHODS

We analyzed the risk of breast cancer among 362 members of 154 families who had deleterious truncating, splice, or deletion mutations in PALB2. The age-specific breast-cancer risk for mutation carriers was estimated with the use of a modified segregation-analysis approach that allowed for the effects of PALB2 genotype and residual familial aggregation.

RESULTS

The risk of breast cancer for female PALB2 mutation carriers, as compared with the general population, was eight to nine times as high among those younger than 40 years of age, six to eight times as high among those 40 to 60 years of age, and five times as high among those older than 60 years of age. The estimated cumulative risk of breast cancer among female mutation carriers was 14% (95% confidence interval [CI], 9 to 20) by 50 years of age and 35% (95% CI, 26 to 46) by 70 years of age. Breast-cancer risk was also significantly influenced by birth cohort (P<0.001) and by other familial factors (P=0.04). The absolute breast-cancer risk for PALB2 female mutation carriers by 70 years of age ranged from 33% (95% CI, 25 to 44) for those with no family history of breast cancer to 58% (95% CI, 50 to 66) for those with two or more first-degree relatives with breast cancer at 50 years of age.

CONCLUSIONS

Loss-of-function mutations in PALB2 are an important cause of hereditary breast cancer, with respect both to the frequency of cancer-predisposing mutations and to the risk associated with them. Our data suggest the breast-cancer risk for PALB2 mutation carriers may overlap with that for BRCA2 mutation carriers. (Funded by the European Research Council and others.).

BRCA1 mRNA levels following a 4-6-week intervention with oral 3,3'-diindolylmethane

Background:

Haploinsufficiency may contribute to the development of breast cancer among women with a BRCA1 mutation. Thus, interventions that enhance BRCA1 expression may represent avenues for prevention. Studies have shown that 3,3′-diindolylmethane (DIM) can upregulate BRCA1 expression in breast cancer cells. This has yet to be demonstrated in vivo.

Methods:

We conducted a study to evaluate the ability of oral DIM to upregulate BRCA1 mRNA expression in white blood cells. A total of 18 women were enroled in the study, including 13 BRCA1 mutation carriers who received 300 mg per day of Rx Balance BioResponse DIM for 4–6 weeks (intervention group) and 5 BRCA1 mutation carriers who did not take DIM (control group). BRCA1 mRNA expression was assessed at baseline and at 4–6 weeks by real-time, quantitative PCR and the relative change in BRCA1 mRNA expression (that is, 2^−ΔΔC_T) was calculated.

Results:

The relative change in BRCA1 mRNA expression among women in the intervention group achieved borderline significance (P paired t-test=0.05). In the intervention group, BRCA1 mRNA expression increased in 10 of the participants, decreased in 2 and remained unchanged in 1 of the participants following DIM intervention (P sign test=0.02). On average, women in the intervention group experienced a 34% increase in BRCA1 mRNA expression (range −24 to 194%). There was no significant difference in the relative change in BRCA1 mRNA expression among women in the control group (P paired t-test=0.45).

Conclusions:

Under the tested conditions, oral DIM was associated with an increase in BRCA1 mRNA expression in women with a BRCA1 mutation. The possibility of mitigating the effect of an inherited deleterious BRCA1 mutation by increasing the physiologic expression of the gene and normalising protein levels represents a clinically important paradigm shift in the prevention strategies available to these high-risk women. Future studies with a larger sample size and higher doses of DIM are warranted.

A prior diagnosis of breast cancer is a risk factor for breast cancer in BRCA1 and BRCA2 carriers

BACKGROUND

The risk of breast cancer in carriers of BRCA1 and BRCA2 mutations is influenced by factors other than the genetic mutation itself. Modifying factors include a woman's reproductive history and family history of cancer. Risk factors are more likely to be present in women with breast cancer than in women without breast cancer, and therefore the risk of cancer in the two breasts should not be independent. It is not clear to what extent modifying factors influence the risk of a first primary or a contralateral breast cancer in BRCA carriers.

METHODS

We conducted a matched case-control study of breast cancer among 3920 BRCA1 or BRCA2 mutation carriers. We asked whether a past history of breast cancer in the contralateral breast was a risk factor for breast cancer.

RESULTS

After adjustment for age, country of residence, and cancer treatment, a previous cancer of the right breast was found to be a significant risk factor for cancer of the left breast among BRCA1 or BRCA2 carriers (relative risk: 2.1; 95% confidence interval: 1.4 to 3.0; p < 0.0001).

CONCLUSIONS

In a woman with a BRCA1 or BRCA2 mutation who is diagnosed with breast cancer, the risk of cancer in the contralateral breast depends on the first diagnosis. That observation supports the hypothesis that there are important genetic or non-genetic modifiers of cancer risk in BRCA carriers. Discovering risk modifiers might lead to greater personalization of risk assessment and management recommendations for BRCA-positive patients.

Earlier age of onset in BRCA carriers-anticipation or cohort effect?: A Countercurrents Series

Is the age of onset of breast cancer in women with a BRCA1 or BRCA2 mutation decreasing?[...].

Plasma micronutrients, trace elements, and breast cancer in BRCA1 mutation carriers: an exploratory study

PURPOSE

Few studies have evaluated the role of micronutrients or trace elements in breast cancer development among BRCA1 mutation carriers. To investigate a possible role of dietary and environmental exposures on cancer risk, we undertook an exploratory study, using a matched case-control design (n = 48 cases and 96 controls), to evaluate the relationships between plasma levels of 14 micronutrients and breast cancer risk among BRCA1 mutation carriers in Poland.

METHODS

We estimated the univariate odds ratios (OR) and 95 % confidence intervals (CI) for breast cancer associated with plasma levels for each of 14 micronutrients.

RESULTS

Of the 14 analytes quantified, significant differences between cases and controls were seen for two (iron and retinol; p = 0.009 and p = 0.03, respectively). Women in the highest tertile of plasma iron had a 57 % lower risk, compared with those in the lowest quartile (OR = 0.43; 95 % CI 0.18-1.04; p for trend = 0.06). Increasing antimony levels were associated with an increased risk of breast cancer (p for trend = 0.05). Women in the highest tertile had a 2.43-fold increase in breast cancer risk compared with women in the lowest tertile (OR = 2.43; 95 % CI 1.00-5.91).

CONCLUSIONS

This study provides some preliminary evidence regarding a role of diet, specifically iron and antimony, in the etiology of BRCA1-associated breast cancer. Prospective studies are necessary to confirm these findings.

Changes in body weight and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

BACKGROUND

Several anthropometric measures have been found to be associated with the risk of breast cancer. Current weight, body mass index, and adult weight gain appear to be predictors of postmenopausal breast cancer. These factors have been associated with a reduced risk of premenopausal breast cancer. We asked whether there is an association between changes in body weight and the risk of breast cancer in women who carry a mutation in either breast cancer susceptibility gene, BRCA1 or BRCA2.

METHODS

A matched case-control study was conducted in 1,073 pairs of women carrying a deleterious mutation in either BRCA1 (n = 797 pairs) or BRCA2 (n = 276 pairs). Women diagnosed with breast cancer were matched to control subjects by year of birth, mutation, country of residence, and history of ovarian cancer. Information about weight was derived from a questionnaire routinely administered to women who were carriers of a mutation in either gene. Conditional logistic regression was used to estimate the association between weight gain or loss and the risk of breast cancer, stratified by age at diagnosis or menopausal status.

RESULTS

A loss of at least 10 pounds in the period from age 18 to 30 years was associated with a decreased risk of breast cancer between age 30 and 49 (odds ratio (OR) = 0.47; 95% confidence interval (CI) 0.28-0.79); weight gain during the same interval did not influence the overall risk. Among the subgroup of BRCA1 mutation carriers who had at least two children, weight gain of more than 10 pounds between age 18 and 30 was associated with an increased risk of breast cancer diagnosed between age 30 and 40 (OR = 1.44, 95% CI 1.01-2.04). Change in body weight later in life (at age 30 to 40) did not influence the risk of either premenopausal or postmenopausal breast cancer.

CONCLUSION

The results from this study suggest that weight loss in early adult life (age 18 to 30) protects against early-onset BRCA-associated breast cancers. Weight gain should also be avoided, particularly among BRCA1 mutation carriers who elect to have at least two pregnancies.

Hereditary breast cancer in Jews

A family history of breast cancer poses higher risks for Jewish versus non-Jewish women, particularly for early-onset breast cancer. This appears to be due in large part to the high prevalence (2.5%) of three BRCA1 and BRCA2 founder mutations in Ashkenazi Jews. About 4 to 8% of non-Jewish male breast cancer cases versus 19% of Jewish male breast cancer cases carry germline BRCA mutations. Jewish women are disproportionately impacted by BRCA mutations throughout life, with a 10% carrier rate for breast cancer diagnosed at any age and a 21 to 30% carrier rate for breast cancer diagnosed by age 40. Comparable rates in non-Jewish populations are 6.1% for breast cancer diagnosed before age 50. Lifetime penetrance estimates based on genotyping of probands have ranged widely in Jewish and non-Jewish populations. However, a study of 1008 Jewish women with breast cancer which extended genotyping to relatives found high penetrance rates with considerably smaller standard errors. This study and studies of early-onset incident breast cancer in non-Jews have found that at least half of high-risk cases would be missed by family history screening alone. While the carrier rate in non-Jewish populations is too low to consider genetic screening, the carrier rate in Ashkenazi Jews is high and genetic screening poses fewer technical barriers. The high genetic attributable cancer risks of Ashkenazi BRCA founder mutations, the sobering lethality of ovarian and early onset breast cancers, and the increasing clarity about effectiveness of medical interventions make imperative further dialogue and research to keep guidelines for genetic screening up to date.

Breast and ovarian cancer risks due to inherited mutations in BRCA1 and BRCA2

Risks of breast and ovarian cancer were determined for Ashkenazi Jewish women with inherited mutations in the tumor suppressor genes BRCA1 and BRCA2. We selected 1008 index cases, regardless of family history of cancer, and carried out molecular analysis across entire families. The lifetime risk of breast cancer among female mutation carriers was 82%, similar to risks in families with many cases. Risks appear to be increasing with time: Breast cancer risk by age 50 among mutation carriers born before 1940 was 24%, but among those born after 1940 it was 67%. Lifetime risks of ovarian cancer were 54% for BRCA1 and 23% for BRCA2 mutation carriers. Physical exercise and lack of obesity in adolescence were associated with significantly delayed breast cancer onset.