Technological readiness and implementation of genomic-driven precision medicine for complex diseases

The fields of human genetics and genomics have generated considerable knowledge about the mechanistic basis of many diseases. Genomic approaches to diagnosis, prognostication, prevention and treatment - genomic-driven precision medicine (GDPM) - may help optimize medical practice. Here, we provide a comprehensive review of GDPM of complex diseases across major medical specialties. We focus on technological readiness: how rapidly a test can be implemented into health care. Although these areas of medicine are diverse, key similarities exist across almost all areas. Many medical areas have, within their standards of care, at least one GDPM test for a genetic variant of strong effect that aids the identification/diagnosis of a more homogeneous subset within a larger disease group or identifies a subset with different therapeutic requirements. However, for almost all complex diseases, the majority of patients do not carry established single-gene mutations with large effects. Thus, research is underway that seeks to determine the polygenic basis of many complex diseases. Nevertheless, most complex diseases are caused by the interplay of genetic, behavioural and environmental risk factors, which will likely necessitate models for prediction and diagnosis that incorporate genetic and non-genetic data.

CYP2D6 genotype predicts tamoxifen discontinuation and drug response: a secondary analysis of the KARISMA trial

BACKGROUND

Guidelines regarding whether tamoxifen should be prescribed based on women's cytochrome P450 2D6 (CYP2D6) genotypes are conflicting and have caused confusion. This study aims to investigate if CYP2D6 metabolizer status is associated with tamoxifen-related endocrine symptoms, tamoxifen discontinuation, and mammographic density change.

PATIENTS AND METHODS

We used data from 1440 healthy women who participated the KARISMA dose determination trial. Endocrine symptoms were measured using a modified Functional Assessment of Cancer Therapy - Endocrine Symptoms (FACT-ES) questionnaire. Change in mammographic density was measured and used as a proxy for tamoxifen response. Participants were genotyped and categorized as poor, intermediate, normal, or ultrarapid CYP2D6 metabolizers.

RESULTS

The median endoxifen level per mg oral tamoxifen among poor, intermediate, normal and ultrarapid CYP2D6 metabolizers were 0.18 ng/ml, 0.38 ng/ml, 0.56 ng/ml and 0.67 ng/ml, respectively. Ultrarapid CYP2D6 metabolizers were more likely than other groups to report a clinically relevant change in cold sweats, hot flash, mood swings, being irritable, as well as the overall modified FACT-ES score, after taking tamoxifen. The 6-month tamoxifen discontinuation rates among poor, intermediate, normal, and ultrarapid CYP2D6 metabolizers were 25.7%, 23.6%, 28.6%, and 44.4%, respectively. Among those who continued and finished the 6-month tamoxifen intervention, the mean change in dense area among poor, intermediate, normal, and ultrarapid CYP2D6 metabolizers were -0.8 cm², -4.5 cm², -4.1 cm², and -8.0 cm² respectively.

CONCLUSIONS

Poor CYP2D6 metabolizers are likely to experience an impaired response to tamoxifen, measured through mammographic density reduction. In contrast, ultrarapid CYP2D6 metabolizers are at risk for exaggerated response with pronounced adverse effects that may lead to treatment discontinuation.

Abstract PD4-06: A clinical model for assessing the individual breast cancer risk in mammography screening

Background. Mammography screening reduces breast cancer mortality, but is suboptimal for the breast cancers that are not detected by the screening. These women are identified as symptomatic interval cancers with more aggressive tumors and worse pronosis. To efficiently screen for breast cancer the individual breast cancer risk should be determined. We describe a model that is suited for bi-annual screening programs and estimates the 2-year risk of breast cancer. The risk model could be used at most mammography screening units without adding substantial cost.

Methods. The study was based on the population based prospective KARMA cohort including 70,877 participants. Mammograms were collected up to five years following baseline mammogram. A prediction model was developed using mammographic features (density, microcalcifications and masses), use of hormone replacement therapy (HRT), family history of breast cancer, menopausal status, and body mass index. Relative risks were calculated using conditional logistic regression and 2-year absolute risks were calculated

Results. Comparing women at highest and lowest mammographic density yielded a 5-fold higher risk of breast cancer for women at highest density. When adding microcalcifications and masses to the model, high-risk women had a nearly 9-fold higher risk of breast cancer compared to those at lowest risk. In the full model, taking HRT use, family history of breast cancer and menopausal status into consideration, area under the curve (AUC) reached 0.73.

We calculated the absolute 2-year risk of breast cancer based on national incidence and mortality rates. We also stratified women into risk groups using the NICE guidelines adapted to 2-year risks. The 20% women with moderate or high breast cancer risk were 7.6 times more likely to develop breast cancer compared to the general risk. Also 18% of the women showed 4 times reduced risk compared to the average population.

Conclusions. This risk model can improve mammography screening by identifying women that are in need of additional examination procedures. There is also a substantial proportion of women with low breast cancer risk who will have little benefit from screening.

Citation Format: Eriksson M, Czene K, Pawitan Y, Hall P. A clinical model for assessing the individual breast cancer risk in mammography screening [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD4-06.

Abstract P4-06-13: BRCA1/2 mutations identified by screening a large unselected breast cancer cohort in Sweden

Background

Treatment options for BRCA1/2 breast cancer include new therapeutic agents, such as poly (ADP-ribose) polymerase (PARP) inhibitors, which selectively target BRCA defective cells. According to current Swedish screening guidelines, eligibility for clinical BRCA1/2 hereditary mutation testing is mainly based on family history of breast or ovarian cancer and early age onset. We aimed at examining the prevalence and characteristics of BRCA1/2 mutation carriers by screening a large unselected breast cancer cohort in Sweden, and comparing our results with BRCA mutation carriers already identified through the national BRCA testing program.

Methods

Germline DNA (blood) from 5122 women diagnosed with breast cancer between 2001-2008 (LIBRO1 study) were analysed for BRCA1/2 mutations by targeted sequencing (next generation sequencing, NGS), of which 5099 samples passed quality control. All patients provided informed consent. Information on patient and tumor characteristics was collected from the LIBRO1 database. Clinical BRCA testing information was obtained from the BRCA Lab (Lund University, Sweden), which carries out mutation screening for all oncogenetic clinics in Sweden.

Multinomial logit models were used to compare tumor characteristics of BRCA1 and BRCA2 versus non-BRCA carriers. Multivariable logistic regression models were used to examine for differences between BRCA carriers identified through the national BRCA testing program and additional BRCA carriers found by sequencing the entire study population (not tested or not identified under current screening guidelines).

Results

In total, 92 (1.8%) BRCA1/2 mutation carriers were identified retrospectively by NGS. The prevalence of BRCA1/2 mutations was 1.6% (38/2363) between years 2001-2004; and 2.0% (54/2736) between years 2005-2008. After controlling for age and year of diagnosis, BRCA2 mutation carriers were in general similar to non-BRCA carriers regarding tumor characteristics (hormone receptor status, grade, tumor size and proliferation index), except for nodal involvement. BRCA1 mutation carriers, however, had more aggressive tumor characteristics than non-BRCA breast cancer patients.

Overall, 55/92 BRCA1/2 mutation carriers (59.8%) found by NGS were not already identified through the national clinical BRCA testing program. The BRCA carriers identified by clinical testing were more likely high-risk individuals, i.e. younger, less likely to have experienced menopause, and more likely to be associated with a familiar ovarian cancer compared to those not identified through clinical testing, after adjusting for year of diagnosis. A larger proportion of BRCA2 (34/42, 80%) than BRCA1 mutations (25/50, 50%) were missed by selectively testing, mainly high-risk individuals.

Conclusion

BRCA1/2 mutations were found in approximately 2.0% of unselected BC patients. Six out of ten BRCA mutation carriers were not identified through the national testing program, which follows the screening guidelines. Revised guidelines might be needed for the effective identification of BRCA1/2 germline mutations.

Citation Format: Li J, Wen SWX, Eriksson M, Kvist A, Christensen HN, Torstensson A, Easton DF, Teo S-H, Borg Å, Grönberg H, Czene K. BRCA1/2 mutations identified by screening a large unselected breast cancer cohort in Sweden [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-06-13.

Abstract P6-12-24: Risk and predictors of psoriasis in breast cancer patients: A Swedish population based cohort study

Background The risk of psoriasis in breast cancer patients is largely unknown, as available evidence is limited to case findings. We systematically examined the incidence and risk factors of psoriasis in breast cancer patients.

Methods Using Cox regression models, a Swedish nationwide cohort of 56,235 breast cancer patients (2001-2012) was compared to 280,854 age-matched reference individuals from the general population to estimate the incidence and hazard ratio (HR) of psoriasis. We also calculated HRs for psoriasis according to treatment, genetic and lifestyle factors in a regional cohort of 8,987 patients.

Results In the nationwide cohort, 599 breast cancer patients were diagnosed with psoriasis during 307,684 person-years (median: 5.1 years) compared to 2,795 cases in the matched individuals during 1,666,038 person-years. Breast cancer patients were at an increased risk of psoriasis (HR=1.17; 95% CI=1.07-1.28) and its most common subtype (psoriasis vulgaris; HR=1.33; 95% CI =1.17-1.52). The risk of psoriasis vulgaris was long-term increased up to 12 years after diagnosis. Treatment specific analyses indicated an increased risk of psoriasis in patients treated with radiotherapy (HR=2.44; 95% CI=1.44-4.12) and mastectomy (HR=1.54, 95% CI=1.03-2.31). Apart from treatment-specific effects, we identified genetic predisposition, obesity and smoking as independent risk factors for psoriasis in breast cancer patients.

Table 1. Hazard ratios for psoriasis according to treatment characteristics   HR (95% CI) Total No.No. of CasesModel 1Model 2Endocrine therapy    No1533271.00 (REF)1.00 (REF)Yes71001210.90 (0.59-1.36)0.80 (0.52-1.24)Chemotherapy    No55441021.00 (REF)1.00 (REF)Yes3070460.82 (0.57-1.19)0.70 (0.47-1.04)Radiotherapy    No2061231.00 (REF)1.00 (REF)Yes65741251.78 (1.14-2.78)2.44 (1.44-4.12)Surgery    Lumpectomy5203941.00 (REF)1.00 (REF)Mastectomy3459550.96 (0.69-1.34)1.54 (1.03-2.31)Model 1: adjusted for age and calendar period of breast cancer diagnosis. Model 2: model 1 plus all the treatment factors.

Table 2. Hazard ratios of psoriasis according to genetic and life style factors   HR (95% CI) Total No.No. of casesModel 1Model 2PRS score    Tertile 11440131.00 (REF)1.00 (REF)Tertile 21442362.74 (1.45-5.17)2.83 (1.50-5.34)Tertile 31483402.94 (1.57-5.49)2.98 (1.59-5.58)BMI    <25 kg/m22331401.00 (REF)1.00 (REF)25-30 kg/m21434281.18 (0.73-1.92)1.15 (0.71-1.87)>30 kg/m2536192.29 (1.32-3.98)2.10 (1.20-3.68)Physical activity per week    0 hours762211.00 (REF)1.00 (REF)0-2 hours1645360.77 (0.45-1.33)0.77 (0.44-1.32)>2 hours1910300.56 (0.32-0.98)0.59 (0.33-1.03)Regular smoker    No1773261.00 (REF)1.00 (REF)Yes2546621.65 (1.04-2.61)1.59 (1.00-2.52)Genetic predisposition for psoriasis was defined by a polygenic risk score (PRS) including 35 SNPs for psoriasis susceptibility. Model 1: adjusted for age and calendar period of breast cancer diagnosis. Model 2: all of the risk factors were put into the model, including treatment.

Conclusions The incidence of psoriasis is elevated among breast cancer patients, with treatment, lifestyle and genetic factors defining the individual risk profile. Our findings underline the complex etiology of psoriasis in breast cancer patients and may help to assess individual risk of psoriasis after a breast cancer diagnosis.

Citation Format: Yang H, Brand JS, Li J, Ludvigsson JF, Ugalde-Morales E, Chiesa F, Hall P, Czene K. Risk and predictors of psoriasis in breast cancer patients: A Swedish population based cohort study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-12-24.

Abstract P4-06-15: Targeted sequencing of BRCA1/2 across a large unselected breast cancer cohort in Sweden

Background

Observed BRCA1/2 mutation frequencies can vary depending on the population screened, screening criteria, founder effects, and methods used for testing. We aimed at examining BRCA1/2 germline mutations, identified through targeted sequencing, in a large unselected breast cancer population in Sweden.

Methods

Sequencing libraries of germline DNA from 5122 breast cancer patients diagnosed between 2001-2008 (LIBRO1) were prepared (48.48 Fluidigm Access Array system, Fluidigm Corp, USA) and sequenced (Next-generation sequencing [NGS], Illumina HiSeq 2500, v2 chemistry, University of Cambridge, UK). A total of 5099 samples (97.8%) passed quality control and were analysed.

BRCA1/2 carriers identified by NGS were compared with those who were already identified by clinical BRCA screening (n=418) performed by the BRCA Lab (Lund University). This unit carries out mutation screening for all oncogenetic clinics in Sweden using denaturing high performance liquid chromatography (DHPLC) and multiple ligation-dependent probe amplification (MLPA).

Results

A total of 50 BRCA1 mutation carriers were identified, of which 28 were unique pathogenic germline mutations. Frameshift insertions and deletions made up 34/50 (68%) of the BRCA1 mutations. Exon 11 harbored 33/50 (66%) of the BRCA1 mutations. The most common mutation was c.3048_3052dupTGAGA (n=8), which is a founder mutation originating from the West coast of Sweden. Three other Swedish founder mutations were also identified (c.1082_1092del [n=5], c.3626delT [n=3] and c.2475delC [n=2]). For BRCA2, 42 mutation carriers were identified; 33 unique deleterious BRCA2 mutations (27 frameshift deletions, 3 frameshift insertions, 9 truncating and 3 splice sites). More than half of the mutations (24/42, 57%) were found on exon 11. Of the 418 women who had attended clinical BRCA testing, 38 deleterious mutations were found. Our screening method confirmed 34 of these mutations, as two each of BRCA1 and BRCA2 mutations were missed, since NGS was proven unsuitable for the detection of large exon duplications. NGS did, however, identify three more carriers not previously identified by clinical testing (c.3048_3052dup, c.2577delA and c.7442delT). Overall, 55/92 BRCA1/2 mutation carriers (59.8%) identified in the present study by NGS were not clinically tested.

Conclusion

NGS is comparable with current BRCA testing tools for the identification of BRCA1/2 germline mutations, suggesting that the technology has the potential to be used in BRCA1/2 clinical testing in unselected breast cancer patients.

Citation Format: Li J, Wen SWX, Eriksson M, Kvist A, Christensen HN, Torstensson A, Easton DF, Teo S-H, Borg Å, Grönberg H, Czene K. Targeted sequencing of BRCA1/2 across a large unselected breast cancer cohort in Sweden [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-06-15.

Abstract P3-09-03: Not presented

This abstract was not presented at the symposium.

Abstract P2-07-03: Insulin and breast cancer risk: Novel insights from mammographic density analyses

Background: Insulin has been suspected to influence breast cancer risk because of its mitogenic effects and impact on sex hormone levels. Epidemiological studies investigating breast cancer occurrence in insulin-treated patients with diabetes have produced conflicting results, but were often underpowered and lacked adequate control for important confounders.

Purpose: To investigate the impact of insulin treatment on mammographic density (MD) as intermediate phenotype for breast cancer risk, and to further explore causation by analyzing associations with a polygenic risk score (PRS) incorporating 18 single nucleotide polymorphisms (SNPs) associated with fasting insulin levels.

Design: We conducted a matched cohort study within a Swedish screening-based cohort including insulin-treated type 1 (T1D, N=122) and type 2 (T2D, N=237) diabetes patients and up to 5 non-diabetic women matched on birth year (N=1,780). Associations between diabetes status and duration of insulin use with volumetric mammographic density were analyzed using general linear models adjusting for a comprehensive set of potential confounders. PRS analyses were performed in an independent sample of non-diabetic women (N=9,437) from the same cohort.

Results: In multivariable analyses, T1D patients had higher percent (11.2 vs. 8.8%; P<0.001) and absolute dense volumes (66.6 vs. 60.8 cm3; P=0.09) and a lower absolute non-dense volume (513.2 vs. 617.7 cm3; P<0.001) compared to age-matched non-diabetics. Percent- and absolute dense volumes increased with increasing T1D duration, while no such trend was observed for the absolute non-dense volume. Similar associations but of smaller magnitude, were found in insulin-treated T2D patients. Genetically predicted higher fasting insulin levels among non-diabetes women were associated with increased percent and absolute dense volumes (% change per sd increase in PRS = 0.8 (0.0-1.6) and 0.9 (0.1-1.8) respectively), but no difference in absolute non-dense volume.

Conclusions: Our results demonstrate higher mammographic density among insulin-treated diabetes patients, and genetic analyses support an effect of insulin on volumetric mammographic density. Further studies into how the observed MD differences translate into breast cancer risk are warranted.

Citation Format: Borgquist S, Rosendahl AH, Czene K, Bhoo-Pathy N, Dorkhan M, Hall P, Brand JS. Insulin and breast cancer risk: Novel insights from mammographic density analyses [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-07-03.

Abstract OT3-06-01: KARISMA, The karma intervention study. - A tamoxifen dose determination trial

Background: Breast cancer incidence is increasing throughout the world. Despite remarkable risk reducing effects demonstrated in preventive randomised endocrine trials; primary preventive strategies are scarcely part of clinical routine. Putative reasons for reluctance may be inadequate tools for identification of women at high risk of breast cancer and reluctance to prescribe pharmaceuticals with considerable side effects in the preventive setting.

Trial Design: A randomized, double blinded, six-armed placebo controlled dose determination study to investigate the optimal dose of tamoxifen with the most favorable side effect spectra. To reduce the number of participants, costs and to shorten the trial period; change in mammographic density will be used as clinical outcome. After randomization and baseline mammography, women will be treated with placebo, 1mg, 2.5mg, 5mg, 10mg or 20mg of tamoxifen for six months where after a subsequent mammogram is performed.

Eligibility criteria: 1) Attending the national Swedish mammography screening program, 2) Having a measurable mammographic density, i.e. ≥4.5 % density (volumetric) measured by Volpara.

Specific aims: The primary aim is to identify the minimum dose of tamoxifen non-inferior in its ability to reduce mammographic density and with fewer side effects compared to 20 mg of tamoxifen. Secondarily, to study the associations between different doses of tamoxifen and changes in circulating levels of a number of proteins, lipids, hormones, and tamoxifen metabolites, including the impact of polymorphisms in the CYP2D6 gene. A translational aim is to study molecular changes in the healthy breast tissue as a result of tamoxifen exposure.

Statistical Methods: Previous studies have shown that ∼ 50% of women treated with 20mg of tamoxifen have a reduction in density and respond to therapy. We therefore use the median density decrease in women treated with 20mg tamoxifen as the predefined response threshold. The primary efficacy endpoint is thus the proportion of responders that reaches this threshold. We will test for non-inferiority after treatment with placebo, 1mg, 2.5mg, 5mg, and 10mg compared to the group of women treated with 20mg tamoxifen. Per definition 50% of the women in the 20mg group are responders. The non-inferiority margin is defined to be 16.7 percentage points; that is the fraction of responders is not less than one third of the treated individuals (50% minus 16.7% = 33.3%).The null hypothesis is thus that the proportion of responders in women treated with placebo, 1mg, 2.5mg, 5mg, and 10mg is 33.3% or higher. Power calculations have determined a need of 1200 participants corresponding to 200 participants in each treatment arm.

Present accrual and target accrual: The trial will start recruiting as of September 2016. Eligible women are identified from the Swedish mammographic screening cohort, i.e. women age 40-74 years invited for biennial screening.

Contact information for people with a specific interest in the trial:

Signe.Borgquist@med.lu.se & Per.Hall@ki.se.

Citation Format: Borgquist S, Eriksson M, Czene K, Hall P. KARISMA, The karma intervention study. - A tamoxifen dose determination trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-06-01.

Abstract P2-05-03: Intra-tumor heterogeneity of the estrogen receptor predicts less benefit from tamoxifen therapy and poor long-term breast cancer patient survival – Retrospective analyses of the STO-3 randomized trial

Background

We and others have shown that the clinically used breast cancer markers alter their expression throughout tumor progression, influencing patient survival (Lindström et al, JCO 2012). What are the likely explanations to our findings? Here, we aimed to determine whether breast cancer intra-tumor heterogeneity of the estrogen receptor (ER) is a marker of tumor aggressiveness and benefit of tamoxifen therapy in a large randomized trial.

Material and methods

The Stockholm Tamoxifen (STO-3) trial enrolled postmenopausal lymph node negative breast cancer patients with a tumor size of less than 30 mm, between 1976 and 1990, to be randomized to receive adjuvant tamoxifen versus not. From the original randomized trial cohort approximately half of the patients (778 patients) had primary tumor formalin-fixed paraffin-embedded blocks available and were included in our study. No significant differences in age and period of diagnosis, type of surgery received, receptor status, tumor grade and size were observed between the treatment arms.

All tumor slides were immunostained in a central laboratory using the SP1 antibody. ER slides were scored by two independent breast cancer pathologists assessing the fraction of cancer cells for each ER intensity level (0, +1, +2 or +3) compared to established standards. The resulting distribution of ER stained tumor cells defines intra-tumor heterogeneity of ER (Rao's quadratic entropy (QE),Potts et al, Lab Invest 2012). Intra-tumor heterogeneity was categorized using the third tertile as cut-off for high heterogeneity (726 patients).

Analyses of long-term breast cancer specific survival (25 years) by intra-tumor heterogeneity of ER were performed using univariate Kaplan-Meier and multivariate Cox proportional hazard modeling adjusting for treatment arm, age and period of diagnoses, ER, progesterone receptor (PR), HER2, Ki-67, tumor grade, and tumor size. Further, a test of correlation was performed to investigate whether intra-tumor heterogeneity of ER was correlated to the percentage of ER positive cells, the H-Score or the Luminal A and B subtype (PAM50).

Results

In the univariate Kaplan-Meier analyses, a statistically significant difference in long-term survival by intra-tumor heterogeneity of ER was seen for all patients (log rank, P=0.018), tamoxifen treated arm (log rank, P=0.0033), but not untreated arm (log rank, P=0.19). However in the multivariate analysis, patients with high intra-tumor heterogeneity of ER in the treated arm as well as in the untreated arm had an almost two-fold increased long-term risk of fatal breast cancer disease as compared to patients with low or intermediate heterogeneity (Treated arm: HR, 2.06; 95% CI, 1.04-4.07 and Untreated arm: HR, 1.71; 95% CI, 1.01-2.87).

No significant correlation of intra-tumor heterogeneity to the tested variables was seen.

Conclusions

Patients with high intra-tumor heterogeneity of ER had less benefit from tamoxifen therapy and an increased long-term risk of fatal breast cancer disease. Our findings should be clinically relevant since therapy benefit was evaluated in a randomized trial with long-term follow-up.

Citation Format: Lindström LS, Yau C, Czene K, Thompson CK, van't Veer LJ, Nordenskjöld B, Stål O, Fornander T, Benz CC, Borowsky AD, Esserman LJ. Intra-tumor heterogeneity of the estrogen receptor predicts less benefit from tamoxifen therapy and poor long-term breast cancer patient survival – Retrospective analyses of the STO-3 randomized trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-03.

Abstract P2-06-06: A clinical model for assessment of the individual breast cancer risk

Background. Most mammography screening programs are not individualized. To efficiently screen for breast cancer the individual risk of the disease should be determined. We describe a model that estimate the 2-year risk of breast cancer and could be used at most mammography screening units without adding substantial cost.

Methods. The study was based on the population based prospective Karma cohort including 70,877 participants. Mammograms were collected up to three years following baseline mammogram. A prediction protocol was developed using mammographic features (density, microcalcifications and masses), use of hormone replacement therapy (HRT), family history of breast cancer, menopausal status, age, and body mass index. Relative risks were calculated using conditional logistic regression. Absolute risks were calculated using the iCARE protocol.

Results. Comparing women at highest and lowest mammographic density yielded a 5-fold higher risk of breast cancer for women at highest density. When adding microcalcifications and masses to the model, high-risk women had a nearly 9-fold higher risk of breast cancer compared to those at lowest risk. The difference in microcalcifications and masses between left and right breast was a better predictor of breast cancer than number of microcalcifications and masses in the breasts.

When calculating the absolute 2-year risk of breast cancer we stratified women using the NICE guidelines for 10-year risk divided by 5 (Table 1). The mean absolute 2-year risk of breast cancer in the different risk categories was 0.12%, 0.33%, 0.83% and 1.95% for women at low, moderate, general, and high risk. In most countries with established mammography screening programs approximately 5 women in a 1000 are diagnosed with breast cancer at regular screening. We managed to identify a low risk group of approximately 10% of all women where 1 woman in a 1000 will be diagnosed with breast cancer, contrasting the 2% of all women at highest risk where 20 women out of a 1000 will be diagnosed with breast cancer within 2 years of last negative screen (Table 1).

In the full model, taking HRT use, family history of breast cancer and menopausal status into consideration, area under the curve (AUC) reached 0.71.

Conclusions. Our model includes three mammographic features that could easily be derived from clinically available software. By adding information on some few established risk factors it is possible to improve clinical care by identifying women in need of additional examination procedures. At the same time there is a substantial proportion of women that will have very little benefit from mammography screening due to their low risk of breast cancer.

Table 1. Absolute 2-year risk of breast cancer in women stratified in to risk categories based on the NICE guidelinesAbsolute 2-year risk (risk group)Percent women at riskMean absolute 2-year risk2Stratified 2-year risk0-0.15 (low)10.30.121.0 (reference)0.15-<0.6 (general)64.80.332.750.6-<1.6 (moderate)22.90.826.83≥1.6 (high)2.01.9516.2

Citation Format: Eriksson M, Czene K, Pawitan Y, Leifland K, Darabi H, Hall P. A clinical model for assessment of the individual breast cancer risk [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-06-06.

Abstract P2-03-03: Molecular differences between screen-detected and interval breast cancers are largely explained by PAM50 subtypes

Purpose:Interval breast cancer is of clinical interest as it exhibits an aggressive phenotype and evades detection by screening mammography. A comprehensive picture of somatic changes that drive tumors to become symptomatic in the screening interval can improve understanding of the biology underlying these aggressive tumors.

Experimental design:Initiated in April 2013, Clinical Sequencing of Cancer in Sweden (Clinseq) is a scientific and clinical platform for the genomic profiling of cancer. The breast cancer pilot study consisted of women diagnosed with breast cancer between 2001-2012 in the Stockholm/Gotland regions. A subset of 318 breast tumors were sequenced, of which 113 were screen-detected and were 60 interval cancers.We applied targeted deep-sequencing of cancer-related genes, low-pass whole-genome sequencing and RNA-sequencing technology to characterize somatic differences in the genomic and transcriptomic architecture by interval cancer status. Mammographic density and PAM50 molecular subtypes were considered.

Results:In the crude analyses, TP53, PPP1R3A, and KMT2B were significantly more frequently mutated in interval cancers than in screen-detected cancers. Acquired somatic copy number aberrations with a frequency difference of at least 15% between the two groups included gains in 17q23-q25.3 and losses in 16q24.2. Gene expression analysis identified 447 significantly differentially expressed genes, of which 120 were replicated in an independent microarray dataset. After adjusting for PAM50, most differences were no longer significant.

Conclusions: Molecular differences by interval cancer status were observed, but they were largely explained by PAM50 subtypes. This work offer new insights into the biological differences between the two tumor groups.

Translational relevance: Although screen-detected cancers are biologically distinct from interval cancers in terms of somatic mutations, copy number aberrations and gene expression, most of the differences are no longer significant after adjusting for breast cancer intrinsic subtypes (PAM50). We also show that the molecular differences appear to form a spectrum from less aggressive (screen-detected) to more aggressive (interval) manifestations of the disease, which can be characterized by PAM50 subtypes, namely, luminal A, luminal B, HER2-enriched and basal-like, in that order. This work clarifies the picture on what type of breast cancer we are likely to identify through population-based screening, and what type of cancer we are likely to miss. Current knowledge of PAM50 subtype-specific risk factors need to be expanded as our findings might influence how we screen women with a higher risk of basal-like breast cancer for example, beyond known risk groups BRCA1 mutation carriers and women of African-American descent.

Citation Format: Czene K, Ivansson E, Klevebring D, Tobin NP, Lindström LS, Holm J, Prochazka G, Hilliges C, Palmgren J, Törnberg S, Humphreys K, Hartman J, Frisell J, Rantalainen M, Lindberg J, Hall P, Bergh J, Grönberg H, Li J. Molecular differences between screen-detected and interval breast cancers are largely explained by PAM50 subtypes [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-03-03.

Abstract P1-07-07: Gene expression signatures and immunohistochemical subtypes add prognostic value to each other

Background: We have previously demonstrated that gene expression signatures and Ki67 stratify the same breast tumour into opposing good/poor prognosis groups in approximately 20% of cases. Given this, we hypothesized that the combination of a clinically relevant gene signature and IHC markers may provide more prognostic information than either classifier alone. We tested this hypothesis in a large independent cohort of Swedish breast cancer patients with long-term follow-up data.

Methods: We assessed Ki67, ER, PR, HER2 and the research versions of the Genomic Grade Index (GGI), Mammaprint, cell-cycle score (CCS), Recurrence Score (RS) and PAM50 gene expression classifiers on matching TMA and microarray data in a Swedish breast cancer cohort of 623 patients. Change in likelihood-ratio (Δ LR-χ2) was used to first determine the additional prognostic information provided by gene expression signatures beyond that provided by 1) Ki67 alone and 2) Ki67 plus ER, PR and HER2, grouped to form the IHC molecular subtypes. Secondly and conversely, we then determined the additional prognostic information provided by Ki67/IHC subtypes beyond gene expression signatures.

Results: Representative images from Ki67/gene signature contrast groups show tumours with high levels of Ki67 expression that are classified as good prognosis by gene signatures and conversely, tumours with low Ki67 that are classified into poor prognosis groups by gene signatures. In all patients (n=623), the majority of signatures provided statistically significant information beyond that of Ki67 alone, however only RS and PAM50 remained significant in the presence of the IHC subtypes (Δ LR-χ2 RS= 11.7 and PAM50 = 15.4; P = 0.002 and 0.004, respectively). Conversely, IHC subtypes added prognostic information beyond gene signatures whilst Ki67 alone did not, a notable exception to this was PAM50.

Conclusions: In general, a combination of the IHC subtypes with gene signatures provides more prognostic information than either classifier alone when considering all breast cancer patients. Subsequent analyses will focus on patient subgroups including ER positive, node positive and ER positive, node negative groups, along with validation of our work in a second dataset of 253 patients.

Change in likelhood ratio with the addition of gene expression signatures to Ki67/IHC subgroups and vice-versa All Patients All PatientsSig. added to Ki67:Sig. Δ LRχ2P-valueSig. added to IHC subtypesSig. Δ LRχ2P-valueGGI6.00.014GGI2.50.108Mammaprint6.30.011Mammaprint1.10.279RS20.8< 0.001RS11.70.002CCS1.70.409CCS2.00.360PAM5025.0< 0.001PAM5015.40.004      Ki67 added to sig.:Ki67 Δ LRχ2P-valueIHC added to sig.:IHC Δ LRχ2P-valueGGI1.60.205GGI14.90.001Mammaprint1.60.199Mammaprint15.30.001RS0.50.477RS12.60.005CCS4.10.041CCS16.10.001PAM502.30.13PAM506.10.107Sig.: Gene expression signature; GGI: Genomic grade index; RS: Recurrence score; CCS: Cell cycle score.

Citation Format: Lundberg A, Lindström LS, Falato C, Carlson JW, Foukakis T, Czene K, Bergh J, Tobin NP. Gene expression signatures and immunohistochemical subtypes add prognostic value to each other [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-07-07.

Abstract P1-07-22: Infectious disease hospitalization in breast cancer patients: Risk and impact on prognosis

Background: Infection-related hospitalizations are a serious complication in breast cancer patients, resulting in treatment delay, prolonged hospitalization and future morbidity and mortality. Little, however, is known about the actual risk, clinical characteristics and outcomes of infection-related hospitalizations in this patient population.

Methods: We conducted a prospective population-based study including 7071 women diagnosed with primary invasive non-metastatic breast cancer between 2001 and 2008 in the Stockholm-Gotland region (Sweden), with complete follow-up until 2010. Standardized incidence ratios (SIRs) for infection-related hospitalizations (overall and by site) were estimated using background rates from the general female population, matched on age and calendar period. Associations with clinical characteristics and breast cancer outcomes (breast cancer death, distant metastasis and locoregional recurrence) were analysed using flexible parametric survival models.

Results: During a medium follow-up of 5.3 years, 657 hospital admissions with infections were observed and 1,2 and 5-year cumulative risks were 3.4, 4.7 and 8.1% respectively. Rates of infection-related hospitalizations were increased compared to the general female population (SIR = 2.12; 95% CI = 1.96-2.29) and site-specific SIRs were most pronounced for sepsis (SIR = 3.65; 95% CI = 3.13-4.26) and skin infections (SIR = 2.93; 95% CI = 2.35-3.64). The overall risk of infections was highest during the first year (SIR = 5.06; 95% CI, 4.46-5.74), and recurrent disease contributed to the long-term risk observed. Older age at diagnosis, chemotherapy, axillary radiotherapy, comorbidities and markers of tumor aggressiveness (large tumors, estrogen receptor negative tumors and lymph node positive tumors) were independent predictors of infectious disease risk. Analyses evaluating the prognostic impact of infections revealed an independent effect on breast cancer death and distant metastasis, associations that were mainly driven by sepsis (HR = 4.53; 95% CI, 3.25-6.33 and 1.69; 95% CI, 1.04-2.79 respectively). No association was found with future risk of locoregional recurrence.

Conclusions: Physicians and patients should be aware of the risk of serious infections which persists beyond the initial treatment period. Infection-related hospitalizations are an independent marker of poor prognosis. Further research is needed to elucidate the role of sepsis in breast cancer progression.

Citation Format: Brand JS, Colzani E, Johansson A, Giesecke J, Clements M, Bergh J, Hall P, Czene K. Infectious disease hospitalization in breast cancer patients: Risk and impact on prognosis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-07-22.

Background risk of breast cancer influences the association between alcohol consumption and mammographic density

Background:

Alcohol consumption has been suggested to increase risk of breast cancer through a mechanism that also increases mammographic density. Whether the association between alcohol consumption and mammographic density is modified by background breast cancer risk has, however, not been studied.

Methods:

We conducted a population-based cross-sectional study of 53 060 Swedish women aged 40–74 years. Alcohol consumption was assessed using a web-based self-administered questionnaire. Mammographic density was measured using the fully-automated volumetric Volpara method. The Tyrer–Cuzick prediction model was used to estimate risk of developing breast cancer in the next 10 years. Linear regression models were used to evaluate the association between alcohol consumption and volumetric mammographic density and the potential influence of Tyrer–Cuzick breast cancer risk.

Results:

Overall, increasing alcohol consumption was associated with higher absolute dense volume (cm³) and per cent dense volume (%). The association between alcohol consumption and absolute dense volume was most pronounced among women with the highest (⩾5%) Tyrer–Cuzick 10-year risk. Among high-risk women, women consuming 5.0–9.9, 10.0–19.9, 20.0–29.9, and 30.0–40.0 g of alcohol per day had 2.6 cm³ (95% confidence interval (CI), 0.2–4.9), 2.9 cm³ (95% CI, −0.6 to 6.3), 4.6 cm³ (95% CI, 1.5–7.7), and 10.8 cm³ (95% CI, 4.8–17.0) higher absolute dense volume, respectively, as compared with women abstaining from alcohol. A trend of increasing alcohol consumption and higher absolute dense volume was seen in women at low (⩽3%) risk, but not in women at moderate (3.0–4.9%) risk.

Conclusion:

Alcohol consumption may increase breast cancer risk through increasing mammographic density, particularly in women at high background risk of breast cancer.

Prognostic information of a previously diagnosed sister is an independent prognosticator for a newly diagnosed sister with breast cancer

BACKGROUND

Breast cancer survival has been shown to be associated among relatives. In this study, we used a population-based cohort of Swedish sisters, both diagnosed with breast cancer, to determine whether prognostic information of a previously diagnosed sibling is useful for the clinical management of a newly diagnosed sibling.

PATIENTS AND METHODS

The population-based cohort included all sister pairs, 1617 sisters, diagnosed with breast cancer in Sweden, from 1 January 1992, through 31 December 2006, with complete follow-up. All information was collected manually from original pathology reports and patient records. The Kappa statistic was used to measure the agreement of primary tumor characteristics between the sisters. We modeled the breast cancer-specific survival using multivariate (Cox) proportional hazard analyses in two steps categorizing the older sister's survival.

RESULTS

Estrogen receptor status was the only tumor characteristic significantly associated between the sisters [κ 0.18 (95% confidence interval (CI) 0.089-0.27)]. Younger sisters with poor older sister survival showed significantly worse survival compared with patients with good older sister survival (log rank, P = 0.017). A twofold increased hazard ratio (HR) for death from breast cancer was found in younger sisters with poor older sister survival compared with patients with good sister survival [HR 2.56 (95% CI 1.16-5.65)], adjusting for age and calendar period of diagnosis, socioeconomic factors, number of children and hospital of primary tumor diagnosis. When further adjusting for primary tumor characteristics and adjuvant therapy, the risk for death from breast cancer in younger sisters with poor older sister survival became more pronounced [HR 3.35 (1.34-8.34)].

CONCLUSIONS

Our findings derived from a population-based cohort of Swedish sister pairs suggest that breast cancer-specific survival is inherited independent of tumor characteristics and treatment in the sibling later diagnosed with the disease. Prognostic information of a previously diagnosed sibling with breast cancer could be important in the clinical management.

Comparison of fully and semi-automated area-based methods for measuring mammographic density and predicting breast cancer risk

BACKGROUND

Mammographic density is a strong risk factor for breast cancer but the lack of valid fully automated methods for quantifying it has precluded its use in clinical and screening settings. We compared the performance of a recently developed automated approach, based on the public domain ImageJ programme, to the well-established semi-automated Cumulus method.

METHODS

We undertook a case-control study within the intervention arm of the Age Trial, in which ∼54,000 British women were offered annual mammography at ages 40-49 years. A total of 299 breast cancer cases diagnosed during follow-up and 422 matched (on screening centre, date of birth and dates of screenings) controls were included. Medio-lateral oblique (MLO) images taken closest to age 41 and at least one year before the index case's diagnosis were digitised for each participant. Cumulus readings were performed in the left MLO and ImageJ-based readings in both left and right MLOs. Conditional logistic regression was used to examine density-breast cancer associations.

RESULTS

The association between density readings taken from one single MLO and breast cancer risk was weaker for the ImageJ-based method than for Cumulus (age-body mass index-adjusted odds ratio (OR) per one s.d. increase in percent density (95% CI): 1.52 (1.24-1.86) and 1.61 (1.33-1.94), respectively). The ImageJ-based density-cancer association strengthened when the mean of left-right MLO readings was used: OR=1.61 (1.31-1.98).

CONCLUSIONS

The mean of left-right MLO readings yielded by the ImageJ-based method was as strong a predictor of risk as Cumulus readings from a single MLO image. The ImageJ-based method, using the mean of two measurements, is a valid automated alternative to Cumulus for measuring density in analogue films.

FGF receptor genes and breast cancer susceptibility: results from the Breast Cancer Association Consortium

BACKGROUND

Breast cancer is one of the most common malignancies in women. Genome-wide association studies have identified FGFR2 as a breast cancer susceptibility gene. Common variation in other fibroblast growth factor (FGF) receptors might also modify risk. We tested this hypothesis by studying genotyped single-nucleotide polymorphisms (SNPs) and imputed SNPs in FGFR1, FGFR3, FGFR4 and FGFRL1 in the Breast Cancer Association Consortium.

METHODS

Data were combined from 49 studies, including 53 835 cases and 50 156 controls, of which 89 050 (46 450 cases and 42 600 controls) were of European ancestry, 12 893 (6269 cases and 6624 controls) of Asian and 2048 (1116 cases and 932 controls) of African ancestry. Associations with risk of breast cancer, overall and by disease sub-type, were assessed using unconditional logistic regression.

RESULTS

Little evidence of association with breast cancer risk was observed for SNPs in the FGF receptor genes. The strongest evidence in European women was for rs743682 in FGFR3; the estimated per-allele odds ratio was 1.05 (95% confidence interval=1.02-1.09, P=0.0020), which is substantially lower than that observed for SNPs in FGFR2.

CONCLUSION

Our results suggest that common variants in the other FGF receptors are not associated with risk of breast cancer to the degree observed for FGFR2.

Abstract P6-06-17: Gene signature model predicts metastatic onset better than standard clinical markers - Nested case-control design uniquely enables enrichment for biologically relevant features

Purpose

Considering that breast cancer is a heterogeneous disease, we aimed to improve prediction of patients at high-risk for metastatic disease utilizing a nested case-control design uniquely enabling enrichment for relevant phenotypes.

Methods

In Sweden cancer registration has a legal basis and the Swedish Cancer Registry has a breast cancer coverage of more than 96% in validation studies.

We identified women diagnosed with primary breast cancer from January 1, 1997, to December 31, 2005, in the Stockholm health care region. Patients developing distant metastatic disease (cases) were selected and controls (free from distant disease) were randomly matched by adjuvant therapy, age and calendar period at diagnosis. The nested case-control study included 768 study subjects (621 patients including two patients with bilateral breast tumors) with detailed manually collected clinical information and complete follow-up (according to the national guidelines by the Swedish Breast Cancer Group (SweBCG)).

Primary tumor grade, Human Epidermal Growth Factor Receptor 2 (HER2) and Ki-67 expression was reassessed and scored by a breast cancer pathologist.

All patients were profiled with the Affymetrix array (Human Cancer G110) containing in total 52,378 probes, both including control probes of different types, as well as probes corresponding to human transcripts.

The study subjects were randomly and equally divided into the discovery set or validation set.

Metastatic onset predictive capacity was compared including either clinical variables only (1) or combining clinical and genetic information (2), estimating ROC curves and AUC.

Results

Convincingly, genes and pathways found to be differentially expressed in our nested case-control study included a wide-spectra of well known as well as candidate regulators of the metastatic cascade. In our study, 313 annotated genes (under the strict Bonferroni cut-off) were differentially expressed in patients developing distant metastatic disease in contrast to patients free from disseminated disease.

Our metastasis gene signature model accommodates 50 genes predicting risk for metastatic disease after adjustment of standard clinical markers. Regulation of immune response activity was a common feature among the genes as included.

It is clear from the area under the ROC curve, AUC, that the predictive capacity of the metastasis gene signature model (2), also validated in the validation set of study subjects, was superior to the model with clinical variables only (1), as evidenced by AUC (0.86; 95% CI, 0.83 to 0.89 for the metastasis gene signature and 0.73; CI, 0.71 to 0.76 for clinical variables only).

The gene signature model predicted both high-risk of early and later onset of metastatic disease.

Conclusion

In our nested case-control study, we identified genes and pathways differentially expressed in patients developing distant metastatic disease compared to patients without disseminated disease.

Our validated metastasis gene signature model enabled better risk prediction compared to standard clinical markers, capturing both high-risk of early and later metastatic disease onset, of potential vital importance in the clinical setting.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-17.

Abstract P2-11-06: Mortality among offspring of women diagnosed with breast cancer; a population based study

Introduction: Survival after breast cancer has improved substantially over the past decades. As a result, an increasing number of breast cancer survivors is starting or extending their family post-diagnosis. We evaluated mortality risks of offspring from women with a history of breast cancer.

Methods: From the Swedish Multi-Generation Register and the Cancer Register we identified all 63,205 children whose mother had ever been diagnosed with invasive breast cancer. For these children, we calculated relative mortality risks as compared to the background population (Standardized Mortality Ratios [SMRs]). We compared SMRs according to the mother's parity status at diagnosis and timing of birth in relation to time of diagnosis, i.e. before (>1 year before), around (between 1 year before and 1 year after) and after (>1 year after) diagnosis.

Results: Children born around their mother's breast cancer diagnosis had an increased mortality risk as compared to the background population (SMR 2.70 95% CI [1.64–4.44]). This risk was particularly high for first-born children (SMR 11.07 (95% CI [2.09–27.13]), who had an absolute excess risk of 6.4% to die before the age of 5 years. Children born more than one year before or after their mother's breast cancer diagnosis had similar mortality risks as the background population.

Conclusion: Children born around their mother's breast cancer diagnosis have significantly increased mortality risks. Offspring of nulliparous women have a particularly high relative mortality risk, suggesting that pregnant breast cancer patients may be keen to keep their first child in spite of potential treatment toxicity.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-11-06.

Abstract P3-07-03: The impact of Carcinoma in situ of the breast and family history on risk of subsequent breast cancer events and mortality - a population based study from Sweden

Purpose: To evaluate the long-term risk of subsequent breast cancer and mortality among women diagnosed with carcinoma in situ of the breast.

Patients and Methods: Using the population-based Swedish Multi-Generation and Cancer Registers we selected 8,111 women diagnosed with in situ breast cancer between 1980 and 2004. We estimated the relative risks of subsequent ipsi- and contralateral invasive breast cancer or a contalateral in situ expressed as standardized incidence ratios (SIRs), in relation to age, year, time since diagnosis and family history (1st degree relative) for breast cancer. The relative risk of death was expressed as standardized mortality ratio, (SMR).

Results: Of 8,111 women identified with first in situ, 859 had a family history for breast cancer. The overall risk of a subsequent invasive breast cancer is over four fold and the risk for contralateral in situ breasts cancer was almost seven fold, compared with the risk in healthy women.

Mammographic density and molecular subtypes of breast cancer

Background:

Gene expression profiling has led to a subclassification of breast cancers independent of established clinical parameters, such as the Sorlie–Perou subtypes. Mammographic density (MD) is one of the strongest risk factors for breast cancer, but it is unknown if MD is associated with molecular subtypes of this carcinoma.

Methods:

We investigated whether MD was associated with breast cancer subtypes in 110 women with breast cancer, operated in Stockholm, Sweden, during 1994 to 1996. Subtypes were defined using expression data from HGU133A+B chips. The MD of the unaffected breast was measured using the Cumulus software. We used multinomial logistic models to investigate the relationship between MD and Sorlie–Perou subtypes.

Results:

Although the distribution of molecular subtypes differed in women with high vs low MD, this was statistically non-significant (P=0.249), and further analyses revealed no association between the MD and Sorlie–Perou subtypes as a whole, nor with individual subtypes.

Conclusion:

These findings suggest that although MD is one of the strongest risk factors for breast cancer, it does not seem to be differentially associated with breast cancer molecular subtypes. However, larger studies with more comprehensive covariate information are needed to confirm these results.

Abstract P3-11-08: Incidence and Outcome of Male and Female Breast Cancer: A Multinational Population Based Study

Background: Male breast cancer is a rare disease as its incidence rate is about 0.5% to 1% of that of female breast cancer. Given its scarcity, few studies have assessed the risk and prognosis.

Methods: We performed a multi-national population based study of 569,771 female breast cancer patients and 3,615 male breast cancer patients diagnosed in Denmark, Finland, Switzerland, Norway, Singapore and Sweden from 1943 to 2007. We calculated incidence and mortality as well as overall survival for both sexes. Life table analysis and Cox proportional hazard model were used to analyze the survival.

Results: The overall incidence rates, adjusted to the World Standard Population, of breast cancer were 60.2 per 100,000 in women and 0.4 per 100,000 in men. Women were diagnosed with breast cancer at a younger median age (61.4 years) than men (68.9 years). Among the 203,093 patients (35%) with information on TNM stage, 50% of the women and 47% of men were classified as stage I whilst stage III and stage IV cases accounted for 11% and 20% for women and men respectively. The 5-year cumulative survival was 66.2% for women and 53.0% for men. The adjusted relative risk of death was 24% higher in men [HR 1.24 (95% CI, 1.19-1.28)] as compared to women after controlling for age and time at diagnosis. Men had an 18% higher relative risk of death [HR 1.18 (95% CI, 1.09-1.27)] compared to women after further adjustment for TNM stage. Conclusion: Male breast cancer patients have later onset and worse prognosis than female patients. This may be due to the difference in tumour characteristics and treatment.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-11-08.

Abstract P4-09-06: Breast Cancer Prognosis Is Inherited Independently of Patient, Tumor and Treatment Characteristics

Fondation Jean Dausset, Paris, France; Karolinska Institute, Stockolm, Sweden; Geneva University Hospitals, Switzerland Introduction: Several studies have suggested that survival of breast cancer is inherited, but none has assessed if this observation is linked to shared tumor characteristics or type of treatment. We studied the association of survival among first-degree relatives (FDRs) with breast cancer, taking into account characteristics of patients, tumors and treatments. Methods: In the population-based Geneva Breast Cancer Registry, we identified 162 pairs of FDRs diagnosed with breast cancer. Based on the breast cancer specific survival status of their proband (i.e. the mother or older sister), we categorized FDRs into poor, medium and good familial survival risk groups. We compared patient, tumor and treatment characteristics between categories and calculated standardized mortality ratios (SMRs) and adjusted disease specific mortality for each group. Results: Breast cancer patients in the poor familial survival risk group were more likely to be diagnosed at later stages than those in the good familial survival risk group. Similarly, they had higher SMRs than those in the medium and good survival risk groups (18.7, 95% Confidence Interval [CI]: 9.4-33.5 versus 16.5 95% CI: 7.6-31.4 and 9.4, 95% CI: 3.4-20.3, respectively). After adjustment for prognostic factors, women in the poor familial survival risk group were almost five times more likely to die of breast cancer than those in the good survival risk group (adjusted Hazard Ratio 4.8, 95% CI: 1.4-16.4).

Conclusion: This study shows that breast cancer prognosis clusters within families, and suggests that the hereditary component is independent of patient, tumor characteristics and type of treatment.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-09-06.

Effect of childbirth after treatment on long-term survival from breast cancer

Background

This study quantified long-term absolute and relative mortality risks of survivors of breast cancer with subsequent childbirth.

Methods

The Singapore Birth Register (n = 319 437), Swedish Multi-Generation Register (n = 11 million) and population-based cancer registries were linked to identify 492 women with childbirth after breast cancer. For these women, cumulative mortality risks and standardized mortality ratios (SMRs) were calculated and compared with those of 8529 women aged less than 40 years with breast cancer without subsequent childbirth, and with those predicted by Adjuvant! Online.

Results

Women with subsequent childbirth had a lower 15-year cumulative overall mortality rate than other women with breast cancer (16·8 (95 per cent confidence interval (c.i.) 13·3 to 20·9) versus 40·7 (39·5 to 41·9) per cent), but a higher relative mortality risk than the background population (SMR 13·6, 95 per cent c.i. 10·6 to 17·3). Mortality risks decreased significantly with increasing interval between diagnosis and subsequent childbirth. Mean 10-year cumulative mortality risks of women with subsequent childbirth were within the range of 10-year mortality predicted by Adjuvant! Online for women with T1 N0 tumours in otherwise perfect health.

Conclusion

This study reinforced the view that pregnancy after breast cancer is not detrimental to survival. However, women who gave birth after this diagnosis had substantially higher mortality risks than young women in the general population. This information may be a valuable addition to routine mortality estimates.

Diagnostic Work-Up of Contralateral Breast Cancers Has Not Improved over Calendar Period

Background: Contralateral breast cancer (CBC) is diagnosed in 1-2.6 % of all breast cancer patients directly at diagnosis, after that the risk still remains high (0.7% per year) throughout life of the patient. Breast cancer patients are followed up by palpation and clinical mammography after their diagnosis, partly to be able to diagnose a possible CBC. The aim of this study is to investigate if the diagnostic work-up of patients with breast cancer has improved over the last thirty years and resulted in earlier CBC diagnosis.Materials and Methods: Synchronous contralateral breast cancer is here defined as two cancers occurring maximum 3 months apart, cancers with longer latency time are defined as metachronous. The study population is restricted to patients with maximum three years between the two cancer diagnoses. In this study we used two cohorts; all CBCs in Sweden 1976-2004 (N: 3260), and all CBCs in Stockholm during 1976-2005 (N: 688), the smaller cohort had more detailed information. The study participants were selected from two population-based registers (Sweden Cancer Register and Stockholm Breast Cancer Register). With logistic regression we calculated the odds ratio of being diagnosed synchronously, as compared to metachronously, adjusted for calendar period and age at first diagnosis.Results: The risk of synchronous diagnosis was increased by 27% per each 5-year period, the change was statistically significant. We then investigate if this risk increase by calendar period was due to improved clinical work-up, by including detection mode in the model. We found that the risk estimates for calendar period persisted, thus giving no evidence for improvement of clinical work-up during the study period. This result did not change when stratifying the study population by age at first diagnosis (below/above 55). Next, we instead included adjuvant therapy for the first cancer in the model and the association with calendar period decreased to non-significant levels. We also showed that the proportion of CBCs detected trough clinical work-up has not increased over calendar period (p=0.89), neither when including, nor excluding, screening mammography as part of the work-up. The mean tumour size of the contralateral breast cancer was 16.0 mm and has not decreased over the study period (p:0.62)Discussion: We found an increase in the proportion of synchonous CBCs compared to metachronous over calendar period, this change is not associated with clinical work-up, but with adjuvant therapy. This study gives no indications of any improvement in diagnostic work-up of contralateral breast cancer over the last thirty years. Such an improvement would potentially be very important for survival of the growing population of (first) breast cancer survivors.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4011.

Childbirth Following Breast Cancer: An Evaluation of the 'Healthy Mothers' Excess Mortality Risk

Background: The favorable outcome of mothers giving birth after breast cancer compared to those who do not, has been attributed to a healthy mother effect. Mainly former breast cancer patients with excellent health status and outlook proceed to having children after their disease. This study evaluates the excess mortality risk among these 'healthy mothers' and factors modifying this risk.Methods: By linking the Singapore Birth Registry (319'437 individuals) and Swedish Multi-Generation Cohort (11 million women) with the respective national cancer registries we identified all 509 women who gave birth >12 months after a breast cancer diagnosis. We calculated excess absolute mortality risks and Standardized Mortality Ratios (SMRs). We used Poisson regression analysis to calculate relative risks of death by country, period of follow up and interval between cancer diagnosis and subsequent birth.Results: The overall 15-year cumulative mortality was 18.2% (95% CI: 13.3 – 20.7%) which is substantially higher than that of the background population (SMR 13.3, 95%CI: 10.4-16.9). Excess mortality risks remained constant over follow up time and were comparable between Sweden and Singapore. Mortality risks decreased significantly with increasing interval between diagnosis and subsequent birth.Conclusion: Despite being 'healthy mothers', women who give birth after a diagnosis of breast cancer have a substantially higher risk of death than the background population. This information may be useful in a woman's decision whether to have a(another) child after breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3173.

CYP11A1 Is a Predictor of Mammographic Breast Density

Mammographic density (MD) is a strong predictor of breast cancer risk and is highly correlated with the hormone exposure profiles of women. It is also a highly heritable risk factor (heritable component ∼67%). As such, many efforts have been made to identify underlying genetic determinants of MD within pathways related to steroid hormone biosynthesis and metabolism. Several associations with genetic polymorphisms in genes involved in estrogen metabolism have been previously described (e.g. COMT and HSD3B1). Still, there is controversy among the conclusions of these studies. In addition, only a few candidate genes have been interrogated at a time. In this study, we assess associations of genetic variants with MD using the most extensive estrogen metabolic pathway coverage to date.Materials and methods:Cases were 891 Swedish-born women who were 50-74 years of age at diagnosis and diagnosed with breast cancer between October 1993 and March 1995. 840 controls were population and frequency matched to the expected age distribution of the cases.MD was measured using a computer-assisted technique (Cumulus, University of Toronto, Canada) and evaluated by comparing the dense area by the total breast area.Genotyping was performed on a total of 239 SNPs in 34 estrogen metabolic genes using the Sequenom (San Diego, California) primer extension-based assay. SNPs with a call rate <85%, minor allele frequency <1% or out of Hardy-Weinberg Equilibrium (p<0.05/239) were excluded from further analysis.The Cochran-Armitage trend test was carried out for all SNPs with adjustments for age, body mass index, menopausal status and hormone replacement therapy usage.Results:We report a novel association finding between MD and the gene CYP11A1. 5 out of 6 SNPs within the gene were found to be significant after adjustment. The average increase in MD attributed to these SNPs is 5.4%. Other genes with significant associations include HSD17B3, STS, and NQO1.Discussion:A high level of endogenous estrogen is well-known to be correlated with an increased risk of breast cancer. CYP11A1 encodes a member of the cytochrome P450 superfamily of enzymes and is of interest as it represents is the first as well as a rate-limiting step in steroid hormone biosynthesis.In addition, a role for CYP11A1 in the metabolism of vitamin D3 has been reported recently. High vitamin D levels have been associated with a decrease in both breast cancer risk and MD. Although the active compound most commonly implicated is 1,25-dihydroxyvitamin D3 derived from a more extensively studied pathway, new studies have shown that a by-product of CYP11A1 exhibits similar functions in the regulation of cell proliferation and differentiation.Although CYP11A1 has been previously reported to be associated with breast cancer, it has never been studied in relation to MD. This novel finding suggests that CYP11A1 exerts an influence on MD through two different pathways linked to breast cancer and affirms MD as an intermediate phenotype for the disease.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5161.

Pathological confirmation of primary lung cancer following breast cancer

PURPOSE

Studies have shown that women who survive breast cancer have an increased risk of a future primary lung cancer, though many are based only on data recorded in tumor registries and none have conducted pathological confirmation. Previous studies and future use of large registries may be affected by misdiagnosis.

METHODS

Pathological analysis was conducted on tumors from 110 women with breast cancer followed by lung cancer using morphology, Estrogen Receptor-alpha (ER), and Thyroid Transcription Factor-1 (TTF1). We developed an algorithm to classify lung tumors as unlikely lung cancer (score=1) to likely lung cancer (score=5).

RESULTS

Mean time to diagnosis of lung cancer after breast cancer was 13 years. 76% of breast tumors and 20% of lung tumors were positive for ER and 51% of lung tumors were positive for TTF-1. 86% of the lung tumors were probable primaries, 7% were probable metastases from the breast, and 7% were of undetermined status. 70% of probable metastases had a latency of longer than 10 years.

CONCLUSION

Prior studies identifying the association of breast cancer and breast cancer treatments with lung cancer are likely to reflect true associations not confounded by misdiagnosis, as evidenced by the low rate of misclassification detected in this study. Analysis of the years of diagnosis suggests that latency may not be an accurate criterion for assignment of primary status, which could be significant in a clinical setting. These data may also benefit future retrospective studies using large registries.

Obesity and poor breast cancer prognosis: an illusion because of hormone replacement therapy?

High body mass index (BMI) and use of hormone replacement therapy (HRT) increase the risk of postmenopausal breast cancer. It has been shown that BMI modifies the effect of HRT, as its influence is most pronounced in lean women. We investigated the influence of BMI and HRT on prognosis in 2640 postmenopausal women diagnosed with breast cancer in Sweden in 1993-1995, taking into account HRT and mammography before diagnosis. Logistic and Cox regression were used. In non-users of HRT, obese women (BMI >30) compared with normal weight women (BMI <25) had a similar prognosis (hazard ratio (HR) 1.1, 95% confidence interval (CI) 0.8-1.6), despite larger tumours found in obese women. Obese HRT users had less favourable tumour characteristics and poorer prognosis compared with normal weight women (HR 3.7, 95% CI 1.9-7.2). The influence of BMI on breast cancer prognosis was similar whether diagnosed by mammographic screening or not. We found a similar prognosis of postmenopausal breast cancer-specific death regardless of BMI in non-users of HRT, but among HRT users obesity was associated with a poorer breast cancer prognosis.