High-risk mammographic parenchymal patterns, hormone replacement therapy and other risk factors: a case-control study

Breast Cancer: Impact of New Treatments?

BACKGROUND

Breast cancer treatment has seen tremendous progress since the early 1980s, with the first findings of new chemotherapy and hormone therapies. Screening started in the same period.

METHODS

A review of population data (SEER and the literature) shows an increase in recurrence-free survival until 2000 and it stagnates afterwards.

RESULTS

Over the period 1980-2000, the 15% survival gain was presented by pharma as a contribution of new molecules. The contribution of screening during that same period was not implemented by them, although screening has been accepted as a routine procedure in the States since the 1980s and everywhere else since 2000.

CONCLUSIONS

Interpretation of breast cancer outcome has largely focused on drugs, whereas other factors, such as screening, prevention, biologics, and genetics, were largely neglected. More attention should now be paid to examining the strategy based on realistic global data.

Hormone replacement therapy and mammographic density: a systematic literature review

PURPOSE

Hormone replacement therapy (HRT) is used to reduce climacteric symptoms of menopause and prevent osteoporosis; however, it increases risk of breast cancer. Mammographic density (MD) is also a strong risk factor for breast cancer. We conducted this review to investigate the association between HRT use and MD and to assess the effect of different HRT regimens on MD.

METHODS

Two of authors examined articles published between 2002 and 2019 from PubMed, Embase, and OVID using Covidence systematic review platform. Any disagreements were discussed until consensus was reached. The protocol used in this review was created in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Quality of each eligible study was assessed using the Oxford Center for Evidence-Based Medicine (OCEBM) hierarchy.

RESULTS

Twenty-two studies met the inclusion criteria. Six studies showed that using estrogen plus progestin (E + P) HRT was associated with higher MD than estrogen alone. Four studies reported that continuous estrogen plus progestin (CEP) users had higher MD than sequential estrogen plus progestin (SEP) and estrogen alone users. However, two studies showed that SEP users had slightly higher MD than CEP users and estrogen alone users.

CONCLUSIONS

Epidemiological evidence is rather consistent suggesting that there is a positive association between HRT use and MD with the highest increase in MD among current users, and CEP users. Our results suggest that due to increase in MD and masking effect, current E + P users may require additional screening procedures, shorter screening intervals, or using advanced imaging techniques.

Change in mammographic density across birth cohorts of Dutch breast cancer screening participants

High mammographic density is a well‐known risk factor for breast cancer. This study aimed to search for a possible birth cohort effect on mammographic density, which might contribute to explain the increasing breast cancer incidence. We separately analyzed left and right breast density of Dutch women from a 13‐year period (2003–2016) in the breast cancer screening programme. First, we analyzed age‐specific changes in average percent dense volume (PDV) across birth cohorts. A linear regression analysis (PDV vs. year of birth) indicated a small but statistically significant increase in women of: 1) age 50 and born from 1952 to 1966 (left, slope = 0.04, p = 0.003; right, slope = 0.09, p < 0.0001); 2) age 55 and born from 1948 to 1961 (right, slope = 0.04, p = 0.01); and 3) age 70 and born from 1933 to 1946 (right, slope = 0.05, p = 0.002). A decrease of total breast volume seemed to explain the increase in PDV. Second, we compared proportion of women with dense breast in women born in 1946–1953 and 1959–1966, and observed a statistical significant increase of proportion of highly dense breast in later born women, in the 51 to 55 age‐groups for the left breast (around a 20% increase in each age‐group), and in the 50 to 56 age‐groups for the right breast (increase ranging from 27% to 48%). The study indicated a slight increase in mammography density across birth cohorts, most pronounced for women in their early 50s, and more marked for the right than for the left breast.

What's new?

Women with dense breast tissue are at increased risk of breast cancer. Here, changes in mammographic density were investigated across birth cohorts in women enrolled in a breast cancer screening program in the Netherlands. The findings reveal an increase in the average fraction of dense tissue in the breast across cohorts. In particular, greater breast density was observed in a higher proportion of women in later‐born than earlier‐born birth cohorts. The increase was most significant among women in their early 50s and may be linked to a reported shift toward older age at menopause among women in Europe.

Hormone replacement therapy, mammographic density, and breast cancer risk: a cohort study

Purpose

Hormone replacement therapy (HRT) use increases breast cancer risk and mammographic density (MD). We examine whether MD mediates or modifies the association of HRT with the breast cancer.

Methods

For the 4,501 participants in the Danish diet, cancer and health cohort (1993–1997) who attended mammographic screening in Copenhagen (1993–2001), MD (mixed/dense or fatty) was assessed at the first screening after cohort entry. HRT use was assessed by questionnaire and breast cancer diagnoses until 2012 obtained from the Danish cancer registry. The associations of HRT with MD and with breast cancer were analyzed separately using Cox’s regression. Mediation analyses were used to estimate proportion [with 95% confidence intervals (CI)] of an association between HRT and breast cancer mediated by MD.

Results

2,444 (54.3%) women had mixed/dense breasts, 229 (5.4%) developed breast cancer, and 35.9% were current HRT users at enrollment. Compared to never users, current HRT use was statistically significantly associated with having mixed/dense breasts (relative risk and 95% CI 1.24; 1.14–1.35), and higher risk of breast cancer (hazard ratio 1.87; 1.40–2.48). Association between current HRT use and breast cancer risk was partially mediated by MD (percent mediated = 10%; 95% CI 4–22%). The current HRT use-related breast cancer risk was higher in women with mixed/dense (1.94; 1.37–3.87) than fatty (1.37; 0.80–2.35) breasts (p value for interaction = 0.15).

Conclusions

MD partially mediates some of the association between HRT and breast cancer risk. The association between HRT and breast cancer seems to be stronger in women with dense breasts.

Breast tissue density change after oophorectomy in BRCA mutation carrier patients using visual and volumetric analysis

OBJECTIVE

BRCA1/2 mutations account for 30-50% of hereditary breast cancers and bilateral oophorectomy is associated with a reduced risk of breast cancer in these patients. Breast density is a well-established breast cancer risk factor and is also associated with increased risk in BRCA carriers. The aim of the study was to evaluate the impact of oophorectomy on mammographic breast density and to assess which method of breast density assessment is more sensitive to change over time.

METHODS

Retrospective study of 50 BRCA1/2 patients who underwent bilateral oophorectomy and had at least a baseline and post-surgery mammogram. Mammographic breast density was determined by Volpara and consensus visual assessment by two radiologists. The primary endpoint was change in density between baseline and the first mammogram post-surgery.

RESULTS

At baseline, there was a non-significant trend for decreased density with increasing age. Volumetric breast density (VBD) significantly decreased after oophorectomy from a median VBD of 12.5% at baseline to 10.2% post-surgery which was driven by a reduction in fibroglandular volume. There was a higher absolute decrease in VBD in patients aged between 40-50 (p < 0.01). Using Volpara Density Grades (analogous to BI-RADS 4th edition density categories), 84% of females displayed a decrease in density category over the study period compared to only 76% using the radiologists' visual classification (p < 0.001) Conclusion: Oophorectomy is associated with a decrease in breast density and younger patients exhibit a larger absolute decrease. Volpara is more sensitive to identify change over time compared to visual assessment. Advances in knowledge: Oophorectomy is associated with a significant decrease in VBD in patients with BRCA mutations and Volpara Density Grades were more sensitive to identify decreases in density compared to visually assessed BI-RADS categories. Decreases in breast density following oophorectomy surgery in BRCA patients may be one of the mechanisms contributing to the observed decreased breast cancer risk after surgery. However, further studies are needed to investigate the relationship between breast density, oophorectomy and breast cancer risk in BRCA patients.

Relationship Between Breast Density and Selective Estrogen-Receptor Modulators, Aromatase Inhibitors, Physical Activity, and Diet: A Systematic Review

Background Lower breast density (BD) is associated with lower risk of breast cancer and may serve as a biomarker for the efficacy of chemopreventive strategies. This review explores parameters that are thought to be associated with lower BD. We conducted a systematic review of articles published to date using the PRISMA strategy. Articles that assessed change in BD with estrogen-receptor modulators (tamoxifene [TAM], raloxifene [RLX], and tibolone) and aromatase inhibitors (AIs), as well as cross-sectional and longitudinal studies (LSs) that assessed association between BD and physical activity (PA) or diet were reviewed. Results Ten studies assessed change in BD with TAM; all reported TAM-mediated BD decreases. Change in BD with RLX was assessed by 11 studies; 3 reported a reduction in BD. Effect of tibolone was assessed by 5 RCTs; only 1 reported change in BD. AI-mediated BD reduction was reported by 3 out of 10 studies. The association between PA and BD was assessed by 21 studies; 4 reported an inverse association. The relationship between diet and BD was assessed in 34 studies. All studies on calcium and vitamin D as well as vegetable intake reported an inverse association with BD in premenopausal women. Two RCTs demonstrated BD reduction with a low-fat, high-carbohydrate intervention. Conclusion TAM induces BD reduction; however, the effect of RLX, tibolone, and AIs on BD is unclear. Although data on association between diet and BD in adulthood are contradictory, intake of vegetables, vitamin D, and calcium appear to be associated with lower BD in premenopausal women.

Association of infertility and fertility treatment with mammographic density in a large screening-based cohort of women: a cross-sectional study

Background

Ovarian stimulation drugs, in particular hormonal agents used for controlled ovarian stimulation (COS) required to perform in vitro fertilization, increase estrogen and progesterone levels and have therefore been suspected to influence breast cancer risk. This study aims to investigate whether infertility and hormonal fertility treatment influences mammographic density, a strong hormone-responsive risk factor for breast cancer.

Methods

Cross-sectional study including 43,313 women recruited to the Karolinska Mammography Project between 2010 and 2013. Among women who reported having had infertility, 1576 had gone through COS, 1429 had had hormonal stimulation without COS and 5958 had not received any hormonal fertility treatment. Percent and absolute mammographic densities were obtained using the volumetric method Volpara™. Associations with mammographic density were assessed using multivariable generalized linear models, estimating mean differences (MD) with 95 % confidence intervals (CI).

Results

After multivariable adjustment, women with a history of infertility had 1.53 cm³ higher absolute dense volume compared to non-infertile women (95 % CI: 0.70 to 2.35). Among infertile women, only those who had gone through COS treatment had a higher absolute dense volume than those who had not received any hormone treatment (adjusted MD 3.22, 95 % CI: 1.10 to 5.33). No clear associations were observed between infertility, fertility treatment and percent volumetric density.

Conclusions

Overall, women reporting infertility had more dense tissue in the breast. The higher absolute dense volume in women treated with COS may indicate a treatment effect, although part of the association might also be due to the underlying infertility. Continued monitoring of cancer risk in infertile women, especially those who undergo COS, is warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0693-5) contains supplementary material, which is available to authorized users.

Breast cancer risk following Hodgkin lymphoma radiotherapy in relation to menstrual and reproductive factors

BACKGROUND

Women treated with supradiaphragmatic radiotherapy (sRT) for Hodgkin lymphoma (HL) at young ages have a substantially increased breast cancer risk. Little is known about how menarcheal and reproductive factors modify this risk.

METHODS

We examined the effects of menarcheal age, pregnancy, and menopausal age on breast cancer risk following sRT in case-control data from questionnaires completed by 2497 women from a cohort of 5002 treated with sRT for HL at ages <36 during 1956-2003.

RESULTS

Two-hundred and sixty women had been diagnosed with breast cancer. Breast cancer risk was significantly increased in patients treated within 6 months of menarche (odds ratio (OR) 5.52, 95% confidence interval (CI) (1.97-15.46)), and increased significantly with proximity of sRT to menarche (Ptrend<0.001). It was greatest when sRT was close to a late menarche, but based on small numbers and needing reexamination elsewhere. Risk was not significantly affected by full-term pregnancies before or after treatment. Risk was significantly reduced by early menopause (OR 0.55, 95% CI (0.35-0.85)), and increased with number of premenopausal years after treatment (Ptrend=0.003).

CONCLUSION

In summary, this paper shows for the first time that sRT close to menarche substantially increases breast cancer risk. Careful consideration should be given to follow-up of these women, and to measures that might reduce their future breast cancer risk.

Physical activity and mammographic breast density: a systematic review

Studies show a protective relationship between physical activity and breast cancer risk across the life course from menarche to postmenopausal years. Mammographic breast density is a known and strong breast cancer risk factor. Whether the association of physical activity with breast cancer risk is mediated through mammographic breast density is poorly understood. This systematic review summarizes published studies that investigated the association between physical activity and mammographic breast density and discusses the methodological issues that need to be addressed. We included in this review studies that were published before October 31, 2011 that were accessible in full-text format and were published in English. We identified 20 studies through the PubMed Central, BioMed Central, Embase, and Scopus and using the search terms "physical activity and breast density" and "exercise and breast density" as well as through manual searches of the bibliographies of the articles identified in electronic searches. We found no evidence of association between physical activity and breast density across the studies by grouping them first by the timing of physical activity assessment (in adolescence, current/recent, past, and lifetime) and then by women's menopausal status (premenopausal and postmenopausal). Given the strength of the relationship between physical activity and breast cancer and the null findings of this review, it is unlikely that the effect of physical activity is mediated through an effect on breast density.

Obstetric history and mammographic density: a population-based cross-sectional study in Spain (DDM-Spain)

High mammographic density (MD) is used as a phenotype risk marker for developing breast cancer. During pregnancy and lactation the breast attains full development, with a cellular-proliferation followed by a lobular-differentiation stage. This study investigates the influence of obstetric factors on MD among pre- and post-menopausal women. We enrolled 3,574 women aged 45–68 years who were participating in breast cancer screening programmes in seven screening centers. To measure MD, blind anonymous readings were taken by an experienced radiologist, using craniocaudal mammography and Boyd’s semiquantitative scale. Demographic and reproductive data were directly surveyed by purpose-trained staff at the date of screening. The association between MD and obstetric variables was quantified by ordinal logistic regression, with screening centre introduced as a random effect term. We adjusted for age, number of children and body mass index, and stratified by menopausal status. Parity was inversely associated with density, the probability of having high MD decreased by 16% for each new birth (P value < 0.001). Among parous women, a positive association was detected with duration of lactation [>9 months: odds ratio (OR) = 1.33; 95% confidence interval (CI) = 1.02–1.72] and weight of first child (>3,500 g: OR = 1.32; 95% CI = 1.12–1.54). Age at first birth showed a different effect in pre- and post-menopausal women (P value for interaction = 0.030). No association was found among pre-menopausal women. However, in post-menopausal women the probability of having high MD increased in women who had their first child after the age of 30 (OR = 1.53; 95% CI = 1.17–2.00). A higher risk associated with birth of twins was also mainly observed in post-menopausal women (OR = 2.02; 95% CI = 1.18–3.46). Our study shows a greater prevalence of high MD in mothers of advanced age at first birth, those who had twins, those who have breastfed for longer periods, and mothers whose first child had an elevated birth weight. These results suggest the influence of hormones and growth factors over the proliferative activity of the mammary gland.

Bodyweight and other correlates of symptom-detected breast cancers in a population offered screening

OBJECTIVE

To determine the factors associated with symptom-detected breast cancers in a population offered screening.

METHODS

We interviewed 1,459 Australian women aged 40-69, 946 with symptom-detected and 513 with mammogram-detected invasive breast cancers ≥ 1.1 cm in diameter about their personal, mammogram, and breast histories before diagnosis and reviewed medical records for tumor characteristics and mammogram dates, calculating ORs and 95% confidence intervals (CIs) for symptom- versus mammogram-detected cancers in logistic regression models.

RESULTS

Lack of regular mammograms (<2 mammograms in the 4.5 years before diagnosis) was the strongest correlate of symptom-detected breast cancer (OR = 3.04 for irregular or no mammograms). In women who had regular mammograms (≥ 2 mammograms in the 4.5 years before diagnosis), the independent correlates of symptom-detected cancers were low BMI (OR < 25 kg/m(2) vs. ≥ 30 kg/m(2) = 2.18, 95% CI 1.23-3.84; p = 0.008), increased breast density (available in 498 women) (OR highest quarter vs. lowest = 3.50, 95% CI 1.76-6.97; p (trend) = 0.004), high-grade cancer, and a larger cancer (each p < 0.01). In women who did not have regular mammograms, the independent correlates were age <50 years, a first cancer, and a ≥ 2-cm cancer. Smoking appeared to modify the association of symptom-detected cancer with low BMI (higher ORs for low BMI in current smokers) and estrogen receptor (ER) status (higher ORs for low BMI in ER cancers).

CONCLUSION

Women with low BMI may benefit from a tailored approach to breast cancer detection, particularly if they smoke.

Physical activity and mammographic parenchymal patterns among Greek postmenopausal women

OBJECTIVE

To examine whether physical activity during the last five years is related to later breast mammographic density in postmenopausal Greek women.

METHODS

We designed a cross-sectional study in 724 women, of ages 45-67 years. An interview-administered questionnaire was used to obtain information on duration and intensity of recreational physical activity during five years preceding study recruitment. Mammograms were evaluated according to BIRADS classification and BIRADS score was also estimated. Multivariate ordinal logistic regression analysis was used to assess associations between physical activity index and breast density according to the BIRADS classification methods.

RESULTS

We observed a statistically significant inverse association of mammographic breast density measured by the BIRADS classification method and recreational exercise (OR=-0.10; 95% CI -0.018, -0.001; p=0.022). For one unit increase in physical activity as expressed by the MET-h/week score, the odds of lower versus higher breast density categories are 1.105 greater, given that all of the other variables in the model are held constant. A modifying effect by age at recruitment was evident among participants, with a stronger inverse association between recreational activity and mammographic breast density among older women (OR=-0.036; 95% CI -0.063, -0.009; p=0.009). An inverse association between physical activity and BIRADS score was evident, not reaching statistical significance (OR=0.00; 95% CI -0.009, 0.008; p=0.887).

CONCLUSIONS

Mammographic breast area was lower in postmenopausal women who participated in sports/recreational physical activity compared to inactive controls. Increasing physical activity levels among postmenopausal women might be a reasonable approach to reduce mammographic density. However, until more physical activity and mammographic breast density studies are conducted that confirm our findings, they have to be interpreted with caution, due to the retrospective nature of our data and the possibility of memory bias.

Mammographic density and its interaction with other breast cancer risk factors in an Asian population

BACKGROUND

Joint effects of mammographic density and other risk factors on breast cancer risk remain unclear.

METHODS

From The Singapore Breast Screening Project, we selected 491 cases and 982 controls. Mammographic density was measured quantitatively. Data analysis was by conditional logistic regression.

RESULTS

Density was a significant risk factor, adjusting for other factors. Density of 76-100% had an odds ratio of 5.54 (95% CI 2.38-12.90) compared with 0-10%. Density had significant interactions with body mass index and oral contraceptive use (P=0.02).

CONCLUSIONS

Percent density increases breast cancer risk in addition to effects of other risk factors, and modifies the effects of BMI and OCs.

Genetic models for the familial aggregation of mammographic breast density

BACKGROUND

Mammographic breast density (MBD) has a strong genetic component. Investigating the genetic models for mammographic density may provide further insights into the genetic factors affecting breast cancer risk.

PURPOSE

To evaluate the familial aggregation of MBD and investigate the genetic models of susceptibility.

METHODS

We used data on 746 women from 305 families participating in the Sisters in Breast Screening study. Retrieved mammograms were digitized, and percent mammographic density was determined using the Cumulus software. Linear regression analysis was done to identify the factors that are associated with mammographic density and a multivariate regression model was constructed. Familial correlations between relative pairs were calculated using the residuals from these models. Genetic models of susceptibility were investigated using segregation analysis.

RESULTS

After adjusting for covariates, the intraclass correlation coefficient among the residuals was 0.26 (95% confidence interval, 0.16-0.36) in sister-sister pairs and 0.67 (0.27-1.00) among the monozygotic twin pairs. The most parsimonious model was a Mendelian single major gene model in which an allele with population frequency 0.39 (95% confidence interval, 0.33-0.46) influenced mammographic density in an additive fashion. This model explained 66% of the residual variance.

CONCLUSION

These results confirm that MBD has a strong heritable basis, and suggest that major genes may explain some of the familial aggregation. These results may have implications for the search of genes that control mammographic density.

Physical activity and mammographic breast density in a Mediterranean population: the EPIC Florence longitudinal study

A protective effect of physical activity (PA) on breast cancer (BC) risk has been suggested. Few studies have examined the influence of PA on mammographic breast density (MBD), a strong risk factor for BC. In a prospective study in Florence, Italy, we identified 2,000 healthy women with a mammogram taken 5 years after enrollment. Individual mammograms were retrieved (83%) and MBD assessed according to Wolfe's classification. Detailed information on PA at work and during leisure time, reproductive history, lifestyle and anthropometric measurements at enrollment were available for 1,666 women. Information on hormone replacement therapy (HRT) was also obtained at mammogram. Women with high-MBD (P2 + DY Wolfe's patterns) were compared with women with low-MBD (N1 + P1) by multivariate logistic models. Overall, high-MBD was inversely associated with increasing levels of leisure time PA (p for trend = 0.04) and among peri-/postmenopausal women, also with increasing levels of recreational activities (p for trend = 0.02). An interaction between PA and HRT emerged, with a stronger inverse association of highest level of recreational activity with MBD among HRT nonusers (p for interaction = 0.02). A modifying effect by body mass index (BMI) was evident among 1,025 peri-/postmenopausal women who did not use HRT at the time of mammogram, with a stronger inverse association between recreational PA and MBD in the highest BMI tertile (OR = 0.34; 95% CI 0.20-0.57; p for interaction = 0.03). This large study carried out in Mediterranean women suggests that leisure time PA may play a role in modulating MBD, particularly in overweight/obese peri-/postmenopausal women.

Physical activity and mammographic density in a cohort of midlife women

PURPOSE

Physical activity (PA) is one of few modifiable breast cancer risk factors. There have been few studies of the relation between PA and mammographic density, especially in multiethnic populations.

METHODS

In a cohort of pre- and early perimenopausal women of non-Hispanic white (N = 373), African American (N = 55), Chinese (N = 178), and Japanese (N = 166) ethnicity, we used multivariable linear regression to examine the association between two measures of mammographic density (percent density and area of density) and mutually exclusive components of recent physical activity (sports, household/caregiving and work activity, active living).

RESULTS

After adjusting for race/ethnicity, menopausal status, parity, past use of hormones, body mass index, waist circumference and education, we observed nonsignificant inverse associations for percent mammographic density and the highest versus the lowest category of each of our PA domains. For example, the adjusted beta for active living = -2.62, 95% confidence interval (CI) (-5.84, 0.60). Nonsignificant inverse associations also were observed for area of density and each PA domain except work activity. However, most associations were nonlinear.

CONCLUSION

Our results are consistent with a modest inverse association between multiple domains of PA and mammographic density, although findings may have been attributable to chance alone.

Impact of hormone replacement therapy on the histologic subtype of breast cancer

OBJECTIVE

Postmenopausal hormone replacement therapy (HRT) is associated with an increase in breast cancer risk, which correlates to the duration of HRT use. We wanted to investigate a possible association between HRT use and the risk of a histologic subtype of breast cancer.

PATIENTS AND METHODS

From 1995 until 2004, 497 cases of primary ductal, lobular or ductulolobular breast cancer in postmenopausal women were diagnosed at the Department of Gynecology and Obstetrics, University Hospital Basel, Switzerland. The data was derived from patient's records. HRT ever use was defined as HRT use for > or =6 months.

RESULTS

Of the 99 cases of lobular cancer 72.7% were invasive lobular cancers, 21.2% were invasive ductulolobular cancers and 6.1% were lobular cancers in situ. Of the 398 cases of ductal cancer, 90.5% were invasive ductal cancers and 9.5% were ductal cancers in situ. Totally 144 women were HRT ever users, and 341 women were HRT never users. HRT status could not be defined in 12 women. HRT ever use was associated with an increased risk for lobular cancer (OR 1.67; 95% CI 1.02-2.73). Also, menopause due to bilateral oophorectomy was associated with an increased risk for lobular cancer (OR 2.42; 95% CI 1.06-5.54).

CONCLUSIONS

There is evidence that HRT as well as menopause due to bilateral oophorectomy may be associated with an increased risk for lobular cancer. This association is of major clinical relevance, since lobular breast cancer is more difficult to diagnose clinically and radiologically than ductal breast cancer.

Breast cancer risk factors and a novel measure of volumetric breast density: cross-sectional study

We conducted a cross-sectional study nested within a prospective cohort of breast cancer risk factors and two novel measures of breast density volume among 590 women who had attended Glasgow University (1948–1968), replied to a postal questionnaire (2001) and attended breast screening in Scotland (1989–2002). Volumetric breast density was estimated using a fully automated computer programme applied to digitised film-screen mammograms, from medio-lateral oblique mammograms at the first-screening visit. This measured the proportion of the breast volume composed of dense (non-fatty) tissue (Standard Mammogram Form (SMF)%) and the absolute volume of this tissue (SMF volume, cm³). Median age at first screening was 54.1 years (range: 40.0–71.5), median SMF volume 70.25 cm³ (interquartile range: 51.0–103.0) and mean SMF% 26.3%, s.d.=8.0% (range: 12.7–58.8%). Age-adjusted logistic regression models showed a positive relationship between age at last menstrual period and SMF%, odds ratio (OR) per year later: 1.05 (95% confidence interval: 1.01–1.08, P=0.004). Number of pregnancies was inversely related to SMF volume, OR per extra pregnancy: 0.78 (0.70–0.86, P<0.001). There was a suggestion of a quadratic relationship between birthweight and SMF%, with lowest risks in women born under 2.5 and over 4 kg. Body mass index (BMI) at university (median age 19) and in 2001 (median age 62) were positively related to SMF volume, OR per extra kg m⁻² 1.21 (1.15–1.28) and 1.17 (1.09–1.26), respectively, and inversely related to SMF%, OR per extra kg m⁻² 0.83 (0.79–0.88) and 0.82 (0.76–0.88), respectively, P<0.001. Standard Mammogram Form% and absolute SMF volume are related to several, but not all, breast cancer risk factors. In particular, the positive relationship between BMI and SMF volume suggests that volume of dense breast tissue will be a useful marker in breast cancer studies.

Preventive oncology in the postmenopausal woman

Breast cancer and endometrial cancer are the most common gynecologic malignancies of the postmenopausal period. As preventive medicine becomes the focus of interest, preventive oncology with special regard to these diseases will undoubtedly become a substantial part of the practicing oncologist's field of duties. The aim of this review is to summarize recommendations dealing with the risk assessment and prevention of breast and endometrial cancer. Obesity, the level of exercise and dietary factors are associated with breast cancer. The selective estrogen receptor modulators tamoxifen and raloxifen have both been shown to decrease the risk to the same extent. Patients at particularly high risk are being detected through the use of the Gail model, a well-known statistical model of risk. Other factors, such as breast density, the serum level of endogenous estrogen and the presence of single nucleotide polymorphisms, have to be taken into consideration.

Different types of postmenopausal hormone therapy and mammographic density in Norwegian women

Postmenopausal hormone therapy (HT) is associated with increased risk of breast cancer. The HTs used in Scandinavia is associated with higher risk estimates than those used in most other countries. Mammographic density is one of the strongest risk factors for breast cancer, and possibly an intermediate marker for breast cancer. We decided to examine the relationship between use of different types of HT and mammographic density in Norwegian women. Altogether, 1,007 postmenopausal participants in the governmental mammographic screening program were asked about current and previous HT use. Mammograms were classified according to percent and absolute mammographic density. Overall, current users of HT had on average 3.6% higher mean percent mammographic density when compared with never users (p < 0.001). After adjustment for age at screening, number of children and BMI in a multivariate model, women using the continuous estradiol (E(2)) plus norethisterone acetate (NETA) combination had a mean percent mammographic density significantly higher than never users (6.1% absolute difference). Those using the continuous E(2) plus NETA combination had an 4.8% (absolute difference) higher mean percent mammographic density after <5 years of use when compared with never users, while the corresponding number for >or=5 years of use was 7% (p-trend < 0.001). We found similar associations when absolute mammographic density was used as the outcome variable. In summary, our study shows a statistical significant positive dose-response association between current use of the continuous E(2) plus NETA combination and both measures of mammographic density.

Dietary and lifestyle determinants of mammographic breast density. A longitudinal study in a Mediterranean population

High mammographic breast density (H-MBD) has been associated with increased breast cancer (BC) risk, even after adjustment for established BC risk factors. Only a few studies have examined the influence of diet on MBD. In a longitudinal study in Florence, Italy, we identified about 2,000 women with a mammogram taken 5 years after enrollment, when detailed information on dietary and lifestyle habits and anthropometric measurements had been collected. Original mammograms have been identified and retrieved (1,668; 83%), and MBD was assessed by 2 experienced readers, according to Wolfe's classification and a semiquantitative scale. By logistic analysis, we compared women with H-MBD (P2 + DY according to Wolfe's classification) with those with low-MBD (N1 + P1). H-MBD was confirmed to be inversely associated with BMI, number of children and breast feeding, while it was directly associated with higher educational level, premenopausal status and a previous breast biopsy. In multivariate analyses adjusted for non-dietary variables, H-MBD was inversely associated with increasing consumption of vegetables (p for trend = 0.005) and olive oil (p for trend = 0.04). An inverse association was also evident between H-MBD and frequent consumption of cheese and high intakes of beta-carotene, vitamin C, calcium and potassium (p for trend < or = 0.05). On the other hand, we found a positive association with increasing consumption of wine (p for trend = 0.01). This large longitudinal study, the first carried out in Mediterranean women, suggests that specific dietary components may play a key role in determining MBD in this population, thus possibly modulating BC risk.

Mammographic Density and Breast Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

High breast density as measured on mammograms is a strong risk factor for breast cancer in the general population, but its effect in carriers of germline BRCA1 and BRCA2 mutations is unclear. We obtained mammograms from 206 female carriers of BRCA1 or BRCA2 mutations, 96 of whom were subsequently diagnosed with breast cancer and 136 relatives of carriers who were themselves noncarriers. We compared the mammographic densities of affected carriers (cases) and unaffected carriers (controls), and of mutation carriers and noncarriers, using a computer-assisted method of measurement and visual assessment by two observers. Analyses were adjusted for age, parity, body mass index, menopausal status, and hormone replacement therapy use. There was no difference in the mean percent density between noncarriers and carriers. Among carriers, increasing mammographic density was associated with an increased risk of breast cancer (P(trend) = 0.024). The odds ratio (OR; 95% confidence interval) for breast cancer associated with a density of > or =50% was 2.29 (1.23-4.26; P = 0.009). The OR did not differ between BRCA1 and BRCA2 carriers or between premenopausal and postmenopausal carriers. The results suggest that the distribution of breast density in BRCA1 and BRCA2 carriers is similar to that in non-carriers. High breast density in carriers is associated with an increased risk of breast cancer, with the relative risk being similar to that observed in the general population. Use of mammographic density could improve individual risk prediction in carriers.

Incidence of malignancy in hormone therapy users with indeterminate calcifications on mammogram

OBJECTIVE

This was a pilot study to determine whether menopausal hormone therapy users have a higher incidence of indeterminate calcifications on screening mammogram and a higher rate of associated malignancy than nonusers.

STUDY DESIGN

A retrospective chart review of routine screening mammograms with indeterminate calcifications was conducted to determine the malignancy rate overall and in hormone therapy users and nonusers. A control group of normal screening mammograms was used to determine whether hormone therapy use was representative of the population that undergo screening mammograms and to compare the malignancy rates.

RESULTS

The rates of hormone therapy use in the study and control groups were similar. The overall malignancy rate was 24.7%; no difference existed between users and nonusers. Comparing estrogen only with estrogen-progestin users demonstrated a malignancy rate of 5.8% and 17.6%, respectively (odds ratio 2.28).

CONCLUSIONS

Hormone therapy users with indeterminate calcifications on screening mammograms are not at an increased risk of malignancy than nonusers. Estrogen-progestin users may be at an increased risk over estrogen-only users.

Nutritional predictors for cellular nipple aspirate fluid: Nutrition and Breast Health Study

The presence of epithelial cells in breast nipple aspirate fluid (NAF), irrespective of abnormality, has been associated with increased risk of breast cancer in previous studies. We sought to investigate whether the presence of epithelial cells in NAF is associated with nutritional parameters among 71 healthy premenopausal women who participated in the Nutrition and Breast Health Study and provided any samples of NAF during the study. Total of 142 samples which were obtained over a 1-year period of intervention with low-fat and/or high vegetable-fruit diets were available for cytological evaluation. The odds ratios (ORs) and 95% confidence intervals (CIs) for the detection of epithelial cells in NAF were estimated by fitting generalized estimating equations models by quartile level of nutritional parameters. The probability of yielding epithelial cell-positive NAF progressively increased with increasing total fat intake (p=0.001). The OR for the highest quartile level of fat intake, compared with lowest, was 7.22 (95% CI 1.14-45.82). On the other hand, there were a marginally significant inverse association with total fiber intake as well as an weak inverse association with the number of servings of fruit and vegetables. Furthermore, the probability of detecting epithelial cells in NAF decreased with increasing plasma levels of lutein and alpha-carotene (p-values for linear trend; 0.001 and 0.049, respectively). The ORs for the highest versus lowest quartile levels are 0.17 (95% CI 0.04-0.65) and 0.19 (95% CI 0.04-0.91), respectively. These results are generally in support of roles of nutritional factors in breast cancer and thus further studies are warranted.

Percentage density, Wolfe's and Tabár's mammographic patterns: agreement and association with risk factors for breast cancer

Introduction

The purpose of this report was to classify mammograms according to four methods and to examine their agreement and their relationship to selected risk factors for breast cancer.

Method

Mammograms and epidemiological data were collected from 987 women, aged 55 to 71 years, attending the Norwegian Breast Cancer Screening Program. Two readers each classified the mammograms according to a quantitative method (Cumulus or Madena software) and one reader according to two qualitative methods (Wolfe and Tabár patterns). Mammograms classified in the reader-specific upper quartile of percentage density, Wolfe's P2 and DY patterns, or Tabár's IV and V patterns, were categorized as high-risk density patterns and the remaining mammograms as low-risk density patterns. We calculated intra-reader and inter-reader agreement and estimated prevalence odds ratios of having high-risk mammographic density patterns according to selected risk factors for breast cancer.

Results

The Pearson correlation coefficient was 0.86 for the two quantitative density measurements. There was moderate agreement between the Wolfe and Tabár classifications (Kappa = 0.51; 95% confidence interval 0.46 to 0.56). Age at screening, number of children and body mass index (BMI) showed a statistically significant inverse relationship with high-risk density patterns for all four methods (all P < 0.05). After adjustment for percentage density, the Wolfe classification was not associated with any of the risk factors for breast cancer, whereas the association with number of children and BMI remained statistically significant for the Tabár classification. Adjustment for Wolfe or Tabár patterns did not alter the associations between these risk factors and percentage mammographic density.

Conclusion

The four assessments methods seem to capture the same overall associations with risk factors for breast cancer. Our results indicate that the quantitative methods convey additional information over the qualitative methods.

Parity in relation to risk of axillary lymph node involvement in women with breast cancer. Results from Swedish population-based series of 3,472 consecutive cases

OBJECTIVE

To investigate the association between parity and axillary lymph node involvement (ALNI) at breast cancer diagnosis.

METHODS

One surgeon has reviewed all breast cancer cases in Malmo, Sweden, diagnosed 1961-1991. This study includes the 3,472 women who had a first-time diagnosis of unilateral invasive breast cancer, and who had undergone axillary dissection. Information was collected regarding date of birth, date of diagnosis, age at diagnosis, menopausal status, tumour size, histological type, tumour location, type of surgery, stage (ALNI), and parity. Parity was investigated in relation to ALNI using logistic regression analysis, adjusted for potential confounders, yielding odds ratios (OR) with 95% confidence intervals (CI). The analyses were repeated in different strata with regard to birth-years cohort, age at diagnosis, and period of diagnosis.

RESULTS

High parity was associated with ALNI, the adjusted OR for ALNI among women with 4 or more children was 1.56 (1.13-2.15). This association was stronger in comparatively old women (> or = 67.45 years), OR 1.78 (1.10-2.88). Considering parity a continuous variable, the OR for ALNI among all women was 1.06 (1.01-1.12).

CONCLUSIONS

We conclude that women with 4 or more children had an increased risk of ALNI at breast cancer diagnosis.

CAD-aided mammogram training

RATIONALE AND OBJECTIVES

Although computer-aided detection (CAD) improves the diagnosis rate of early breast cancer, it has not been well integrated into radiology residency and technician training program. Moreover, CAD performance studies ignore the reader's training and experience with CAD. The purpose of this study was to investigate whether CAD training via a cognitive-perceptual based hypermedia program has effects on the performance studies of mammogram reading.

MATERIALS AND METHODS

Three observers read a pretest set of 80 breast cancer cases (43 negative, 23 benign, and 14 malignant cancer cases). During 4 weeks' training, the observers used a hypermedia instructional program in CAD-aided mammography interpretation. The program includes modules of CAD attention-focusing schemes, CAD procedural knowledge, and case-based simulations in mammography interpretation in consensus with CAD. By the end of the fourth week of the training, they reviewed a posttest set of cases. Data were analyzed with multireader, multicase receiver operating characteristic methods.

RESULTS

Three readers performed better in mammogram reading after training in CAD knowledge than they did before CAD training. CAD training and experience improved the performance of CAD-aided mammography interpretation.

CONCLUSION

A statistically significant difference was found in each observer's performance in CAD-aided mammogram reading before and after the training. CAD training will influence the perception, recognition, and interpretation of early breast cancer and CAD performance studies. Furthermore, the young generation of radiologic professionals can have more training in various attention-focusing features, declarative knowledge, procedural knowledge, and conditional knowledge of CAD and incorporate them into their knowledge base and strategic processing for the purpose of improving the accuracy of mammography interpretation performance.

Understanding breast cancer risk -- where do we stand in 2005?

Breast cancer is the most frequent cancer in women and represents the second leading cause of cancer death among women (after lung cancer). The etiology of breast cancer is still poorly understood with known breast cancer risk factors explaining only a small proportion of cases. Risk factors that modulate the development of breast cancer discussed in this review include: age, geographic location (country of origin) and socioeconomic status, reproductive events, exogenous hormones, lifestyle risk factors (alcohol, diet, obesity and physical activity), familial history of breast cancer, mammographic density, history of benign breast disease, ionizing radiation, bone density, height, IGF- 1 and prolactin levels, chemopreventive agents. Additionally, we summarized breast cancer risk associated with the following genetic factors: breast cancer susceptibility high-penetrance genes (BRCA1, BRCA2, p53, PTEN, ATM, NBS1 or LKB1) and low-penetrance genes such as cytochrome P450 genes (CYP1A1, CYP2D6, CYP19), glutathione S-transferase family (GSTM1, GSTP1), alcohol and one-carbon metabolism genes (ADH1C and MTHFR), DNA repair genes (XRCC1, XRCC3, ERCC4/XPF) and genes encoding cell signaling molecules (PR, ER, TNFalpha or HSP70). All these factors contribute to a better understanding of breast cancer risk. Nonetheless, in order to evaluate more accurately the overall risk of breast tumorigenesis, novel genetic and phenotypic traits need to be identified.

The relationship between mammographic density and duration of hormone therapy: effects of estrogen and estrogen–progestin

BACKGROUND

The purpose of this study was to examine the effects of duration of hormone therapy (HT) and treatment regimens on mammographic density.

METHODS

A retrospective study was carried out of of 467 post-menopausal women who received estrogen or estrogen-progestin and had regular mammographic density determination by the Breast Imaging Reporting and Data System between 1994 and 2001.

RESULTS

The fraction of women using HT who had an increase in mammographic density became more important over time. Further analysis of the effects of regimens after 4 years of HT shows that the increase in mean density was much greater in women receiving combined HT than in those receiving estrogen alone. The incidence of increased mammographic density showed significantly progressive increases over the duration of combined HT from 7.5 to 22.4%.

CONCLUSIONS

Although most women using HT maintained breast density at pre-treatment levels, there is a note of caution for women using long-term HT, especially those using combined estrogen-progestin.

The etiology of alcohol-induced breast cancer

Breast cancer is the most common cancer in women in the United States, and it is second among cancer deaths in women. Results of most epidemiologic studies, as well as of most experimental studies in animals, have shown that alcohol intake is associated with increased breast cancer risk. Alcohol consumption may cause breast cancer through different mechanisms, including through mutagenesis by acetaldehyde, through perturbation of estrogen metabolism and response, and by inducing oxidative damage and/or by affecting folate and one-carbon metabolism pathways. Alcohol-metabolizing enzymes are present in human breast tissue. Acetaldehyde is a known, although weak, mutagen. However, results of some studies with human subjects implicate this agent in the context of genetic susceptibilities to increased ethanol metabolism. Reactive oxygen species, resulting from ethanol metabolism, may be involved in breast carcinogenesis by causing damage, as well as by generating DNA and protein adducts. Alcohol interferes with estrogen pathways in multiple ways, influencing hormone levels and effects on the estrogen receptors. With regard to one-carbon metabolism, alcohol can negatively affect folate levels, and the folate perturbation affects DNA methylation and DNA synthesis, which is important in carcinogenesis. Some study results indicate that genetic variants of one-carbon metabolism genes might increase alcohol-related breast cancer risk. For all these pathways, genetic polymorphisms might play a role in increasing further a woman's risk for breast cancer. Additional studies are needed to determine the relative importance of these pathways, as well as the modifying influence by genetic variation.

A mammographic image analysis method to detect and measure changes in breast density

We present an image analysis method that can detect and measure breast density from digitised mammograms. We present initial results on applying our method to characterise breast changes, in particular, changes due to Hormone Replacement Therapy (HRT). It has been established that long-term use of certain hormone replacement therapies can increase the risk of breast cancer, a fact that encourages the notion that objective measures of tissue density can be an important development in breast cancer image analysis. A set of 59 temporal pairs of mammograms of patients undergoing HRT (two images per patient) were used. The clinician's assessment of density changes constituted the ground truth for evaluating the proposed quantitative measures of density change. The measures we developed are based on the Standard Mammogram Form (SMF) representation of interesting tissue and their performance (agreement with the expert's description) is also compared to the "interactive thresholding" method that has been used in the past to characterise mammographic density. The results clearly indicate that present methods for measuring mammographic density fail to characterise temporal changes while the proposed measures have the potential to aid the radiologist in assessing temporal density changes both on a global and a local basis.

Strategies for managing breast cancer risk after the menopause

Postmenopausal women in Western societies are conscious of breast cancer as a potential cause of death and ill health, which they wish to avoid with the advice of their doctors. Yet many factors that predispose women to the development of cancer will have been laid down before the menopause, in their genetic makeup or during their adolescent years. Even in middle age it is important to take account of the intrinsic level of risk, and to give women advice tailored to their own individual risk level. This results from their family history, previous diseases such as benign breast disease, and previous treatment for breast cancer or Hodgkin's disease. For those at the highest level of risk, strategies will include regular screening, prophylactic mastectomy, and the use of chemoprevention agents, such as tamoxifen. These women should avoid hormone replacement therapy (HRT) and control their menopausal symptoms and osteoporosis through the use of other agents now available - venlafaxine for menopausal symptoms and bisphosphonates for osteoporosis. Raloxifene is an agent under trial that may be valuable for breast cancer control as well as for osteoporosis. Women at standard population risk will require less robust preventive strategies, which will include screening and lifestyle modification. Their decisions regarding HRT should now be modified by recent evidence of associated risks. Recent studies show that tibolone causes less mammographic density and has a lower relative risk of breast cancer than combined estrogen/progestogen preparations. There is limited evidence that controlling obesity, participating in exercise and adopting a diet low in fats and high in fruit and vegetables will alter risk at this age. These precautions will, however, reduce the risk of other diseases common in this age group, such as hypertension, heart disease, stroke, and type 2 diabetes mellitus. Alcohol, even in small amounts, is a risk factor for breast cancer. Given the cardioprotective effect of moderate alcohol intake, advice on alcohol must reflect the individual relative risk of cardiovascular disease and breast cancer. Personal risk assessment is relevant for all women. Screening and a healthy lifestyle are worthwhile approaches for all, with the more aggressive approaches such as chemoprevention and prophylactic surgery reserved for those who have substantially elevated levels of risk. Once the menopause has passed, screening is probably the most effective evidence-based tool for breast cancer control by early diagnosis.

Correlates of high-density mammographic parenchymal patterns by menopausal status in a rural population in Northern Greece

Reproductive factors affect breast cancer risk, but less is known of their associations with mammographic density and whether these differ by menopausal status. We report on a cross-sectional study of 1946 pre- and 3047 post-menopausal women who joined a breast screening programme in Northern Greece during 1993-1997. The odds of having a high-density Wolfe pattern (P2/DY) was inversely associated with age (P for linear trend <0.001) in both pre- and post-menopausal women and, for post-menopausal women, with years since menopause (P < 0.001). The odds of a P2/DY pattern declined with higher parity (P < 0.001) and younger age at first pregnancy (P = 0.05) in both pre- and post-menopausal women. They also decreased with the duration of breast-feeding in pre-menopausal women (P = 0.03 in pre- and P = 0.69 in post-menopausal women; test for interaction with menopausal status: P = 0.07). Age at menarche, age at menopause and the number of miscarriages/abortions were not associated with mammographic density. Age at first pregnancy and parity were strong correlates of mammographic density in pre- and post-menopausal women while duration of breast-feeding appeared to be particularly important in pre-menopausal women.

Hormones and mammographic breast density

Mammographic density reveals information about the hormonal environment along with the heritability in which breast cancer develops. This is made possible by the widespread use of population screening by mammography. Increasingly this is an important observation not just for population studies, which reveal disease determinants, but also for the individual. Density reveals the effect of the intrinsic hormonal environment and its background genetics, and also the effect of pharmaceuticals--agents used for disease control and prevention and hormone replacement therapy (HRT) used for well-being around the menopause. Increasingly this focus on the individual will need methods of measurement of density that can be monitored with greater accuracy than the widely used BI-RADS 4 categories. For this purpose studies are under way to measure volume of dense tissue as a continuous variable. In due course, measurement of density will be used as a biomarker of risk, employed in risk models and to monitor interventions. Before this can happen more knowledge will be needed of the change occurring naturally through the menopause and the differences between individuals. This will need specific study backed up with detailed information about the patient on large numbers of women and their mammograms. Currently the widespread use of HRT has increased the prevalence of the dense patterns and potentially may adversely affect the effectiveness of mammographic screening programmes. There is a large literature recording this from which we see that combined continuous preparations of oestrogen progestin are more likely to cause increased density than oestrogen alone or tibolone. Breast density, measured more accurately, has the potential to be an important adjunct to risk estimation and to monitor interventions for breast cancer prevention with pharmaceuticals (such as SERMS) and by change in lifestyle behaviours.

Can computer-aided detection with double reading of screening mammograms help decrease the false-negative rate? Initial experience

PURPOSE

To retrospectively evaluate the role of computer-aided detection (CAD) in reducing the rate of false-negative (FN) findings on screening mammograms considered normal at initial double reading.

MATERIALS AND METHODS

At the authors' institution, independent prospective double readings in which the second reader is not blinded to results of the first reading are performed routinely for all mammograms. When cancer is diagnosed, prior mammograms also are reviewed with double reading to determine cancer visibility. Findings are categorized as (a) no evidence of cancer on any prior screening mammogram and patient presents more than 1 year after prior screening, (b) no evidence of cancer on any prior screening mammogram and patient presents with symptoms within 1 year after prior screening (year-interval occult false-negative), or (c) cancer visible. The clinical director separately evaluates each case in the same way. In 2000, 519 histologically proved breast cancers were diagnosed, including 132 for which patients sought a second opinion and FN findings were not tracked. Prior screening mammograms were available in 318 of the other 387 cases. Five radiologists in two reading sessions independently reviewed current and prior mammograms to categorize visible cancers as either threshold or actionable FN findings. Visible cancers deemed actionable by at least three of five readers were analyzed with a commercially available CAD system. FN rates were calculated prior to and after CAD analysis.

RESULTS

Twenty-seven occult and 71 visible cancers were found (total FN findings, 98). Three of five readers considered 52 (73%) of 71 visible cancers actionable. The CAD system correctly marked 37 (71%) of these 52 on prior screening mammograms (19 [65%] of 29 masses, seven [88%] of eight microcalcifications, seven [78%] of nine architectural distortions, and four [67%] of six masses with microcalcifications). The FN rate was 98 (31%) of 318 before CAD and 61 (19%) of 318 after CAD.

CONCLUSION

In this retrospective review of this small subset of cancers, it appears that CAD has the potential to decrease the FN rate at double reading by more than one-third (from 31% to 19%). The CAD system correctly marked 37 (71%) of 52 actionable findings read as negative in previous screening years.

Prospective estimation of rates of change in mammographic parenchymal patterns: influence of age and of hormone replacement therapy

The objective of this study was to assess the effect of age, breast size and use of hormone replacement therapy (HRT) on the rate of change of mammographic parenchymal patterns, and the effect of age on the probability of misclassification between patterns. It was designed as a longitudinal study of the members of the treatment arm of a non-randomized screening trial in which subjects were assigned to screening or not by year of birth. The subjects were women in the Kotka district of Finland, each of whom attended for four or five mammographic screens. Participants were all women living in the district who were born in the relevant years and accepted an invitation to screening. A model was fitted to the longitudinal data comprising the observed Wolfe patterns on each woman, with age and breast size as predictors of breast density at first screen, age and HRT use as predictors of change in density at future screens, and age as a predictor of misclassification of true density between favourable (non-dense) and unfavourable (dense) patterns (according to the Wolfe classification). Relevant posterior probability estimates (with 95% credible intervals) were as follows. The probability that a woman of age 43.5 is truly in the favourable state ranged from 0.35 (0.34-0.37) for smallest breast size to 0.74 (0.72-0.76) for the largest. The probability that a woman is truly in the favourable state at first screen increased from 0.37 (0.36-0.38) at age 40 to 0.59 (0.58-0.60) at age 47. The probability that a woman having a later screen who had truly been in the unfavourable state at her previous screen changed to the favourable state increased from 0.12 (0.11-0.13) at age 42 to 0.48 (0.46-0.50) at age 55 for a woman not taking HRT, and from 0.10 (0.09-0.11) to 0.43 (0.40-0.45) at the same ages for a woman taking HRT. The probability that a woman would have changed from being truly in the favourable state to the unfavourable state was 0.003 (0.001-0.003) for any age and HRT use. The probability that a woman truly in a favourable state would be correctly classified rose from 0.87 (0.85-0.89) at age 40 to 0.998 (0.997-0.998) at age 55. The probability that a woman truly in the unfavourable state would be correctly classified decreased from 0.96 (0.95-0.97) to 0.93 (0.91-0.94) between the same ages. The probability of being in a non-dense, favourable state increases with age, as does the rate of change from dense to non-dense patterns. These are consistent with previous work. The probability of non-dense patterns and the rate of change to non-dense patterns are reduced with HRT use. Errors of classification are relatively rare, but are dependent on the age of the subject.

Deterministic models for breast cancer progression: application to the association between mammographic parenchymal pattern and histologic grade of breast cancers

Dense mammographic patterns are a risk factor for breast cancer. In a recent case-control study, dense patterns were observed to be associated with a higher relative risk estimate for the more aggressive grade 3 tumors than for grade 1 or 2 tumors. The present study was designed to ascertain, by reference to odds ratio estimates of relative risk by tumor size and histologic grade, whether this was more likely to be due to increased innate predisposition of dense parenchymal patterns to grade 3 tumors, or to dedifferentiation of cases missed at screening due to dense patterns. If the observation were due entirely to dedifferentiation, then for a given size the relative risk of grade 3 tumors would be the same as for grades 1-2. Size-specific relative risks of grade 3 tumors were higher than those of grade 1-2 tumors. It is concluded that the majority of the enhanced risk of grade 3 tumors is due to enhanced innate predisposition to grade 3 tumors in dense breasts.

Impact of false-positive mammography on subsequent screening attendance and risk of cancer

BACKGROUND

One area of concern within the largely successful UK National Health Service breast screening programme is the relatively high proportion of women showing mammographic abnormalities who undergo further diagnostic tests that prove negative. Previous studies suggest that, in addition to increasing anxiety, such false-positive mammography is associated with increased risk of subsequent interval cancer. In the present article, we quantify this increased risk, investigate whether it extends to cancers detected at rescreening, and determine whether cancers differ between women who have, and have not, experienced false-positive mammography.

METHODS

This was a retrospective cohort study of 140,387 women aged 49-63 years routinely invited for first screening by the East Anglian National Health Service breast screening programme. Proportions reattending, and subsequent risk and pathological attributes of cancer were compared between women who underwent further (negative) assessment following false-positive mammography and women mammographically normal at first screen.

RESULTS

At first screen, 108,617 (91.9%) of the screened women were mammographically normal, 4278 (3.6%) were assessed and then judged normal, and 514 (0.4%) underwent benign biopsy. Compared with nonassessed normal women, reattendance was lower among assessed women: 83.1% (95% confidence interval [CI], 82.0-84.1) versus 85.7% (95% CI, 85.5-85.9) (odds ratio [OR], 0.82; 95% CI, 0.76-0.89). Assessed women were at greater risk of interval cancer (rate per 1000 women screened, 9.6 [95% CI, 6.8-12.4] versus 3.0 [95% CI, 2.7-3.4]; OR, 3.19 [95% CI, 2.34-4.35]), and also of cancer detected at second screen (rate per 1000, 8.4 [95% CI, 5.8-10.9] versus 3.9 [95% CI, 3.5-4.3]; OR, 2.15 [95% CI, 1.55-2.98]). More cancers in assessed women measured >or = 20 mm (OR, 1.59; 95% CI, 0.99-2.55).

CONCLUSIONS

Women undergoing false-positive mammography at first screen were less likely to reattend for subsequent screens than were nonassessed women, yet they were more likely to develop interval cancers or cancers at second screen, and their cancers were larger. Factors predisposing for false-positive mammography require investigation. Women should be encouraged to continue with screening.