DY Pattern Research Articles

Association Between Mammographic Density and Age-Related Lobular Involution of the Breast

Mammographic density and lobular involution are both significant risk factors for breast cancer, but whether these reflect the same biology is unknown. We examined the involution and density association in a large benign breast disease (BBD) cohort. Women in the Mayo Clinic BBD cohort who had a mammogram within 6 months of BBD diagnosis were eligible. The proportion of normal lobules that were involuted was categorized by an expert pathologist as no (0%), partial (1% to 74%), or complete involution (>or= 75%). Mammographic density was estimated as the four-category parenchymal pattern. Statistical analyses adjusted for potential confounders and evaluated modification by parity and age. We corroborated findings in a sample of women with BBD from the Mayo Mammography Health Study (MMHS) with quantitative percent density (PD) and absolute dense and nondense area estimates. Women in the Mayo BBD cohort (n = 2,667) with no (odds ratio, 1.7; 95% CI, 1.2 to 2.3) or partial (odds ratio, 1.3; 95% CI, 1.0 to 1.6) involution had greater odds of high density (DY pattern) than those with complete involution (P trend < .01). There was no evidence for effect modification by age or parity. Among 317 women with BBD in the MMHS study, there was an inverse association between involution and PD (mean PD, 22.4%, 21.6%, 17.2%, for no, partial, and complete, respectively; P trend = .04) and a strong positive association of involution with nondense area (P trend < .01). No association was seen between involution and dense area (P trend = .56). We present evidence of an inverse association between involution and mammographic density.

Lobular Involution and Mammographic Density: Independent Contributors to Breast Cancer Risk.

Abstract Background: Women with benign breast disease are at elevated breast cancer risk. In order to accurately predict a woman's individual risk of breast cancer, a breast cancer risk-prediction model is needed that incorporates significant breast cancer risk factors. This report describes two factors: tissue based assessment of lobular involution, and radiological marker- mammographic density (MD). Lobular involution, or physiologic atrophy of the breast glandular epithelium, is inversely associated with breast cancer risk. MD is a strong positive risk factor for breast cancer. With increasing age, the extent of lobular involution increases while MD decreases. However, it is unclear whether involution and MD represent independent breast cancer risk factors. We examined breast cancer risk associated with lobular involution and MD in women with benign breast disease (BBD) to determine whether these features are independently associated with breast cancer risk.Methods: Using the Mayo Clinic Surgical and Pathology Indices, 9376 women ages 18 to 85 with benign excisional breast biopsy between January 1, 1967 and December 31, 1991 were identified and formed the Mayo BBD cohort. We studied a sub-cohort of women diagnosed with BBD between 1985 and 1991 (when MD was clinically assessed and recorded) who had a mammogram within 6 months of the BBD diagnosis. Breast cancer outcomes were determined through the Mayo medical records and a study-specific questionnaire. Lobular involution extent was assessed in background tissue as 'none' (0% lobules involuted), 'partial' (1-74% lobules involuted) or 'complete' (≥75% lobules involuted). MD was classified as Wolfe's parenchymal pattern (PP) as N1/ fatty; P1; P2; and DY/ homogenously dense. Hazard ratios and confidence intervals were calculated using Cox regression analyses, adjusting for confounders: age, parity, BMI, BBD histology, menopausal status, family history, PP and involution extent.Results: A total of 2666 women in the Mayo BBD cohort, with biopsies between 1985 and 1991, had a mammogram within 6 months of the breast biopsy. The mean age at biopsy was 54.6 years. After a mean follow-up of 13.3 years, 172 (6.5%) women developed breast cancer. After adjustment for PP and other confounders, women with no or partial involution had elevated risk compared to women with complete involution (HR 2.62 [95% CI 1.39, 4.94] for no involution and 1.61 [95% CI 1.03, 2.53] for partial involution; complete involution as reference group; p for trend 0.003). Moreover, women with dense breasts were at greater risk compared to women with nondense breasts (HR 1.67 [95% CI 1.0, 2.73] for DY pattern, 1.96 [95% CI 1.2 – 3.21] for P2, 1.23 [95% CI 0.67, 2.26] for P1; N1 category as reference group; p for trend 0.02). Multivariate analyses also showed that women with the combination of no involution and dense breasts had greater risk compared to those with complete involution and nondense breasts (HR 4.08 [95% CI 1.72, 9.68]).Conclusion: Lobular involution and MD are both risk factors for breast cancer; this report is the first to demonstrate that each provides unique information about breast cancer risk. These findings emphasize the potential for inclusion of both these factors in future breast cancer risk-prediction models. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6064.

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

IntroductionThe 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.MethodMammograms 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.ResultsThe 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.ConclusionThe 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.

Size, node status and grade of breast tumours: association with mammographic parenchymal patterns.

A case-control study was designed to assess the association of mammographic parenchymal patterns with the risk of in-situ and invasive breast cancer. In addition, the relationship between tumour characteristics and mammographic patterns were also investigated. A total of 875 patients with breast cancer were selected and matched with 2601 controls. Mammographic parenchymal patterns of breast tissue were assessed according to Wolfe's classification, and statistical analysis was by conditional logistic regression. Relative to the N1 pattern, the odds ratios of having an invasive breast cancer associated with the P2 and DY patterns were 1.8 and 1. 4, respectively. In addition, the odd ratios of having an invasive grade 3 breast cancer associated with the P2 and DY patterns were 2. 8 and 3.9, respectively. Relative to the combined N1/P1 pattern, the odd ratios of having a breast cancer smaller than 14 mm, 15-29 mm, or larger than 30 mm associated with the combined high-risk P2/DY pattern (P2 + DY) were 1.2, 1.6, and 2.0, respectively. Finally, women with the P2/DY pattern were twice as likely to have a breast cancer which had already spread to the axillary nodes, compared to women with women with the N1/P1 pattern (odds ratios of 2.1 and 1.4, respectively). Our results confirm previous findings suggesting that mammographic parenchymal patterns may serve as indicators of risk for breast cancer. Our results also suggest that mammographic parenchymal patterns are associated with the stage at which breast cancer is detected.

Is a Dense Mammographic Parenchymal Pattern a Contraindication to Hormonal Replacement Therapy?

The aim of the study was to find out whether the effect of hormonal replacement therapy (HRT) is modified by the mammographic parenchymal patterns on the risk of breast cancer. Subjects were 4163 Finnish women aged 40-47 years at entry who were invited to breast cancer screening every second year from 1982 to 1990. Mammographic parenchymal patterns (Wolfe's classification) were recorded at each screening round. The information, on use of HRT, was recorded from 1984. The follow-up ended in 1993 and up until that time 68 new breast cancers were diagnosed. A Poisson regression model was used in the analysis of the data. Use of HRT was not related to the risk of breast cancer (RR = 0.7, 95% CI 0.4-1.4), whereas mammographic parenchymal pattern was statistically significantly associated with risk of breast cancer. The age-adjusted relative risk of breast cancer among women with P2 versus N1 pattern was 2.5 (95%CI 1.3-4.8) and with DY versus N1 pattern 4.9 (95%CI 1.6-15.1). Women using HRT and with DY pattern were at substantially increased risk of breast cancer (RR = 11.6, 95%CI 2.5-53.6) compared with women not using HRT and with N1 pattern. There was an increased risk of breast cancer among women with DY mammographic parenchymal pattern who used HRT, which was consistent with a synergistic joint effect.

Unfavourable change in mammographic patterns and the breast cancer risk factors.

The purpose of the study was to estimate the incidence of unfavourable mammographic pattern by risk factors of breast cancers. Data consisted of 1890 Finnish women with mammographic pattern of either N1 or P1 (Wolfe's classification) at the initial screening. The screening was repeated every second year from 1982 to 1990 and at each screening round the mammographic pattern was assessed. The incidence rate of P2,DY pattern was 1.9/100 woman years. The incidence of P2,DY pattern was significantly related to age. The age-adjusted odds ratio (OR) (based on logistic regression) was 2.0 (95% CI 1.0-3.9) among women with hormonal replacement therapy (HRT), 0.6 (95% CI 0.4-0.9) among postmenopausal women, 0.2 (95% CI 0.1-0.4) among women with large breasts and 0.2 (95% CI 0.1-0.3) among women with large body mass index (BMI). After multivariate adjustment by logistic regression only the effect of BMI remained statistically significant, odds ratio of P2,DY pattern for women with BMI 25 or more was 0.2 (95% CI 0.1-0.6) compared to women with BMI less than 20.

Mammographic parenchymal patterns and mode of detection: implications for the breast screening programme.

To assess the effects of mammographic parenchymal patterns on the risk of breast cancer detected at first screen, second screen, and in the interval between these two screens. A nested case-control study within a screening cohort in East Anglia was designed. The study group comprised 502 patients with cancer at the prevalence screening round, 198 patients with interval cancer, and 175 with cancer at the first incidence screen. These patients were matched with 2601 controls. The mammographic parenchymal patterns of breast tissue were assessed according to Wolfe's classification. Statistical analysis was by conditional logistic regression. Overall, 67% of patients and 59% of controls were considered to have high risk pattern (P2 + DY) mammogram. The risk associated with P2 or DY mammographic patterns compared with N1 was higher for interval cancers (odds ratios (ORs) 2.2 and 2.4 respectively) than for screen detected cancers (ORs 1.7 and 1.1 respectively). For interval cancers in the first 18 months after the last negative mammogram, the risk was particularly high (ORs 3.8 for P2 and 4.1 for DY compared with N1). The high risk associated with P2 and DY patterns was concentrated on invasive ductal grade III cancers (ORs 2.7 and 3.8) rather than grade I or II cancers (ORs 1.6 and 1.2). The study strongly suggests that screening effectiveness is reduced for high risk parenchymal patterns which are associated with high grade cancers. Changes should aim at improving screening sensitivity for dense parenchymal patterns, and the diagnosis of high grade tumours.

Favorable change in mammographic parenchymal patterns and breast cancer risk factors.

The aim of our study was to estimate the incidence of favorable mammographic patterns and to assess the incidence by risk factors of breast cancer. Data relate to 1,947 women aged 40-47 years who were screened by mammography every second year and whose mammographic parenchymal pattern at initial screening was either P2 or DY (Wolfe's classification). The pattern was assessed at each screening round. The incidence of N1,P1 parenchymal pattern by risk factors was estimated. The Cox proportional hazards model was applied in univariate and multivariate analyses of the data. The incidence of N1,P1 pattern was 12.5/100 woman years among women with P2,DY pattern at the beginning of follow-up. The relative risk of N1,P1 pattern adjusted for the other risk factors for women aged 45 years or more was 1.7 [95% confidence interval (CI) 1.5-1.9] compared with younger women. The adjusted relative risk of N1,P1 pattern among women with a body mass index (BMI) of 25 or more was 2.1 (95% CI 1.6-2.8) compared with women with a BMI of less than 20; women with more than 2 pregnancies had a 30% higher adjusted relative risk (RR = 1.3, 95% CI 1.1-1.6) than women with no pregnancies. The incidence of favorable mammographic parenchymal pattern was significantly related to old age, large BMI and multiparity. The effects of age and BMI on incidences of favorable and unfavorable change potentiate each other but not that of parity.

Short communication: breast parenchymal patterns and their changes with age.

In studies on mass screening, it has often been reported that tumours in breasts with dense parenchyma are difficult to detect and may have a more advanced stage at diagnosis. Shorter rescreening intervals have been suggested for these women but, before recommending such a strategy, it is important to investigate how often dense breast parenchyma (P2 and DY patterns according to Wolfe) is actually present in a screening population and to what extent these patterns change with age. The prevalence of dense breast parenchyma (P2 and DY) in our study population was 33% at first examination (n = 2581), which is fairly low compared with other screening populations. Its presence was strongly, inversely age-dependent. Breast patterns of 1177 women, aged 35-85 years, were followed for 12 years. In 39% (182/461) of the women with a P2 or DY pattern at their first examination, regression to a lucent pattern (N1 and P1) occurred over the years. The majority of these women were assumed to have reached menopause in the follow-up period. These findings support the hypothesis that the presence of dense breast parenchyma is related to the reproductive period and indicate that shortening the rescreening intervals would be most effective in pre-menopausal age groups.

The influence of risk factors for breast cancer on mammographic patterns: a multivariate analysis

The relationship between the mammographic parenchymal patterns and known risk factors for breast cancer was investigated in the population of Merseyside. Two sample populations of self-referred women were studied. The ‘index’ population was drawn from the employees of a number of major companies on Merseyside and comprised 5413 women aged 35–60 years. The ‘test’ population of 2224 women aged 35–65 years was drawn from the wider Merseyside population. Full histories were recorded on questionnaires and the women were examined by a nurse examiner who recorded her findings on the same proforma. Mammography was carried out and the films were then coded according to Wolfe's classification of mammographic parenchymal patterns. All this data was transferred to the University of Liverpool mainframe computer. Analysis of the data was undertaken using the Statistical Package for the Social Sciences-X (SPSSX). The frequency of the occurrence of the relevant factors within both populations was determined. The relationship between the various factors and the parenchymal patterns in the index population was calculated using crosstabulation analysis. Those factors which showed a statistically significant relationship to the breast patterns were then entered in to a multivariate analysis using a ‘logit’ regression form of loglinear regression. The equations derived by this method were tested by calculating predicted values for the proportion of given breast patterns in the subgroups of the population with specified characteristics and comparing the predicted values with the actual values within the population. Those equations which were found to be satisfactory were then tested in the ‘test’ population. From this study it was deduced that the parenchymal patterns are associated strongly with body build. Parity and a history of breast biopsy also have a significant effect. Age at first pregnancy and a history of breast feeding have a minor effect on some of the patterns. The equations for the DY pattern and for ‘high risk’ versus ‘low risk’ patterns are accurate predictors of the proportion of these patterns in the population. The equations for the P 2 pattern are poor predictors of the proportion of P 2. The existence of a relationship between risk factors for breast cancer and the mammographic parenchymal patterns has been confirmed.

Dietary habits and mammographic patterns in patients with breast cancer.

Between 1983 and 1986, dietary history interviews were conducted with 238 women aged 50-65 years who had surgery for stage I-II breast cancer. Diagnostic mammograms were coded in line with Wolfe's criteria in N1, P1, P2, and Dy patterns. Women with Dy pattern reported significantly higher intake of total fat, monounsaturated fatty acids (FA), polyunsaturated FA, n-3 FA, n-6 FA in per cent of energy (E%), and alpha-tocopherol in mg/10 MJ. Fat intake was lowest in women with N1 pattern and highest in those having Dy pattern. Patients having ER-rich cancers and Dy pattern reported significantly higher intake of total fat, monounsaturated FA, polyunsaturated FA, n-6 FA (E%), and alpha-tocopherol (mg/10 MJ), as well as significantly lower intake of carbohydrate (E%) and calcium (g/10 MJ). In the stepwise multivariate analysis, the multivariate-odds ratio (OR) for having P2 + Dy patterns was 1.06 (95% confidence interval (CI), 1.02-1.12) for each increment in E% of total fat. In women with ER-rich tumors this OR was 1.09 (95% CI, 1.02-1.16). The highest self-reported body mass index (BMI) was observed in women with N1 + P1 patterns. OR for having P2 + Dy patterns was 0.91 (95% CI, 0.83-0.98) for each increment in 1 kg/m2 of BMI. The results suggest that dietary habits affect the mammographic parenchymal pattern in women with breast cancer and that a high fat intake is associated with a higher proportion of mammograms with Dy pattern in such patients.

Quantitative magnetic resonance imaging parameters and their relationship to mammographic pattern.

Breast cancer exhibits wide international variation in incidence, which has led to the identification of several factors correlating with the risk of the disease. Magnetic resonance imaging (MRI) techniques can provide quantitative information about the biological and physical properties of tissue. This work tested several magnetic resonance tissue parameters for their ability to distinguish quantitatively between breast tissues in subjects at substantially different risk for breast cancer as defined indirectly by their parenchymal pattern on mammograms. Quantitative MRI parameters (relative water content, longitudinal relaxation time [T1], and transverse relaxation time [T2]) were measured for breast tissue using newly developed techniques in two groups of women with mammographic parenchymal appearance associated with high (Dy pattern [i.e., extensive nodular or diffuse density]; n = 12) or low (N1 pattern [i.e., breast containing mainly fat]; n = 11) risk of breast cancer. The two groups have significantly different average relative water content (P less than .0001) and average T1 (P less than .0001). Pixel histograms of T2 values show marked differences between the two groups which can be characterized with a fourth moment parameter. Quantitative MRI techniques exhibit good potential for assessing tissue characteristics in the breast that are associated with risk of breast cancer. Future work will address the direct correlation of MRI parameters with risk of breast cancer.

Lobular carcinoma in situ of the breast: clinical, pathologic, and mammographic features.

Lobular carcinoma in situ (LCIS) was diagnosed in 165 surgical specimens (119 patients) at our institution between 1974 and 1987. LCIS was seen more often in younger women (mean age, 49 years) than other breast carcinomas were (mean age, 58 years). Sampling of a single breast revealed multifocal disease in 70% (96/138). When both breasts were sampled, bilateral foci were found in 50% (41/82). Of 165 breasts with foci of LCIS, 37% (61/165) had simultaneously occurring invasive cancers in the same breast. Direct mammographic-pathologic correlation of foci of LCIS was possible in 73 breasts (67 patients). Microcalcifications were an indication for biopsy in 49% (20/41) of breasts with a mammographic abnormality, but were a nonspecific finding often found in tissues adjacent to foci of LCIS. The mammogram was normal in 44% (32/73) of breasts with foci of LCIS. The mammograms of patients with LCIS and those from a group of age-matched control subjects were compared by using a modified form of Wolfe's criteria and the percentage of fibroglandular elements. LCIS was seldom found in an N1 breast (1% vs 29%) or in a breast with less than 25% of its parenchymal area occupied by fibroglandular density (3% vs 33%). Compared with the control group, breasts with LCIS had more than 50% fibroglandular density (85% vs 45%) and a much higher frequency of the DY pattern (56% vs 36%). More fibroglandular density was seen in the LCIS group at all ages. Postmenopausally, the frequencies of the DY pattern and fibroglandular density greater than 50% in LCIS patients were nearly double those in the control group. LCIS patients have disease of the entire breast parenchyma, characterized by multifocality and bilaterality of various forms of lobular disease. Their mammograms reveal a higher rate of the DY pattern and higher percentages of fibroglandular or parenchymal density than those of age-matched controls. In LCIS patients, persistence of the DY pattern, or large amounts of fibroglandular density postmenopausally supports the concept that mammographically dense breasts are a marker for increased cancer risk in women 50 years old and older.

The relationship of “high risk” mammographic patterns to histological risk factors for development of cancer in the human breast

In the UK Trial for the Early Detection of Breast Cancer in Nottingham, 119 women were identified as having fibrocystic change with epithelial hyperplasia or in situ carcinoma. Their mammograms were classified according to Wolfe's criteria and the corresponding histology for each patient was classified for degrees of epithelial hyperplasia, atypia and in situ neoplasia using Page's criteria. A control population of patients presenting for breast screening was used to represent the general population. No correlation was found between the four mammographic Wolfe patterns, N1, P1, P2 and DY and histological evidence of epithelial hyperplasia, atypia or in situ carcinoma. A further study was carried out to determine histological features of Wolfe pattern, using radiological examination of resected breast tissue. The variation in Wolfe pattern was related to the distribution of fibrous and adipose tissue in the breast interlobular stroma and appeared to have no relationship to epithelial parenchymal content. This information does not support the hypothesis that radiographic densities of P2 and DY patterns correspond to high risk epithelial proliferation.

Relationship of Mammographic Parenchymal Patterns with Breast Cancer Risk Factors and Risk of Breast Cancer in a Prospective Study

A prospective study has been conducted on 4954 female volunteers from the Island of Guernsey between 1977 and 1985 to examine risk factors for breast cancer and their relationship to mammographic parenchymal patterns as assessed by Wolfe's method of grading. Up to September 1988, 69 women had developed breast cancer, 11 of whom were prevalent cases being diagnosed within six months of mammography. The remaining incident cases were diagnosed six to 126 months (median 65 months) after entry to the study. Univariate analysis showed that the distribution of Wolfe grades in the population was significantly associated with menopausal status, age, parity, adiposity, age at menarche, age at first childbirth and use of oral contraception, but not with a family history of breast cancer. Multivariate analysis of the data for these variables from either pre- and/or post-menopausal women indicated that age, parity and adiposity were significantly related to Wolfe grade pattern. Age had an opposite effect in pre- compared with postmenopausal women thus the probability of either a P2 or DY pattern increased with increasing age in premenopausal but decreased in postmenopausal women so that incidence peaked around the menopause. Other variables did not achieve significance in the multivariate analysis. Odds ratios (ORs) were calculated for women with P2 or DY patterns using those with N1 or P1 grades as the reference group. The ORs were determined at two censoring times; one at five years and the other to include the most recent follow-up of this cohort. The ORs were adjusted for years of follow-up, age and adiposity and in postmenopausal women adjustment was also made for age at menarche.(ABSTRACT TRUNCATED AT 250 WORDS)

Mammographic parenchymal patterns in women receiving noncontraceptive estrogen treatment.

Two population-based registers, one of women with at least one estrogen prescription, and the other of women who had undergone mammographic screening, were linked by means of the national registration number, revealing 3,436 estrogen-treated women who had attended the mammography screening program. Their mammographic parenchymal pattern was classified according to the criteria of Wolfe into two groups, one with a low risk and the other with a high risk of development of breast cancer. Estrogen replacement therapy was more common in women with a high risk than in those with a low risk mammographic parenchymal pattern (standardized morbidity ratio = 1.3). The increased probability of receiving noncontraceptive estrogen treatment in women with a high risk mammographic parenchymal pattern remained when the impact of several possible confounding factors had been taken into account in a logistic regression analysis (odds ratio = 1.36, 95% confidence interval 1.24-1.49). No evidence was found of a shift toward the unfavorable mammographic parenchymal pattern during treatment, which suggests that the treatment itself was not responsible for the high proportion of P2 and DY patterns. The mammographic parenchymal pattern must therefore be looked upon as a confounder in the context of studying breast cancer risk after estrogen treatment.

Mammographic parenchymal patterns as indicators of breast cancer risk.

Mammographic parenchymal patterns have been suggested as indicators of breast cancer risk. However, few well-controlled studies have used prediagnostic mammograms to determine the pattern classification. The authors studied 266 cases of breast cancer and 301 controls from 25 screening centers of the Breast Cancer Detection and Demonstration Project, a nationwide screening program conducted between 1973 and 1980 to evaluate the risk associated with mammographic patterns using mammograms taken four years before the detection of breast cancer. Mammograms of the cancerous breast of cases and of the ipsilateral breast in the control matched to each case were blindly assessed by one of the investigators (J.N.W.), originator of the mammographic pattern classification. The breast cancer odds ratio among women with the combined P2 + DY patterns, compared with women with the N1 pattern, was 2.8 (95% confidence interval (CI): 1.6-5.1). This estimate of relative risk was comparable with the risk associated with other recognized breast cancer risk factors. The odds ratio among P2 + DY women with a first-degree family history of breast cancer was 5.5 (95% CI: 2.6-11.8) compared with N1 women without a family history. These data provide additional evidence that mammographic patterns are indicators for subsequent development of breast cancer, particularly among women with a first-degree family history of this malignancy.

Factors associated with mammographic parenchymal patterns

The relationship between mammographic parenchymal patterns and known risk factors for breast cancer was studied in 5319 consecutive women presenting for breast screening. Using a multivariate analysis, correlations were found in pre-menopausal women between breast size, weight, age at first pregnancy, history of biopsy and history of cyclical breast pain and parenchymal pattern. In post-menopausal women the parenchymal pattern correlates with breast size, weight, weight change, age at first pregnancy, a history of biopsy and a history of breast feeding. The DY pattern correlated with age, breast size, weight, history of biopsy and menopausal status. When pre-menopausal women were considered separately the DY pattern correlated only with weight and breast size.

Mammographic parenchymal patterns and quantitative evaluation of mammographic densities: a case-control study.

The classification of breast parenchymal patterns (N1, P1, P2, DY) and the percentage of the breast containing radiographic densities are two highly correlated radiographic measures proposed as predictors of the risk of breast cancer. In this case-control study, 160 cases of breast cancer and 160 matched controls from a mammography referral practice were compared to determine the risk of breast cancer associated with each of these two radiographic measures. The mammographic densities were quantified on caudal projections by means of a compensating polar planimeter. A relative risk estimate of 3.3 (p less than .05) was associated with the P2 + DY patterns compared with the N1 + P1 patterns. Significantly elevated risks of 4.3 to 5.5 also were observed among women whose breasts contained at least 25% mammographic densities, compared with women with less than 25% involvement. These radiographic measures tended to be more predictive of the risk of breast cancer in black women than in white women. Although the precise clinical roles of breast parenchymal patterns and densities have not been defined fully, the results of this study suggest that they are useful in the recognition of women at high risk of breast cancer. We make no claims that the findings of this study are sufficiently developed to be used as a basis for screening strategies.

Changes in Wolfe mammographic patterns with aging.

Mammograms of 212 women were examined at a mean interval of 15 (range 11-17) years, to determine whether there was any change in Wolfe mammographic pattern with age. The mean age of the patients at repeat mammography was 52 (range 32-75) years. The DY pattern tended to change to P2 or P1 with age. Those in whom the DY pattern remained tended to be younger (mean age 47 years) than those who changed to P2 (57 years), or P1 (55 years). Women whose pattern changed from DY to N1 had a mean age of 42 years. These findings support the hypothesis that the perilobular connective-tissue elements are the structures responsible for the dense appearance of the DY breast, as these elements would be most active between 15 and 45 years (peak reproductive period) and tend to regress later.