Mammographic density as a marker of susceptibility to breast cancer: a hypothesis.

We propose that radiological features of breast tissue provide an index of cumulative exposure to the current and past hormonal and reproductive events that influence breast cancer incidence. The changes in breast tissue that occur with ageing, and changes in the associated radiological features of the breast, are similar to the concept of "breast tissue ageing" proposed by Pike, and may explain features of the age-specific incidence of breast cancer, both within the population and between populations. These radiological features can be observed and measured, can be related directly to risk of breast cancer, and are likely to be of value in research into the etiology of breast cancer. Identification of the sources of variation in this radiological characteristic of the breast is likely to lead to a better understanding of the factors that cause breast cancer and to new approaches to prevention of the disease.

Association of involvement in psychological self-regulation with longer survival in patients with metastatic cancer: an exploratory study.

There have been numerous anecdotal claims that when patients are dedicated users of a variety of psychological self-regulation strategies, including relaxation, mental imaging, cognitive restructuring and meditation, such dedication may have a life-prolonging effect. Our aim was to test this possibility more rigorously, in patients with metastatic cancer.A prospective, longitudinal, correlative study was carried out on 22 patients with varying kinds of medically incurable metastatic cancer. The intervention was one year of weekly group psychological therapy. Extensive verbal data (patients' written homework and therapists' notes) were collected over the year. The extent of each patient's involvement with psychological work was estimated following a qualitative analysis of these data. Patients were classed as showing high, moderate, or low involvement on the basis of a quantitative rating of categories defined by the analysis. These three subgroups did not differ significantly in their expected median survival duration as estimated from independent quantitative predictions by a large panel of oncologists who analyzed the patients' medical charts at time of study entry.A significant relationship was found between degree of involvement in psychological work and survival duration. Results are presented as Kaplan-Meier survival curves (Fig. 2;P = 0. 006, Log Rank test) and as a graphic display of the median survival of each of the three groups (Fig. 3). The main likely confounders (medical status, age, quality of life, and attendance at therapy) were similar across subgroups and did not change the relation between psychological work and survival duration. Limitations in the design are discussed. However, the strong effects observed support clinical observations that dedicated involvement in psychological self-regulation may prolong the life of some patients with metastatic cancer.

A prospective, longitudinal study of the relationship of psychological work to duration of survival in patients with metastatic cancer.

This study is a prospective, longitudinal investigation of the psychological factors associated with the duration of survival in patients with metastatic cancers of various kinds who were receiving group psychotherapy. A correlative approach rather than an experimental (trials) design was used in the study because our aim was to relate the psychological attributes of each individual to survival rather than to test the efficacy of the intervention. Twenty-two patients with medically incurable metastatic cancer of various kinds received weekly group psychotherapy for up to 1 year, the great majority remaining well enough to attend the group for at least 8 months. During this time, they provided extensive verbal data, through written homework, and from notes taken by the therapists at interviews and during group sessions. These data were subjected to detailed qualitative analysis, as a result of which a number of psychological themes were defined. A quantitative rating was assigned to the data for each theme in each individual patient through team discussions. The scores for the individual themes were summed to produce a 'total psychological score', representing the degree of each patient's involvement with psychological self-help work. The values for each patient were then related to his or her survival duration. Cox regression analyses showed that this composite score, and five of six major themes, were significantly related to survival duration. These themes were: ability to act and change; willingness to initiate change; application to self-help work; relationships with others; and quality of experience. In contrast, there was no relationship between survival and four standard psychometric measures taken at the onset of therapy. However, results on a 5-point scale measuring the subject's expectancy that psychological efforts would affect the disease showed a strong relationship to survival. To control for differences in severity of disease as a factor possibly influencing psychological work, the analyses were repeated, using the survival duration predicted for each patient by a panel of oncologists as a covariate. Closely similar results were obtained. Limitations on the interpretation of the results are discussed. Within these limits, it appears that there is a strong association between longer survival and psychological factors related to the involvement of cancer patients in psychological self-help activities. While causality cannot be inferred, reasons are given for believing that this is not a result of the disease influencing the patients' psychology, but rather the converse.

Mammographic densities and the prevalence and incidence of histological types of benign breast disease. Reference Pathologists of the Canadian National Breast Screening Study.

There is now a large amount of evidence indicating that women with extensive areas of mammographic densities are 4-6 times more likely to develop breast cancer than those with little or no density in the mammogram. We have examined one potential biological explanation for this association by estimating the incidence of various histological types of benign breast disease in relation to mammographic density. We studied the large cohort of women taking part in the National Breast Screening Study (NBSS), a randomized trial of screening with mammography. Mammograms from subjects with biopsies (n = 423) and from a comparison group of subjects randomly selected from the NBSS (n = 465) were included. Histological slides from biopsied subjects (n = 353) were classified independently by the pathologists of the NBSS and by a review pathologist (H.M.J.). Mammographic density in more than 75% of the breast area was associated with an increased risk of incidence of hyperplasia without atypia, and of atypical hyperplasia and/or carcinoma in situ. The classifications of the review pathologist showed that, compared to women with no density, the relative risk of incident lesions for women with density in more than 75% of breast was 13.85 (95% CI 2.65-72.49) for hyperplasia, and 9.23 (95% CI 1.66-51.48) for atypical hyperplasia and/or carcinoma in situ. These findings suggest that the association between extensive mammographic density and breast cancer risk may, at least in part, be attributable to biological processes in the breast that give rise to these histological features that are known to be related to breast cancer risk.

Mammographic densities and risk of breast cancer among subjects with a family history of this disease.

BACKGROUND: A family history of breast cancer is known to increase risk of the disease, but other genetic and environmental factors that modify this risk are likely to exist. One of these factors is mammographic density, and we have sought evidence that it is associated with increased risk of breast cancer among women with a family history of breast cancer. METHODS: We used data from a nested case-control study based on the Canadian National Breast Screening Study (NBSS). From 354 case patients with incident breast cancer detected at least 12 months after entry into the NBSS and 354 matched control subjects, we analyzed subjects who were identified as having a family history of breast cancer according to one of three, nonmutually exclusive, criteria. We compared the mammographic densities of case patients and control subjects by radiologic and computer-assisted methods of measurement. RESULTS: After adjustment for other risk factors for breast cancer, the relative risks (RRs) between the most and least extensive categories of breast density were as follows: For at least one first-degree relative with breast cancer, RR = 11.14 (95% confidence interval [CI] = 1.54-80.39); for at least two affected first- or second-degree relatives, RR = 2.57 (95% CI = 0.23-28.22); for at least one first- or second-degree relative with breast cancer, RR = 5.43 (95% CI = 1.85-15.88). CONCLUSIONS: These results suggest that mammographic density may be strongly associated with risk of breast cancer among women with a family history of the disease. Because mammographic densities can be modified by dietary and hormonal interventions, the results suggest potential approaches to the prevention of breast cancer in women with a family history of breast cancer.

Glypican-3-deficient mice exhibit developmental overgrowth and some of the abnormalities typical of Simpson-Golabi-Behmel syndrome.

Glypicans are a family of heparan sulfate proteoglycans that are linked to the cell surface through a glycosyl-phosphatidylinositol anchor. One member of this family, glypican-3 (Gpc3), is mutated in patients with the Simpson-Golabi-Behmel syndrome (SGBS). These patients display pre- and postnatal overgrowth, and a varying range of dysmorphisms. The clinical features of SGBS are very similar to the more extensively studied Beckwith-Wiedemann syndrome (BWS). Since BWS has been associated with biallelic expression of insulin-like growth factor II (IGF-II), it has been proposed that GPC3 is a negative regulator of IGF-II. However, there is still no biochemical evidence indicating that GPC3 plays such a role.Here, we report that GPC3-deficient mice exhibit several of the clinical features observed in SGBS patients, including developmental overgrowth, perinatal death, cystic and dyplastic kidneys, and abnormal lung development. A proportion of the mutant mice also display mandibular hypoplasia and an imperforate vagina. In the particular case of the kidney, we demonstrate that there is an early and persistent developmental abnormality of the ureteric bud/collecting system due to increased proliferation of cells in this tissue element. The degree of developmental overgrowth of the GPC3-deficient mice is similar to that of mice deficient in IGF receptor type 2 (IGF2R), a well characterized negative regulator of IGF-II. Unlike the IGF2R-deficient mice, however, the levels of IGF-II in GPC3 knockouts are similar to those of the normal littermates.

Psychological response to long-term group therapy: a randomized trial with metastatic breast cancer patients.

Research has demonstrated that short-term psychological interventions improve the quality of life of cancer patients. However, there is much less evidence for the efficacy of long-term interventions. We report the psychometric results from a randomized clinical trial (n = 66) assessing the effects of an 8 month, weekly psychological intervention on 30 metastatic breast cancer patients. Subjects were assessed at baseline, 4, 8 and 14 months for mood, quality of life and adjustment to cancer. Results demonstrated little psychometric difference between the control (n = 36) and intervention groups over this length of time, in spite of the fact that when the intervention subjects attended a weekend of support and training in coping skills, the usual significant, short-term changes were observed. In the long-term intervention, subjects did experience more anxious preoccupation and less helplessness than the controls but no recorded improvements in mood or quality of life. However, profound clinical changes were observed by the therapists, similar to those noted by Spiegel et al. (1981). We conclude that many of the psychological changes made by subjects in long-term interventions may elude conventional psychometric assessment. Further research, of a rigorous qualitative nature, is required to develop a clearer understanding of the experience of living and eventually dying of cancer within the context of a long-term intervention.

Macronutrient intake and change in mammographic density at menopause: results from a randomized trial.

To examine the effects of dietary fat intake on breast cancer risk, we are conducting a randomized trial of dietary intervention in women with extensive areas of radiologically dense breast tissue on mammography, a risk factor for breast cancer. Early results show that after 2 years on a low-fat, high-carbohydrate diet there is a significant reduction in area of density, particularly in women going through menopause. In women who went through menopause during the 2-year follow-up, the mean decreases in area of density and percentage of density in the intervention group were 11.0 cm2 and 11.0%, respectively, whereas the control group decreased 4.5 cm2 and 5.2%. The purpose of this analysis was to determine whether changes in intake of specific macronutrients could account for the observed reduction in breast density in these women. Differences between 2-year and baseline values of macronutrients (averaged over 3 nonconsecutive days of food intake) were calculated. We examined the effect of dietary variables, adjusted for changes in total calorie intake and weight and for family history of breast cancer, on changes in area of density and percentage of density using linear regression. Reduction in total or saturated fat intake or cholesterol intake was significantly associated with decreased dense area (p < or = .004). The most significant dietary variable associated with reduction in percentage of density was reduction in dietary cholesterol intake (P = 0.001), although reducing saturated fat intake was of borderline significance (P = 0.05). The effect of the membership in the intervention and control groups on change in area of density or percentage of density was reduced by models that included changes in intake of any fat, or cholesterol, or carbohydrates. The observation of an effect of diet at menopause on breast density, a marker of increased risk of breast cancer, may be an indication that exposures at this time have an enhanced effect on subsequent risk.

Mammographic densities and breast cancer risk.

The radiological appearance of the female breast varies among individuals because of differences in the relative amounts and X-ray attenuation characteristics of fat and epithelial and stromal tissues. Fat is radiolucent and appears dark on a mammogram, and epithelium and stroma are radiodense and appear light. We review here the evidence that these variations, known as mammographic parenchymal patterns, are related to risk of breast cancer. Studies that used quantitative measurement to classify mammographic patterns have consistently found that women with dense tissue in more than 60-75% of the breast are at four to six times greater risk of breast cancer than those with no densities. These risk estimates are independent of the effects of other risk factors and have been shown to persist over at least 10 years of follow up. Estimates of attributable risk suggest that this risk factor may account for as many as 30% of breast cancer cases. Mammographically dense breast tissue is associated both with epithelial proliferation and with stromal fibrosis. The relationship between these histological features and risk of breast cancer may by explained by the known actions of growth factors that are thought to play important roles in breast development and carcinogenesis. Mammographically dense tissue differs from most other breast cancer risk factors in the strength of the associated relative and attributable risks for breast cancer, and because it can be changed by hormonal and dietary interventions. This risk factor may be most useful as a means of investigating the etiology of breast cancer and of testing hypotheses about potential preventive strategies.

The relationship of anthropometric measures to radiological features of the breast in premenopausal women.

We studied 273 premenopausal women recruited from mammography units who had different degrees of density of the breast parenchyma on mammography, in whom we measured height, weight and skinfold thicknesses. Mammograms were digitized to high spatial resolution by a scanning densitometer and images analysed to measure the area of dense tissue and the total area of the breast. Per cent density and the area of non-dense tissue were calculated from these measurements. We found that the mammographic measures had different associations with body size. Weight and the Quetelet index of obesity were strongly and positively associated with the area of non-dense tissue and with the total area of the breast, but less strongly and negatively correlated with the area of dense tissue. We also found a strong inverse relationship between the areas of radiologically dense and non-dense breast tissue. Statistical models containing anthropometric variables explained up to 8% of the variance in dense area, but explained up to 49% of the variance in non-dense area and 43% of variance in total area. These results suggest that aetiological studies in breast cancer that use mammographic density should consider dense and non-dense tissues separately. In addition to per cent density, methods should be examined that combine information from these two tissues.

Analysis of mammographic density and breast cancer risk from digitized mammograms.

To evaluate the association between mammographic density and breast cancer risk, a simple, observer-assisted technique called interactive thresholding was developed that allows reliable quantitative assessment of mammographic density with use of a computer workstation. Use of this technique helps confirm that mammographic density is one of the strongest risk factors for breast cancer and is present in a large proportion of breast cancer cases. The strong relationship between mammographic density and breast cancer risk suggests that the causes of breast cancer may be better understood by identifying the factors associated with mammographically dense tissue and determining how such tissue changes as these factors vary. Furthermore, because it can be modified, mammographic density may also be a good vehicle for the development and monitoring of potential preventive strategies. Areas of ongoing investigation include evaluating a potential genetic component of mammographic density by comparing density measurements in twins and understanding changes in density relative to age, menopausal status, exogenous hormone use, and exposure to environmental carcinogens. In addition, work is ongoing to establish measurements from imaging modalities other than mammography and to relate these measurements directly to breast cancer risk.

What attitudes and beliefs underlie patients' decisions about participating in chemotherapy trials?

The theory of reasoned action, which postulates that personal attitudes and external social influences predict intentions to undertake a behavior, was used as a conceptual framework for developing a questionnaire to elicit beliefs and attitudes associated with the decision to participate in a hypothetical cancer chemotherapy trial. After completing the questionnaire, two-thirds of the 150 respondents indicated they would enroll in such a trial if it were available. Considerable variation existed in both "universal" and "trial-specific" beliefs and attitudes underpinning their intentions. A substantial amount of the variance in "intention" to participate was explained by "attitude" alone (75%). Social influences, although statistically significant, made a mere 1% additional contribution. One interpretation is that subjective expected-utility theory, which essentially predicts beliefs or "attitude," is a better model. The authors conclude that both theories may be criticized regarding how well they capture the rationality and nuances of decision behavior.

A randomized controlled trial of the effects of group psychological therapy on survival in women with metastatic breast cancer.

In order to test the effect of a psychological intervention on survival from cancer, 66 women with metastatic breast cancer, all receiving standard medical care, were randomly assigned into two groups; one group (n = 30) attended the psychological intervention, consisting of 35 weekly, 2 h sessions of supportive plus cognitive behavioral therapy; the control group (n = 36) received only a home study cognitive behavioral package. No significant difference was found in survival post-randomization between the groups as assessed by a log rank test 5 years after the commencement of the study. As expected, several prognostic factors were significant predictors of survival: metastatic site, hormonal receptor status, and chemotherapy prior to randomization. While many personal and demographic variables did not influence survival, there was a significant effect of self-reported exercise (possibly due to better health). A small subgroup of intervention subjects who attended outside support groups also survived significantly longer than those who did not. The strengths and limitations of the present study are discussed, and the results contrasted with those of a well known study by Spiegel et al. (Spiegel, D., Bloom, J.R., Kraemer, H.C. and Gottheil, E. (1989) Lancet ii, 888-891). We propose that a different experimental design (correlative) may be needed to show any effect of self-help behaviors and psychological attributes in a small minority of patients.

Breast cancer risk and measured mammographic density.

It has been well established that there is a positive correlation between the dense appearance of breast stroma and parenchyma on a mammogram and the risk of breast cancer. Subjective assessment by radiologists indicated relative risks on the order of 4 to 6 for the group of women whose mammograms showed a density of over 75% or more of the projected area compared to those with an absence of density. In order to obtain a more quantitative, continuous and reproducible means of estimating breast density, which is sensitive to small changes, we have developed quantitative methods for the analysis of mammographic density, which can be applied to digitized mammograms. These techniques have been validated in a nested case-control study on 708 women aged 40-59 years (on entry) who participated in a national mammographic screening study. An interactive image segmentation method and two completely automated techniques based on image texture and grey scale histogram measures have been developed and evaluated. While our methods all show statistically significant risk factors for dense breasts, the interactive method currently provides the highest risk values (relative risk 4.0, 95% confidence interval (CI) = 2.12-7.56) compared to a measure based on the shape of the image histogram (relative risk 3.35, 95% CI = 1.57-7.12) or the fractal dimension of the mammogram (relative risk 2.54, 95% CI = 1.14-5.68). All methods were highly consistent between images of the left and right breast and between the two standard views (cranio-caudal and medio-lateral oblique) of each breast, so that studies can be done by sampling only one of the four views per examination. There is a large number of factors in addition to breast density which affect the appearance of the mammogram. In particular, the assessment of density is made difficult where the breast is not uniformly compressed, e.g. at the periphery. We have designed and are currently evaluating an image processing algorithm that effectively corrects for this problem and have considered methods for controlling some of the variables of image acquisition in prospective studies. Measurements of breast density may be helpful in assigning risk groups to women. Such measurements might guide the frequency of mammographic screening, aid the study of breast cancer aetiology, and be useful in monitoring possible risk-modifying interventions. Using our techniques, we have been able to show that reduction of the proportion of fat in the diet can result in reductions of breast density, although the direct connection to risk has not yet been made. The relationship between breast density and hormone-related and genetic factors is also of great interest. It is often not possible or ethical to obtain mammograms on some groups of women for whom information on density would be very useful. This includes younger women as well as groups in which it would be desirable to obtain such information at frequent intervals. For this reason, we are exploring the use of imaging approaches such as ultrasound and magnetic resonance imaging, which do not require ionizing radiation, to make measurements analogous to those now being performed by using X-ray mammograms.

Self-reported physical and emotional health of women in a low-fat, high-carbohydrate dietary trial (Canada).

OBJECTIVES: While decreased intake of dietary fat may have significant positive effects on women's health by reducing the risk of cancer and other diseases, little research has been carried out to determine the potential adverse effects of dietary fat reduction. This study compares the self-reported physical and emotional health of 402 low fat intervention and control group participants in the Canadian Diet and Breast Cancer Prevention Trial. METHODS: Subjects who had been participating in the dietary intervention trial for at least 2 years completed 3 mailed questionnaires: two designed to assess physical and emotional health (MOS 36-Item Short-Form Health Survey (SF-36) and the Women's Health Questionnaire (WHQ)) and a Health Practices Survey. RESULTS: There were no significant differences between the study groups on total scores or any of the subscales/health domains for the SF-36 or the WHQ. In premenopausal women only, intervention group subjects scored significantly lower on the vasomotor symptoms scale, indicating less symptom experience. Frequency of visits to physicians and alternative health practitioners were not significantly different between the study groups. CONCLUSIONS: The results of this study suggest that participation in a low-fat, high-carbohydrate dietary intervention did not have any detrimental effects on participants' self-reported physical health or emotional well-being.

Mammographic densities and breast cancer risk.

Variations between individuals in the radiographic appearance, or mammographic pattern, of the female breast arise because of differences in the relative amounts and X-ray attenuation characteristics of fat and connective and epithelial tissue. Studies using quantitative methods of assessment have consistently shown these variations to be strongly related to risk of breast cancer. Individuals with extensive areas of radiologically dense breast tissue on the mammogram have been found to have a risk of breast cancer that is four to six times higher than women with little or no density. In this paper, we propose a model for the relationship of mammographic densities to risk of breast cancer. We propose that the risk of breast cancer associated with mammographically dense breast tissue is due to the combined effects of two processes: cell proliferation (mitogenesis), induced by growth factors and sex hormones and influenced by reproductive risk factors for breast cancer; and damage to the DNA of dividing cells (mutagenesis) by mutagens generated by lipid peroxidation. We review the evidence that each of these processes is associated with mammographic densities and propose further work that we believe should be done to clarify these relationships.

Automated analysis of mammographic densities and breast carcinoma risk.

BACKGROUND: There is considerable evidence that one of the strongest risk factors for breast carcinoma can be assessed from the mammographic appearance of the breast. However, the magnitude of the risk factor and the reliability of the prediction depend on the method of classification. Subjective classification requires specialized observer training and suffers from inter- and intraobserver variability. Furthermore, the categoric scales make it difficult to distinguish small differences in mammographic appearance. To address these limitations, automated analysis techniques that characterize mammographic density on a continuous scale have been considered, but as yet, these have been evaluated only for their ability to reproduce subjective classifications of mammographic parenchyma. METHODS: In this study, using a nested case-control design, the authors evaluated the direct association between breast carcinoma risk and quantitative image features derived from automated analysis of digitized film mammograms. Two parameters, one describing the distribution of breast tissue density as reflected by brightness of the mammogram (regional skewness) and the other characterizing texture (fractal dimension), were calculated for images from 708 subjects identified from the Canadian National Breast Screening Study. RESULTS: These parameters were evaluated for their ability to distinguish cases (those women who developed breast carcinoma) from controls. It was found that both the skewness and fractal parameters were significantly related to risk of developing breast carcinoma. CONCLUSIONS: Although the relative risk estimates were moderate (typically > 2.0) and less than those from subjective classification or for an interactive computer method the authors have previously described, they are comparable to other risk factors for the disease. The observer independence and reproducibility of the automated methods may facilitate their more widespread use.

Assessment of a food frequency questionnaire as a screening tool for low fat intakes.

This study tested the ability of a self-administered food frequency questionnaire (FFQ) to identify women with low fat intakes. FFQs were completed by 95 control participants of a dietary trial at a mean 2.9 +/- 0.8 years post-randomization. Subjects were selected in approximately equal numbers from women who were low-fat eaters (< or = 30% of energy from fat) and high-fat eaters (> 30% of energy from fat). Percentage energy from fat derived from food records and FFQ were similar in both the low- and high-fat eaters. Percentage of energy from carbohydrate and total grams of carbohydrate (low-fat eaters only) were slightly higher measured by FFQ than by food records, and percentage of energy from protein was slightly lower. The correlation between nutrient intake measured by FFQ and food records for the whole group was 0.74 for percentage of energy from fat, 0.50 for total fat, 0.59 for percentage of energy from carbohydrate, 0.43 for total carbohydrate, 0.53 for percentage of energy from protein, 0.27 for total protein, and 0.32 for energy intake. Correlations were slightly lower when the low- and high-fat eaters were examined separately. The area under the receiver operating characteristic (ROC) curve, 0.83, was significantly above 0.5 (p < < 0.001), indicating that the FFQ discriminated between low- and high-fat eaters significantly better than chance. The FFQ cutoff point of 30% of energy from fat had a true positive rate of 0.63 and false positive rate of 0.24. The use of this cutoff point for screening would result in the loss of 36% of potential subjects and an estimated increase in baseline percentage of energy from fat intake of 2.3 percentage points.