Risk factors for breast cancer in women undergoing mammography

Exposures in childhood, adolescence and early adulthood and breast cancer risk: a systematic review of the literature

A growing body of work indicates that exposures over the life course have important roles to play in the aetiology of breast cancer. This review synthesises the literature that has been published in the area of early life events and female breast cancer risk. The review finds some evidence, primarily from cohort studies on the relationship between birthweight and breast cancer, to suggest that in utero events are related to breast cancer risk in adulthood. Strong evidence to support a positive association between height and breast cancer exists. Postulated mechanisms for this relationship include the role of early diet in subsequent disease risk, and the influence of endogenous growth factors mediating the relationship. There is some evidence to suggest that leg length is the component of height which is generating the observed associations between height and breast cancer. There is no consistent pattern of association between relative weight in childhood or adolescence and risk of breast cancer. The evidence to suggest an association between physical activity in early life and breast cancer risk is convincing from case-control studies, but is not fully substantiated by the results of three cohort studies. There are inconsistent results regarding the association between smoking at a young age and breast cancer risk. There is little evidence for an association between passive smoking in early life and breast cancer risk. No clear association between early drinking and breast cancer risk exists. These results are discussed in relation to possible underlying mechanisms and health promotion strategies which could reduce breast cancer risk.

Presence of carotenoid, an anticarcinogenic marker, in nipple aspirates postlactation

Case-controlled studies have identified a protective effect of lactation against breast cancer; however, little is known about the nature of this protective mechanism. The purpose of this study was to examine postweaned, nipple aspirate fluid (NAF) from women, ages 18 to 45, for carotenoid, a known antioxidant and anticarcinogenic marker, and compare carotenoid availability in NAF with that reported in colostrum. Women who had lactated at least 6 months and weaned for at least 6 months were recruited into the study A prestudy and poststudy serum prolactin level was obtained. NAF was obtained through a nipple aspirator method. Total carotenoid ranged from 0.4 to 4.0 microg/mL, with a mean level of 1.9+/-1.2 (SD). Women who had weaned earlier (<12mo) had significantly more carotenoids than those who had lactated longer (>12mo) (P = 0.04). These levels were similar to those known to occur in colostrum. This research elucidates possible mechanisms of the protective effect of lactation on the microenvironment of the breast.

Breastfeeding

A large and growing body of scientific evidence suggests that breastfeeding provides immediate and long-lasting health advantages for the mother and her infant. In the United States, breastfeeding rates currently are the highest recorded in 30 years, although premature weaning owing to the largely avoidable problems of breast pain and concern about adequate milk supply is still common. The advantages of breastfeeding will be more widely appreciated when all health care professionals acquire competence in evidence-based lactation management strategies. These strategies include helping women to position and attach their newborns correctly, encouraging frequent and effective feedings at the breast from birth onward, teaching new parents the signs of adequate milk intake, and providing the resources for promoting breastfeeding without the competition of commercial product promotion.

Parenting self-efficacy and perception of insufficient breast milk

OBJECTIVE

Insufficient breast milk is a major reason why mothers give up breastfeeding and may be related to low levels of maternal confidence. This study explored the relationship between parenting self-efficacy (PES) and perception of insufficient breast milk.

DESIGN

Cross-sectional descriptive correlational study.

SETTING

Four private primary care pediatric practices in the northern United States.

PARTICIPANTS

Sixty breastfeeding mothers of infants ages 1 to 11 weeks.

PROCEDURES

Mothers were recruited during well-baby pediatric visits. They returned completed questionnaires by mail. Data were analyzed using descriptive statistics, t tests, and multiple regression analysis.

MAIN OUTCOME MEASURE

The Perception of Insufficient Milk (PIM) questionnaire, an investigator-developed instrument.

RESULTS

There was a significant correlation (r = .487, p < .01) between the self-efficacy and perceived insufficient milk scores. Regression analysis revealed that 23% of the variance in PIM was explained by PES, after maternal age, education, and parity had been taken into account.

CONCLUSIONS

Although further research is needed to refine the measurement of perceived insufficient milk and differentiate breastfeeding self-efficacy from general parenting self-efficacy, nursing interventions to enhance self-efficacy may improve mothers' confidence in the adequacy of their milk supply.

Effects of breastfeeding on the mother

In the rush to find nutrient alternatives to breastfeeding, a theme that dominated research on infant feeding throughout the twentieth century, only recently have new findings that reconfirm the importance of breastfeeding for maternal and child health begun to influence medical texts and health policy. Approximately 30 years of increasingly rigorous and positive research findings have led to the rediscovery of breastfeeding as a valid and evidence-based health intervention for infants. Unfortunately, because much of the research was designed to assess human milk as a nutrient replacement for infant formula, the literature on the effects of breastfeeding on maternal health remain limited. Nonetheless, a clear pattern of positive physiologic changes that lead to improved short-term and long-term health sequelae are emerging. All patients and their families should be informed fully as to the positive preventive health effects of breastfeeding not only for infants but also for mothers. Women have many difficult choices to make; it behooves physicians to ensure that they receive all of the facts on which to base these decisions.

Adverse effects of increased body weight on quantitative measures of mammographic image quality

OBJECTIVE

The purpose of our study was to show that compressed breast thickness on mammograms in overweight and obese women exceeds the thickness in normal-weight women and that increased thickness results in image degradation.

SUBJECTS AND METHODS

Three hundred consecutive routine mammograms were reviewed. Patients were categorized according to body mass index. Compression thickness, compressive force, kilovoltage, and milliampere-seconds were recorded. Geometric unsharpness and contrast degradation were calculated for each body mass index category.

RESULTS

Body mass index categories were lean (3%), normal (36%), overweight (36%), and obese (25%). Body mass index was directly correlated with compressed thickness. In the mediolateral oblique view, the mean thickness of the obese category exceeded normal thickness by 18 mm (p < 0.01), corresponding to a 32% increase in geometric unsharpness. Mean obese thickness exceeded lean thickness by 33 mm (p < 0.01), corresponding to a 79% increase in unsharpness. Similar trends were observed for the craniocaudal view. In the mediolateral oblique projection, there was an increase of 1.0 kVp (p < 0.01) for obese compared with normal and 1.7 kVp (p < 0.01) between lean and obese, corresponding, respectively, to a 16% and a 25% decrease in image contrast because of scatter and kilovoltage changes. Milliampere-seconds increased by 47% on the mediolateral oblique images in the obese category compared with normal body mass index.

CONCLUSION

An increased body mass index was associated with greater compressed breast thickness, resulting in increased geometric unsharpness, decreased image contrast, and greater potential for motion unsharpness.

The association of increased weight, body mass index, and tissue density with the risk of breast carcinoma in Vermont

BACKGROUND

Etiologic studies of breast carcinoma have indicated that weight, body mass index (BMI), and breast tissue density are important determinants of a woman's risk for the disease. This study looked at the independent effects of these risk factors.

METHODS

Data from the Vermont Breast Cancer Surveillance System (VBCSS), collected between May 1996 and November 1997, were used to identify 529 breast carcinoma cases with no prior history of the disease. Each case was matched to four randomly chosen women of the same age who had mammograms during the same time period and had no biopsy-confirmed breast carcinoma. Logistic regression was used to assess the effects of weight, BMI, and breast tissue density on breast carcinoma risk for pre- and postmenopausal women.

RESULTS

Weight and BMI were found to be significantly associated with postmenopausal breast carcinoma after adjustment for breast density, and vice versa. The density-adjusted odds ratio for women weighing over 81 kg, relative to women weighing under 63 kg, was 2.1, with a 95% confidence interval (CI) of 1.3-3.2. Relative to women with breasts consisting entirely of fat, the weight-adjusted odds ratios for women with heterogeneously dense and extremely dense breasts were 2.3 (CI: 1.3-4.3) and 4.5 (CI: 1.9-10.6), respectively.

CONCLUSIONS

Among postmenopausal Vermont women, weight, BMI, and breast density were independently associated with breast carcinoma risk. Because breast density and weight or BMI are inversely related, estimates of their independent effects should be used when evaluating a woman's risk for breast carcinoma.

Effect of obesity on screening mammography: outcomes analysis of 88,346 consecutive examinations

OBJECTIVE

We determined differences in the rates of recall, biopsy, and cancer detection for screening mammography as a function of adiposity.

MATERIALS AND METHODS

Eighty-eight thousand three hundred forty-six consecutive screening mammography examinations were performed from April 1985 to August 1997. Patient weights were normalized to ideal weight correcting for height and were subdivided into adiposity cohorts including underweight by greater than 10%; ideal weight +/- 10%; overweight by 11-24%; overweight by 25-39%; and overweight by greater than 40%. The rates of recall, biopsy, cancer detection, and cancer stage were calculated and were analyzed using the chi-square test for trend. Cancer size was analyzed using linear regression analysis.

RESULTS

Reliable (p < 0.05) and meaningful differences were seen between cohorts of increasing adiposity for rates of recall, biopsy, and cancer detection. An increase in recall rate occurred with progressively increasing adiposity (3.88%, 4.89%, 5.11%, 5.47%, 5.55% [p < 0.0001]). The rate of biopsy also increased with increasing adiposity (0.98%, 1.31%, 1.35%, 1.59%, 1.65% [p < 0.0002]), as did the rate of screening-detected cancer (number of cases of cancer per 1000 women screened) (3.74, 4.29, 5.34, 4.70, 6.04 [p < 0.015]). Finally, increased adiposity also correlated with increased median cancer size (p < 0.02) and with more advanced stage at diagnosis (p = 0.046).

CONCLUSION

Increasing adiposity correlates with progressive increases in the rates of recall, biopsy, and cancer detection for women undergoing screening mammography. Increasing adiposity also correlates with increased cancer size and stage, providing further support for obesity as a risk factor for breast cancer.

Selection criteria for breast cancer chemoprevention subjects

Early phase chemoprevention trials differ from standard therapeutic clinical trials because asymptomatic, healthy people are treated with a potentially toxic intervention for a prolonged period of time. Current subject selection protocols have relied upon epidemiological methods to identify high-risk individuals. Most available data provide risk estimates for various individual risk factors, but few have reported risk estimates for combinations of risk factors. Selection criteria for the large tamoxifen intervention trial (NSABP P1) were developed from the work of Gail et al. [1]. The Gail model takes into account non-genetic factors (e.g., nulliparity, age at menarche, preexisting pathological conditions) and genetic factors (family history). Using a lifetime risk of 10% of developing breast cancer as a standard to intervene, NSABP P1 uses the Gail algorithm to select pre- and postmenopausal women for a primary intervention trial. This approach has been criticized for being insufficiently selective (i.e., all women > or = 60 yrs), but appears to be the best available method to select subjects for a chemoprevention trial. Other approaches have been based on identification of very high-risk women with acknowledged pathologic conditions [lobular carcinoma in situ, ductal carcinoma in situ (DCIS)]. Attempting to use these proliferative lesions as pathologic endpoints for drug effect has not been attempted. DCIS as a risk factor for tamoxifen intervention was excluded because of controversies over its management and because of frequent difficulties in distinguishing microinvasive from non-invasive lesions. Women treated for early stage breast cancer (Stage I) may be subjects for early stage chemopreventive interventions.(ABSTRACT TRUNCATED AT 250 WORDS)