Donna R. Brogan

Intake of food groups and associated micronutrients in relation to risk of early-stage breast cancer†

Epidemiologic studies have evaluated the risk of breast cancer related to dietary fat intake, but only recently have other dietary factors received attention. Frequent intakes of fruit, vegetables and fiber have been associated with low risk of the disease in some studies but results are inconsistent. In a large case‐control study of early‐onset breast cancer, we evaluated risk related to a variety of food groups, associated micronutrients and non‐nutritive constituents. Cases treated with chemotherapy appeared to have altered reporting of food intake and were excluded. Analyses were restricted to 568 cases with in situ and localized disease and 1,451 population‐based controls. Reduced risks were observed for high intake of cereals and grains [odds ratio (OR) = 0.84, 95% confidence interval (CI) = 0.6–1.1 for highest compared with lowest quartile], vegetables (OR = 0.86, 95% CI = 0.6–1.1), beans (OR = 0.87, 95% CI = 0.7–1.2) and fiber from beans (OR = 0.88, 95% CI = 0.7–1.2). However, no trends of decreasing risk across quartiles of increasing intake were observed. Risk was not associated with dietary constituents related to these food groups including dietary fiber, carotenoids, vitamins A, C and E and folate. Incorporation of information from vitamin supplements did not alter the results for micronutrients. Our data suggest that intakes of cereals and grains, vegetables and beans are associated with minimal, if any, reduction in risk of early‐stage breast cancer among young women. Int. J. Cancer 82:315–321, 1999. Published 1999 Wiley‐Liss, Inc.

Epidemiology of in situ and invasive breast cancer in women aged under 45.

The incidence of in situ breast cancer in the USA has increased rapidly in recent years, even among young women. A population-based case-control study of 1616 breast cancer cases aged under 45 in the USA was used to examine risk factors for in situ, local and regional/distant tumours. Almost 60% of in situ tumours were detected by routine mammograms compared with 18% of local tumours and 8% of regional/distant tumours. After adjustment for screening history and established risk factors, family history of breast cancer in a first-degree relative and African-American race were associated with an increased risk of all stages of breast cancer. The associations with nulliparity, a previous breast biopsy and body mass index were significantly stronger for in situ tumours than for local or regional/distant disease. Alcohol consumption was associated with an increasing trend in risk of regional/distant tumours but not of earlier stage tumours, indicating that alcohol may be involved in late-stage events. Analyses by histological type of in situ tumours suggested that both ductal and lobular carcinoma in situ were associated with most established breast cancer risk factors, and the magnitude of association tended to be greater for the ductal form.

Pregnancy characteristics and maternal risk of breast cancer

In a population-based case-control study of parous women less than 45 years of age, we evaluated the relations of various pregnancy characteristics to maternal breast cancer risk. Cases (N = 1,239) diagnosed with in situ or invasive breast cancer from 1990 to 1992 in Atlanta, GA, Seattle/Punt Sound, WA, and five counties in central New Jersey, and population controls (N = 1,166) identified by random-digit dialing, were interviewed regarding the details of their pregnancies. We used logistic regression to estimate relative risks (RR) and 95% confidence intervals (CI) and to adjust for breast cancer risk factors. Women who reported nausea or vomiting in their first pregnancy had a slightly lower risk of breast cancer (RR = 0.87; 95% CI = 0.72–1.0). We found no strong or consistent associations for maternal risk related to gestational length, pregnancy weight gain, gestational diabetes, pregnancy hypertension, or gender of the offspring, although we found some evidence for reductions in risk for toxemia (RR = 0 81; 95% CI = 0.61–1.1) and specific sex (RR for female twins vs singletons = 0.48; 95% CI = 0.20–1.3) and timing characteristics of twinning. Overall, these data provide little support for the hypothesis that pregnancy hormone levels are associated with subsequent maternal risk of breast cancer in young women. (Epidemiology 1998; 9:641–647)

Hormonal content and potency of oral contraceptives and breast cancer risk among young women

Recent use of oral contraceptive pills is associated with a modest risk of breast cancer among very young women. In this US population-based case–control study, we evaluated whether the excess risk associated with recent oral contraceptive use is ubiquitous for all pill types or attributable to specific oral contraceptive preparations. Hormonal content and potency of combination oral contraceptives used for the longest duration within 5 years of interview for breast cancer cases aged 20–44 years (N=1640) were compared with age-matched community controls (N=1492). Women who recently used oral contraceptives containing more than 35 μg of ethinyl oestradiol per pill were at higher risk of breast cancer than users of lower dose preparations when compared to never users (respective relative risks of 1.99 and 1.27, Ptrend<0.01). This relationship was more marked among women <35 years of age, where risks associated with high- and low-dose ethinyl oestradiol use were 3.62 and 1.91 (Ptrend<0.01), respectively. We also found significant trends of increasing breast cancer risk for pills with higher progestin and oestrogen potencies (Ptrend<0.05), which were most pronounced among women aged <35 years of age (Ptrend<0.01). Risk was similar across recently used progestin types. Our findings suggest that newer low-potency/low oestrogen dose oral contraceptives may impart a lower risk of breast cancer than that associated with earlier high-potency/high-dose preparations.

The electrocardiogram in normal pregnancy

vascular obstruction is unknown. Accordingly, we have studied the effects of several laser sources (including argon-ion, Neodymium-YAG, and CO*) upon human cadaver coronary arteriosclerotic occlusions. Intact coronary arteries with obstructing atheromatous plaques were extracted at necropsy from patients who died of ischemic heart disease. The involved vessels were sectioned transversely and subjected to laser radiation throughout a wide spectrum of specific power intensities and time exposures employing a Laserscope (Trimedyne, Inc., Arlington Heights, Ill.). Strikingly, the argon-ion vaporization beam effected patency in fibrous (Fig. l), lipoid (Fig. Z), and calcified (Fig. 3) plaque obstructions. Investigations are currently in progress to extend this new therapeutic modality to the clinical relief of atherosclerotic obstructions in the coronary and other vascular beds.

Risk of breast cancer in young women in relation to body size and weight gain in adolescence and early adulthood.

SummaryFindings have been inconsistent on effects of adolescent body size and adult weight gain on risk of breast cancer in young women. These relations were examined in a population-based case control study of 1590 women less than 45 years of age newly diagnosed with breast cancer during 1990–1992 in three areas of the US and an age-matched control group of 1390 women. Height and weight were measured at interview and participants asked to recall information about earlier body size. Logistic regression was used to estimate the relative risk of breast cancer adjusted for other risk factors. Women who were either much heavier or lighter than average in adolescence or at age 20 were at reduced risk. Weight gain after age 20 resulted in reduced risk, but the effect was confined to early-stage and, more specifically, lower grade breast cancer. Neither the risk reduction nor the variation by breast cancer stage or grade was explained by the method of cancer detection or by prior mammography history. These findings suggest that relations between breast cancer risk in young women and body weight at different ages is complex and that the risk reduction with adult weight gain is confined to less aggressive cancers.

Comparative Analyses of Pretest-Posttest Research Designs

Abstract Two common methods of analyzing data from a two-group pretest-posttest research design are (a) two-sample t test on the difference score between pretest and posttest and (b) repeated-measures/split-plot analysis of variance. The repeated-measures/split-plot analysis subsumes the t test analysis, although the former requires more assumptions to be satisfied. A numerical example is given to illustrate some of the equivalences of the two methods of analysis. The investigator should choose the method of analysis based on the research objective(s).

Increased risk of early-stage breast cancer related to consumption of sweet foods among women less than age 45 in the United States

Objectives: To evaluate the associations of dietary macronutrients, food groups, and eating patterns with risk of breast cancer in a population-based case–control study. Methods: In this study among women 20–44 years of age, 568 cases with breast cancer and 1451 population-based controls were included. They completed a detailed in-person interview, a self-administered food-frequency questionnaire and were measured for anthropometric indices. Logistic regression was used to estimate odds ratios (OR) and their 95% confidence intervals (CI) of breast cancer, adjusted for age, study site, race, education, alcohol consumption, oral contraceptive usage, smoking status, and body mass index. Results: There was no association between breast cancer risk and intake of calories, macronutrients, or types of fat. Risk of breast cancer was unrelated to intakes of a variety of food groups, including red meats, dairy, high-fat snacks and desserts, or foods high in animal fat. Increased risk was observed for high intake of a food group composed of sweet items, particularly sodas and desserts. Risk increased linearly with percent of calories from sweets and frequency of sweets intake. Consumption of sweets 9.8 or more times per week compared with <2.8 times per week was associated with an adjusted OR of 1.32 (95% CI = 1.0–1.8). This association did not appear to be due to the high-fat foods or carbonated beverages that comprised the food group. Compared with women reporting one or two meals and snacks per day, reduced risks were noted for women reporting six or more (OR = 0.69, 95% CI = 0.4–1.1). Conclusions: These data suggest a modest relationship between intakes of sweet items with risk of in-situ and localized breast cancer in young women. This relation is consistent with the hypothesized link of high insulin exposure and risk of breast cancer. There was some suggestion that women who ate many times during the day were at reduced risk of disease, which is also consistent with an insulin-related mechanism.

Breast cancer risk among women under 55 years of age by joint effects of usage of oral contraceptives and hormone replacement therapy.

Objective:To assess effects on breast cancer risk of exposure to both oral contraceptives and menopausal hormones, an increasingly common exposure. Design:A case-control study of breast cancer among women under the age of 55 years in Atlanta, GA involving 1,031 cases and 919 population controls was conducted. Results:Ever use of oral contraceptives was associated with a relative risk of 1.1 (95% 0.9–1.4), whereas the relative risk for hormone replacement therapy was 0.9 (95% CI 0.7–1.2). Seventeen percent of the cases versus 19% of the population controls reported exposure to both agents, resulting in a relative risk of 1.0 (95% CI 0.7–1.4) relative to those unexposed to either preparation. Although there was little variation in risk associated with joint effects by either age or race, there were statistically nonsignificant elevations in risk for this exposure among women who had experienced a natural menopause (relative risk = 2.0, 95% CI 0.7–5.6), were relatively thin (relative risk = 1.5, 0.8–3.0), or who had a first degree relative with breast cancer (relative risk = 2.0, 0.6–7.0). When joint effects of longer term use of both agents were considered, subjects who reported use of oral contraceptives for 10 or more years and hormone replacement for 3 or more years had a relative risk of 3.2 (95% CI 1.4–7.4) compared with nonusers of either preparation. Conclusions:Although our results must be cautiously interpreted given small numbers within subgroups, they raise concern and emphasize the need for further evaluation on breast cancer risk of the increasingly common exposure to both oral contraceptives and hormone replacement therapy.

Dietary relationships with early onset (under age 45) breast cancer in a case-control study in the United States: influence of chemotherapy treatment

Methodologic investigations have addressed selection and recall biasin case-control studies of diet and breast cancer, whereas the effect ofdisease progression and medical treatment on estimates of dietary intake hasbeen largely overlooked. In a multicenter, population-based case-controlstudy of breast cancer in the United States, 1,588 newly diagnosed cases and1,451 controls completed a self-administered food-frequency questionnaire.Initial evaluation suggested increased risk related to high intakes ofcalories, carbohydrates, fat, and protein. All nutrient associations werediminished after adjustment for calories. Evaluation by stage of diseaserevealed no relation of calories to risk among women with in situ disease,but elevated risks among women with localized (odds ratio [OR] = 1.33, 95percent confidence interval [CI] = 1.0-1.7 highest cf lowest quartile) orregional and distant disease (OR = 1.79, CI = 1.3-2.4). Further evaluationshowed that the increased risk a ssociated with calories was restricted tocases who reported having been treated with chemotherapy (OR = 1.66, CI =1.3-2.1). A gradient of increasing risk with time interval from diagnosis tointerview suggested the chemotherapy regimen itself and not necessarilycharacteristics of tumors requiring this treatment was responsible for theobserved increased risk. These results indicate that epidemiologic studies ofdiet and breast cancer, particularly among young women, should evaluatepossible bias related to post-diagnosis influences.