Hormonal strategies for the prevention of breast cancer.
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Biomedical subjects
Publications and source records attributed to R R Love.
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OBJECTIVES: To determine the effects of low-dose oral eflornithine hydrochloride (difluoromethylornithine [DFMO]) administration on hearing and to identify factors that influence those effects. DESIGN: Combined data from 2 studies: a prospective, randomized phase 1 clinical trial of eflornithine (n = 26 subjects) and a prospective, randomized, placebo-controlled phase 2 clinical trial of eflornithine (n = 40 subjects). SETTING: Ambulatory academic tertiary care referral center. PARTICIPANTS: Sixty-six volunteer subjects who had previously treated bladder, prostate, or colon cancer with no current evidence of neoplastic disease, or who were healthy individuals at increased risk for colon cancer, all without need of hearing amplification. INTERVENTIONS: Subjects were randomized to receive oral eflornithine at daily doses between 0.5 and 3 g per square meter of body surface area (g/m2) for 6 to 12 months (phase 1 study) or randomized to receive placebo or eflornithine, 0.5 g/m2 for 12 months (phase 2 study). OUTCOME MEASURES: Auditory thresholds were measured before, during, and after eflornithine administration. Auditory thresholds and threshold shifts were evaluated with regard to eflornithine dose, serologic variables, and demographic factors. RESULTS: Predictable shifts in auditory thresholds occurred following administration of eflornithine. As the daily dose of eflornithine increased, the magnitude and incidence of threshold shift increased, and the time until onset of threshold shift decreased. Threshold changes were greater in the lower frequencies than in the higher frequencies. Subjects' sex, age, and renal function had no effect on eflornithine-associated threshold shifts. Threshold shifts were reversible after eflornithine treatment was discontinued. CONCLUSIONS: Administration of eflornithine is associated with a predictable shift in auditory thresholds. The magnitude and incidence of threshold shift correlate with the daily eflornithine dose.
OBJECTIVES: The current study examined the relationship between chronic disease status and the receipt of cancer preventive services over a 3-year period. METHODS: Adults (n = 4320) cared for by 167 nonacademic physicians in 42 primary care group practices were studied. Medical records were audited for each patient, as were patient responses to two questionnaires assessing health and sociodemographic characteristics. RESULTS: While the odds of having received counseling to obtain regular checkups were increased for men (1.56) and women (1.46) with hypertension, the odds were reduced (range = 0.32 to 0.81) for having received a sigmoidoscopy (women with diabetes or hypertension, men with hypertension or heart disease), fecal occult blood test (men with diabetes or heart disease, women with heart disease), mammogram or counseling about smoking (women with diabetes), clinical breast exam (women with heart disease), and Pap test (women with diabetes or heart disease). CONCLUSIONS: The presence of common chronic health problems in older adults is associated with lower levels of cancer screening services.
The ultimate goal of breast cancer prevention strategies is to reduce the incidence of this disease in populations. Greater understanding of recently identified associations of lactation, alcohol, exercise, and diet with breast cancer is necessary to bring these to bear favorably on the behavior of populations. As a hormonally related process, breast cancer incidence is associated with two major physiologic mechanisms: (1) extent of lobular maturation, which is profoundly influenced by the occurrence of a full-term pregnancy, and (2) hormonal exposure of the breast epithelium, which is influenced by a spectrum of lifestyle factors. Manipulation of these processes by technologically simple and practical means is a major goal of research. Modulation of preclinical growth of breast cancers by chemopreventive means poses significant challenges, due to the absence of target-organ specificity and frequent toxicity. With the emergence of well-supported models of breast cancer development, behavioral and social strategies are likely to be key to achieving the ultimate goal.
BACKGROUND: Adult preventive services provided at intervals recommended by expert panel guidelines may reduce morbidity and mortality. As part of an intervention trial to increase primary preventive services in urban primary care practices, baseline data were collected on primary prevention and screening test rates in older adults and on patient characteristics associated with provision of these services. METHODS: A questionnaire on preventive services offered or provided over the past 2 years was completed by patients aged 52 to 77 years and another by their 42 participating physicians. Logistic regression was used to identify patient characteristics associated with increased provision of these services. RESULTS: Usable questionnaires were completed by 1457 (80.9%) patients. Patient age and sex were not associated with the provision of primary preventive and counseling services. The presence of two or more chronic diseases was predictive of primary preventive services (P < .02), but was not associated with an increase in screening tests or procedures. Age was positively associated with delivery of prostate-specific antigen blood tests (P < .001) and rectal examinations (P < .001) in men, but was negatively associated with mammography (P < .001) and Papanicolaou (Pap) tests (P = .02) in women. The negative trend in screening mammography was evident even for women aged 50 to 65 years despite the national consensus regarding the benefits of screening for this age group. Patients with health management organization insurance reported significantly more mammography (P = .002), cervical Pap tests (P = .050), sigmoidoscopies (P = .002), and fecal occult blood tests (P = .035). CONCLUSIONS: In our study patients, the provision of primary preventive and screening services was closer to consensus guidelines than is typically reported in the literature. The data suggest that future investigations and interventions to improve primary prevention and screening services in older adults who have access to primary care do not need to be directed at fundamental changes in the way preventive services are delivered, but rather should target procedures of proven benefit, such as mammography, where rates remain below recommended guidelines.
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The current study examined the relationship of several variables at the patient (n = 2780), physician (n = 166), and group practice (n = 45) levels for predicting receipt of annual mammography screening. Patient-level variables included constructs from the Triandis Model of Choice; physician-level variables included measures of barriers and receptivity to prevention, as well as demographic information. Hierarchical modeling demonstrated that variables at the patient and physician level reliably predict annual mammography screening, while frequency of screening did not vary across group practices after accounting for patient and physician variables. Patient-level predictors included social norms, perceived consequences and perceived barriers. The only physician-level predictor identified was annual mammography recommendation. These findings add to data which emphasize the importance of public education and social support in health maintenance activities.
There are increasing numbers of cancer prevention and control investigator trainees. On the basis of experience as research proposal reviewers and on reviews of a large number of current trainees, we offer some perspectives on the discipline and important aspects of optimal training programs. The historical importance of public health activities, the significant differences between prevention and treatment, and the breadth and public interest in prevention all have significant implications for trainees. In training, the need to focus efforts and to have active mentoring are critical. More attention to data analysis and complete development of a specific research proposal are also key elements of high-quality training. Although the need for cancer prevention and control investigators is great, more attention to the quality of their training is warranted.
This intergroup trial was developed to determine the toxicity of relatively low doses of difluoromethylornithine (DFMO) administered to humans for 1 year. The goal was to find an appropriate DFMO dose for use in human chemoprevention trials. Patients with resected superficial bladder cancers were studied. Following stratification, they were randomized to daily DFMO doses of 0.125, 0.25, 0.5, or 1.0 g/day for a planned period of 1 year. Patients were followed closely for evidence of drug toxicity. Seventy-six patients were evenly randomized (19 per group) to receive each dose of DFMO. Forty-nine patients received DFMO for more than 200 days while 35 received the drug for > or = 350 days. No substantial drug-related toxicity was observed at any dose. DFMO doses of > or = 1 g/day for periods up to 1 year appear to be without significant toxicity in most patients. This dose range may be appropriate for use in future human cancer chemoprevention trials.
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BACKGROUND: Women practice breast self-examination (BSE) according to their own schedule and skill. This variation in how BSE is performed has complicated the interpretation of studies of BSE efficacy and utilization. METHODS: We compared two methods commonly used to assess BSE competency, self-report of practice and ability to detect lumps in a model, among 81 women participating in a controlled toxicity trial of tamoxifen. Subjects were postmenopausal, were under 65 years of age, and had a history of breast cancer within the past 10 years but were currently free of disease. Women were asked to describe their usual BSE practice and were assigned a score (0-10) based on the number of recommended techniques and positions mentioned. Subjects were then instructed to examine a silicone breast model embedded with lumps (HealthEdCo) and to report any abnormalities. RESULTS: Overall proficiency was low by both measures. No significant correlation (r = 0.16, P = 0.15) was found between the two measures of proficiency. Higher correlations were observed among older women and among those practicing BSE monthly. CONCLUSIONS: This study suggests that the two techniques are not comparably evaluating BSE proficiency. Further, both of these methods are likely to be poor measures of true BSE practice.
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PURPOSE: While tamoxifen has been shown to alter concentration of many hormones and their binding globulins, there have been conflicting results regarding its effects on thyroid function tests. We sought to clarify these effects by studying subjects in a controlled clinical trial. PATIENTS AND METHODS: We evaluated a subset of postmenopausal women who had participated in a longitudinal, double-blind, randomized, placebo-controlled toxicity study of tamoxifen 10 mg orally, twice daily. There were 14 subjects in both the tamoxifen and placebo groups. Measurement of thyroid-binding globulin (TBG), thyroxine uptake (T-Uptake), thyroxine (T4), and thyroid-stimulating hormone (TSH), and an indirect estimate of the free T4 index (FTI), were made for each subject before and after 3 months of treatment. RESULTS: For T-Uptake, T4, and TBG, there were significant increases in the mean change from baseline to 3 months in the tamoxifen group compared with the placebo group (P = .02, .0001, and .003, respectively), while there were no significant changes in the measured TSH and in the calculated FTI. CONCLUSION: We conclude that tamoxifen therapy in postmenopausal women results in increased TBG, with secondary increases in measured T-Uptake and T4 following. However, TSH and FTI levels are unchanged, and treated women remain eumetabolic.
In the face of an apparently increasing incidence of postmenopausal breast cancer, and with frustratingly limited gains in treatment, significant possibilities for widespread prevention of breast cancer must be vigorously explored. However, progress with this approach has been painfully slow, and the multifactorial etiology of breast cancer development is most responsible for this delay. The challenges in our approaches are to recognize the major differences between treatment and prevention and to demand a comprehensive biological rationale, an absence of serious toxic effects and likely long-term acceptability to women of interventions coming to definitive clinical trial.
OBJECTIVE: To determine the level of intervention provided by primary care physicians to individuals who smoke. SETTING: 45 primary care clinics throughout the upper Midwest. PATIENTS: 6,086 men and women (M:F = 1:2), ages 50 to 68, who sought medical care at any one of the 45 primary care clinics and completed two questionnaires regarding preventive medical services received during the previous 3 years (1990-1993). RESULTS: Of patients who smoke, 92% reported that their clinician had asked about their smoking status. Additionally, 86% reported being informed at their clinic of the dangers of tobacco use. A smaller percentage of individuals (60.1%) reported being explicitly advised on how to quit, and fewer still (27.2%) reported being referred to a stop smoking program. CONCLUSIONS: While most clinicians inquire about their patients' smoking status and recommend they quit, there currently exists a deficiency in the translation of these recommendations into concise, explicit instructions on how to quit. By increasing the frequency of clinicians giving specific advice about how to quit, the overall success rate of the public health campaign against tobacco use will be greatly enhanced.
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