Should women with a family history of breast cancer avoid use of oral contraceptives?
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Adult↗
Biomedical subjects
M C Pike
Publications and source records attributed to M C Pike.
Declining cancer rates in the 1990s.
PURPOSE: To provide evidence of a substantial decline in cancer rates for the period 1991 through 1995 and characterize major risk factors that seem to be driving secular trends in cancer mortality and incidence. DESIGN: Incidence and mortality rates were calculated using national surveillance data collected through the Surveillance, Epidemiology, and End Results (SEER) program and the National Center for Health Statistics. RESULTS: All-sites cancer incidence and mortality fell in the period 1991 through 1995; this decline is largely attributable to decreases in the smoking-related cancers, especially lung cancer. Of the 20 leading incident cancers today, both incidence and mortality are decreasing among 11 sites for men and 12 for women. In men, the decline in mortality has been notable and is especially apparent for the smoking-related cancers, including those of the lung, oral cavity and pharynx, larynx, and, to a lesser extent, bladder. In women, all-sites mortality decreased only approximately 0.4% from 1991 through 1995. Three cancers continued to show substantial increases in mortality through 1995 for both men and women (liver, multiple myeloma, and non-Hodgkin's lymphoma), while incidence rates continued to climb for liver cancer, non-Hodgkin's lymphoma, and melanoma. CONCLUSION: Data from the SEER program on recent trends in cancer incidence and mortality show that cancer rates are generally on the decline, largely because of reductions in smoking-related cancers. A consistent increase in mortality rates due to liver cancer poses a new health care challenge, one that will require the development of an effective treatment for individuals currently infected with hepatitis C or B to prevent mortality rates from continuing to increase.
Female↗
Hormonal contraception and chemoprevention of female cancers.
Oral contraceptive (OC) use significantly reduces the risk of endometrial and ovarian cancer, has only a minimal effect on breast cancer, but may increase the risk of cervical cancer. These effects can be readily explained in terms of the effects of OCs on cell proliferation in these tissues. This analysis suggests how a hormonal contraceptive based on a GnRH agonist plus low-dose add-back sex steroids could be made that would greatly reduce lifetime risk of breast and ovarian cancer. Such a hormonal contraceptive is also likely to significantly reduce the lifetime risk of cervical cancer. It is also likely to reduce the risk of endometrial cancer, although not to the same extent as OCs.
Adult↗
A meta-analysis of soyfoods and risk of stomach cancer: the problem of potential confounders.
It has been suggested that consumption of soyfoods may be associated with a reduction in risk of various cancers, including nonhormonally dependent cancers. The purpose of this meta-analysis was to examine the relationship between fermented and nonfermented soyfoods and risk of stomach cancer. We searched the reference lists of English language publications of diet and stomach cancer studies that were conducted in Asia or among Asians living in the United States or elsewhere between 1966 and 1999. All of the analytic epidemiological studies that obtained individual data on intake of soyfoods and presented risk estimates of the association between intake of soyfoods and risk of stomach cancer were identified and included in this review. Our pooled analysis of 14 studies with data on fermented soyfoods yielded an odds ratio/relative risk of 1.26 (95% confidence interval, 1.11-1.43) in association with high intake of such foods. In contrast, our pooled analysis of 10 studies with data on nonfermented soyfoods found an odds ratio/relative risk of 0.72 (95% confidence interval, 0.63-0.82) in association with high intake of these foods. However, further analyses suggest that fermented and nonfermented soyfoods may be associated with salt and fruit/vegetable intake, respectively; salt and fruit/vegetable intake are directly associated with stomach cancer risk. In almost all of the studies we reviewed, the possible confounding role of salt, fruit/vegetable, and other dietary factors had not been considered in the soyfood analyses. In conclusion, the role of soyfoods in the etiology of stomach cancer cannot be determined with confidence until the roles of potential confounders, including salt, fruit/vegetables, and other dietary factors, are more adequately adjusted for.
Adult↗
Expression of metastases-associated genes in cervical cancers resected in the proliferative and secretory phases of the menstrual cycle.
Previous retrospective studies suggest that the phase of the menstrual cycle at surgery (proliferative versus secretory) for breast cancer may significantly affect patient survival. Fluctuations during the menstrual cycle of the expression of genes involved in metastases in breast cancer tissue have also been reported. We hypothesized that the menstrual phase may also affect similar changes in gene expression of other cancers. We focused our attention on cancer of the uterine cervix because the hysterectomy specimen obtained at original surgery for the cancer can be used retrospectively to determine cycle phase. We analyzed tumor specimens from 36 premenopausal cervical cancer patients who had undergone hysterectomy as their primary treatment. We used reverse transcription-PCR to quantify gene expression during the different phases of the menstrual cycle as determined from the endometrial specimen. We explored a panel of genes that may affect metastatic propensity, namely, metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-2 (TIMP-2), cyclooxygenase 1 and 2 (COX-1 and COX-2), and vascular endothelial growth factor (VEGF). A significantly higher level of TIMP-2 and COX-2 gene expression (P = 0.007 and 0.030, respectively) was detected during the proliferative phase compared to the secretory phase of the cycle. The expression of the other genes was not significantly affected by the stage of the menstrual cycle. The finding that TIMP-2 and COX-2 expression in cervical cancer may be affected by the stage of the menstrual cycle supports the hypothesis that ovarian hormones may affect the expression of genes involved in metastasis. These findings need to be replicated, and their implications for tumor angiogenesis, invasion, and metastatic propensity need to be explored both in human studies and in experimental models.
Cervix Uteri↗
Association of mis-sense substitution in SRD5A2 gene with prostate cancer in African-American and Hispanic men in Los Angeles, USA.
BACKGROUND: Prostate cancer is a very common disease in more-developed countries, but its cause is largely unknown. It is an androgen-dependent cancer, and androgens have been proposed as having a substantial role in predisposition to the disease. Thus, variations in androgen metabolism genes may affect risk of this disease. METHODS: We screened 216 African-American and 172 Hispanic men with prostate cancer, and 261 African-American and 200 Hispanic healthy men (controls), from a large prospective cohort study (the Hawaii-Los Angeles Multiethnic Cohort Study) for a mis-sense substitution in the human prostatic (or type II) steroid 5alpha-reductase (SRD5A2) gene, the product of which controls metabolic activation of testosterone to dihydrotestosterone. This mis-sense substitution results in an alanine residue at codon 49 being replaced with threonine (A49T). We also reconstructed this mutation in the SRD5A2 cDNA, and overexpressed the enzyme in mammalian tissue culture cells. FINDINGS: The A49T aminoacid substitution in the SRD5A2 gene increased the risk of clinically significant disease 7.2-fold in African-American men (95% CI=2.17-27.91; p=0.001) and 3.6-fold in Hispanic men (1.09-12.27; p=0.04). The mutant enzyme had a higher in-vitro Vmax than the normal enzyme (9.9 vs 1.9 nmol min(-1) mg(-1)). INTERPRETATION: The A49T variant of the SRD5A2 gene may be a significant contributor to the incidence of prostate cancer in African-American and Hispanic men in Los Angeles. We estimate that the population attributable risk due to this aminoacid substitution for clinically significant disease is about 8% in both populations. Increased conversion of testosterone to dihydrotestosterone catalysed by this variant steroid 5alpha-reductase enzyme may be the cause of the increased risk.
3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
Breast cancer and oral contraceptive use in Asian-American women.
Breast cancer incidence has historically been 4-7 times higher in the United States than in Asia. A previous study by the authors in Asian-American women demonstrated a substantial increase in breast cancer risk in women who migrated from Asia to the United States, with the risk almost doubling during the first decade after migration. Increased use of oral contraceptives soon after migration to the United States could possibly explain this rapid rise in risk. In a population-based case-control study of Chinese, Filipino, and Japanese-American women, aged 20-55 years, who lived in San Francisco-Oakland, California; Los Angeles, California; and Oahu, Hawaii during 1983-1987, 597 cases (70% of those eligible) and 966 controls (75%) were interviewed. Controls were matched to cases on age, ethnicity, and area of residence. Oral contraceptive (OC) use increased with time since migration; 15.0% of Asian-born women who had been in the West <8 years, 33.4% of Asian-born women who had been in the West > or =8 years, and 49.6% of Asian women born in the West had ever used OCs. However, duration of OC use (adjusted for age, ethnicity, study area, years since migration, education, family history of breast cancer and age at first full-term birth) was not associated with increased risk of breast cancer. Moreover, neither OC use before age 25 years nor before first full-term birth was associated with increased risk. Results were unchanged when restricted to women under age 45 years or under age 40 years. After adjustment for duration of OC use, women who had been in the United States > or =8 years were still at almost twice the risk of breast cancer compared with women who had been in the United States 2-7 years. This study suggests that OC use cannot explain the elevated risk observed in Asian women who migrated to the United States > or =7 years ago.
Adult↗
Cytochrome P450c17alpha gene (CYP17) polymorphism predicts use of hormone replacement therapy.
We investigated whether a polymorphism in the cytochrome P450c17alpha gene (CYP17), which is associated with higher endogenous hormone levels, influences the use of hormone replacement therapy (HRT). The study included 749 postmenopausal women ages 44-75 years at baseline randomly selected from a larger multiethnic cohort. African-American, Japanese, Latina, and white women were included in the study. Women who carry the CYP17 A2/A2 genotype were about half as likely as women with the A1/A1 genotype to be current HRT users (odds ratio = 0.52; 95% confidence interval, 0.31-0.86). This association was present in all four racial/ethnic groups and for women above and below the median weight of 150 pounds. These findings suggest that the actual risk of breast cancer associated with HRT use may be higher than previously reported.
Adult↗
Urinary 2-hydroxyestrone/16alpha-hydroxyestrone ratio and risk of breast cancer in postmenopausal women.
BACKGROUND: It has been suggested that women who metabolize a larger proportion of their endogenous estrogen via the 16alpha-hydroxylation pathway may be at elevated risk of breast cancer compared with women who metabolize proportionally more estrogen via the 2-hydroxylation pathway. However, the supporting epidemiologic data are scant. Consequently, we compared the ratio of urinary 2-hydroxyestrone (2-OHE1) to 16alphahydroxyestrone (16alpha-OHE1) in postmenopausal women with breast cancer and in healthy control subjects. METHODS: Estrogen metabolites were measured in urine samples obtained from white women who had participated in a previous population-based, breast cancer case-control study at our institution. All P values are from two-sided tests. RESULTS: All of the urinary estrogens measured, with the exception of estriol, were higher in the 66 case patients than in the 76 control subjects. The mean value of urinary 2-OHE1 in case patients was 13.8% (P = .20) higher than that in control subjects, 16alpha-OHE1 was 12.1% (P = .23) higher, estrone was 20.9% higher (P = .14), and 17beta-estradiol was 12.0% higher (P = .36). The ratio of 2-OHE1 to 16alpha-OHE1 was 1.1% higher in the patients (P = .84), contrary to the hypothesis. Compared with women in the lowest third of the values for the ratio of urinary 2-OHE1 to 16alpha-OHE1, women in the highest third were at a nonstatistically significantly increased risk of breast cancer (odds ratio = 1.13; 95% confidence interval = 0.46-2.78), again contrary to the hypothesis. CONCLUSION: This study does not support the hypothesis that the ratio of the two hydroxylated metabolites (2-OHE1/16alpha-OHE1) is an important risk factor for breast cancer.
Aged↗
Meta-analysis: dietary fat intake, serum estrogen levels, and the risk of breast cancer.
BACKGROUND: There is compelling evidence that estrogens influence breast cancer risk. Since the mid-1980s, dietary fat intervention studies have been conducted to investigate the effect of fat intake on endogenous estrogen levels. To further our understanding of the possible relationship between dietary fat and breast cancer, we conducted a meta-analysis of dietary fat intervention studies that investigated serum estradiol levels, and we reviewed the nature of the evidence provided by prospective analytic studies of fat consumption and breast cancer risk. METHODS: A computerized search of the English language literature on estrogen/estradiol and dietary fat intervention studies published from January 1966 through June 1998 was conducted using the MEDLINE database. Pooled estimates were derived from the change in estradiol levels associated with fat reduction from 13 studies. Analyses were conducted separately for premenopausal and postmenopausal women and in both groups combined. RESULTS AND CONCLUSIONS: Statistically significant reductions in serum estradiol levels of -7.4% (95% confidence interval [CI] = -11.7% to -2.9%) among premenopausal women and -23.0% (95% CI = -27.7% to -18.1%) among postmenopausal women were observed, with an overall -13.4% (95% CI = -16.6% to -10.1%) reduction observed. The greatest reductions occurred in two studies in which dietary fat was reduced to 10%-12% of calories compared with 18%-25% of calories in the other studies. A statistically significant reduction in estradiol levels of -6.6% (95% CI = -10.3% to -2.7%) remained after exclusion of these two studies. Review of prospective analytic epidemiologic studies that allowed for dietary measurement error suggests that the possibility that reducing fat consumption below 20% of calories will reduce breast cancer risk cannot be excluded. IMPLICATIONS: Dietary fat reduction can result in a lowering of serum estradiol levels and such dietary modification may still offer an approach to breast cancer prevention.
Adult↗
Risk factors for testicular germ cell tumours by histological tumour type. United Kingdom Testicular Cancer Study Group.
There are two main histological groups of testicular germ cell tumours, which may have different risk factors. Some authors have analysed potential risk factors by histological group but few consistent differences have been identified. In this paper we examine risk factors for pure seminoma and other tumours using data from the United Kingdom case control study of testicular cancer. Seven hundred and ninety-four cases were included in the study, each with a matched control; 400 cases had pure seminoma tumours, and 394 had other testicular tumours. The risk of seminoma associated with undescended testis was slightly higher than that for other tumours (odds ratio of 5.3 compared with 3.0). When split at the median age at diagnosis, this difference was greater in men aged 32 and over (odds ratio of 11.9 compared with 5.1) than in the younger men (3.0 compared with 2.5). Risks associated with testicular or groin injuries were higher in the non-seminoma group, as was the risk for a history of sexually transmitted disease. The protective effect of a late puberty was more marked for tumours of other histologies. Some differences were also detected for participation in sports. Whilst some of the differences detected may have arisen by chance, the stronger association between undescended testis and pure seminoma has been identified by a number of other studies and may reflect a genuine difference in aetiology.
Adult↗
Re: "Associations of race/ethnicity, education, and dietary intervention with the validity and reliability of a food frequency questionnaire. The Women's Health Trial Feasibility Study in Minority Populations".
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Diet↗
Androgen metabolism and prostate cancer: establishing a model of genetic susceptibility.
The prostate is an androgen-regulated organ, which has led to long-standing interest in the role of androgens in prostate carcinogenesis. Although evidence of a hormonal etiology for prostate cancer is strong, it is almost entirely circumstantial. Much of the problem in proving a causal relationship relates to the continued difficulties in reliably measuring human tissue-specific exposure to endogenous steroid hormones. The international and racial-ethnic variations in prostate cancer incidence, combined with the effects of migration on risk patterns, have suggested that whereas environmental factors are likely to be important, genetic factors might also play a central role in determining prostate cancer risk. We are developing a polygenic model of prostate carcinogenesis focused around a series of genes involved in androgen biosynthesis and androgen activation, transport, and metabolism in the prostate. In this developing model, we have initially targeted four genes based on three main criteria: (a) all encode products that play important roles in inducing androgen stimulation in the prostate; (b) all are polymorphic; and (c) all show substantial allelic variation in the polymorphic marker among the racial-ethnic groups of greatest interest in terms of prostate cancer risk. In addition to studying how the polymorphic markers of interest are related to prostate cancer development within and between racial-ethnic groups, we are concurrently evaluating whether genotypic variations correlate in the anticipated direction with biochemical parameters in vitro and in vivo. We summarize the development of this model and the state of knowledge related to each of the genes comprising the current model. We discuss the extent to which the current model can explain demographic variation in prostate cancer risk as well as the potential for future expansion of the model to incorporate environmental risk factors as well as additional genes. The model, when fully developed, can potentially provide a basis for targeting populations for screening interventions and/or preventive strategies aimed at the multigene products or at the genes themselves.
3-Hydroxysteroid Dehydrogenases↗
Problems involved in including women with simple hysterectomy in epidemiologic studies measuring the effects of hormone replacement therapy on breast cancer risk.
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Adult↗
Cytochrome P450c17alpha gene (CYP17) polymorphism is associated with serum estrogen and progesterone concentrations.
An increased level of serum estrogen is one marker of breast cancer risk. We have recently reported that increased risk of advanced breast cancer is associated with a common allele of the cytochrome P450c17alpha gene (CYP17), designated A2. We now show that CYP17 genotype is associated with serum hormone levels among 83 young, nulliparous women. Serum estradiol (E2) levels measured around day 11 of the menstrual cycle were 11 and 57% higher (P = 0.04), respectively, among women hetero- and homozygous for the CYP17 A2 allele compared to A1/A1 women. Similarly, around cycle day 22, E2 levels were 7 and 28% higher (P = 0.06), and progesterone levels were 24 and 30% higher (P = 0.04), respectively. These data provide direct evidence of genetic control of serum hormone levels.
Adult↗
The effect of finasteride on the prostate gland in men with elevated serum prostate-specific antigen levels.
Prostate cancer is a disease associated with androgens. It has been hypothesized that reducing the conversion of testosterone (T) to dihydrotestosterone (DHT) in the prostate by the use of the drug finasteride, a 5alpha-reductase inhibitor, will reduce the incidence of prostate cancer. We investigated the chemopreventive potential of finasteride by evaluating its effect on the prostate gland of men with elevated serum prostate-specific antigen (PSA). Fifty-two men with elevated PSA and prostate sextant biopsies negative for cancer were randomized to receive finasteride 5 mg day(-1) (27 patients) or no medication (25 patients) for 12 months and were rebiopsied at 12 months. The biopsies were evaluated for the presence of cancer, the proportion of glandular and hyperplastic tissue, and the presence of high-grade prostatic intraepithelial neoplasia (PIN). Epithelial proliferation was assessed in the prestudy and 12-month biopsies by immunohistochemistry using antibody to proliferating cell nuclear antigen (PCNA). Serum blood samples were drawn at baseline and after 1, 3, 6 and 12 months of study. In the control group, serum levels of PSA and T were unchanged throughout the 12 months. In the finasteride group, PSA decreased 48% (P < 0.001), DHT decreased 67% (P < 0.001) and T increased 21% (P < 0.001). Histological evaluation of prestudy and 12-month biopsy specimens revealed that the finasteride group had a 30% reduction in the percentage of hyperplastic epithelial tissue (P = 0.002), although this decrease was not statistically significantly different between the finasteride and control groups (P = 0.11). In patients with PIN on prestudy biopsy, no change occurred in the PIN lesions with finasteride treatment. Finasteride also had no effect on the proliferation index of prostatic epithelial cells. Of the 27 patients treated with finasteride, eight (30%) had adenocarcinoma of the prostate detected on the 12-month biopsy, compared with one (4%) of the control patients (P = 0.025). In the treatment group, six cancers occurred in the eight patients with PIN on the prestudy biopsy; in the observation group no cancers were detected in the five patients with PIN on the prestudy biopsy (P = 0.021). Two cancers occurred in the 19 men in the treatment group with no evidence of PIN on the prestudy biopsy, compared with one cancer in the 20 men in the observation group with no evidence of PIN on the prestudy biopsy (P = 0.60). This study, using a novel model for evaluating short-term efficacy of chemopreventive or therapeutic agents in men at high risk of prostate cancer, provides little evidence that finasteride is an effective chemopreventive agent for prostate cancer in men with elevated PSA.
Adenocarcinoma↗
Soy intake and risk of breast cancer in Asians and Asian Americans.
Evidence from case-control studies suggests, although not entirely consistently, that soy intake may protect against breast cancer. The designs and findings of studies conducted in Asian women living in Japan, Singapore, China, and the United States are reviewed. Because of the considerably higher intake of soy by native Asians than by Asian Americans living in California and Hawaii, these studies investigated different segments of the dose-response relation between soy intake and breast cancer risk. Data are not sufficient to determine the amount or frequency of soy intake effective in protecting against breast cancer. Of concern is that soy intake may be homogeneously high in Asia, making it difficult to identify differences in breast cancer risk between high and moderate daily consumers. In studies conducted in Asian Americans, it is difficult to be certain that soy intake is not a marker of other factors related to Western lifestyle that are causally associated with risk of breast cancer. Additional studies assessing the role of soy and breast cancer are needed. These studies should assess intake of all food sources of soy, considering portion size as well as other dietary and nondietary factors that may confound the soy-breast cancer association. A better understanding of the mechanisms whereby soy intake may influence the risk of breast cancer is also needed. Dietary intervention studies with soy will provide information on the acute effects of soy on endogenous hormone concentrations. Cross-sectional and longitudinal studies are necessary to investigate the longer-term relations between hormone concentrations and soy intake in women.
Asian↗
The detection of changes in mammographic densities.
We previously reported reductions in mammographic densities in women participating in a trial of a gonadotropin-releasing hormone agonist (GnRHA)-based regimen for breast cancer prevention. In our previous report, we compared (by simultaneous evaluation) three basic elements of mammographic densities. The purpose of the present study was to evaluate whether a standard (expert) method of measuring mammographic densities would detect such changes in densities and whether a novel nonexpert computer-based threshold method could do so. Mammograms were obtained from 19 women at baseline and 12 months after randomization to the GnRHA-based regimen. The extent of mammographic densities was determined by: (a) a standard expert outlining method developed by Wolfe and his colleagues (Am. J. Roentgenol., 148: 1087-1092, 1987); and (b) a new computer-based threshold method of determining densities. The results from both the expert outlining method and the computer-based threshold method were highly consistent with the results of our original (simultaneous evaluation) method. All three methods yielded statistically significant reductions in densities from baseline to the 12-month follow-up mammogram in women on the contraceptive regimen. The difference between the treated and the control group was statistically significant with the expert outlining method and was of borderline statistical significance with the computer-based threshold method. The computer-based results correlated highly (r > 0.85) with the results from the expert outlining method. Both the standard expert outlining method and the computer-based threshold method detected the reductions we had previously noted in mammographic densities induced by the GnRHA-based regimen.
Adult↗