Dietary lactose intake, lactose intolerance, and the risk of epithelial ovarian cancer in southern Ontario (Canada)

Effects of dairy products, calcium and vitamin D on ovarian cancer risk: a meta-analysis of twenty-nine epidemiological studies

Findings for the roles of dairy products, Ca and vitamin D on ovarian cancer risk remain controversial. We aimed to assess these associations by using an updated meta-analysis. Five electronic databases (e.g. PubMed and Embase) were searched from inception to 24 December 2019. Pooled relative risks (RR) with 95 % CI were calculated. A total of twenty-nine case–control or cohort studies were included. For comparisons of the highest v. lowest intakes, higher whole milk intake was associated with increased ovarian cancer risk (RR 1·35; 95 % CI 1·15, 1·59), whereas decreased risks were observed for higher intakes of low-fat milk (RR 0·84; 95 % CI 0·73, 0·96), dietary Ca (RR 0·71; 95 % CI 0·60, 0·84) and dietary vitamin D (RR 0·80; 95 % CI 0·67, 0·95). Additionally, for every 100 g/d increment, increased ovarian cancer risks were found for total dairy products (RR 1·03; 95 % CI 1·01, 1·04) and for whole milk (RR 1·07; 95 % CI 1·03, 1·11); however, decreased risks were found for 100 g/d increased intakes of low-fat milk (RR 0·95; 95 % CI 0·91, 0·99), cheese (RR 0·87; 95 % CI 0·76, 0·98), dietary Ca (RR 0·96; 95 % CI 0·95, 0·98), total Ca (RR 0·98; 95 % CI 0·97, 0·99), dietary vitamin D (RR 0·92; 95 % CI 0·87, 0·97) and increased levels of circulating vitamin D (RR 0·84; 95 % CI 0·72, 0·97). These results show that whole milk intake might contribute to a higher ovarian cancer risk, whereas low-fat milk, dietary Ca and dietary vitamin D might reduce the risk.

Milk, yogurt, and lactose intake and ovarian cancer risk: a meta-analysis

Inconclusive information for the role of dairy food intake in relation to ovarian cancer risk may associate with adverse effects of lactose, which has been hypothesized to increase gonadotropin levels in animal models and ecological studies. Up to now, several studies have indicated the association between dairy food intake and risk of ovarian cancer, but no identified founding was reported. We performed this meta-analysis to derive a more precise estimation of the association between dairy food intake and ovarian cancer risk. Using the data from 19 available publications, we examined dairy food including low-fat/skim milk, whole milk, yogurt and lactose in relation to risk of ovarian cancer by meta-analysis. Pooled odds ratio (OR) with 95% confidence interval (CI) were used to assess the association. We observed a slightly increased risk of ovarian cancer with high intake of whole milk, but has no statistical significance (OR = 1.228, 95% CI = 1.031-1.464, P = 0.022). The results of other milk models did not provide evidence of positive association with ovarian cancer risk. This meta-analysis suggests that low-fat/skim milk, whole milk, yogurt and lactose intake has no associated with increased risk of ovarian cancer. Further studies with larger participants worldwide are needed to validate the association between dairy food intake and ovarian cancer.

Dairy foods and nutrients in relation to risk of ovarian cancer and major histological subtypes

Inconsistent results for the role of dairy food intake in relation to ovarian cancer risk may reflect the potential adverse effects of lactose, which has been hypothesized to increase gonadotropin levels, and the beneficial antiproliferative effects of calcium and vitamin D. Using data from the New England case-control study (1,909 cases and 1,989 controls), we examined dairy foods and nutrients in relation to risk of ovarian cancer overall, histological subtypes and rapidly fatal versus less aggressive disease. We used logistic regression and polytomous logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs). In models that were simultaneously adjusted for total (dietary plus supplements) calcium, total vitamin D and lactose, we observed a decreased overall risk of ovarian cancer with high intake of total calcium [Quartile 4 (Q4, >1,319 mg/day) vs. Quartile 1 (Q1, <655 mg/day), OR = 0.62, 95% CI = 0.49-0.79]; the inverse association was strongest for serous borderline and mucinous tumors. High intake of total vitamin D was not associated overall with ovarian cancer risk, but was inversely associated with risk of serous borderline (Q4, >559 IU/day vs. Q1, <164 IU/day, OR = 0.51, 95% CI = 0.34-0.76) and endometrioid tumors (Q4 vs. Q1, OR = 0.55, 95% CI = 0.39-0.80). We found no evidence that lactose intake influenced ovarian cancer risk or that risk varied by tumor aggressiveness in the analyses of intake of dairy foods and nutrients. The overall inverse association with high intake of calcium and the inverse associations of calcium and vitamin D with specific histological subtypes warrant further investigation.

Use of dairy products, lactose, and calcium and risk of ovarian cancer - results from a Danish case-control study

BACKGROUND

A number of epidemiological studies have examined the association between use of dairy products and risk of ovarian cancer, but results are conflicting. Using data from a large Danish population-based case-control study we here further examined the association between dairy consumption, lactose, and calcium and risk of overall ovarian cancer and histological types of ovarian cancer.

MATERIAL AND METHODS

In the period 1995-1999 we included 554 women with epithelial ovarian cancer and 1554 randomly selected age-matched controls (35-79 years). All women participated in a detailed personal interview that included questions about dairy consumption. Data were analysed using multiple logistic regression models.

RESULTS

Total dairy intake was associated with ovarian cancer risk (OR = 1.11; 95% CI: 1.07-1.15 per 100 ml/day). The association was strongest for milk [OR = 1.14; 95% CI: 1.03-1.27 per glass (200 ml)/day], soured milk products [OR = 1.49; 95% CI: 1.22-1.81 per portion (250 ml)/day] and yoghurt [OR = 1.65; 95% CI: 1.22-2.23 per portion (250 ml)/day]. In contrast, intake of cheese was associated with a decreased risk [OR = 0.70; 95% CI: 0.55-0.89 for > 1 portion (100 ml)/day compared with no intake]. Intake of lactose, but not calcium, was also associated with an increased ovarian cancer risk (OR = 1.24; 95% CI: 1.10-1.40 per 10 g of lactose/day). Similar risk patterns were observed for the different histological types of ovarian cancer, indicating virtually identical aetiologies with regard to dairy intake, lactose, and calcium.

CONCLUSIONS

Our results indicate that intake of dairy products is associated with a modest increased risk of ovarian cancer. In addition, ovarian cancer development was associated with lactose intake.

Synergistic effect of high lactase activity genotype and galactose-1-phosphate uridyl transferase (GALT) mutations on idiopathic presenile cataract formation

OBJECTIVES

To evaluate the possible synergistic role of partial galactose metabolism defects, high lactase (LPH) genotype and lactose and galactose ingestion in presenile cataract formation.

DESIGN AND METHODS

51 patients with idiopathic presenile cataracts and 172 healthy cataract-free subjects were genotyped to determine their galactose-1-phosphate uridyl transferase (GALT) and LPH status. Whole milk, skimmed milk and yoghurt consumption was recorded in 19 cataract patients and 172 controls by questionnaire.

RESULTS

GALT mutations and whole milk consumption increased the risk of cataract formation in high LPH genotype group, but not in lactose intolerant subjects. Logistic regression analysis showed the synergistic effect of GALT and LPH mutations on cataract formation.

CONCLUSIONS

High lactase activity genotypes and mutations in galactose-1-phosphate uridyl transferase have a synergistic effect on presenile cataract formation.

Pathophysiology of impaired ovarian function in galactosaemia

Classical galactosaemia is an inherited inborn error of the major galactose assimilation pathway, caused by galactose-1-phosphate uridyltransferase (GALT) deficiency. Many GALT mutations have been described, with different clinical consequences. In severe forms, newborns present with a life-threatening, acute toxic syndrome that rapidly regresses under a galactose-restricted diet. However, long-term complications, particularly cognitive and motor abnormalities, as well as hypergonadotrophic hypogonadism in female patients are still unavoidable. The pathogenesis of galactose-induced ovarian toxicity remains unclear but probably involves galactose itself and its metabolites such as galactitol and UDP-galactose. Possible mechanisms of ovarian damage include direct toxicity of galactose and metabolites, deficient galactosylation of glycoproteins and glycolipids, oxidative stress and activation of apoptosis. As there is no aetiological treatment, clinical management of ovarian failure in galactosaemic patients principally relies on hormonal replacement therapy to induce pubertal development and to prevent bone loss and other consequences of estrogen deprivation. Further investigations will be necessary to better understand the metabolic flux of galactose through its biochemical pathways and the mechanisms of these secondary complications. The aim of this article is to present an extensive review on the pathogenesis and clinical management of galactose-induced premature ovarian failure.

Dairy products and ovarian cancer: a pooled analysis of 12 cohort studies

BACKGROUND

Dairy foods and their constituents (lactose and calcium) have been hypothesized to promote ovarian carcinogenesis. Although case-control studies have reported conflicting results for dairy foods and lactose, several cohort studies have shown positive associations between skim milk, lactose, and ovarian cancer.

METHODS

A pooled analysis of the primary data from 12 prospective cohort studies was conducted. The study population consisted of 553,217 women among whom 2,132 epithelial ovarian cases were identified. Study-specific relative risks and 95% confidence intervals were calculated by Cox proportional hazards models and then pooled by a random-effects model.

RESULTS

No statistically significant associations were observed between intakes of milk, cheese, yogurt, ice cream, and dietary and total calcium intake and risk of ovarian cancer. Higher lactose intakes comparing > or = 30 versus <10 g/d were associated with a statistically significant higher risk of ovarian cancer, although the trend was not statistically significant (pooled multivariate relative risk, 1.19; 95% confidence interval, 1.01-1.40; P(trend) = 0.19). Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings.

DISCUSSION

Overall, no associations were observed for intakes of specific dairy foods or calcium and ovarian cancer risk. A modest elevation in the risk of ovarian cancer was seen for lactose intake at the level that was equivalent to three or more servings of milk per day. Because a new dietary guideline recommends two to three servings of dairy products per day, the relation between dairy product consumption and ovarian cancer risk at these consumption levels deserves further examination.

Milk, milk products and lactose intake and ovarian cancer risk: a meta-analysis of epidemiological studies

It has been proposed, on the basis of animal models and ecological studies, that consumption or metabolism of dairy sugar may increase the risk of ovarian cancer. Case-control and cohort studies of the association between lactose and dairy food consumption and ovarian cancer risk, however, have yielded varied findings. We summarized the available literature on this topic using a meta-analytic approach. Random-effects models were used to estimate the summary relative risks (RR(summary)). A linear regression analysis of the natural logarithm of the RR was carried out to assess a possible dose-response relationship between lactose intake and ovarian cancer risk. Eighteen case-control and 3 prospective cohort studies were eligible for inclusion in the meta-analysis. The findings of case-control studies were heterogeneous, and, except for whole milk (RR(summary) for highest vs. lowest category = 1.27, 95% confidence interval [CI] = 0.97-1.68), do not provide evidence of positive associations between dairy food and lactose intakes with risk of ovarian cancer. In contrast, the 3 cohort studies are consistent and show significant positive associations between intakes of total dairy foods, low-fat milk, and lactose and risk of ovarian cancer. The RR(summary) for a daily increase of 10 g in lactose intake (the approximate amount in 1 glass of milk) was 1.13 (95% CI = 1.05-1.22) for cohort studies. In conclusion, prospective cohort studies, but not case-control studies, support the hypothesis that high intakes of dairy foods and lactose may increase the risk of ovarian cancer.

Estrogen bioactivation, genetic polymorphisms, and ovarian cancer

Recent experimental evidence has shown that catechol estrogens can be activated through metabolism to form depurinating DNA adducts and thereby initiate cancer. Limited data are available regarding this pathway in epithelial ovarian cancer. We conducted a case-control study of 503 incident epithelial ovarian cancer cases at the Mayo Clinic in Rochester, MN, and Jacksonville, FL, and a 48-county region in North Carolina. Six hundred nine cancer-free controls were frequency matched to the cases on age, race, and residence. After an interview to obtain data on risk factors, a sample of blood was collected for DNA isolation. Subjects were genotyped for seven common single nucleotide polymorphisms in four genes involved in catechol estrogen formation (CYP1A1 and CYP1B1) or conjugation (COMT and SULT1A1). Data were analyzed using logistic regression, stratified by race, and with adjustment for design factors and potential confounders. None of the individual genotypes were significantly associated with ovarian cancer risk. However, an oligogenic model that considered the joint effects of the four candidate genes provided evidence for an association between combinations of these genes and ovarian cancer status (P = 0.015). Although preliminary, this study provides some support for the hypothesis that low-penetrance susceptibility alleles may influence risk of epithelial ovarian cancer.

Lactase persistence and ovarian carcinoma risk in Finland, Poland and Sweden

Ovarian carcinoma is the fourth most common cause of cancer death in women. The cause and pathogenesis of this disease has remained obscure. Galactose, the hydrolyzing product of the milk sugar lactose, has been hypothesized to be toxic to ovarian epithelial cells and consumption of dairy products and lactase persistence has been suggested to be a risk factor for ovarian carcinoma. In adults, downregulation of lactase depends on a variant C/T-13910 at the 5' end of the lactase gene. To explore whether lactase persistence is related to the risk of ovarian carcinoma we determined the C/T-13910 genotype in a cohort of 782 women with ovarian carcinoma. The C/T-13910 genotype was defined by solid phase minisequencing from 327 Finnish, 303 Polish, 152 Swedish patients and 938 Finnish, 296 Polish and 97 Swedish healthy individuals served as controls. Lactase persistence did not associate significantly with increased risk for ovarian carcinoma in the Finnish (odds ratio [OR]=0.77, 95% confidence interval [CI]=0.57-1.05, p=0.097), in the Polish (OR=0.95, 95% CI=0.68-1.33, p=0.75), or in the Swedish populations (OR=1.63, 95% CI=0.65-4.08, p=0.29). Our results do not support the hypothesis that lactase persistence increases the ovarian carcinoma risk. On the contrary, lactase persistence may decrease the ovarian carcinoma risk at least in the Finnish population.

Milk/dairy products consumption, galactose metabolism and ovarian cancer: meta-analysis of epidemiological studies

Ovarian cancer is the fifth most common cause of cancer death among women and the leading cause of gynaecological cancer death in the United States. Milk/dairy products consumption was considered to be a risk factor for ovarian cancer mainly because milk carbohydrate-lactose and galactose metabolism is toxic to oocytes. However, recent evidence does not support this hypothesis completely. We collected epidemiological studies related to the association between milk/dairy products consumption or galactose metabolism (lactose, galactose, galactose-1-phosphate uridyltransferase, lactose/transferase) and ovarian cancer published between January 1966 and August 2003 and found 27 items from 22 independent studies. Twenty studies were case-control studies and the other two were cohort studies. A meta-analysis method was conducted to estimate relative risk combining all relative data. In general, we did not find any association between milk/dairy products or galactose metabolism and ovarian cancer risk in this meta-analysis. The consumption of whole milk and butter, which contain relatively high amounts of fat, was positively (relative risk > 1.2), but not significantly, associated with an increased risk.

Molecular genetics of adult-type hypolactasia

Adult-type hypolactasia (lactase non-persistence; primary lactose malabsorption) is characterized by the down-regulation of the lactase enzyme activity in the intestinal wall after weaning. The down-regulation is genetically determined and a mutation has occurred that has made part of mankind tolerate milk (lactase persistence). A DNA-variant, single nucleotide polymorphism C/T-13910 located 13 910 base pairs (bp) upstream of the lactase gene (LCT) at chromosome 2q21-22 has been shown to associate with the lactase persistence/non-persistence trait both in family and case-control studies. The C/T-13910 variant is located in a non-coding region in the genome in intron 13 of the minichromosome maintenance type 6 gene (MCM6). Significant correlation between the C/T-13910-variant and lactase activity in the intestinal biopsy specimens has been demonstrated. Molecular epidemiological studies on the prevalence of the C/C-13910 genotype associated with low lactase activity are in agreement with the prevalence figures for adult type hypolactasia in>70 diverse ethnic groups studied. Recent functional studies have suggested that this variant has an enhancer effect over the lactase gene. Based on the biochemical, functional, genetic and molecular epidemiological studies of the C/T-13910 variant, genetic testing for adult type hypolactasia has been introduced into clinical practice in Finland. Identification of the genetic change has highlighted the role of non-coding variants in the regulation of common genes and created new tools to study the mechanism of lactase enzyme activation.

Milk and lactose intakes and ovarian cancer risk in the Swedish Mammography Cohort

BACKGROUND

High intakes of dairy products and of the milk sugar lactose have been hypothesized to increase ovarian cancer risk, but prospective data are scarce.

OBJECTIVE

We examined the association between intakes of dairy products and lactose and the risk of total epithelial ovarian cancer and its subtypes.

DESIGN

This was a prospective population-based cohort study of 61 084 women aged 38-76 y who were enrolled in the Swedish Mammography Cohort. Diet was assessed in 1987-1990 with the use of a self-administered food-frequency questionnaire. During an average follow-up of 13.5 y, 266 women were diagnosed with invasive epithelial ovarian cancer; 125 of those women had serous ovarian cancer.

RESULTS

After adjustment for potential confounders, women who consumed >/=4 servings of total dairy products/d had a risk of serous ovarian cancer (rate ratio: 2.0; 95% CI: 1.1, 3.7; P for trend = 0.06) twice that of women who consumed <2 servings/d. No significant association was found for other subtypes of ovarian cancer. Milk was the dairy product with the strongest positive association with serous ovarian cancer (rate ratio comparing consuming >/=2 glasses milk/d with consuming milk never or seldom: 2.0; 95% CI: 1.1, 3.7; P for trend = 0.04). We observed a positive association between lactose intake and serous ovarian cancer risk (P for trend = 0.006).

CONCLUSIONS

Our data indicate that high intakes of lactose and dairy products, particularly milk, are associated with an increased risk of serous ovarian cancer but not of other subtypes of ovarian cancer. Future studies should consider ovarian cancer subtypes separately.

A Case-Control Study of Diet and the Risk of Ovarian Cancer

Epidemiologic studies have suggested that some dietary factors may play a role in the etiology of ovarian cancer, but the findings have been inconsistent. We assessed the association of ovarian cancer with dietary factors in a population-based case-control study in Canada. Diet information was collected on 442 incident cases of ovarian cancer diagnosed in 1994 to 1997 and 2,135 population controls via a self-administered questionnaire. Compared with women in the lowest quartile of cholesterol intake, those in the second, third, and fourth quartiles had a multivariate adjusted odds ratio [OR; 95% confidence interval (95% CI)] of 1.12 (0.81–1.56), 1.20 (0.85–1.68), and 1.42 (1.03–1.97), respectively (P for trend = 0.031). Higher egg consumption was also associated with a nonsignificant increase in ovarian cancer risk. The ORs (95% CIs) for ovarian cancer were 0.77 (0.60–1.04) and 0.76 (0.56–0.99) among women in the highest quartile of total vegetable and cruciferous vegetable intake as compared with women in the lowest quartile. Women who took supplements of vitamin E, β-carotene, and B-complex vitamins for ≥10 years had ORs (95% CIs) of 0.49 (0.30–0.81), 0.31 (0.11–0.91), and 0.61 (0.36–1.05), respectively. However, we did not observe an association of ovarian cancer risk with dietary fat intake, including saturated, monounsaturated, and polyunsaturated fatty acids, protein, carbohydrate, dietary fiber, fruit, dairy products, meat products, fish, chicken, grain products, nut products, baked desserts, margarine, butter, mayonnaise, and supplement of multiple vitamins, vitamin A, vitamin C, calcium, iron, zinc, and selenium. Our findings suggested that ovarian cancer risk was positively associated with higher consumption of dietary cholesterol and eggs and inversely associated with higher intake of total vegetables and cruciferous vegetables and supplementation of vitamin E, β-carotene, and B-complex vitamins.

A prospective study of dietary lactose and ovarian cancer

The milk sugar lactose is an hypothesized risk factor for epithelial ovarian cancer because of possible direct toxic effects of its metabolites on oocytes or by compensatory gonadotropin stimulation. Women are presently encouraged to consume dairy products as a source of calcium to prevent osteoporosis. The objective of our study was to prospectively assess lactose, milk and milk product consumption in relation to ovarian cancer risk among 80326 participants in the Nurses' Health Study who had no history of cancer other than nonmelanoma skin cancer. Participants in the Nurses' Health Study reported on known and suspected ovarian cancer risk factors in questionnaires mailed biennially from 1976 to 1996. Food frequency questionnaires were included in the years 1980, 1984, 1986 and 1990. Newly reported ovarian cancer was documented by review of medical records. During 16 years of follow-up (1980-1996), 301 cases of invasive epithelial ovarian cancer were confirmed. Pooled logistic regression was used to control for age, body mass index (kg/m(2)), caffeine intake, oral contraceptive use, smoking history, parity and tubal ligation. For all subtypes of invasive ovarian cancer combined, we observed a nonsignificant 40% greater risk for women in the highest category of lactose consumption compared to the lowest (multivariate relative risk (RR) 1.40, 95% confidence interval (CI), 0.98-2.01). We observed a 2-fold higher risk of the serous ovarian cancer subtype among those in the highest category of lactose consumption compared to the lowest (RR 2.07, 95% CI, 1.27-3.40). For each 11-gram increase in lactose consumption (the approximate amount in one glass of milk), we observed a 20% increase in risk of serous cancers (RR 1.20, 95% CI, 1.04-1.39). Skim and low-fat milk were the largest contributors to dietary lactose. Women who consumed one or more servings of skim or low-fat milk daily had a 32% higher risk of any ovarian cancer (RR 1.32, 95% CI, 0.97-1.82) and a 69% higher risk of serous ovarian cancer (RR 1.69, 95% CI, 1.12-2.56) compared to women consuming 3 or less servings monthly. Controlling for fat intake did not change our findings. Our findings provide some support for the hypothesis that lactose intake increases risk of epithelial ovarian cancer. However, the observed excess risk appeared limited to the serous subtype of ovarian cancer in our study.

The experience of Japan as a clue to the etiology of breast and ovarian cancers: relationship between death from both malignancies and dietary practices

Although breast and ovarian cancers are rare in Japan compared with other developed countries, the death rates for both are increasing. In Japan, dramatic lifestyle changes occurred after World War II. Over the past 50 years (1947-1997), the age-standardized death rates of breast and ovarian cancers increased about 2- and 4-fold, respectively, and the respective intake of milk, meat, and eggs increased 20-, 10-, and 7-fold. The increase in the annual death rates from breast and ovarian cancers might be due to the lifestyle changes (increased consumption of animal-derived food) that occurred after 1945. Among the food, milk and dairy products should receive particular attention since they contain considerable amounts of estrogens.

Diet and ovarian cancer risk: a case-control study in Italy

To assess the dietary correlates of cancer of the ovary, the consumption of a wide range of food groups has been investigated in a case-control study conducted between January 1992 and September 1999 in 4 Italian areas. Cases were 1,031 women with incident, histologically confirmed epithelial ovarian cancer; controls were 2,411 women admitted to the same network of hospitals as the cases for acute, non-malignant and non-gynecological conditions, unrelated to hormonal or digestive tract diseases or to long-term modifications of diet. The subjects' usual diet was investigated through a validated food frequency questionnaire including 78 foods and recipes, then grouped into 18 food groups. Odds ratios (OR), and the corresponding 95% confidence intervals (CI) were estimated using unconditional multiple logistic regression models including terms for age, study center, education, year at interview, parity, oral contraceptive use and energy intake. Significant trends of increasing risk emerged for red meat (OR = 1.53 for the highest compared with the lowest quintile of consumption), whereas inverse associations were observed for consumption of fish (OR = 0.51), raw (OR = 0.47) and cooked vegetables (OR = 0.65), and pulses (OR = 0.77).

Epithelial ovarian carcinoma and European birthplace of grandparents

OBJECTIVE

The aim of this study was to determine whether the risk of ovarian carcinoma was related to latitude or to genetically based patterns of European geographic origin.

PATIENTS AND METHODS

We studied the countries of origin of European-born grandparents of 168 newly diagnosed patients in two hospitals in New York City, compared with 159 controls from similar neighborhoods. We measured the risk of this cancer associated with having one or more white, non-Jewish grandparents born in North Europe versus none or in South Europe versus none. We also classified geographic origins in other ways to reflect the two main trends in genetic variations between Europeans mapped by Cavalli-Sforza et al. (The History and Geography of Human Genes, Princeton University Press, Princeton, 1994). Unconditional logistic regression was used to control for age, parity, years of use of oral contraception, age at menarche, education, Catholic religion, and area of residence and for numbers of Jewish grandparents, siblings, and first-degree relatives with breast or ovarian cancer.

RESULTS

Approximately half of the subjects had least one white, non-Jewish grandparent born in Europe. There was no significant effect of ancestral latitude: among women born in the United States the odds ratio (OR) and 95% confidence limits associated with North European ancestry were 0.87 (0.47--1.63) compared with a reference group of women with no such ancestry. The corresponding OR for South Europe was 0.73 (0.39--1.74). Using the genetically based classifications of countries of origin, however, we found significant differences between cases and controls; ancestries from North West Europe and those from countries concentrically near Spain showed lower risks of ovarian carcinoma.

CONCLUSIONS

The results support the hypothesis that the previously observed effects of latitude must act through environmental effects or through gene-environment interactions. Other variations in risk related to geographic origins are consistent with known patterns of genetic differences, but require confirmation in larger, population-based studies.

Ovarian cancer: epidemiology, biology, and prognostic factors

Ovarian cancer varies widely in frequency among different geographic regions and ethnic groups, with a high incidence in Northern Europe and the United States, and a low incidence in Japan. The majority of cases are sporadic, and only 5% to 10% of ovarian cancers are familial. The etiology of ovarian cancer is poorly understood. Models of ovarian carcinogenesis include the theory of incessant ovulation, in which a person's age at ovulation, i.e., lifetime number of ovulatory cycles, is an index of her ovarian cancer risk. Excessive gonadotropin and androgen stimulation of the ovary have been postulated as contributing factors. Exposure of the ovaries to pelvic contaminants and carcinogens may play a role in the pathogenesis of ovarian cancer. Epidemiologic and molecular-genetic studies identify numerous risk and protective factors. The most significant risk factor is a family history of the disease. Recent advances in molecular genetics have found mutations in the BRCA1 and BRCA2 tumor suppressor genes responsible for the majority of hereditary ovarian cancer. Additional risk factors include nulliparity and refractory infertility. Protective factors include multiparity, oral contraceptives, and tubal ligation or hysterectomy. With five years of oral contraceptive use, women can cut their risk of ovarian cancer approximately in half; this also holds true for individuals with a family history. Stage at diagnosis, maximum residual disease following cytoreductive surgery, and performance status are the three major prognostic factors. Using a multimodality approach to treatment, including aggressive cytoreductive surgery and combination chemotherapy, five-year survival rates are as follows: Stage I (93%), Stage II (70%), Stage III (37%), and Stage IV (25%).

A toxicological review of lactose to support clinical administration by inhalation

Although lactose is widely used in the pharmaceutical industry as an excipient in preparations given by several routes of administration, including by inhalation, there is no comprehensive review of its toxicological properties. This document seeks to review the available oral preclinical and clinical safety data from the literature, together with that generated by Fisons in animals using the inhalation route. In animal toxicity studies, lactose has been administered primarily by the inhalation and dietary routes to the rat, dog and/or primate. Adverse findings, such as abdominal distension and diarrhoea, have been demonstrated in rodent feeding studies. However, these changes are considered to be due to non-specific effects associated with high dietary doses of lactose, with a subsequent production of a dietary imbalance which results in physiological disturbances and an overload in the metabolic processes particularly involving calcium. These changes at high dietary intakes of lactose are considered to be of little relevance for man under the normal conditions of use of the material as an excipient in pharmaceutical formulations. No adverse local effects to the lung have been demonstrated in the animal studies using the inhalation route. Although the inhalation dose of lactose in the animal studies, of which most is subsequently swallowed, is markedly higher than the clinical dose, it is considerably less than consumed in animal studies using the dietary route. Consequently, it is not surprising that lactose is well tolerated by the inhalation route. In a small number of susceptible humans, intolerance to lactose is generally observed with oral intake of lactose, usually as a constituent of milk and is associated with lactase deficiency. Swallowed lactose at the levels present in inhaled preparations is unlikely to present any significant problems in patients with lactase deficiency. In conclusion, lactose is well recognized as a safe pharmaceutical excipient for use in oral or inhalation formulations and is not likely to constitute any significant toxicological hazard to man.