PPP2R1A mutations are common in the serous type of endometrial cancer

Recently unbiased sequencing efforts identified PPP2R1A mutations in clear cell ovarian cancers (OCC). Similar mutations were also noted with high frequency in uterine serous carcinoma. Because the endometrium develops from the same developmental precursors we further examined the hypothesis that PPP2R1A mutations might also occur in diverse histologic subtypes of uterine cancer. We sequenced the PPP2R1A in 22 cell line models of uterine cancer and 10 primary cancers. We found no mutations in the cell lines originally derived from endometrioid (n = 13), undifferentiated (n = 3), clear cell (n = 1), and carcinosarcoma (n = 3) cancers. However, we found a CCC (Pro) to CGC (Arg) codon 179 mutation in the ACI‐158 serous carcinoma cell line, a CCC (Pro) to CTC (Leu) in a primary serous carcinoma as well as a CGC (Arg) to CAC (His) codon 258 mutation in a poorly differentiated endometrioid cancer. We sequenced a large panel of endometrial malignancies (n = 181) and found 12 mutants. Importantly, we confirmed a high frequency of mutation in 8 of 25 (32%) serous carcinomas a subtype with well‐recognized poor prognosis. Mutations were infrequent in endometrioid cancer and absent in clear cell and carcinosarcoma subtypes. The PPP2R1A mutation regions are conserved among species and known to interact with the regulatory subunits of the PP2A enzyme. PPP2R1A mutant endometrial cancers may represent good candidates for personalized drug therapies particularly for women with the lethal serous histologic variant of uterine cancer. © 2011 Wiley Periodicals, Inc.     

GSTM1 null polymorphism and susceptibility to endometriosis and ovarian cancer

It is likely that heritable genetic factors contribute to the development of endometriosis, which is a putative precursor of the endometrioid and clear cell histological subtypes of ovarian cancer. The phase II glutathione S-transferases (GSTs) are a family of enzymes responsible for metabolism of a broad range of xenobiotics and carcinogens. Allelic variants of GSTs that have impaired detoxification function may increase the rate of genetic damage and thereby increase the susceptibility to cancer. The null genetic polymorphism in the gene encoding the GST class mu (GSTM1) enzyme has been reported to be significantly elevated in endometriosis patients and may represent an endometriosis susceptibility allele. In this study the frequency of the GSTM1 null genotype was investigated in 84 cases of endometriosis, 293 cases of ovarian cancer and 219 controls. All cases and controls were derived from women resident in the south east of England. The frequency of the GSTM1 null allele was not over-represented in the endometriosis patients (47.6%) compared with the controls (48.9%) (P = 0.898). In the ovarian cancer group the GSTM1 null genotype was significantly elevated compared with controls (59.0 versus 48.9%, P = 0.025). When stratified according to histological subtype a significantly increased GSTM1 null genotype was only observed for the endometrioid (65.4%, P = 0.013) and the combined endometrioid/clear cell ovarian cancers (67.0%, P = 0.004). We conclude that the GSTM1 null allele is not an endometriosis susceptibility allele, however, it may predispose endometriotic lesions to malignant transformation to endometrioid and clear cell ovarian cancer.     

Loss of heterozygosity on 10q23.3 and mutation of the tumor suppressor gene PTEN in benign endometrial cyst of the ovary: possible sequence progression from benign endometrial cyst to endometrioid carcinoma and clear cell carcinoma of the ovary

Loss of heterozygosity (LOH) at locus 10q23.3 and mutation of the PTEN tumor suppressor gene occur frequently in both endometrial carcinoma and ovarian endometrioid carcinoma. To investigate the potential role of the PTEN gene in the carcinogenesis of ovarian endometrioid carcinoma and its related subtype, clear cell carcinoma, we examined 20 ovarian endometrioid carcinomas, 24 clear cell carcinomas, and 34 solitary endometrial cysts of the ovary for LOH at 10q23.3 and point mutations within the entire coding region of the PTEN gene. LOH was found in 8 of 19 ovarian endometrioid carcinomas (42.1%), 6 of 22 clear cell carcinomas (27.3%), and 13 of 23 solitary endometrial cysts (56.5%). In 5 endometrioid carcinomas synchronous with endometriosis, 3 cases displayed LOH events common to both the carcinoma and the endometriosis, 1 displayed an LOH event in only the carcinoma, and 1 displayed no LOH events in either lesion. In 7 clear cell carcinomas synchronous with endometriosis, 3 displayed LOH events common to both the carcinoma and the endometriosis, 1 displayed an LOH event in only the carcinoma, and 3 displayed no LOH events in either lesion. In no cases were there LOH events in the endometriosis only. Somatic mutations in the PTEN gene were identified in 4 of 20 ovarian endometrioid carcinomas (20.0%), 2 of 24 clear cell carcinomas (8.3%), and 7 of 34 solitary endometrial cysts (20.6%). These results indicate that inactivation of the PTEN tumor suppressor gene is an early event in the development of ovarian endometrioid carcinoma and clear cell carcinoma of the ovary.     

Epithelial Ovarian Cancer with Endometriosis is not Associated with Menopausal Status: a Co-Association Study at Prapokklao Hospital

Objective: To determine any association between the menopausal status and epithelial ovarian cancer coexistingwith endometriosis (EOC-E). In addition, the prevalence and possible risk factors were assessed. Methods: Medicalrecords of 172 women with epithelial ovarian cancer between January 2011 and December 2016 at Prapokklao Hospitalwere reviewed and divided into two groups: EOC-E defined as the case group and without endometriosis (EOC-NE)as the control group. Results: The proportion of EOC-E was 18% (31/172). There were no significant differencesbetween the two groups in baseline clinical characteristics and presenting symptoms except for history of smokingand abnormal uterine bleeding found more often in EOC-E cases. Most EOC-E were of clear cell histological typefollowed by endometrioid and serous types (35.5, 25.8 and 22.6 %; respectively). The clear cell type was 8 timesmore likely in the EOC-E than in the EOC-NE (OR 8.0, 95% CI 2.97-21.89, p-value <0.001) group. Nulliparity andsmoking increased risk of EOC-E 2 and 7 times, respectively (OR 2.3, 95%CI 1.03-5.00, p-value 0.041 and OR 7.4,95%CI 1.18-46.63, p-value 0.032). Conclusions: EOC-E are relatively common. Abnormal uterine bleeding is the onlysignificant presenting symptom in the EOC-E as compared with the EOC-NE group. Endometriosis was a predictivefactor for clear cell and endometrioid type I EOC. Menopausal status and age were not associated with a presentationof endometriosis with EOC.     

The N314D polymorphism of galactose-1-phosphate uridyl transferase does not modify the risk of ovarian cancer.

It has been proposed that high levels of galactose consumption increase the risk of ovarian cancer. Galactose levels are determined, in part, by the galactose-1-phosphate uridyl transferase gene (GALT). The N314D allele of the GALT gene has been associated with low GALT activity and with an increased risk of ovarian cancer. We screened for the presence of the N314D GALT allele in 891 incident cases of epithelial ovarian cancer and in 364 unaffected female controls. No significant difference in the prevalence of the N314D allele was observed between the cases (18.1%) and the controls (18.7%). The odds ratio associated with the presence of one N314D allele was 0.94 (95% confidence interval (CI), 0.68-1.3; P = 0.70), and the odds ratio associated with two N314D alleles was 1.62 (95% CI, 0.34-7.7; P = 0.54). Subanalyses of the cases by histological type, by age, by ethnic group, by family history, and by BRCA1/2 mutation status did not reveal any significant associations. We conclude that the GALT N314D allele does not predispose to epithelial ovarian cancer.     

Galactose-1-phosphate uridyl transferase (GALT) genotype and phenotype, galactose consumption, and the risk of borderline and invasive ovarian cancer (United States)

Objective: Previous studies have suggested that high levels of galactose consumption and/or low levels of galactose-1-phosphate uridyl transferase (GALT) activity may result in an increased risk of epithelial ovarian cancer. Similarly, some have reported that carriers of the N314D (asparagine at codon 314 replaced by aspartate) GALT polymorphism, which can be associated with low GALT activity, may have a higher risk of ovarian cancer. We examined these issues as part of a large case–control study of ovarian cancer conducted in Los Angeles between 1992 and 1998. Methods: A total of 1439 histologically confirmed borderline and invasive ovarian cancer cases among English-speaking non-Asian women were ascertained through the population-based cancer registry for Los Angeles County and completed in-person interviews were obtained from 689 of these (78% of cases approached). Controls consisted of 645 English-speaking non-Asian women with at least one intact ovary matched to cases on race/ethnicity (African-American, Latina, non-Latina White), date of birth (±3 years), and neighborhood of residence. Interviewer-administered questionnaires included information on reproductive factors, exogenous hormone use, medical history, and diet. Dietary information for the year before each case's diagnosis (and the same period for her matched control) was obtained using a self-administered food-frequency questionnaire. Blood samples were obtained from 452 controls, 136 cases with borderline ovarian cancer, and 312 cases with invasive ovarian cancer. The N314D polymorphism was characterized using PCR-RFLP and GALT enzyme activity, and was determined for a sample of the subjects with GALT genotype using an erythrocyte-based radioactive enzyme assay. Results: We found no effect of N314D GALT genotype on the risk of borderline ovarian cancer (odds ratio (OR) = 0.91; 95% confidence interval (CI) = 0.54–1.6) or invasive ovarian cancer (OR = 0.78; 95% CI & equals; 0.53–1.2). Neither did we observe a relationship between GALT activity or lactose/galactose intake and risk of borderline or invasive ovarian cancer. Among N314D carriers, galactose consumption was associated with an increased risk of borderline (OR = 2.7, p = 0.01), but not invasive (OR = 1.2, p = 0.34), ovarian cancer; however, this result was based on only 24 N314D-positive borderline cases. Conclusions: Differences in galactose intake and GALT metabolism do not contribute significantly to the risk of ovarian cancer. There is some evidence that galactose intake may play a role in the development of borderline ovarian cancer among women who carry the uncommon GALT N314D polymorphism. More data are needed if this latter suggestion is to be definitively addressed.     

Hormone replacement therapy and risk of epithelial ovarian cancer.

It has been suggested that oestrogen replacement therapy is associated with risk of epithelial ovarian cancer of the endometrioid type. Using data from an Australian population-based case-control study, the relation between unopposed oestrogen replacement therapy and epithelial ovarian cancer, both overall and according to histological type, was examined. A total of 793 eligible incident cases of epithelial ovarian cancer diagnosed from 1990 to 1993 among women living in Queensland, New South Wales and Victoria were identified. These were compared with 855 eligible female controls selected at random from the electoral roll, stratified by age and geographic region. Trained interviewers administered standard questionnaires to obtain detailed reproductive and contraceptive histories, as well as details about hormone replacement therapy and pelvic operations. No clear associations were observed between use of hormone replacement therapy overall and risk of ovarian cancer. Unopposed oestrogen replacement therapy was, however, associated with a significant increase in risk of endometrioid or clear cell epithelial ovarian tumours (odds ratio (OR) 2.56; 95% confidence interval (CI) 1.32-4.94). In addition, the risk associated with oestrogen replacement therapy was much larger in women with an intact genital tract (OR 3.00; 95% CI 1.54-5.85) than in those with a history of either hysterectomy or tubal ligation. Post-menopausal oestrogen replacement therapy may, therefore, be a risk factor associated with endometrioid and clear cell tumours in particular. Additionally, the risk may be increased predominantly in women with an intact genital tract. These associations could reflect a possible role of endometriosis in the development of endometrioid or clear cell ovarian tumours.     

Mutation of the PIK3CA gene in ovarian and breast cancer

Phosphatidylinositol 3'-kinases are lipid kinases with important roles in neoplasia. Recently, a very high frequency of somatic mutations in PIK3CA has been reported among a large series of colorectal cancers. However, the relevance of PIK3CA mutation in other cancer types remains unclear because of the limited number of tumors investigated. We have screened a total of 284 primary human tumors for mutations in all coding exons of PIK3CA using a combination of single stranded conformational polymorphism and denaturing high-performance liquid chromatography analysis. Among 70 primary breast cancers, 40% (28 of 70) harbored mutations in PIK3CA, making it the most common mutation described to date in this cancer type. Mutations were not associated with histologic subtype, estrogen receptor status, grade or presence of tumor in lymph nodes. Among the primary epithelial ovarian cancers only 11 of 167 (6.6%) contain somatic mutations, but there was a clear histologic subtype bias in their distribution. Only 2 of 88 (2.3%) of serous carcinomas had PIK3CA mutations compared with 8 of 40 (20.0%) endometrioid and clear cell cancers, which was highly significant (P = 0.001). In contrast, PIK3CA gene amplification (>7-fold) was common among all histologic subtypes (24.5%) and was inversely associated with the presence of mutations. Overall, PIK3CA mutation or gene amplification was detected in 30.5% of all ovarian cancers and 45% of the endometrioid and clear cell subtypes. Our study is the first direct evidence that PIK3CA is an oncogene in ovarian cancer and greatly extends recent findings in breast cancer.     

Genetic and epigenetic analysis of the putative tumor suppressor km23 in primary ovarian, breast, and colorectal cancers.

PURPOSE: A very high frequency of somatic mutations in the transforming growth factor-beta signaling component km23 has been reported in a small series of ovarian cancers (8 of 19, 42%). Functional studies showed that some mutations disrupt km23 function, resulting in aberrant transforming growth factor-beta signaling and presumably enhanced tumorigenicity. If verified, this would elevate mutation of km23 as the single most frequent somatic event in ovarian cancer. EXPERIMENTAL DESIGN: We sought to verify the frequency of silencing of km23 among 104 primary ovarian cancers (49 serous, 18 mucinous, 29 endometrioid/clear cell, and 8 undifferentiated) as well as 72 breast and 61 colorectal cancers by undertaking both somatic mutation and promoter methylation analyses. All four exons of km23 were individually amplified from genomic DNA with primers complementary to surrounding intronic sequences and analyzed by single-stranded conformational polymorphism analysis. RESULTS: Two germ line polymorphisms were identified, but none of the 237 tumors analyzed harbored somatic km23 mutations. In addition, promoter methylation analysis showed that in all cases, the 5' CpG island was unmethylated. CONCLUSIONS: Our data suggest that silencing of km23, either through somatic genetic mutation or promoter hypermethylation, is rare in ovarian, breast, and colorectal cancers.     

Comparative immunohistochemical studies of bcl-2 and p53 proteins in benign and malignant ovarian endometriotic cysts

BACKGROUND: A number of histologic and epidemiologic studies have suggested an association between endometriosis and ovarian carcinoma. Some reports have described a transition from endometriosis to atypical endometriosis to carcinoma. Using immunohistochemistry, the authors compared staining patterns in benign endometriotic cysts with ovarian tumors and the endometriotic cyst lining from which they arose, in an attempt to identify sequential or etiologic correlations. METHODS: One hundred thirteen formalin-fixed, paraffin-embedded sections were studied (30 benign ovarian endometriotic cysts, 24 endometriotic cysts containing endometrioid carcinomas, 19 endometriotic cysts harboring clear cell carcinomas, and 40 ovarian papillary serous cystadenocarcinomas). All sections were immunostained with anti-bcl-2 and anti-p53 antibodies using the streptavidin-biotin method. RESULTS: bcl-2 was reported to stain 23% of benign endometriotic cysts, 67% of endometrioid carcinomas, 73% of clear cell carcinomas, and 50% of papillary serous carcinomas. Approximately 42% of benign endometriotic lesions adjacent to the endometrioid carcinoma and 73% adjacent to clear cell carcinomas were found to stain for bcl-2 (p = 0.274 [not significant (NS)] and P = 0.008, respectively). p53 staining was negative in the benign endometriotic cyst group and was positive in 37-55% of the group with tumors. p53 staining was positive in 25% of the benign endometriotic lesions next to the endometrioid carcinoma and in 9% of the benign endometriotic lesions next to clear cell carcinoma (P = 0.014 and P = 0.239 [NS], respectively). CONCLUSIONS: The results of the current study suggest that alterations in bcl-2 and p53 may be associated with the malignant transformation of endometriotic cysts.     

Talcum powder, chronic pelvic inflammation and NSAIDs in relation to risk of epithelial ovarian cancer

Chronic inflammation has been proposed as the possible causal mechanism that explains the observed association between certain risk factors, such as the use of talcum powder (talc) in the pelvic region and epithelial ovarian cancer. To address this issue we evaluated the potential role of chronic local ovarian inflammation in the development of the major subtypes of epithelial ovarian cancer. Factors potentially linked to ovarian inflammation were examined in an Australia-wide case-control study comprising 1,576 women with invasive and low malignant potential (LMP) ovarian tumours and 1,509 population-based controls. We confirmed a statistically significant increase in ovarian cancer risk associated with use of talc in the pelvic region (adjusted odds ratio 1.17, 95% CI: 1.01-1.36) that was strongest for the serous and endometrioid subtypes although the latter was not statistically significant (adjusted odds ratios 1.21, 95% CI 1.03-1.44 and 1.18, 95% CI 0.81-1.70, respectively). Other factors potentially associated with ovarian inflammation (pelvic inflammatory disease, human papilloma virus infection and mumps) were not associated with risk but, like others, we found an increased risk of endometrioid and clear cell ovarian cancer only among women with a history of endometriosis. Regular use of aspirin and other nonsteroidal anti-inflammatory drugs was inversely associated with risk of LMP mucinous ovarian tumours only. We conclude that on balance chronic inflammation does not play a major role in the development of ovarian cancer.     

Endometrioid and clear cell ovarian cancers: a comparative analysis of risk factors

Endometrioid and clear cell subtypes of ovarian cancer are both known to be closely associated with endometriosis and endometrial pathology, and so have often been combined in studies of causation. We have examined these ovarian cancers separately for potentially distinct risk factors in our population-based, Australia-wide case control study of 142 women with incident invasive endometrioid, 90 with clear cell ovarian cancers and 1508 population controls. Multivariate logistic regression was used to calculated odds ratios (ORs) and 95% confidence intervals (CIs). Increasing parity, and hormonal contraceptive use for > or = 5 years, strongly decreased the risks of both subtypes. Breast feeding and tubal ligation were also inversely associated, but significantly so only for the endometrioid subtype. As expected endometriosis increased the risk of both subtypes (OR 2.2, 95% CI 1.2-3.9 for endometrioid and OR 3.0, 95% CI 1.5-5.9 for clear cell). Obesity was associated only with clear cell cancers, where we observed a two-fold increased risk (OR 2.2, 95% CI 1.2-4.1). Also a significant trend of decreasing risk with increasing intensity of smoking (p trend 0.02) and education beyond high school was associated with decreased development of clear cell cancers only. Endometrioid and clear cell ovarian cancers have some shared as well as some distinct risk factors, and therefore should be considered separately in studies of ovarian cancer.     

Increased synthesis of indoleamine-2,3-dioxygenase protein is positively associated with impaired survival in patients with serous-type, but not with other types of, ovarian cancer

We previously reported that indoleamine-2,3-dioxygenase (IDO) is associated with paclitaxel resistance and that IDO serves as a marker of poor prognosis in ovarian serous adenocarcinomas (SA). In this study, to explore the role of IDO in the development of various histological types of ovarian cancer, we further examined IDO expression not only in SA but also in other types of ovarian cancers. Expression of IDO protein was analyzed by immunohistochemistry for a total of 122 ovarian cancers including 40 SA, 67 clear cell adenocarcinomas (CCA), and 15 endometrioid adenocarcinomas (EA) with informed consent. Among these cases, there were 11 CCA accompanied with endometriosis and 60 cases with lymph node metastasis. We classified the samples into four categories by IDO staining pattern. IDO staining was positive in 57.5% of SA, 49.2% of CCA, and 73.3% of EA, respectively. The Kaplan-Meier survival curve showed a clear relationship between staining score and overall survival for patients with advanced (stages III and IV) SA (n=33) who underwent optimal surgery and paclitaxel-carboplatin (TC) chemotherapy as a first-line regimen. There was no association between IDO staining score and overall survival in the CCA cases. Eight of 11 cases (72.7%) of CCA accompanied by endometriosis presented identical staining patterns of IDO between CCA and endometriosis. In 43 of 60 cases (71.6%) with lymph node metastasis, the staining patterns of IDO showed a correspondence between the primary lesion and metastatic site. These results suggested that the increased synthesis of IDO protein was positively associated with impaired survival only in the serous type of ovarian cancer.     

Risk factors for ovarian cancer histotypes

To analyse the risk factors for different histologic types of ovarian cancer, we conducted a case-control study. The cases included 750 women with incident, histologically confirmed invasive epithelial ovarian cancer subdivided into: 493 serous, 81 mucinous, 78 endometrioid, and 98 other histologies. The controls included 2411 women admitted to the same hospitals as cases. The odds ratios for women with three or more births, in comparison with nulliparae, were 0.6 for serous, 0.4 for endometrioid, 1.0 for mucinous and 0.7 for other histological types of ovarian cancer. Family history of ovarian/breast cancer was associated to the risk of all ovarian cancer types, except mucinous ones. Selected dietary factors were less strongly directly (meat and starch), or inversely (fish and vitamin E) related to mucinous than to other histological types of ovarian cancer. High occupational physical activity was inversely related to the risk of ovarian cancer, with no heterogeneity across histologies. In conclusion, the association of reproductive factors and of selected dietary habits was weaker for mucinous ovarian cancer than for other histologic types.     

Relationship of benign gynecologic diseases to subsequent risk of ovarian and uterine tumors.

OBJECTIVE: Although endometriosis and uterine leiomyomas are common conditions, the extent to which either is associated with certain types of malignancies remains uncertain. METHODS: Using record linkage techniques, we assessed the relationships between hospital and outpatient admissions for endometriosis or leiomyomas and the development of ovarian and uterine cancers in Denmark between 1978 and 1998. Based on a population-based cohort exceeding 99,000 women, including 2,491 ovarian cancers, 860 borderline ovarian tumors, and 1,398 uterine cancers, we derived relative risks (RR) and 95% confidence intervals (95% CI) associated with overall and histology-specific tumor risks after adjustment for calendar time and reproductive characteristics. RESULTS: Endometriosis seemed to predispose to the development of ovarian cancer, with the association restricted to endometrioid or clear cell malignancies. Five or more years after the diagnosis of endometriosis, the RRs (95% CIs) were 2.53 (1.19-5.38) for endometrioid (7 exposed cases) and 3.37 (1.24-9.14) for clear cell (4 exposed cases) malignancies. Uterine leiomyomas were associated with increases in the risk of uterine malignancies, particularly sarcomas, where the RRs (95% CIs) were 20.80 (11.32-38.22) for women with 1 to 4 years of follow-up (11 exposed cases) and 5.70 (2.27-14.32) for those with more extended follow-up (5 exposed cases). CONCLUSION: In combination with clinical, pathologic, and molecular data, our results support that some endometriotic lesions may predispose to clear cell and endometrioid ovarian cancers. Uterine leiomyomas also showed a strong connection with subsequent uterine sarcomas, although it was difficult to decipher whether this reflected detection bias, shared risk factors, or an etiologic relationship.     

Distinct molecular profiles in Lynch syndrome‐associated and sporadic ovarian carcinomas

Ovarian carcinoma in Lynch syndrome (LS) is associated with unexpectedly high survival; yet, beyond DNA mismatch repair (MMR) defects, the developmental mechanisms are unknown. We used established (genetic) and new (epigenetic) classifiers of ovarian cancer to explore similarities and differences between LS‐associated and sporadic diseases. To this end, all available ovarian carcinomas (n = 20) from MMR gene mutation carriers ascertained through a nation‐wide registry and 87 sporadic ovarian carcinomas of the main histological types were molecularly profiled. LS‐ovarian carcinomas were mostly of nonserous histology (12 endometrioid, seven clear cell and one serous), diagnosed at a mean age of 45.7 years, and associated with a 10‐year survival of 87%. Among LS‐ovarian carcinomas, 19/20 (95%) were MMR‐deficient vs. 11/87 (13%) among sporadic cases (p < 0.0001). In a striking contrast to the sporadic cases, the expression of p53 was normal and KRAS/BRAF mutations absent in all LS‐ovarian carcinomas. PIK3CA mutations, suggested to be a favorable prognostic factor, occurred with a frequency of 6/20 (30%), which was comparable to sporadic tumors of endometrioid or clear cell type. Tumor suppressor genes were more frequently methylated and LINE‐1 hypomethylation less common in LS‐ovarian carcinomas compared to their sporadic counterparts. The patterns of genetic and epigenetic alterations reflected the origin as LS vs. sporadic cases on one hand and the histological type on the other hand. In conclusion, the significant molecular differences observed between LS‐associated and sporadic ovarian carcinomas help explain the different behavior of these tumors and emphasize the need for tailored clinical management.     

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.     

Risk of epithelial ovarian cancer in relation to benign ovarian conditions and ovarian surgery

Objective  Some forms of ovarian neoplasms may be preventable through the removal of precursor lesions. We assessed the risk associated with a prior diagnosis of, and ovarian surgery following, ovarian cysts and endometriosis, with a focus on characterizing risk among tumor subgroups. Methods  Information was collected during in-person interviews with 812 women with ovarian cancer diagnosed in western Washington State from 2002 to 2005 and 1,313 population-based controls. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Results  The risk of a borderline mucinous ovarian tumor associated with a history of an ovarian cyst was increased (OR=1.7, 95% CI: 1.0–2.8), but did not vary notably according to receipt of subsequent ovarian surgery. While risk of invasive epithelial ovarian cancer was slightly increased among women with a cyst who had no subsequent ovarian surgery, it was reduced when a cyst diagnosis was followed by surgery (OR = 0.6, 95% CI: 0.4–0.9). This reduction in risk was most evident for serous invasive tumors. Women with a history of endometriosis had a threefold increased risk of endometrioid and clear cell invasive tumors, with a lesser risk increase among women who underwent subsequent ovarian surgery. Conclusions  Our results suggest differences in the relation of ovarian cysts and endometriosis with risk of specific subtypes of ovarian cancer as well as the possibility that ovarian surgery in women with these conditions may lower the risk of invasive disease. Funding for this work was provided by the National Institutes of Health (RO1 CA87538).     

Tubal ligation and ovarian cancer risk in a large cohort: Substantial variation by histological type

Histopathological and molecular studies suggest that different histological subtypes (histotypes) of ovarian cancer have different aetiologies. Few studies have been large enough to explore reliably the effect of tubal ligation (sterilization), which has been associated with a reduced overall risk of ovarian cancer, on different tumour histotypes. In a prospective study of 1.1 million UK women without prior cancer or bilateral oophorectomy, 8,035 ovarian cancers occurred during mean follow‐up of 13.8 years. Using a Cox proportional hazards model, we estimated adjusted relative risks of ovarian cancer associated with tubal ligation. Overall, there was substantial heterogeneity in tumour risk associated with tubal ligation for the four main histotypes, serous, endometrioid, mucinous and clear cell (heterogeneity: p < 0.0001). For serous tumours, the most common histotype (n = 3,515), risks differed significantly between high‐grade (RR: 0.77, 95% CI: 0.67–0.89) and low‐grade tumours (RR: 1.13, 95% CI: 0.89–1.42); heterogeneity: p = 0.007. Relative risks were almost halved for endometrioid (n = 690, RR: 0.54, 95% CI: 0.43–0.69) and clear cell tumours (n = 401, RR: 0.55, 95% CI: 0.39–0.77), but there was no association between tubal ligation and mucinous tumours (n = 836, RR: 0.99, 95% CI: 0.84–1.18). For the main tumour histotypes we found little variation of risk by timing of tubal ligation. The significant differences by tumour histotype are unlikely to be due to confounding and are consistent with hypotheses that high‐grade and low‐grade serous tumours have different origins, and that some endometrioid and clear cell tumours might arise from cells and/or carcinogens travelling through the fallopian tubes.