Clonal analysis favours a monoclonal origin for serous borderline tumours with peritoneal implants

Nut and peanut butter intake and the risk of colorectal cancer and its anatomical and molecular subtypes: the Netherlands Cohort Study

Nut intake has been associated with reduced total cancer-related mortality, but evidence for colorectal cancer (CRC) risk is inconclusive. We investigated the associations between nut and peanut butter intake and anatomical CRC subtypes. To account for molecular heterogeneity, associations between nut and peanut butter intake and colorectal tumors harboring APC, KRAS or BRAF mutations, p53 overexpression or microsatellite instability were examined in secondary analyses. In the Netherlands Cohort Study (n = 120 852), lifestyle habits were measured with a questionnaire in 1986. After 20.3 years follow-up, 3567 CRC cases were included in case–cohort analyses. For the analyses of molecular CRC subtypes, 574 cases were included after 7.3 years follow-up. In categorical analyses, total nut intake was not significantly associated with CRC [HR (95% CI) 10+ g/day versus non-consumers = 0.94(0.78–1.15) in men; 0.96(0.75–1.22) in women]. In restricted cubic spline analyses, significant non-linear inverse associations with rectal cancer were observed for total nut, peanut and peanut butter intake in women, and borderline significant non-linear inverse associations for total nut and peanut intake in men. Regarding the molecular CRC subtypes, peanut butter intake was significantly associated with an increased risk of colorectal tumors that did not develop through the serrated neoplasia pathway in men [HR (95% CI) per 5 g/day increment = 1.22(1.07–1.38)]. Nut and peanut butter intake are non-linearly inversely associated with rectal cancer risk in women. In men, nut intake is borderline significantly non-linearly associated with a reduced rectal cancer risk. Peanut butter is associated with an increased risk of colorectal tumors that do not develop through the serrated neoplasia pathway in men.

Clinicopathologic and Molecular Features of Paired Cases of Metachronous Ovarian Serous Borderline Tumor and Subsequent Serous Carcinoma

Although risk factors have been established for the development of serous carcinoma after a diagnosis of serous borderline tumor (SBT), comprising atypical proliferative serous tumor (APST) (ie, conventional SBT) and noninvasive low-grade serous carcinoma (niLGSC) (ie, micropapillary SBT), subsequent invasive carcinoma still occurs in a subset of women who are not at increased risk. Whether subsequent serous carcinoma in women with a prior SBT represents malignant progression/recurrence or an independent primary tumor is unclear, and the combined clinicopathologic and molecular features of SBTs and their subsequent carcinomas have not been fully characterized. In this study, we analyzed a cohort of 42 women initially diagnosed with SBT who subsequently developed serous carcinoma of a total of 1025 cases of ovarian SBT from a nationwide population-based cohort. Review of the diagnostic slides was performed from this subset of SBTs and matched metachronous invasive serous carcinomas (39 low grade, 3 high grade). DNA was extracted from tissue blocks available for 41 cases (both SBT and carcinoma, n=36; SBT only, n=3; carcinoma only, n=2). Samples were subjected to digital droplet PCR to analyze mutation hotspots in KRAS (codon 12) and BRAF (V600E), which are frequently found in low-grade serous tumors. Eighty-one percent of SBTs (34/42) were APST, and 19% (8/42) were niLGSC. Forty percent of cases (17/42) were FIGO stage I, the majority of which were APST (14/17; 82%). The median time to development of carcinoma was 9 years (range, 0.6 to 25 y). Mutations in SBTs were distributed as follows: 5/39 (13%) BRAF mutant, 22/39 (56%) KRAS mutant, and 12/39 (31%) wild-type for both genes. There was a significant relationship between SBT gene mutation and histologic type, with BRAF mutations occurring exclusively in APST and a higher frequency of niLGSC among SBTs wild-type for BRAF and KRAS (P=0.01). The diffuse presence of tumor cells with abundant eosinophilic cytoplasm was significantly associated with the BRAF mutation (P=0.001). Mutational analyses of matched SBT/carcinoma pairs revealed concordant profiles in 33/36 (92%) cases, of which 19 (53%) were KRAS mutant, 4 (11%) were BRAF mutant, and 10 (28%) were wild type for both genes. The 3 discordant cases consisted of a wild-type niLGSC with a subsequent BRAF-mutant invasive LGSC, a KRAS-mutant APST with a KRAS-mutant LGSC, and a BRAF-mutant APST with subsequent development of a KRAS-mutant high-grade serous carcinoma. In conclusion, some women with SBTs can subsequently develop serous carcinoma, occasionally over 10 years later. Most subsequent carcinomas are low grade, but a small subset can be high grade. The type of gene mutation in SBT correlates with various histologic features. While most cases of serous carcinoma developing after a diagnosis of SBT probably represent tumor progression, a minority are independent primary tumors, presumably arising from endosalpingiosis.

Potential for Mitochondrial DNA Sequencing in the Differential Diagnosis of Gynaecological Malignancies

In the event of multiple synchronous gynecological lesions, a fundamental piece of information to determine patient management, prognosis, and therapeutic regimen choice is whether the simultaneous malignancies arise independently or as a result of metastatic dissemination. An example of synchronous primary tumors of the female genital tract most frequently described are ovarian and endometrial cancers. Surgical findings and histopathological examination aimed at resolving this conundrum may be aided by molecular analyses, although they are too often inconclusive. High mitochondrial DNA (mtDNA) variability and its propensity to accumulate mutations has been proposed by our group as a tool to define clonality. We showed mtDNA sequencing to be informative in synchronous primary ovarian and endometrial cancer, detecting tumor-specific mutations in both lesions, ruling out independence of the two neoplasms, and indicating clonality. Furthermore, we tested this method in another frequent simultaneously detected gynecological lesion type, borderline ovarian cancer and their peritoneal implants, which may be monoclonal extra-ovarian metastases or polyclonal independent masses. The purpose of this review is to provide an update on the potential use of mtDNA sequencing in distinguishing independent and metastatic lesions in gynecological cancers, and to compare the efficiency of molecular analyses currently in use with this novel method.

A guided tour of selected issues pertaining to metastatic carcinomas involving or originating from the gynecologic tract

Epithelial metastases originating from the gynecologic tract or secondarily involving it frequently display a different morphology when compared to the primary tumor. Furthermore, issues such as modes of metastasis, appropriate nomenclature and prognostic significance remain subjects of discussion and some skepticism. In this review, we will discuss: metastases to uterine adnexa; serous tubal intraepithelial carcinoma (STIC); serous borderline tumors; metastases from the uterine corpus; and “synchronous” endometrial and ovarian tumors. Three additional themes that will run through the discussions are those that are peculiar, although not restricted to the gynecologic tract: metastasis from non-invasive primary tumors, metastases that look benign and metastases that are benign or clinically indolent.

The molecular pathology of ovarian serous borderline tumors

Molecular studies in ovarian serous borderline tumors (OSBTs) have been used to understand different aspects of this neoplasm. (i) Pathogenesis, Kras and Braf mutations represent very early events in the tumorigenesis of OSBT as both are detected in serous cystadenomas associated with OSBTs. In contrast, serous cystadenomas without OSBTs do not show Kras or Braf mutations. In OSBTs, Kras mutations range from 17% to 39.5%, while Braf mutations range from 23% to 48%. The former is comparable with the range of Kras mutations in ovarian low-grade serous carcinomas (OLGSCa), 19%-54.5%. In contrast, Braf mutations in OLGSCa range from 0% to 33%. Serous cystadenomas appear to progress to OSBT due to a Braf mutation, but this mutation is rarely involved in the progression to OLGSCa. OSBTs with Braf mutation are associated with cellular senescence and up-regulation of tumor suppressor genes. In contrast, OSBTs without a Braf mutation may progress to OLGSCa due to Kras mutation or some other genetic alterations. (ii) The relationship between OSBTs and the extraovarian disease, a monoclonal versus mutifocal origin? This is still matter of debate as studies using different techniques have failed to settle this controversy. (iii) Biological behavior, Braf mutations appear to have a protective role against the progression of OSBT to OLGSCa, while Kras mutations are commonly seen in cases of OSBT that recurred as LGSCa. Nevertheless, LGSCa as a recurrence of an OSBT can originate from OSBTs with or without detectable Kras mutations. Also, it appears to be an association between Kras G12v mutation and a more aggressive phenotype of OSBT that recurred as LGSCa. (iv) Actionable targets, currently there are limited data. It has been reported that cancer cell lines with Kras G12v mutation are more sensitive to selumetinib than cell lines with wild-type Kras.

Synchronous tumours of the female reproductive tract

Many ovarian endometrioid carcinomas present with concurrent endometrial carcinoma, and these organ-confined, low-grade synchronous endometrial and ovarian tumours consistently behave as independent primary tumours, rather than a single advanced-stage carcinoma; they are associated with a very favourable prognosis and there is no need for adjuvant treatment. This phenomenon of synchronous tumours involving two or more sites within the female reproductive tract is well recognised, occurring in 1-2% of cases. Although some tumours can be recognised as metastasis, in many the relationship between the synchronous tumours is uncertain. Recently, application of next generation sequencing to synchronous endometrial and ovarian carcinomas has shed light on the relationship between these tumours, but raised more questions about the biology of this curious phenomenon. Herein, we review synchronous tumours involving more than one site in the female genital tract, discuss the pathogenesis, and offer guidelines for how to handle in routine practice.

Mitochondrial DNA sequencing demonstrates clonality of peritoneal implants of borderline ovarian tumors

Borderline ovarian tumors are rare low malignant potential neoplasms characterized by the absence of stromal invasion, whose main prognostic factors are stage and type of peritoneal implants. The latter are defined as invasive when cell proliferation invades the underlying tissue (peritoneal surface, omentum and intestinal wall), or noninvasive. It is still unknown if these implants are metastatic spread from the primary ovarian mass or a neoplastic transformation de novo of the peritoneal surface. Mitochondrial DNA sequencing was performed to assess clonality in eight patients presenting both borderline ovarian tumors and implants. In 37.5% of the cases, the same mitochondrial DNA mutation was present in both borderline ovarian tumors and the peritoneal implant, being this evidence that implants may arise as a consequence of a spread from a single ovarian site.

Pathology of borderline and invasive cancers

Epithelial ovarian tumors are heterogeneous neoplasms primarily classified according to cell type. They are further subdivided into benign, borderline, and malignant (carcinomas), and this subdivision is very important as it correlates with behavior. Borderline ovarian tumors show epithelial proliferation higher than that seen in their benign counterparts and variable nuclear atypia; however, in contrast to carcinomas, there is no destructive stromal invasion, and their prognosis is much better. Ovarian carcinomas are the most common ovarian cancers and the most lethal gynecological malignancies. On the basis of histopathology and molecular genetics, they are divided into five types (high-grade serous (70%), endometrioid (10%), clear cell (10%), mucinous (3%), and low-grade serous carcinomas (<5%)), which are morphologically diverse and account for over 95% of cases. These tumors are essentially distinct diseases, as indicated by differences in epidemiological and genetic risk factors, precursor lesions, patterns of spread, molecular alterations, response to chemotherapy, and prognosis. For a successful specific treatment, reproducible histopathological diagnosis of the tumor cell type is critical.

CHFR promoter methylation indicates poor prognosis in stage II microsatellite stable colorectal cancer

PURPOSE

Data on the prognostic significance of promoter CpG island methylation in colorectal cancer (CRC) are conflicting, possibly due to associations between methylation and other factors affecting survival such as genetic alterations and use of adjuvant therapy. Here, we examine the prognostic impact of promoter methylation in patients with CRC treated with surgery alone in the context of microsatellite instability (MSI), BRAF and KRAS mutations.

EXPERIMENTAL METHODS

One hundred and seventy-three CRCs were analyzed for promoter methylation of 19 tumor suppressor and DNA repair genes, the CpG island methylator phenotype (CIMP), MSI, the exon 15 V600E BRAF mutation and KRAS codon 12 and 13 mutations.

RESULTS

Unsupervised hierarchical clustering based on methylation status of 19 genes revealed three subgroups: cluster 1 [CL1, 57% (98/173) of CRCs], cluster 2 [CL2, 25% (43/173) of CRCs], and cluster 3 [CL3, 18% (32/173) of CRCs]. CL3 had the highest methylation index (0.25, 0.49, and 0.69, respectively, P = <0.01) and was strongly associated with CIMP (P < 0.01). Subgroup analysis for tumor stage, MSI, and BRAF status showed no statistically significant differences in survival between CL1, CL2, and CL3 nor between CIMP and non-CIMP CRCs. Analyzing genes separately revealed that CHFR promoter methylation was associated with a poor prognosis in stage II, microsatellite stability (MSS), BRAF wild-type (WT) CRCs: multivariate Cox proportional HR = 3.89 [95% confidence interval (CI), 1.58-9.60, P < 0.01; n = 66] and HR = 2.11 (95% CI, 0.95-4.69, P = 0.068, n = 136) in a second independent population-based study.

CONCLUSIONS

CHFR promoter CpG island methylation, which is associated with MSI, also occurs frequently in MSS CRCs and is a promising prognostic marker in stage II, MSS, BRAF WT CRCs.

Monoclonal origin of peritoneal implants and lymph node deposits in serous borderline ovarian tumors (s-BOT) with high intratumoral homogeneity

Molecular studies have shown that the most prevalent mutations in serous ovarian borderline tumors (s-BOT) are BRAF and/or KRAS alterations. About one third of s-BOT represent peritoneal implants and/or lymph node involvement. These extraovarian deposits may be monoclonal or polyclonal in origin. To test both the hypotheses, mutational analyses using pyrosequencing for BRAF codon 600 and KRAS codon 12/13 and 61 of microdissected tissue was performed in 15 s-BOT and their invasive and noninvasive peritoneal implants. Two to 6 implants from different peritoneal sites were examined in 13 cases. Lymph node deposits were available for the analysis in 3 cases. Six s-BOT showed mutation in exon 2 codon 12 of the KRAS proto-oncogen. Five additional cases showed BRAF p.V600E mutation representing an overall mutation rate of 73.3%. Multiple (2-6) peritoneal implants were analyzed after microdissection in 13 of 15 cases. All showed identical mutational results when compared with the ovarian site of the disease. All lymph node deposits, including those with multiple deposits in different nodes, showed identical results, suggesting high intratumoral mutational homogeneity. The evidence presented in this study and the majority of data reported in the literature support the hypothesis that s-BOT with their peritoneal implants and lymph node deposits show identical mutational status of BRAF and KRAS suggesting a monoclonal rather than a polyclonal disease regarding these both tested genetic loci. In addition, a high intratumoral genetic homogeneity can be suggested. In conclusion, the results of the present study support the monoclonal origin of s-BOT and their peritoneal implants and lymph node deposits.

Mutational analysis of BRAF and KRAS in ovarian serous borderline (atypical proliferative) tumours and associated peritoneal implants

There is debate as to whether peritoneal implants associated with serous borderline tumours/atypical proliferative serous tumours (SBT/APSTs) of the ovary are derived from the primary ovarian tumour or arise independently in the peritoneum. We analysed 57 SBT/APSTs from 45 patients with advanced-stage disease identified from a nation-wide tumour registry in Denmark. Mutational analysis for hotspots in KRAS and BRAF was successful in 55 APSTs and demonstrated KRAS mutations in 34 (61.8%) and BRAF mutations in eight (14.5%). Mutational analysis was successful in 56 peritoneal implants and revealed KRAS mutations in 34 (60.7%) and BRAF mutations in seven (12.5%). Mutational analysis could not be performed in two primary tumours and in nine implants, either because DNA amplification failed or because there was insufficient tissue for mutational analysis. For these specimens we performed VE1 immunohistochemistry, which was shown to be a specific and sensitive surrogate marker for a V600E BRAF mutation. VE1 staining was positive in one of two APSTs and seven of nine implants. Thus, among 63 implants for which mutation status was known (either by direct mutational analysis or by VE1 immunohistochemistry), 34 (53.9%) had KRAS mutations and 14 (22%) had BRAF mutations, of which identical KRAS mutations were found in 34 (91%) of 37 SBT/APST-implant pairs and identical BRAF mutations in 14 (100%) of 14 SBT/APST-implant pairs. Wild-type KRAS and BRAF (at the loci investigated) were found in 11 (100%) of 11 SBT/APST-implant pairs. Overall concordance of KRAS and BRAF mutations was 95% in 59 of 62 SBT/APST-implant (non-invasive and invasive) pairs (p < 0.00001). This study provides cogent evidence that the vast majority of peritoneal implants, non-invasive and invasive, harbour the identical KRAS or BRAF mutations that are present in the associated SBT/APST, supporting the view that peritoneal implants are derived from the primary ovarian tumour.

A novel classification of colorectal tumors based on microsatellite instability, the CpG island methylator phenotype and chromosomal instability: implications for prognosis

BACKGROUND

We studied the overlap between the major (epi)genomic events microsatellite instability (MSI), the CpG island methylator phenotype (CIMP) and chromosomal instability (CIN) in colorectal cancer (CRC), and whether specific (epi)genotypes were associated with CRC-related deaths.

PATIENTS AND METHODS

Molecular analyses using tumor DNA were successful in 509 CRC cases identified within the Netherlands Cohort Study in the period 1989-1993. Follow-up for the vital status until May 2005 was 100%.

RESULTS

MSI (12.6%), CIMP-only (5.3%), CIMP + CIN (13.4%), CIN-only (58.2%) and triple-negative tumors (10.6%) differed significantly regarding tumor localization, differentiation grade, initial adjuvant therapy (AT) use and genetic characteristics (P ≤ 0.03). CIMP-only, CIMP + CIN and triple-negative tumors, compared with CIN-only tumors, were significantly associated with a 3.67, 2.44 and 3.78-fold risk of CRC-related deaths after 2-year follow-up (95% confidence intervals, CIs, 1.70-7.91, 1.35-4.41 and 1.97-7.25, respectively), but not after late follow-up. MSI tumors were borderline significantly associated with a 0.40-fold risk of CRC-related deaths after late follow-up (95% CI 0.15-1.03).

CONCLUSION(S)

This is the first study to show that specific (epi)genotypes may hold a differential prognostic value that may vary over time. Although no specific treatment data were available, an explanation for the differential findings over time might be that (epi)genotypes modify therapy response.

Detection of the BRAF V600E mutation in serous ovarian tumors: a comparative analysis of immunohistochemistry with a mutation-specific monoclonal antibody and allele-specific PCR

Mutations of components of the mitogen-activated protein kinase pathway, mainly BRAF, are common in serous ovarian borderline tumors, whereas high-grade serous ovarian carcinomas rarely show this feature. With the advent of specific kinase inhibitors active against BRAF-mutated cancers, rapid and sensitive detection of the BRAF V600E, by far the most common mutation of this gene, is of great practical relevance. Currently, BRAF mutations are detected by DNA-based techniques. Recently, a monoclonal antibody (VE1) specific for the BRAF V600E protein suitable for archival tissues has been described. In this study, we compared detection of the V600E mutation in serous ovarian tumors by VE1 immunostaining and by allele-specific polymerase chain reaction. All 141 cases of high-grade serous ovarian cancer showed negative or rarely weak, diffuse background VE1 immunostaining, and BRAF wild type was confirmed by molecular analysis in all tested cases. In contrast, 1 (14%) of 7 low-grade serous carcinomas and 22 (71%) of 31 serous borderline tumors revealed moderate to strong VE1 positivity. Immunostaining was clearly evaluable in all cases with sufficient tumor cells, and only rare cases with narrow cytoplasm were difficult to interpret. The V600E mutation was confirmed by allele-specific polymerase chain reaction and sequencing in all VE1-positive cases. Two VE1-positive cases with low epithelial cell content required repeat microdissection to confirm the presence of the mutation. Immunohistochemistry with the VE1 antibody is a specific and sensitive tool for detection of the BRAF V600E mutation in serous ovarian tumors and may provide a practical screening test, especially in tumor samples with low epithelial content.

Body size and risk for colorectal cancers showing BRAF mutations or microsatellite instability: a pooled analysis

BACKGROUND

How body size influences risk of molecular subtypes of colorectal cancer (CRC) is unclear. We investigated whether measures of anthropometry differentially influence risk of tumours according to BRAF c.1799T>A p.V600E mutation (BRAF) and microsatellite instability (MSI) status.

METHODS

Data from The Netherlands Cohort Study (n = 120,852) and Melbourne Collaborative Cohort Study (n = 40,514) were pooled and included 734 and 717 colorectal cancer cases from each study, respectively. Hazard ratios (HRs) and 95% confidence intervals (CIs) for body mass index (BMI), waist measurement and height were calculated and compared for subtypes defined by BRAF mutation and MSI status, measured from archival tissue.

RESULTS

Results were consistent between studies. When pooled, BMI modelled in 5 kg/m(2) increments was positively associated with BRAF wild-type (HR: 1.16, 95% CI: 1.08-1.26) and MS-stable tumours (HR: 1.15, 95% CI: 1.06-1.24). Waist measurement was also associated with BRAF wild-type (highest vs lowest quartile, HR: 1.59, 95% CI: 1.33-1.90) and MS-stable tumours (highest vs lowest quartile HR: 1.68, 95% CI: 1.31-2.15). The HRs for BRAF mutation tumours and MSI tumours were smaller and non-significant, but differences between the HRs by tumour subtypes were not significant. Height, modelled per 5-cm increase, was positively associated with BRAF wild-type and BRAF mutation tumours, but the HR was greater for tumours with a BRAF mutation than BRAF wild-type (HR: 1.23, 95% CI: 1.11-1.37, P(heterogeneity) = 0.03). Similar associations were observed with respect to height and MSI tumours (HR: 1.26, 95% CI: 1.13-1.40, P(heterogeneity) = 0.02).

CONCLUSIONS

Generally, overweight increases the risk of CRC. Taller individuals have an increased risk of developing a tumour with a BRAF mutation or MSI.

Ovarian carcinomas: five distinct diseases with different origins, genetic alterations, and clinicopathological features

Malignant epithelial tumors (carcinomas) are the most common ovarian cancers and also the most lethal gynecological malignancies. Based on histopathology and molecular genetic alterations, ovarian carcinomas are divided into five main types (high-grade serous (70%), endometrioid (10%), clear cell (10%), mucinous (3%), and low-grade serous carcinomas (<5%)) that account for over 95% of cases. These types are essentially distinct diseases, as indicated by differences in epidemiological and genetic risk factors, precursor lesions, patterns of spread, and molecular events during oncogenesis, response to chemotherapy, and prognosis. For a successful specific treatment, reproducible histopathological diagnosis of the tumor cell type is critical. The five tumor types are morphologically diverse and resemble carcinomas of the uterus. Actually, recent investigations have demonstrated that a significant number of cancers, traditionally thought to be primary ovarian tumors (particularly serous, endometrioid, and clear cell carcinomas), originate in the fallopian tube and the endometrium and involve the ovary secondarily. This review summarizes recent advances in the molecular pathology which have greatly improved our understanding of the biology of ovarian carcinoma and are also relevant to patient management.

Fallopian tube correlates of ovarian serous borderline tumors

Ovarian serous borderline tumors (SBTs) are presumed to originate in the ovarian cortex or peritoneal surface. The pathogenetic role of the fallopian tube (FT) is unclear; however, recently, secretory cell outgrowths (SCOUTs) lacking PAX2 expression were described in benign FTs. This study addressed (1) the differentiation characteristics of SBTs and (2) the frequency of SCOUTs lacking PAX2 expression in the FTs of patients with SBTs and compared (3) SCOUT morphology and (4) PAX2 expression with SBTs. SBTs and FT epithelium shared both ciliated (p73) and secretory (HMFG2) differentiation. PAX2-null SCOUT frequency in FT cross-sections from patients with SBTs was 0.28 (110 of 398) versus 0.112 in benign hysterectomies and nearly 0 in pediatric and postpartum sterilization specimens (P = < 0.001). When adjusted for age, the differences narrowed but remained significant (P = 0.010). SCOUTs were heterogeneous, some displaying ciliated differentiation and papillary architecture. Two cases of discrete multifocal papillary SCOUTs in the FTs were associated with SBTs. All SBTs had heterogeneous PAX2 staining with areas of PAX2 loss. This study shows for the first time that PAX2-null SCOUTs are more common in the oviducts of women with SBTs and that loss of PAX2 expression occurs in most SBTs. These discoveries link both morphologic and functional gene (PAX2) alterations in the oviduct to SBTs, similar to that reported in high-grade serous carcinoma. Further study is warranted to clarify the relationship of the oviduct to serous neoplasia.

Clinical management of borderline ovarian tumors

Borderline ovarian tumors (BOTs) are epithelial tumors of the ovaries characterized by cellular proliferation and nuclear atypia but without an infiltrative growth pattern. As they frequently affect younger patients the clinical management is complicated by considerations such as preserving fertility and reducing postoperative morbidity. Over the past several decades surgical therapy has shifted from a radical approach to more conservative treatment. There are various modes of surgery applied to the patients. All these developments have to be considered from an oncologic standpoint as BOTs represent a potentially malignant disease. Oncologic safety, as well as patients' desires and expectations, have to be balanced to reach the most appropriate treatment for BOTs. For this reason current literature will be discussed in this review to give a thorough overview of this topic and to develop recommendations for the surgical management of these patients. Open questions will be identified to elaborate the need for future surveys and research.

Oncomutations as biomarkers of cancer risk

Cancer risk assessment impacts a range of societal needs, from the regulation of chemicals to achieving the best possible human health outcomes. Because oncogene and tumor suppressor gene mutations are necessary for the development of cancer, such mutations are ideal biomarkers to use in cancer risk assessment. Consequently, DNA-based methods to quantify particular tumor-associated hotspot point mutations (i.e., oncomutations) have been developed, including allele-specific competitive blocker-PCR (ACB-PCR). Several studies using ACB-PCR and model mutagens have demonstrated that significant induction of tumor-associated oncomutations are measureable at earlier time points than are used to score tumors in a bioassay. In the particular case of benzo[a]pyrene induction of K-Ras codon 12 TGT mutation in the A/J mouse lung, measurement of tumor-associated oncomutation was shown to be an earlier and more sensitive endpoint than tumor response. The measurement of oncomutation by ACB-PCR led to two unexpected findings. First, oncomutations are present in various tissues of control rodents and "normal" human colonic mucosa samples at relatively high frequencies. Approximately 60% of such samples (88/146) have mutant fractions (MFs) >10(-5), and some have MFs as high as 10(-3) or 10(-4). Second, preliminary data indicate that oncomutations are present frequently as subpopulations in tumors. These findings are integrated into a hypothesis that the predominant preexisting mutations in particular tissues may be useful as generic reporters of carcinogenesis. Future research opportunities using oncomutation as an endpoint are described, including rodent to human extrapolation, dose-response assessment, and personalized medicine.

v-Raf Murine Sarcoma Viral Oncogene Mutation Status in Serous Borderline Ovarian Tumors and the Effect on Clinical Behavior

Aims:

To determine the incidence of activating v-raf murine sarcoma viral oncogene (BRAF) mutations in 30 serous borderline tumors (SBTs) of the ovary and the accompanying implants and to link BRAF mutation status to the clinical behavior of these tumors.

Methods and Results:

Serous borderline tumors and noninvasive implants of 30 patients were analyzed for the presence of the BRAF V599E mutation, and mutation status was correlated to 70 months of clinical follow-up. Mutation status could be assessed in 27 SBTs. Eleven (41%) showed a BRAF mulation. Four (80%) of 5 patients with bilateral SBT showed a BRAF mutation in both ovaries. From the 8 implants that were analyzed for BRAF, 2 (25%) were mutated together with their primary tumor. v-Raf murine sarcoma viral oncogene mutation positive SBTs tend to present with a lower International Federation of Gynecology and Obstetrics stage and a higher tumor volume and are less frequently aneuploid. Seventy months' follow-up indicated no significant recurrence-free survival difference between these groups.

Conclusions:

v-Raf murine sarcoma viral oncogene mutations are common in ovarian SBT, are strongly associated with bilateral tumors, and are also found in implants. A larger number of tumors should be investigated to assess clinical importance of BRAF mutation status in SBTs.

Low-grade serous carcinoma of the ovary displaying a macropapillary pattern of invasion

Invasive micropapillary serous carcinoma (MPSC) also designated "low-grade serous carcinoma" (LGSC) of the ovary is characterized by small micropapillae that infiltrate underlying tissue (ovarian stroma). On occasion these tumors in addition to the micropapillae contain large macropapillae lined by bland epithelium. In rare cases, the entire tumor is composed of macropapillae. In these cases, the question of whether this is an invasive carcinoma or an unusual type of adenofibroma has been raised. The goal of this study was to describe this unusual macropapillary pattern of invasion in LGSC. Cases of LGSC containing macropapillae were retrieved from the files of the Johns Hopkins Hospital. In addition to a detailed morphologic analysis, the mutational status of KRAS and BRAF in the macropapillary, noninvasive, and invasive MPSC components was analyzed by nucleotide sequencing. There were 14 cases containing macropapillae (11 cases of LGSC, 2 cases of atypical proliferative serous tumor (APST) with microinvasion, and 1 case of APST with a focus of LGSC with macropapillae in perivaginal soft tissue). In 3 cases, extraovarian metastases contained macropapillae. Molecular analysis of the primary tumor components (macropapillary, noninvasive, and invasive MPSC and/or APST) was performed in 7 cases and of a lymph node metastasis with macropapillae in 1 case. The identical KRAS mutation was detected in all of the analyzed components of the primary ovarian tumors in 4 cases. In one of these cases, macropapillae in the lymph node metastasis contained a KRAS mutation identical to the primary tumor. The BRAF mutation identified in 1 case was identical in all components of the ovarian tumor. The identical mutations in the macropapillae and the other tumor components in each case indicate that they are clonally related. The finding of macropapillae within lymph nodes supports the interpretation that the macropapillary component is another manifestation of invasion in LGSC. The recognition of this pattern is important, especially in cases when a tumor is composed entirely of macropapillae.

MGMT and MLH1 promoter methylation versus APC, KRAS and BRAF gene mutations in colorectal cancer: indications for distinct pathways and sequence of events

BACKGROUND

To study how caretaker gene silencing relates to gatekeeper mutations in colorectal cancer (CRC), we investigated whether O6-methylguanine DNA methyltransferase (MGMT) and Human Mut-L Homologue 1 (MLH1) promoter hypermethylation are associated with APC, KRAS and BRAF mutations among 734 CRC patients.

METHODS

We compared MGMT hypermethylation with G:C > A:T mutations in APC and KRAS and with the occurrence of such mutations in CpG or non-CpG dinucleotides in APC. We also compared MLH1 hypermethylation with truncating APC mutations and activating KRAS and BRAF mutations.

RESULTS

Only 10% of the tumors showed both MGMT and MLH1 hypermethylation. MGMT hypermethylation occurred more frequently in tumors with G:C > A:T KRAS mutations (55%) compared with those without these mutations (38%, P < 0.001). No such difference was observed for G:C > A:T mutations in APC, regardless of whether mutations occurred in CpG or non-CpG dinucleotides. MLH1 hypermethylation was less common in tumors with APC mutations (P = 0.006) or KRAS mutations (P = 0.001), but was positively associated with BRAF mutations (P < 0.001).

CONCLUSIONS

MGMT hypermethylation is associated with G:C > A:T mutations in KRAS, but not in APC, suggesting that MGMT hypermethylation may succeed APC mutations but precedes KRAS mutations in colorectal carcinogenesis. MLH1-hypermethylated tumors harbor fewer APC and KRAS mutations and more BRAF mutations, suggesting that they develop distinctly from an MGMT methylator pathway.

Two sites of head and neck squamous cell carcinoma: utility of loss of heterozygosity

OBJECTIVES

The prevalence of distant metastasis and second primary tumors is increasing with improved locoregional control in patients with head and neck squamous cell carcinoma. Traditionally, clinicopathologic evidence has been the gold standard used to distinguish distant metastasis from second primary tumors. We report a case in which loss of heterozygosity testing was used to clarify the clonal relationship between the 2 sites of head and neck squamous cell carcinoma.

METHODS

A patient with squamous cell carcinoma in the larynx and mandible underwent loss of heterozygosity testing.

RESULTS

The loss of heterozygosity testing confirmed that the mandibular cancer was a metastatic presentation of the laryngeal squamous cell carcinoma.

CONCLUSIONS

We conclude that loss of heterozygosity testing can be useful in differentiating distant metastasis from second primary cancers in patients with 2 sites of head and neck squamous cell carcinoma, consequently providing important prognostic and staging information.

Associations of dietary methyl donor intake with MLH1 promoter hypermethylation and related molecular phenotypes in sporadic colorectal cancer

Intake of dietary factors that serve as methyl group donors may influence promoter hypermethylation in colorectal carcinogenesis. We investigated whether dietary folate, vitamin B2 and vitamin B6, methionine and alcohol were associated with mutL homologue 1 (MLH1) hypermethylation and the related molecular phenotypes of MLH1 protein expression, microsatellite instability (MSI) and BRAF mutations in patients with colorectal carcinomas. Within the Netherlands Cohort Study on diet and cancer (n = 120 852), 648 cases (367 men and 281 women) and 4059 subcohort members were available for data analyses from a follow-up period between 2.3 and 7.3 years after baseline. Gender-specific adjusted incidence rate ratios (RRs) were calculated over categories of dietary intake in case-cohort analyses. The intakes of folate, vitamin B2, methionine and alcohol were not associated with risk of tumors showing MLH1 hypermethylation, those lacking MLH1 protein expression or with MSI. Among men, we observed strong positive associations between folate and BRAF-mutated tumors (RR = 3.04 for the highest versus lowest tertile of intake, P(trend) = 0.03) and between vitamin B6 and tumors showing MLH1 hypermethylation (highest versus lowest tertile: RR = 3.23, P(trend) = 0.03). Among women, the relative risks of tumors with BRAF mutations or MLH1 hypermethylation were also increased in the highest tertiles of folate and vitamin B6 intake, respectively, but these did not reach statistical significance. The positive associations between folate intake and tumors harboring BRAF mutations and between vitamin B6 intake and those showing MLH1 hypermethylation were most pronounced among men and may suggest that these vitamins enhance colorectal cancer risk through genetic as well as epigenetic aberrations.

Integrated analysis of chromosomal, microsatellite and epigenetic instability in colorectal cancer identifies specific associations between promoter methylation of pivotal tumour suppressor and DNA repair genes and specific chromosomal alterations

Colorectal cancer (CRC) is a complex and heterogeneous disease in which genomic instability and DNA promoter methylation play important roles. The aim of this study was to investigate the relationship between chromosomal instability (CIN), microsatellite instability (MSI) and promoter methylation of CRC-associated genes. Therefore, 71 CRCs were analysed for CIN and MSI by comparative genomic hybridization and the mononucleotide marker BAT-26, respectively. Promoter methylation of the tumour suppressor and DNA repair genes hMLH1, O(6)-MGMT, APC, p14(ARF), p16(INK4A), RASSF1A, GATA-4, GATA-5 and CHFR was analysed using methylation-specific polymerase chain reaction. These integrative analyses showed that in CIN+ CRCs, promoter methylation of GATA-4 and p16(INK4A) was inversely related to chromosomal loss at 15q11-q21 and gain at 20q13, respectively (P values: 3.8 x 10(-2) and 4.5 x 10(-2), respectively). Interestingly, promoter methylation of RASSF1A, GATA-4, GATA-5 and CHFR, as well as a high methylation index (MI), was positively related to chromosomal gain at 8q23-qter (P values: 1.5 x 10(-2), 3.8 x 10(-2), 3.9 x 10(-2), 4.9 x 10(-2) and 8.2 x 10(-3), respectively). MSI was associated with BRAF mutation, promoter methylation of hMLH1, APC and p16(INK4A) and a high MI (total number of methylated genes) (P values: 2.4 x 10(-2), 2.5 x 10(-3), 1.8 x 10(-2), 4.6 x 10(-2) and 1.0 x 10(-2), respectively). Therefore, we conclude that promoter methylation of pivotal tumour suppressor and DNA repair genes is associated with specific patterns of chromosomal changes in CRC, which are different from methylation patterns in MSI tumours.