Carol Sweeney

Poor Survival Associated with the BRAF V600E Mutation in Microsatellite-Stable Colon Cancers

The BRAF V600E mutation has been associated with microsatellite instability and the CpG island methylator phenotype (CIMP) in colon cancer. We evaluated a large population-based sample of individuals with colon cancer to determine its relationship to survival and other clinicopathologic variables. The V600E BRAF mutation was seen in 5% (40 of 803) of microsatellite-stable tumors and 51.8% (43 of 83) of microsatellite-unstable tumors. In microsatellite-stable tumors, this mutation was related to poor survival, CIMP high, advanced American Joint Committee on Cancer (AJCC) stage, and family history of colorectal cancer [odds ratio, 4.23; 95% confidence interval (95% CI), 1.65-10.84]. The poor survival was observed in a univariate analysis of 5-year survival (16.7% versus 60.0%; P < 0.01); in an analysis adjusted for age, stage, and tumor site [hazard rate ratio (HRR), 2.97; 95% CI, 2.05-4.32]; in stage-specific, age-adjusted analyses for AJCC stages 2 to 4 (HRR, 4.88, 3.60, and 2.04, respectively); and in Kaplan-Meier survival estimates for AJCC stages 2 to 4 (P < 0.01 for all three stages). Microsatellite-unstable tumors were associated with an excellent 5-year survival whether the V600E mutation was present or absent (76.2% and 75.0%, respectively). We conclude that the BRAF V600E mutation in microsatellite-stable colon cancer is associated with a significantly poorer survival in stages 2 to 4 colon cancer but has no effect on the excellent prognosis of microsatellite-unstable tumors.

Association of genetic variation in tamoxifen-metabolizing enzymes with overall survival and recurrence of disease in breast cancer patients

SummaryTamoxifen has been a mainstay of adjuvant therapy for breast cancer for many years. We sought to determine if genetic variability in the tamoxifen metabolic pathway influenced overall survival in breast cancer patients treated with tamoxifen. We examined functional polymorphisms in CYP2D6, the P450 catalyzing the formation of active tamoxifen metabolites, and UGT2B15, a Phase II enzyme facilitating the elimination of active metabolite in a retrospective study of breast cancer patients. We also examined whether the combination of variant alleles in SULT1A1 and UGT2B15 had more of an impact on overall survival in tamoxifen-treated patients than when the genes were examined separately.We conducted a retrospective study using archived paraffin blocks for DNA extraction and data from pathology reports and hospital tumor registry data for information on clinical characteristics, treatment, and outcomes (162 patients receiving tamoxifen and 175 who did not). Genotypes for CYP2D6 and UGT2B15 were obtained and Cox proportional hazards modeling was performed.After adjusting for age, race, stage of disease at diagnosis, and hormone receptor status, we found no significant association between CYP2D6 genotype and overall survival in either group of breast cancer patients. Tamoxifen-treated patients with UGT2B15 high activity genotypes had increased risk of recurrence and poorer survival. When UGT2B15 and SULT1A1 ‘at-risk’ alleles were combined, women with two variant alleles had significantly greater risk of recurrence and poorer survival than those with common alleles. These studies indicate that genetic variation in Phase II conjugating enzymes can influence the efficacy of tamoxifen therapy for breast cancer.

Diet and lifestyle factor associations with CpG island methylator phenotype and BRAF mutations in colon cancer

It has been proposed that dietary factors such as folate, alcohol and methionine may be associated with colon cancer because of their involvement in DNA methylation processes. Data from a large population‐based case‐control study of incident colon cancer were used to evaluate whether intake of dietary, obesity, physical activity and nonsteroidal antiinflammatory drugs are associated with a CpG island methylator phenotype (CIMP). The BRAF V600E mutation and 5 CpG island markers (MINT1, MINT2, MINT31, p16 and hMLH1) were assessed in 1154 cases of colon cancer. We hypothesized that dietary factors involved in DNA methylation, cruciferous vegetables and use of aspirin/NSAIDs would be associated with CIMP‐high tumors. Dietary folate, vitamins B6 and B12, methionine and alcohol were not associated with increased likelihood of colon tumors with the CIMP‐high (2 or more markers methylated) phenotype. Dietary fiber, physical activity and aspirin and other nonsteroidal antiinflammatory drugs were inversely associated with both CIMP‐low and CIMP‐high tumors. Our results also suggested non‐CIMP pathways as well. Obese individuals were at 2‐fold increased risk of having a CIMP‐low tumor. Alcohol was associated with an increased risk of tumors that were MSI+ and CIMP‐low. In the presence of smoking 20 or more cigarettes per day, use of NSAIDs did not protect against a BRAF mutation. Our data suggest multiple pathways to colon cancer. They do not support a unique role for dietary folate, alcohol, vitamins B6 and B12 and methionine in a CpG island methylator phenotype.

Alcohol Consumption and Breast Cancer Recurrence and Survival Among Women With Early-Stage Breast Cancer: The Life After Cancer Epidemiology Study

PURPOSE To examine the association of alcohol consumption after breast cancer diagnosis with recurrence and mortality among early-stage breast cancer survivors. PATIENTS AND METHODS Patients included 1,897 LACE study participants diagnosed with early-stage breast cancer between 1997 and 2000 and recruited on average 2 years postdiagnosis, primarily from the Kaiser Permanente Northern California Cancer Registry. Alcohol consumption (ie, wine, beer, and liquor) was assessed at cohort entry using a food frequency questionnaire. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% CI with adjustment for known prognostic factors. RESULTS Two hundred ninety-three breast cancer recurrences and 273 overall deaths were ascertained after an average follow-up of 7.4 years. Nine hundred fifty-eight women (51%) were considered drinkers (> 0.5 g/d of alcohol), and the majority drank wine (89%). Drinking ≥ 6 g/d of alcohol compared with no drinking was associated with an increased risk of breast cancer recurrence (HR, 1.35; 95% CI, 1.00 to 1.83) and death due to breast cancer (HR, 1.51; 95% CI, 1.00 to 2.29). The increased risk of recurrence appeared to be greater among postmenopausal (HR, 1.51; 95% CI, 1.05 to 2.19) and overweight and obese women (HR, 1.60; 95% CI, 1.08 to 2.38). Alcohol intake was not associated with all-cause death and possibly associated with decreased risk of non-breast cancer death. CONCLUSION Consuming three to four alcoholic drinks or more per week after a breast cancer diagnosis may increase risk of breast cancer recurrence, particularly among postmenopausal and overweight/obese women, yet the cardioprotective effects of alcohol on non-breast cancer death were suggested.

APC Mutations and Other Genetic and Epigenetic Changes in Colon Cancer

Relationships between adenomatous polyposis coli (APC) mutations, BRAF V600E mutations, and the CpG island methylator phenotype (CIMP) in colon cancer have not been explored. In addition, controversies exist about the proportion of tumors with APC mutations in the mutation cluster region (MCR); how commonly APC, Ki-ras, and p53 mutations occur in the same tumor; and whether APC mutations occur in sporadic microsatellite-unstable tumors. The APC gene was therefore sequenced in 90 colonic adenocarcinomas previously evaluated for CIMP, microsatellite instability, BRAF, Ki-ras, and p53. APC mutations were inversely related to BRAF mutations (P = 0.0003) and CIMP (P = 0.02) and directly related to p53 and Ki-ras mutations (P = 0.04). Slightly more than half of APC mutations occurred outside of the MCR, and frameshift mutations were more likely than nonsense mutations to occur in the MCR (21 of 28 versus 12 of 40, P = 0.0003). APC mutations were found in sporadic microsatellite-unstable tumors and were more likely to be frameshifts in short nucleotide repeats (P = 0.007). The occurrence of APC, Ki-ras, and p53 mutations together in the same tumor was uncommon (11.1%). In conclusion, an analysis restricted to the MCR will miss more than half of APC mutations as well as mischaracterize their mutational spectrum. The conventional wisdom that most colon cancers contain APC, Ki-ras, and p53 mutations is incorrect. Microsatellite instability may precede acquisition of APC mutations in sporadic microsatellite-unstable tumors. The relationships of APC mutations to other genetic and epigenetic alterations add to the already impressive genetic heterogeneity of colon cancer. (Mol Cancer Res 2007;5(2):165–70)

A comparison of colon and rectal somatic DNA alterations

PURPOSE: Differences in acquired mutations in colon and rectal tumors may account for differences in risk factors. In this study, we examined similarities and differences in somatic alterations in colon and rectal tumors. METHODS: Cases were identified from two large population-based case-control studies of colon cancer and rectal cancer. We sequenced Exons 5 to 8 of the p53 gene and Codons 12 and 13 of the Ki-ras gene to identify tumor mutations. Microsatellite instability was determined based on BAT26 and TGF&bgr;RII analysis; CpG island methylator phenotype was determined based on having two or more of the following markers methylated p16, MLH1, MINT1, MINT2, and MINT31. RESULTS: p53 mutations were observed in 39.7% of proximal, 51.0% of distal, and 46.6% of rectal tumors; Ki-ras mutations were observed in 36.0% of proximal, 26.9% of distal, and 30.5% of rectal tumors. Although 40.9% of proximal tumors were considered CpG island methylator phenotype positive (having two or more of five markers methylated), only 12.9% of distal and 11.9% of rectal tumors were CpG island methylator phenotype positive. Likewise, microsatellite instability was observed in 23.7% of proximal and only 3.8% of distal and 2.0% of rectal tumors. More than 50% of distal colon or rectal tumors had only one acquired mutation, whereas only 35.1% of proximal tumors had one mutation. The most common single mutation for colon and rectal tumors was p53 followed by Ki-ras mutations. CONCLUSIONS: Our findings suggest that unique mutational pathways are involved in the development of most colorectal tumors. Proximal colon cancers are more likely than rectal and distal colon tumors to have microsatellite instability, CpG island methylator phenotype, and Ki-ras mutations, whereas rectal and distal colon tumors are more likely than proximal colon tumors to have a p53 mutation. Overall, rectal and distal colon tumors share similar mutational frequencies which are different from those observed in proximal colon tumors.

Associations between ERα, ERβ, and AR Genotypes and Colon and Rectal Cancer

Estrogen and androgens are thought to be involved in the etiology of colorectal cancer. We evaluate genetic variants of the estrogen receptor genes (ERα and ERβ) and the androgen receptor gene (AR). We use data from two large case-control studies of colon (n = 1,580 cases and 1,968 controls) and rectal (n = 797 cases and 1,016 controls) cancer. We evaluated the 351A>G XbaI polymorphism of ERα, the 1,082 G>A and CA repeat polymorphisms of ERβ, and the CAG repeat of AR. Having two 25 or more CA repeats in ERβ was associated with an increased relative risk of colon cancer in women [odds ratio (OR), 2.13; 95% confidence interval (95% CI), 1.24-3.64] but not in men (Pinteraction relative excess risk from interaction < 0.01; multiplicative = 0.03). Increasing number of AR CAG repeats was directly associated with colon cancer among men (OR, 1.28; 95% CI, 1.06-1.54), but not women (OR, 0.83; 95% CI, 0.68-1.02); the interaction P value for AR gene × sex was <0.01. Taking hormone replacement therapy (HRT) was associated with a reduced risk of colon cancer in the presence of the R allele of the ERβ gene, whereas an R allele was associated with increased risk among postmenopausal women who did not take HRT. Postmenopausal women not using HRT who had ≥25 CA repeats of the ERβ gene had over a 6-fold increased risk of colon cancer (OR, 6.71; 95% CI, 2.89-15.6). Our results suggest that the ERβ gene is more important than ERα in the etiology of colorectal cancer. (Cancer Epidemiol Biomarkers Prev 2005;14(12):2936–42)

IL6, Aspirin, Nonsteroidal Anti-inflammatory Drugs, and Breast Cancer Risk in Women Living in the Southwestern United States

Interleukin-6 is a cytokine thought to be involved in inflammation, insulin, and estrogen-related pathways. We evaluate genetic variation in the IL6 gene with risk of breast cancer. We also evaluate breast cancer associations with aspirin and nonsteroidal anti-inflammatory drugs. A breast cancer case-control study (n = 1,527 non-Hispanic white cases, 1,601 non-Hispanic white controls, 798 Hispanic/Native American cases, and 924 Hispanic/Native American controls) was conducted among women living in the southwestern United States (4-Corners Breast Cancer Study). Five IL6 single nucleotide polymorphisms (SNP) and IL6 haplotypes based on these SNPs were evaluated. Allele frequencies were significantly different between non-Hispanic white and Hispanic/Native American women. Among postmenopausal women not recently exposed to hormones, the AG/GG genotypes of rs1800797 (−596A>G) and the GC/CC genotypes of rs1800795 (−174G>C) significantly reduced risk of breast cancer among non-Hispanic white women [odds ratio (OR), 0.69; 95% confidence interval (95% CI), 0.48-1.00 and OR, 0.68; 95% CI, 0.47-0.99, respectively] and Hispanic/Native American women (OR, 0.48; 95% CI, 0.28-0.83 and OR, 0.44; 95% CI, 0.26-0.99, respectively). Haplotypes of the five IL6 SNPs further defined these associations. Recent aspirin use significantly decreased risk of breast cancer among postmenopausal Hispanic/Native American women not recently exposed to hormones (OR, 0.56; 95% CI, 0.33-0.96). Among non-Hispanic white, the inverse association with aspirin was not statistically significant. IL6 genotype and haplotype significantly modified the association between aspirin and breast cancer, with the greatest effect modification being among women not recently exposed to hormones [P interaction = 0.06 (for non-Hispanic white) and 0.04 (for Hispanic/Native American) and SNP rs1800796 or −572G>C]. These data suggest that IL6 is associated with breast cancer risk and modifies the association between estrogen and aspirin and breast cancer risk. (Cancer Epidemiol Biomarkers Prev 2007;16(4):747–55)

NSAID use and survival after breast cancer diagnosis in post-menopausal women

Many epidemiologic studies, although not all, have shown an inverse relation between non-steroidal anti-inflammatory drug (NSAID) use and risk of incident breast cancer, but the possible influence of NSAID use on breast cancer survival has not been evaluated. We examined the association between self-reported NSAID use and survival after invasive breast cancer diagnosis among 591 postmenopausal women in a prospective study. Cox proportional hazards regression was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer death as well as all-cause mortality associated with NSAID use. There was an indication of reduced risk of breast cancer mortality and all-cause mortality for women reporting any versus no use of NSAIDs, with multivariate-adjusted HRs of 0.64 (95% CI 0.39–1.05) and 0.57 (95% CI 0.40–0.81), respectively. There was no trend of decreasing risk of death with increasing frequency of NSAID use per week. While the results from this exploratory analysis are preliminary, there is biological plausibility for such an association. Further studies should consider whether NSAIDs, which have biological activity affecting tumor promotion and progression and appear to protect against breast cancer incidence, may be associated with better prognosis after a diagnosis of invasive breast cancer.

Associations between vitamin D, vitamin D receptor gene and the androgen receptor gene with colon and rectal cancer

The transcriptional activity of the vitamin D receptor (VDR) gene is regulated, at least in part, by the androgen receptor (AR) gene. We evaluate how the number of polyglutamine (CAG) repeats of the AR gene influence colorectal cancer in conjunction with vitamin D, sunshine exposure and VDR. Studies of colon (1,580 cases and 1,968 controls) and rectal (797 cases and 1,016 controls) cancer were used. Vitamin D intake and average hours of sunshine exposure interacted with AR genotype in men. Men with low vitamin D intake or low levels of sunshine exposure who had 23+ CAG repeats of the AR gene had the greatest risk of colon cancer. ORs for men with 23 or more CAG repeats of the AR gene and in the lowest tertile of vitamin D intake or sunshine exposure were 1.71 (95% CI 1.14, 2.56) and 1.51 (95% CI 1.09, 2.09). Men with high levels of sunshine exposure were at reduced risk of developing rectal cancer if they had 23 or more CAG repeats (OR 0.62 95% CI 0.39, 0.97) than if they had fewer than 23 CAG repeats. The FF genotype of the Fok1 VDR gene was associated with reduced risk of colon cancer among women with any allele of 23+ CAG repeats (OR 0.62 95% CI 0.44, 0.88), whereas men with the LL/bb VDR genotypes were at reduced risk of rectal cancer if they also had 23+ CAG repeats (OR 0.71 95% CI 0.48, 1.05) relative to men with fewer than 23 CAG repeats of the AR gene. These data provide support for the role of vitamin D and sunshine exposure in the etiology of colorectal cancer and suggest that AR gene may modulate the association.