Increased risk of colorectal cancer in patients diagnosed with breast cancer in women

Synchronous or metachronous breast and colorectal cancers in younger-than-average-age patients: a case series

BACKGROUND

The incidence of breast and colorectal cancer (CRC) in younger-than-average-age patients is rising and poorly understood. This is the largest study on patients with both cancers who are less than 60 years old and aims to characterize demographic, clinicopathologic, and genetic features and describe therapeutic dilemmas and management strategies.

MATERIALS AND METHODS

This is a retrospective medical records review of patients at the University of California San Francisco with both primary breast and CRC before age 60.

RESULTS

Fifty-one patients were identified; 41 had detailed medical records. Median age of diagnosis with breast cancer was 43 (range 27-59) and CRC was 50 (28-59). Most were Caucasian (38, 74.5%) and never smokers (23, 56.1%); about half were current alcohol consumers (20, 48.8%) and about one-third had sedentary jobs (14, 34.1%). Average BMI was 25.8 (range: 14-49), and 30% were overweight or obese. Breast was the first cancer diagnosed in 36 patients (70.6%) and 44 (86.3%) had a metachronous CRC diagnosis. Breast cancer was early stage (0-2) in 32 (78.0%) patients whereas CRC was split between early stage (1-2) in 14 (34.1%) and later stage (3-4) in 19 (46.2%). Ten patients (24.3%) had a known germline mutation, although 23 (56.1%) had a family history of cancer in a first-degree relative.

CONCLUSION

Younger patients with both breast and CRC are a unique cohort, often without known risk factors. Alcohol consumption and sedentary jobs were the most common risk factors, and about one-quarter had a known genetic predisposition. Comanagement of both cancers requires individualized, multidisciplinary care.

Bidirectional Mendelian randomization analysis investigating the genetic association between primary breast cancer and colorectal cancer

Purpose

With the advancement in early diagnosis and treatment, the prognosis for individuals diagnosed with breast cancer (BC) has improved significantly. The prognosis of primary breast cancer (PBC) survivors can be significantly influenced by the occurrence of colorectal cancer (CRC) as a secondary primary cancer (SPC). The objective of this study is to explore the possible genetic association between PBC and CRC, aiming to lay a groundwork for the development of preventive strategies against SPC-CRC following BC surgery.

Methods

We employed a bidirectional two-sample Mendelian randomization (MR) approach to thoroughly examine genetic instrumental variables (IVs) derived from genome-wide association studies (GWAS) conducted on PBC and CRC. And applied inverse variance weighted (IVW) and multiple other MR methods (weighted median, simple median, MR-PRESSO and MR-RAPS) to evaluate the association between the two cancers (PBC and CRC) at genetic level. Furthermore, the robustness of the findings was further confirmed through the utilization of the genetic risk score (GRS) method in a secondary analysis.

Results

Forward MR analysis, a total of 179 BC genetic IVs, 25 estrogen receptor-negative (ER-) genetic IVs and 135 ER-positive (ER+) genetic IVs were screened. Reverse MR analysis, 179 genetic IVs of CRC, 25 genetic IVs of colon cancer, 135 genetic IVs of rectal cancer, 25 genetic IVs of left colon cancer and 135 genetic IVs of right colon cancer were screened. IVW and other MR methods found no significant genetic association between PBC and CRC (P > 0.05). Subgroup analysis also showed that ER- BC and ER+ BC were not correlated with the occurrence of CRC (P > 0.05). The findings of the secondary analysis using GRS were consistent with those obtained from the primary analysis, thereby confirming the robustness and reliability of this study.

Conclusions

Our findings do not provide any evidence supporting the association between PBC and CRC at the genetic level. Further large-scale prospective studies are warranted to replicate our findings.

Role of the intestinal microbiota and diet in the onset and progression of colorectal and breast cancers and the interconnection between both types of tumours

Colorectal cancer (CRC) is among the leading causes of mortality in adults of both sexes worldwide, while breast cancer (BC) is among the leading causes of death in women. In addition to age, gender, and genetic predisposition, environmental and lifestyle factors exert a strong influence. Global diet, including alcohol consumption, is one of the most important modifiable factors affecting the risk of CRC and BC. Western dietary patterns promoting high intakes of xenobiotics from food processing and ethanol have been associated with increased cancer risk, whereas the Mediterranean diet, generally leading to a higher intake of polyphenols and fibre, has been associated with a protective effect. Gut dysbiosis is a common feature in CRC, where the usual microbiota is progressively replaced by opportunistic pathogens and the gut metabolome is altered. The relationship between microbiota and BC has been less studied. The estrobolome is the collection of genes from intestinal bacteria that can metabolize oestrogens. In a dysbiosis condition, microbial deconjugating enzymes can reactivate conjugated-deactivated oestrogens, increasing the risk of BC. In contrast, intestinal microorganisms can increase the biological activity and bioavailability of dietary phytochemicals through diverse microbial metabolic transformations, potentiating their anticancer activity. Members of the intestinal microbiota can increase the toxicity of xenobiotics through metabolic transformations. However, most of the microorganisms involved in diet-microbiota interactions remain poorly characterized. Here, we provide an overview of the associations between microbiota and diet in BC and CRC, considering the diverse types and heterogeneity of these cancers and their relationship between them and with gut microbiota.

In Vitro Cytotoxicity Evaluation of Plastoquinone Analogues against Colorectal and Breast Cancers along with In Silico Insights

Colorectal cancer (CRC) and breast cancer are leading causes of death globally, due to significant challenges in detection and management. The late-stage diagnosis and treatment failures require the discovery of potential anticancer agents to achieve a satisfactory therapeutic effect. We have previously reported a series of plastoquinone analogues to understand their cytotoxic profile. Among these derivatives, three of them (AQ-11, AQ-12, and AQ-15) were selected by the National Cancer Institute (NCI) to evaluate their in vitro antiproliferative activity against a panel of 60 human tumor cell lines. AQ-12 exhibited significant antiproliferative activity against HCT-116 CRC and MCF-7 breast cancer cells at a single dose and further five doses. MTT assay was also performed for AQ-12 at different concentrations against these two cells, implying that AQ-12 exerted notable cytotoxicity toward HCT-116 (IC₅₀ = 5.11 ± 2.14 μM) and MCF-7 (IC₅₀ = 6.06 ± 3.09 μM) cells in comparison with cisplatin (IC₅₀ = 23.68 ± 6.81 μM and 19.67 ± 5.94 μM, respectively). This compound also augmented apoptosis in HCT-116 (62.30%) and MCF-7 (64.60%) cells comparable to cisplatin (67.30% and 78.80%, respectively). Molecular docking studies showed that AQ-12 bound to DNA, forming hydrogen bonding through the quinone scaffold. In silico pharmacokinetic determinants indicated that AQ-12 demonstrated drug-likeness with a remarkable pharmacokinetic profile for future mechanistic anti-CRC and anti-breast cancer activity studies.

Incidence of other cancer diagnoses in women with breast cancer: a retrospective cohort study with 42,248 women

PURPOSE

The aim of the present study was to determine whether women diagnosed with breast cancer (BC) have an increased incidence of other cancers, e.g., gastric cancer, lung cancer, skin cancer, and so on, compared to healthy women without a breast cancer diagnosis.

METHODS

This retrospective cohort study was based on data from the Disease Analyzer database (IQVIA) and included adult women with an initial diagnosis of BC documented in one of 1,274 general practices in Germany between January 2000 and December 2018. Women with BC were matched to women without cancer by age, index year, yearly consultation frequency, and co-diagnoses. Univariate Cox regression models were used to study the association between BC and the incidence of other cancer diagnoses.

RESULTS

21,124 women with BC and 21,124 women (mean age: 63 years) without cancer were included. Within 10 years of the index date, 14.3% of women with BC and 10.0% of women without cancer were diagnosed with cancer (p < 0.001). BC was significantly associated with the incidence of other cancer diagnoses (HR: 1.42, p < 0.001). The strongest association was observed for respiratory organ cancer (HR = 1.69, p < 0.001), followed by female genital organ cancer (HR = 1.61, p < 0.001) and cancer of lymphoid and hematopoietic tissue (HR: 1.59, p < 0.001).

CONCLUSION

The results of this study show that women with BC have an increased incidence of another cancer compared to women without cancer. Therefore, it is important to pay particular attention to the development of other malignancies during follow-up in patients with BC. This should be considered especially in patients with a proven genetic mutation.

Clinical characteristics and prognostic analysis of multiple primary malignant neoplasms in female patients with breast cancer or genitalia malignancies

Background

As public awareness of health has increased and diagnostic and treatment options have improved, the survival of patients with malignant tumors has continued to extend, and the population has been aging, the number of multiple primary malignant neoplasms has gradually increased in recent years. There are few reports concerning female patients with multiple primary malignant neoplasms of breast cancer or genitalia malignancies. In this study, we aimed to analyze the clinical characteristics and prognosis of multiple primary malignant neoplasms in female patients with breast cancer or genitalia malignancies, as well as further explore the factors that affect the survival.

Methods

We collected clinical data on 80 female patients diagnosed with multiple primary malignant neoplasms of the breast or genitalia, described their clinical features. Furthermore, we calculated the survival and prognostic factors for 52 participants.

Results

In our study, the prevalence rate of multiple primary malignant neoplasms was 0.66% (367/55404). Corresponding to female patients with multiple primary malignant neoplasms of breast cancer or genitalia malignancies, it was 1.4% (80/5707). the median age of diagnosis for the first tumor was 48 years, and the median age of diagnosis for the second tumor was 52 years. Regarding the interval, 67.57% (50/74) of patients were within five years. Most tumors were located in the breast (44.68%), followed by the uterus (20.21%), the ovary (17.02%), and the cervix (15.96%). The overall 12-, 36-and 60-month survival rates of the patients were 86.4%, 74.3%, and 69.8%. For the female patients, the stage (III-IV) (P = 0.046), non-radical surgery (P = 0.002), and types of the last tumor (breast cancer or genitalia malignancies) (P = 0.019) were associated with the poor prognosis.

Conclusions

Female patients with breast cancer or genital malignancies should pay attention to screening for the second tumor, especially within 4 years after the first tumor diagnosed. Furthermore, during tumor screening, it may be recommended for these patients to focus on colorectal cancer and lung cancer. Compared with previous studies, in addition to clinical staging and types of surgery, we found whether the last tumor was breast cancer or genitalia malignancies should also be considered a prognostic factor.

High Positive Predictive Value of Multitarget Stool DNA After Aerodigestive Tract Radiotherapy

BACKGROUND AND AIMS:

Multitarget stool DNA (mt-sDNA) is approved for average-risk colorectal cancer screening; test performance in persons with prior radiation therapy (RT) has not been studied. RT can induce gastrointestinal bleeding and alter DNA methylation, which may affect mt-sDNA accuracy. Among patients previously treated with RT, we aimed to measure the positive predictive value (PPV) of mt-sDNA and compare these results to historical estimates of mt-sDNA PPV among average-risk patients.

METHODS:

After institutional review board approval, we conducted a retrospective cohort study of a multisite academic and community-based practice. Patients with RT and subsequent mt-sDNA use during the study period (2014–2016) were identified. The findings at diagnostic colonoscopy were compared with published reports among average-risk patients. Nominal P values were generated by 2-tailed Fisher’s exact testing in comparisons of colorectal neoplasia (CRN) rates between groups.

RESULTS:

There were 220 patients who had RT before mt-sDNA testing. RT was delivered along the aerodigestive tract in 108 patients. Mt-sDNA tests were positive in 45 of 220 patients (20%), and colonoscopy findings were available for 42; 31 of 42 patients (74%) had CRN. PPV by mt-sDNA was similar when stratified by site of prior RT (along vs outside the aerodigestive tract; P = 1.00). Detection of advanced CRN (36%) was nominally higher than previously published retrospective (27%) and prospective (20%) studies. The median time from the start of RT to mt-sDNA use was 7 (interquartile range, 3–14) years.

CONCLUSION:

With a test positivity rate and PPV for CRN similar to reports among average-risk patients, prior RT does not appear to adversely affect mt-sDNA performance.

Survey of germline variants in cancer-associated genes in young adults with colorectal cancer

Colorectal cancer (CRC) incidence in young adults is rising. Identifying genetic risk factors is fundamental for the clinical management of patients and their families. This study aimed to identify clinically significant germline variants among young adults with CRC. Whole-exome sequencing data of blood-derived DNA from 133 unrelated young CRC patients (<55 years of age) underwent a comprehensive analysis of 133 cancer-predisposition/implicated genes. All patient tumors were evaluated for mismatch repair deficiency (dMMR). Among 133 patients (aged 16-54 years), 15% (20/133) had clinically actionable pathogenic or likely pathogenic (P/LP) variants in at least 1 well established cancer-predisposing gene: dMMR genes (6), MUTYH [bi-allelic (2), mono-allelic (3)], RNF43 (1), BMPR1A (1), BRCA2 (4), ATM (1), RAD51C (1), and BRIP1 (1). Five patients (4%) had variants in genes implicated in cancer but where the significance of germline variants in CRC risk is uncertain: GATA2 (1), ERCC2 (mono-allelic) (1), ERCC4 (mono-allelic) (1), CFTR (2). Fourteen (11%) had dMMR tumors. Eighteen (14%) reported a first-degree relative with CRC, but only three of these carried P/LP variants. Three patients with variants in polyposis-associated genes showed no polyposis (one each in MUTYH [bi-allelic], RNF43, and BMPR1A). Approximately one in five young adults in our series carried at least one P/LP variant in a cancer-predisposing/implicated gene; 80% of these variants are currently considered clinically actionable in a familial cancer setting. Family history and phenotype have limitations for genetic risk prediction; therefore multigene panel testing and genetic counseling are warranted for all young adults with CRC regardless of those two factors.

Interaction of Gut Microbiome and Host microRNAs with the Occurrence of Colorectal and Breast Cancer and Their Impact on Patient Immunity

Breast and colorectal cancers are two primary malignancies on which most of the research done worldwide investigates the potential genetic and environmental risk factors and thereby tries to develop therapeutic methods to improve prognosis. Breast cancer is the most diagnosed cancer type in women, while colorectal cancer is diagnosed in males as the third most and females as the second most cancer type. Though these two cancer types are predominantly seen in adult patients worldwide, in the current context, these malignancies are diagnosed at a younger age with a significant rate of incidents than previous. Such early-onset cancers are generally present at an advanced stage of the most aggressive type with a poor prognosis. In the past, the focus of the research was mainly on studying possible candidate genes to understand the onset. However, it is now recognized that genetics, epigenetics, and other environmental factors play a pivotal role in cancer susceptibility. Thus, most studies were diversified to study the behavior of host microRNAs, and the involvement of gut microbiota and good communication between them surfaced in the occurrence and state of the disease. It is understood that the impact of these factors affects the outcome of the disease. Out of the adverse outcomes identified relating to the disease, immunosuppression is one of the most concerning outcomes in the current world, where such individuals remain vulnerable to infections. Recent studies revealed that microbiome and microRNA could create a considerable impact on immunosuppression. This review focused on the behavior of host microRNAs and gut microbiome for the onset of the disease and progression, thereby influencing an individual's immunosuppression. Understanding the interactions among microRNA, microbiome, presentation of the disease, and impact on the immune system will be immensely useful for developing future therapeutic strategies based on targeting host microRNA and the patient's gut microbiome. Therapies such as inhibitory-miRNA therapies, miRNA mimic-based therapeutics, immune checkpoint blockade therapies, and bacteria-assisted tumor-targeted therapies help modulate cancer. At the same time, it paid equal attention to potential noninvasive biomarkers in diagnosis, prognosis, and therapeutics in both cancers.

Clinicopathologic Characteristics and Survival of Patients With Double Primary Malignancies: Breast and Colorectal Cancer

Purpose

This study aimed to investigate the clinicopathologic features and survival in patients with both breast cancer (BrC) and colorectal cancer (CRC).

Methods

Between 1996 and 2019, patients who were diagnosed with both BrC and CRC were evaluated retrospectively. Patients with distant metastasis, palliative resection, and previous cancer histories except for BrCs or CRCs were excluded. Altogether, 105 patients were divided into the B=C group (n=21), B-first group (n=40), and C-first group (n=44) according to the definition of synchronous and metachronous cancers. The clinicopathologic features and overall survival were evaluated.

Results

TNM stages and histologic types were comparable among the 3 groups (P=0.434). The interval of diagnosis was 67.1±40.4 and 59.3±47.2 months in the B- and C-first groups, respectively. The incidence of adjuvant chemotherapy in the B-first group was 57.5%, which was higher than the B=C and C-first groups (P<0.001). The estrogen receptor, progesterone receptor, Ki-67, and HER-2 molecular markers were not significantly different among the groups. The overall survival of the B-first group showed lower survival rates than the C-first group (P=0.039). In the logistic regression, HER-2 status (hazard ratio [HR], 11.9; P=0.032) and lymph node metastasis of CRC (HR, 5.8; P=0.036) were prognostic factors affecting overall survival.

Conclusion

B-first group had poorer survival outcomes than the C-first group in patients with the metachronous BrC and CRC. HER2 positivity and CRC lymph node metastasis may be prognostic factors that affect overall survival in these patients. The findings support that a colorectal cancer screening program should be included during BrC surveillance.

Pattern of nucleotide variants of TP53 and their correlation with the expression of p53 and its downstream proteins in a Sri Lankan cohort of breast and colorectal cancer patients

BACKGROUND

Breast cancer (BC) is known to be the most common malignancy in females whereas colorectal cancer (CRC) incidence also higher in both genders in Sri Lanka. TP53 is an important tumour suppressor gene and its somatic mutations are reported in approximately 27% of BC and 43% of CRC cases. Analysis of TP53 gene variants not only provides clues for the aetiology of the tumour formation, but also has an impact on treatment efficacy. The current study was conducted to investigate the pattern of TP53 variants in patients with BC and CRC from Sri Lanka.

METHODS

30 patients with BC, 21 patients with CRC and an equal number of healthy controls were screened for mutational status of TP53 by polymerase chain reaction (PCR) followed by direct sequencing. In addition, a subset of these samples were analysed for the protein expression of p53 and comparison made with the mutational status of TP53. We also analysed the protein expression of p21 and MDM2 as potential indicators of p53 functional status and compared it with the protein expression of p53. Additionally, hotspot codons of the KRAS, BRAF and PIK3CA genes were also analysed in a subset of CRC patients.

RESULTS

Twenty seven sequence variants, including several novel variants in the TP53 gene were found. Nine BC and seven CRC tumour samples carried pathogenic TP53 variants. Pathogenic point missense variants were associated with strong and diffuse positive staining for p53 by immunohistochemistry (IHC), whereas, wild type TP53 showed complete absence of positive IHC staining or rare positive cells, regardless of the type of cancer. There was no direct correlation between p21 or MDM2 expression and p53 expression in either BCs or CRCs. Four of the CRC patients had pathogenic hotspot variants in KRAS; three of them were on codon 12 and one was on codon 61.

CONCLUSION

The prevalence of pathogenic somatic TP53 variants was 31 and 33.33% in the studied BC and CRC cohorts respectively. All of them were located in exons 5-8 and the pathogenic missense variants were associated with strong immuno-positive staining for p53.

A Cross-sectional Study of Knowledge, Attitude and Barriers to Colorectal Cancer Screening among Cancer Survivors

Introduction:

Understanding behaviour of cancer survivors is imperative as they are at risk of recurrence or second cancers. Colorectal cancer (CRC) is one of the most common cancers globally. We aim to determine the uptake rate, barriers and predictors of CRC screening among cancer survivors.

Methods:

Within a public hospital in Singapore, 150 non-CRC survivors were enrolled. Questionnaire on knowledge, screening behaviour, motivators and barriers towards CRC screening was administered.

Results:

Majority were survivors of breast (69.3%), prostate (7.3%), endometrial (4%) and ovarian (4%) cancers. More than half had high knowledge scores for CRC symptoms, screening tests and risk factors. About a third had received physician’s recommendation on CRC screening. Approximately half had undergone screening. The most common barriers to CRC screening were lack of symptoms and physician’s recommendation. Cancer survivors with higher education, higher household income, family history and those who perceived “great need” or “some need” were more likely to have undergone screening (56.4% vs 30.6%, p=0.003; 62.2% vs 41.9%, p=0.022; 70.6% vs 45.1%, p=0.048; 70.8% vs 27.4%, p<0.001). Physician’s recommendation (76.4% vs 31.6%, p<0.001) and high CRC symptom knowledge (55.8% vs 34.5%, p=0.012) were associated with increased likelihood of screening.On multivariate analysis, physician’s recommendation, higher household income and survivors’ perceived need to undergo screening remained strong predictors for CRC screening (p<0.001; p=0.010; p<0.001).

Conclusion:

The uptake rate of CRC screening among non-CRC survivors was modest. Physicians need to be more active in discussing CRC screening with cancer survivors as part of the survivorship care plan.

Healthcare

Quality analysis of the treatment of cancer has been an objective of e-health services for quite some time. The objective is to predict the stage of breast cancer by using diverse input parameters. Breast cancer is one of the main causes of death in women when compared to other tumors. The classification of breast cancer information can be profitable to anticipate diseases or track the hereditary of tumors. For classification, an artificial neural network (ANN) structure was carried out. In the structure, nine training algorithms are used and the proposed is the Levenberg-Marquardt algorithm. For optimizing the hidden layer and neuron, three optimization techniques are used. In the result, the best approval execution is anticipated and the diverse execution evaluation estimation for three optimization algorithms is researched. The correlation execution diagram for an accuracy of 95%, a sensitivity of 98%, and a specificity of 89% of a social spider optimization (SSO) algorithm are shown.

A novel potential role of pituitary gonadotropins in the pathogenesis of human colorectal cancer

Background

Colorectal cancer (CRC) is a leading cause of death in the western world, and its incidence increases with patient age. It is also known that with age there occur changes in the levels of certain hormones, including an increase in the secretion of pituitary gonadotropins (PtGs) as a result of the loss of gonadal hormone feedback. We recently reported that functional PtG receptors are expressed in human lung cancer cells, rhabdomyosarcoma cells, and malignant hematopoietic stem cells.

Findings

Here we report for the first time that the receptors for follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are expressed in primary tumor samples isolated from CRC patients as well as in the established human CRC cell lines HTC116 and HTB37. Moreover, we also report that PtGs stimulate chemotaxis, adhesion, and proliferation of these cell lines.

Conclusions

Our results suggest that PtGs play an important and underappreciated role in CRC pathogenesis, and we call for further studies to better define their role in gastrointestinal malignancies and their direct effect on putative CRC cancer stem cells.

Estrogen Activation by Steroid Sulfatase Increases Colorectal Cancer Proliferation via GPER

CONTEXT

Estrogens affect the incidence and progression of colorectal cancer (CRC), although the precise molecular mechanisms remain ill-defined.

OBJECTIVE

The present study investigated prereceptor estrogen metabolism through steroid sulphatase (STS) and 17β-hydroxysteroid dehydrogenase activity and subsequent nongenomic estrogen signaling in human CRC tissue, in The Cancer Genome Atlas colon adenocarcinoma data set, and in in vitro and in vivo CRC models. We aimed to define and therapeutically target pathways through which estrogens alter CRC proliferation and progression.

DESIGN, SETTING, PATIENTS, AND INTERVENTIONS

Human CRC samples with normal tissue-matched controls were collected from postmenopausal female and age-matched male patients. Estrogen metabolism enzymes and nongenomic downstream signaling pathways were determined. CRC cell lines were transfected with STS and cultured for in vitro and in vivo analysis. Estrogen metabolism was determined using an ultra-performance liquid chromatography-tandem mass spectrometry method.

PRIMARY OUTCOME MEASURE

The proliferative effects of estrogen metabolism were evaluated using 5-bromo-2'-deoxyuridine assays and CRC mouse xenograft studies.

RESULTS

Human CRC exhibits dysregulated estrogen metabolism, favoring estradiol synthesis. The activity of STS, the fundamental enzyme that activates conjugated estrogens, is significantly (P < 0.001) elevated in human CRC compared with matched controls. STS overexpression accelerates CRC proliferation in in vitro and in vivo models, with STS inhibition an effective treatment. We defined a G-protein-coupled estrogen receptor (GPER) proproliferative pathway potentially through increased expression of connective tissue growth factor in CRC.

CONCLUSION

Human CRC favors estradiol synthesis to augment proliferation via GPER stimulation. Further research is required regarding whether estrogen replacement therapy should be used with caution in patients at high risk of developing CRC.

Quantifying the Genetic Correlation between Multiple Cancer Types

Background: Many cancers share specific genetic risk factors, including both rare high-penetrance mutations and common SNPs identified through genome-wide association studies (GWAS). However, little is known about the overall shared heritability across cancers. Quantifying the extent to which two distinct cancers share genetic origin will give insights to shared biological mechanisms underlying cancer and inform design for future genetic association studies.Methods: In this study, we estimated the pair-wise genetic correlation between six cancer types (breast, colorectal, lung, ovarian, pancreatic, and prostate) using cancer-specific GWAS summary statistics data based on 66,958 case and 70,665 control subjects of European ancestry. We also estimated genetic correlations between cancers and 14 noncancer diseases and traits.Results: After adjusting for 15 pair-wise genetic correlation tests between cancers, we found significant (P < 0.003) genetic correlations between pancreatic and colorectal cancer (rg = 0.55, P = 0.003), lung and colorectal cancer (rg = 0.31, P = 0.001). We also found suggestive genetic correlations between lung and breast cancer (rg = 0.27, P = 0.009), and colorectal and breast cancer (rg = 0.22, P = 0.01). In contrast, we found no evidence that prostate cancer shared an appreciable proportion of heritability with other cancers. After adjusting for 84 tests studying genetic correlations between cancer types and other traits (Bonferroni-corrected P value: 0.0006), only the genetic correlation between lung cancer and smoking remained significant (rg = 0.41, P = 1.03 × 10-6). We also observed nominally significant genetic correlations between body mass index and all cancers except ovarian cancer.Conclusions: Our results highlight novel genetic correlations and lend support to previous observational studies that have observed links between cancers and risk factors.Impact: This study demonstrates modest genetic correlations between cancers; in particular, breast, colorectal, and lung cancer share some degree of genetic basis. Cancer Epidemiol Biomarkers Prev; 26(9); 1427-35. ©2017 AACR.

Association between breast cancer and the risk of colorectal cancer

BACKGROUND

The literature to date has suggested a potential increase in colorectal cancer (CRC) among patients with breast cancer.

METHODS

We performed a systematic review of the literature and included 37 retrospective cohort studies and 8 case-control studies. The primary aim was to determine the prevalence of CRC. Secondary aims included analysis of adenomatous polyps and analysis of CRC prevalence by age. We calculated pooled prevalence rates and odds ratios (ORs) using random effects models with 95% confidence intervals (CI).

RESULTS

We identified 1,055,917 individuals with breast cancer among whom 9097 cases of CRC were detected. The pooled event rate for CRC was 0.7% (95% CI, 0.6%-0.9%; I²=97%). Four case-control studies reported prevalence of CRC (N=17,873 patients with breast cancer and 70,366 controls), including 46 cases of CRC in the patients with breast cancer, and 272 CRC in the controls (OR, 1.2; 95% CI, 0.4%-3.7%; P = .7). Six studies reported prevalence of advanced adenomas in patients with breast cancer (N=1087) compared with controls (N=1356) with 62 cases of advanced adenomas in patients compared with 47 in the controls (OR, 1.5; 95% CI, 0.97-2.2; P = .07). In patients with breast cancer <50 years old (4 studies, N=64,706), the pooled OR was increased (OR, 2.5; 95% CI, 1.7-3.5; P =.001). In 3 studies of women <45 years old (N=92,594), the risk was increased (OR, 2.3; 95% CI, 1.7-2.6; P < .001).

CONCLUSIONS

Patients with breast cancer should not undergo CRC screening at intervals different from the general population. In patients with breast cancer <50 years old, CRC screening should be considered at age 45 years.