The incidence of early-onset colorectal cancer has been rising over the last two decades. Tumors in young patients have distinct features compared to older patients. They predominantly arise in the distal colon and rectum and have poor histological features. Patients tend to present at a more advanced stage and be exposed to more aggressive management approaches; however, this has not translated into a significant survival benefit compared to their older counterparts. This chapter will share current evidence on risk factors and management options for early onset colorectal cancer with a focus on rectal cancer.

Applying the concept of a \"natural history\" to hereditary colorectal cancer is an interesting exercise because the way the syndromes are approached has changed so drastically. However, the exercise is instructive as it forces us to think in depth about where we are, where we have been, and, most helpfully, about where we may be going. In this article the diagnosis, along with endoscopic and surgical management of hereditary colorectal cancer are discussed in the context of their history and the changes in genomics and technology that have occurred over the last one hundred years.

The coming of age for cancer treatment has experienced exponential growth in the last decade with the addition of immunotherapy as the fourth pillar to the fundamentals of cancer treatment-chemotherapy, surgery, and radiation-taking oncology to an astounding new frontier. In this time, rapid developments in computational biology coupled with immunology have led to the exploration of priming the host immune system through vaccination to prevent and treat certain subsets of cancer such as melanoma and hereditary colorectal cancer. By targeting the immune system through tumor-specific antigens-namely, neoantigens (neoAgs)-the future of cancer prevention may lie within arm\'s reach by employing neoAg vaccines as an immune-preventive modality for hereditary cancer syndromes like Lynch syndrome. In this review, we discuss the history, current trends, utilization, and future direction of neoAg-based vaccines in the setting of hereditary colorectal cancer.

BACKGROUND: Familial adenomatous polyposis (FAP) syndrome has a near-100% lifetime risk of colorectal cancer. Early surveillance and prophylactic surgery have been advocated to reduce this risk. However, the surveillance practices among FAP individuals in Saudi Arabia are unknown. We aimed to explore surveillance compliance in our population, as well as the disease impact on their quality of life (QoL).
METHODS: All patients with FAP who underwent surgical resection at King Saud University Medical City between 2016 and 2022 were included. Demographic data, clinical features, family history, and compliance with surveillance were collected and analyzed. QoL questionnaires: Short-form health survey (SF-36) and European Organization for Research and Treatment (EORTC) were conducted by phone interview.
RESULTS: A total of 14 patients were included with an average age of 25 years. Three patients (21.4%) were the first of their family members to develop FAP. Nine patients (64%) were untested for genetic mutation due to lack of referral to geneticists. The compliance rate toward both pre-operative colonoscopy and upper endoscopy were 78%. However, 38% and 27% compliance rates were observed toward initial and post-operative colonoscopy, respectively. The compliance rate was 14% toward thyroid ultrasound. QoL scores varied among patients, with a mean score above 60 across all SF-36 domains.
CONCLUSIONS: An overall poor compliance was observed among our participants, particularly toward thyroid ultrasound. Increased health awareness and patient education are essential. In addition, the importance of surveillance and genetic counseling should be emphasized among physicians treating these patients.

Here we reported a particular case of MUTYH-associated polyposis (MAP) that had only one rare heterozygous variant, but some particular clinical manifestations contributed to occur in this male patient by only one defective MUTYH allele were worth of further investigation. We reported a case of MAP. It is about a 33-year-old man with chief complaints of hematochezia who had multiple polyps that were found in his colon via colonoscopy. He followed his doctor\'s advice and performed a genetic analysis examination. Germline test was positive for a major heterozygous variant: chr1:45800165 on the MUTYH gene. MUTYH gene sequence analysis confirmed the following heterozygous variant: c.55CT (p.R19X) in exon 2 (ClinVar NM_001128425). Unfortunately, his mother and daughter have the ILK variant according to genetic analysis. However, this variant at the site was not detected in his father. Various types of polyps were found on repeated colonoscopy, which tended to become latent cancerous in the future. This case indicated that awareness of the risk of carcinogenesis of polyps in carriers of monoallelic variants might accordingly increase, and our understanding of the type of genetically related disease will be enhanced by us.

OBJECTIVE: Describe the structure of pathogenic germline variants and clinical and anatomical features in colorectal cancer patients in Moscow.
METHODS: The whole genome sequencing results of patients with suspected hereditary cancer syndrome were evaluated. All identified genetic variants were validated using Sanger sequencing.
RESULTS: The study included 238 patients with colorectal cancer, 41/238 (17.2%) patients have pathogenic germline variants associated with hereditary cancer syndromes or increased cancer risk. Lynch syndrome accounts for 8% of all colorectal cancer cases (19/238), and familial adenomatous polyposis - 1.7% (4/238). 5 new genetic variants were described for the first time in a Russian colorectal cancer patients: MLH1 c.1921dup (p.Leu641fs), APC c.2929C>T (p.Gln977Ter), PMS2 c.327del (p.Ala110LeufsTer2), MSH2 c.1857dup (p. Val620CysfsTer24), ATM c.895G>T (p.Glu299Ter). In 197 of 238 patients, no significant variants were identified or variants with an uncertain clinical underlying cause were identified.
CONCLUSIONS: According to the results of the study, an earlier manifestation of a malignant neoplasm and a more frequent occurrence of high-grade carcinomas in the presence of pathogenic germline mutations were noted compared to the group of patients without clinically significant varianrs, while in the group with identified mutations, the frequency of regional and distant metastasis was not increased.
UNASSIGNED: Описание структуры патогенных герминальных вариантов при колоректальном раке в выборке пациентов Москвы.
UNASSIGNED: Проведена оценка результатов полногеномного секвенирования ДНК пациентов с колоректальным раком с подозрением на наследственный опухолевый синдром. Все выявленные генетические варианты валидированы с помощью секвенирования по Сэнгеру.
UNASSIGNED: В исследование включены 238 пациентов с диагностированным колоректальным раком, из них у 41 (17,2%) выявлены патогенные герминальные варианты, ассоциированные с наследственными опухолевыми синдромами или повышенным риском развития злокачественных новообразований, из них на синдром Линча приходится 8% всех случаев колоректального рака в исследуемой выборке (19/238), а на аденоматозный полипозный синдром — 1,7% (4/238). Впервые описано 5 новых генетических вариантов в российской выборке пациентов: MLH1 c.1921dup (p.Leu641fs), APC c.2929C>T (p.Gln977Ter), PMS2 c.327del (p.Ala110LeufsTer2), MSH2 c.1857dup (p.Val620CysfsTer24), ATM c.895G>T (p.Glu299Ter). У 197 из 238 пациентов не обнаружено клинически значимых вариантов или выявлены варианты с неопределенной клинической значимостью.
UNASSIGNED: По результатам исследования отмечена более ранняя манифестация злокачественного новообразования и более частая встречаемость карцином высокой степени злокачественности при наличии патогенных герминальных мутаций по сравнению с группой пациентов без клинически значимых мутаций, при этом в группе с выявленными мутациями частота регионарного и отдаленного метастазирования не повышена.

The incidence of early-onset colorectal cancer (EOCRC) is rapidly increasing. Pathogenic germline variants (PGVs) are detected in 16% to 20% of patients who have EOCRC, highlighting a need for genetic counseling (GC) and multigene panel testing in these patients. We aimed to determine the rate of referral to GC and uptake and outcomes of germline testing in patients with EOCRC.
We conducted a retrospective cohort study of patients aged <50 years diagnosed with colorectal cancer (CRC) from 2010 to 2019 at Cleveland Clinic. Demographic data were extracted, including age, sex, self-reported race, and family history of CRC. The proportions of patients with GC referral and completion of GC and genetic testing were investigated, and genetic testing results were analyzed. Multivariable logistic regression analysis was conducted to identify factors independently associated with GC referral and uptake.
A total of 791 patients with EOCRC (57% male and 43% female) were included; 62% were referred for GC, and of those who were referred, 79% completed a GC appointment and 77% underwent genetic testing. Of those who underwent testing, 21% had a PGV detected; 82% were in known CRC-associated genes, with those associated with Lynch syndrome and familial adenomatous polyposis the most common, and 11% were in other actionable genes. Referral to GC was positively associated with family history of CRC (odds ratio [OR], 2.11; 95% CI, 1.51-2.96) and more recent year of diagnosis (2010-2013 vs 2017-2019; OR, 5.36; 95% CI, 3.59-8.01) but negatively associated with older age at diagnosis (OR, 0.89; 95% CI, 0.86-0.92).
Referral to GC for patients with EOCRC is increasing over time; however, even in recent years, almost 25% of patients were not referred for GC. We found that 1 in 5 patients with EOCRC carry actionable PGVs, highlighting the need for health systems to implement care pathways to optimize GC referral and testing in all patients with EOCRC.

OBJECTIVE: Family history of colorectal cancer (CRC) is a known risk factor for CRC. However, its prognostic value in patients with CRC remains controversial. This study aimed to clarify the prognostic impact of a family history of CRC.
METHODS: We retrospectively reviewed the database from 1978 to 2018 and enrolled 3,655 consecutive patients with CRC. We investigated the clinicopathological factors of patients with CRC with and without a family history. After propensity score matching, we performed a survival analysis of patients with CRC with and without a family history.
RESULTS: Patients with CRC with a family history of CRC had a young onset (63.2 and 65.9; p<0.001), were more likely to be female (54.3% and 49.7%; p=0.042), had less symptomatic disease (76.9% and 80.8%; p=0.008), were more likely to have right-sided colon cancer (27.5% and 26.1%), and had less distant metastases (11.3% and 14.9%; p=0.023) and multiple CRCs (10.2% and 7.8%) compared with those without a family history of CRC. Prior to propensity score matching, CRC-specific survival analysis showed that a family history of CRC was a good prognostic factor (p=0.022). After propensity score matching, survival curves overlapped between the two groups.
CONCLUSIONS: Patients with CRC with a family history of CRC had specific clinicopathological features including younger onset, female sex, proximal colon location, fewer symptoms, smaller number of distant metastases, likelihood of multiple diseases, and earlier cancer stage. Family history of CRC in patients with CRC was not a prognostic factor.

Polyketide synthase (pks) island harboring Escherichia coli are, under the right circumstances, able to produce the genotoxin colibactin. Colibactin is a risk factor for the development of colorectal cancer and associated with mutational signatures SBS88 and ID18. This study explores colibactin-associated mutational signatures in biallelic NTHL1 and MUTYH patients. Targeted Next Generation Sequencing (NGS) was performed on colorectal adenomas and carcinomas of one biallelic NTHL and 12 biallelic MUTYH patients. Additional fecal metagenomics and genome sequencing followed by mutational signature analysis was conducted for the NTHL1 patient. Targeted NGS of the NTHL1 patient showed somatic APC variants fitting SBS88 which was confirmed using WGS. Furthermore, fecal metagenomics revealed pks genes. Also, in 1 out of 11 MUTYH patient a somatic variant was detected fitting SBS88. This report shows that colibactin may influence development of colorectal neoplasms in predisposed patients.

OBJECTIVE: The current procedure for identifying hereditary colorectal cancer (HCRC) is time consuming in clinical practice. This study aimed to develop a time-saving approach to diagnosing HCRC.
METHODS: A total of 100 suspected HCRC patients were prospectively enrolled (cohort 1) and 116 colorectal cancer patients with DNA mismatch repair-deficient were retrospectively included (cohort 2). Next-generation sequencing (NGS) tests were performed on tumors and matched white blood cells (WBCs) or normal tissues. Using the conventional method upon WBC/normal tissue-based NGS data as a reference, the performance of the ColonCore method using tumor-only-based NGS data in predicting germline variants was explored in cohort 1 and validated in cohort 2.
RESULTS: In cohort 1, the ColonCore method diagnosed 17 Lynch syndrome (LS) and 14 familial adenomatous polyposis (FAP); and by the conventional method, the cases were 16 and 10, respectively. The ColonCore method showed sensitivities of 100% in diagnosing LS (positive predictive value [PPV] 94.1%) and FAP (PPV 71.4%). Moreover, two of seven patients with multiple adenomas/polyps who did not meet existing clinical criteria for HCRC were predicted to harbor germline variants in APC and MUTYH. Additionally, the sensitivity of the ColonCore method in identifying LS patients from cohort 2 reached 85.7% with a PPV of 85.7%.
CONCLUSIONS: The ColonCore method might be an acceptable tool for predicting germline variants associated with HCRC. Our work indicates the essentiality of NGS tests in CRC patients for precision diagnosis and treatment.