Screening For Colorectal Malignancy & Familial Colorectal Carcinoma

Screening For Colorectal Malignancy & Familial Colorectal Carcinoma

Amir Amirul Shaznain

Sayrah Ain Roshini

INTRODUCTION • Colorectal carcinoma (CRC) is the second most common cancer in Malaysia (12.3%) as reported in Malaysian National Cancer Registry Report 2007-2011. • According to National Cancer Patient Registry on Colorectal Cancer 2008-2013, the overall incidence rate for CRC was 21.3 cases per 100,000 population. • Age-adjusted incidence rate was 1.33 times higher among male than female. • The incidence was highest in Chinese followed by Malay and Indian. • Overall mortality rate was 9.8 cases per 100,000 population and age-adjusted mortality rate was 1.42 times higher in male than female.

Anatomic Location of CRC • • • • • • •

Cecum Ascending colon Transverse colon Descending colon Sigmoid colon Rectosigmoid junct. Rectum

14 % 10 % 12 % 7% 25 % 9% 23 %

WHO Classification of CRC •

Adenocarcinoma in situ / severe dysplasia

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Adenocarcinoma

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Mucinous (colloid) adenocarcinoma (>50% mucinous)

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Signet ring cell carcinoma (>50% signet ring cells)

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Squamous cell (epidermoid) carcinoma

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Adenosquamous carcinoma

•

Small-cell (oat cell) carcinoma

•

Medullary carcinoma

•

Undifferentiated Carcinoma

Colon cancers result from a series of pathologic changes that transform normal epithelium into invasive carcinoma. Specific genetic events, shown by vertical arrows, accompany this multistep process.

Pathogenesis • •

• • •

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Development is a multistep process where in carcinomas arise from benign adenomas. The mucosal epithelium progresses through a series of molecular and cellular events that lead to altered proliferation, cellular accumulation, and glandular disarray leading to the formation of adenomatous polyps. Further genetic alteration results in higher degrees of cellular atypia and glandular disorganization (dysplasia) , which may evolve to a carcinoma. The adenoma-to-carcinoma sequence is always associated with genetic changes, even in sporadic colon cancers . Sporadic polyps and cancers are associated with multiple somatic mutations contributed by environmental insults. Genetic changes that lead to development of adenomas include: – Alteration in proto-oncogenes – Loss of tumor suppressor gene : In more than 75% of cases , stepwise tumor progression is associated with loss of tumor suppressor gene designated D C C (deleted in colorectal cancer) on chromosome 1 8q- (maintains normal cell-cell adhesive interactions) . – Deletions of chromosome 1 7p involving the p-53 tumor suppressor gene – Abnormalities of genes involved in DNA repair

History and PE

Focused history • Age, sex , race – age >50 male predominace, Chinese>malay>in dian • Diet hx – low fibre food, increased intake of refined carbohydrates, fat diet, red meat • Social lifestyle hx- smoking, alcohol • Past medical hx – chlecyctectomy , hx of colon Ca, ovarian and uterine Ca, IBD, Pre cancerous conditions-adenomatous polyps/post polypectomy • Familial syndromes such as: • Heriditary non polyposis colorectal Ca , Familial adenomatous polyps , Gardner’s and Turcot sx.

• For rectal bleeding: colour, location • For altered bowel habit: alternating constipation and diarrhoea • Perianal symptoms (lump, pruritus, pain, discharge) • Symptoms of anaemia (look for causes)

Presence of any of the following signs or symptoms: • • • • • • • • • • •

per rectal bleeding mucoid stool tenesmus constipation anaemia altered bowel habits palpable abdominal mass palpable anorectal mass loss of weight or appetite abdominal discomfort perianal symptoms

Right sided lesion• Asymptomatic until advanced stage • Chronic low grade per rectal bleeding • Usually no obstructive symptoms due to fecal matter being liquid in nature • Sometimes palpable mass felt

Left sided lesion : • Obstructive symptoms because fecal matter is solid in nature • Contipation • Colicky abd pain • tenesmus • Rectal bleed

Rectal lesion • • • • •

Per rectal bleeding – at the end of defecation Tenesmus Pain Early morning diarrhea Alternating bowel habits

Focused physical examination • • • •

Weight – loss of weight & appetite Look for signs of anaemia – due to blood loss Abdominal examination for mass Digital rectal examination for rectal Ca – neoplasm felt as nodular like indurated bases , irregular edges , may ulcerate and have contact bleeding. Fixity of mass can also be assessed

Screening

Family History And Risk Factor • Family history (FH) is a well-established risk factor for colorectal cancer (CRC). It is affected by first-, second- and third-degree relatives, and might include positive family history from both parents. • Familial Relative Risk (FRR) of developing CRC increases with greater number of affected FDRs irrespective of seconddegree relatives (SDRs) or third-degree relatives (TDRs).

Familial Factors – Risks for CRC Syndrome

Distrubution Histology

Malignant potential

Other Lesions

Familial Large Intestine Adenoma Adenomatous Polyposis

Common

none

Gardner Syndrome

Large and Adenoma Small Intestine

Common

Multiple Malignancies

Turcot Syndrome

Large Intestine Adenoma

Common

BrainTumors

Nonpolyposis Large Intestine Adenoma Syndrome

Common

Endometrial and Ovarian Tumors

Peutz Jeghers Syndrome

Small,Large Intestine, Stomach

Hamartoma

Rare

Multiple Malignancies

Juvenile Polyposis

Large and Hamartoma Small Intestine

Rare

Congenital Anomalies

Other Risk Factors • • • • •

Smoking Diabetes mellitus Obesity Alcohol consumption Meat consumption

Genetic Changes in CRC • GENETIC CHANGES  Activation of protooncogenes (K-ras)  Loss of tumour- suppressor gene activity (APC,DCC)  Abnormalities in DNA repair genes (hMSH2, hMLH1), especially HNPCC syndromes

MECHANISM – the mutational activation of an oncogene followed by and coupled with the loss of genes that normally suppress tumorigenesis

FOBT • Faecal test is a non-invasive tool for screening CRC in general population. It can detect presence of blood, proteins e.g. enzyme M2-PK and DNA. 2 ways – iFOBT, Gfobt • In a meta-analysis of fair to high quality evidence, the pooled sensitivity to detect CRC was 74% (95% CI 62 to 83) for quantitative test methods and 79% (95% CI 61 to 90) for qualitative test methods.

Sigmoidoscopy • Flexible sigmoidoscopy needs less rigorous bowel preparation and can be performed as a clinic base procedure without the need for sedation. Small polyps can be biopsied during procedure but excision of larger lesions (>1cm) is usually performed during subsequent colonoscopy. • Sigmoidoscopy reduces the CRC incidence by 1832% and mortality by 26-38% in general population. There is low incidence of bowel perforations associated with it.

Colonoscopy • Colonoscopy is the screening modality that has the ability to visualise the colonic mucosa directly, perform biopsy and excise polyps. It can detect proximal lesions that would be missed by screening sigmoidoscopy and has been shown to reduce risk of cancer in the right colon. • Screening colonoscopy reduces overall CRC incidence significantly by 56% and death by 68%. For those who has had colonoscopy especially for screening, the risk of CRC is strongly reduced by 91% up to 10 years.

CCE • Colon capsule endoscopy (CCE) is able to obtain images of the colon by using tiny video cameras embedded in the two ends of an ingested capsule that take images as the capsule traverses the colon. The technique is less invasive but does not allow biopsy or polyp removal.

CT colonography •

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CT colonography involves in obtaining multiple, thin slice CT data and using computers to construct images of the bowel mucosa in two or three dimensions thus enabling polyps to be detected. CT colonography requires bowel preparation similar to optical colonoscopy and during procedure air or carbon dioxide are introduced into the rectum via a rubber catheter. No sedation is required and patient is usually able to return to work post procedure.

CEA • There is no recommendation made by the US Preventive Services Task Force, NICE guidelines and SIGN guidelines on the use of serum carcinoembryonic antigen (CEA) test for CRC screening.

Referrence • CPG Management of Colorectal Carcinoma 2017