Polyps & Colorectal Cancers😍

Polyps

1. Non-cancerous (Non-Neoplastic):

• Hyperplastic polyps:
• Never cause cancer.
• Serrations only in upper crypts.

• Hamartomatous polyps:
• Most Important

2. Cancerous (Neoplastic/Precancerous):

• Sessile serrated adenoma

• Tubular adenoma

• Villous adenoma

• Tubulovillous adenoma

• Definition: Any adenoma in GIT is precancerous.

Types of Polyps

• Inflammatory: 
• Pseudopolyps (seen in Ulcerative Colitis)

• Hamartomatous:
• Single juvenile polyp: Not premalignant.
• Juvenile polyposis: ↑↑ risk of cancer.
• Seen in Peutz-Jeghers syndrome.

• Adenomatous Polyp: 
• Increased risk of cancer.

Adenoma-Carcinoma Sequence

• Normal mucosa → Hyperproliferative epithelium → Early adenoma → Intermediate adenoma → Late adenoma → Carcinoma.

• Molecular Hits (Sequential Progression):

• mnemonic AK53
• First Hit: APC
• Second Hit: K-RAS
• Third Hit: DCC (CHR 18)
• Last Hit: p53

Hamartomatous Polyps:

1. Juvenile Rectal Polyp (JRP) /
Juvenile Polyposis:

 

• Genetics: SMAD2, SMAD4, BMPR1A.
• Mnemonic: "juvenile" numbers

• Age: Typically in juveniles (< 5 years).

• Presentation: 
• Bleeding per rectum.
• Can have digital clubbing
• Rectal Polyp

• Microscopy: Cystically dilated glands.

• Mnemonic: Smack (smad 2, 4) juvenile kids, in hands (digital clubbing) and ass (rectl polyp → bleed), till it swell up (dilated glands) → He is Bumper 1 (BMPR1A)

2. Peutz-Jeghers Polyp:

• Autosomal Dominant

• Genetics: STK11 or LKB1
• Mnemonic: "111" for age and gene

• CHR 19

• Age: Around 11 years.

• Mnemonic:
• Putes Jeggers → P, J
• Pigmentation (lips, mucosa, digits and perianal skin), 
• JEjunal polyp (more in jejunum)*

• "P" for periorificial lentigines
• Lentigines along the oral mucosa

• Polyp appearance: 
• Tree-like, Christmas tree, or arborizing.
• Branches made of smooth muscle.
• Mnemonic: Jegher → Jungle, jejunum → Tree

• m/c Location of Polyps: Jejunum

• Increased Risk of Cancer (non-colonic):
• Pancreatic (100x higher risk)
• Duodenal
• Thyroid

• Clinical Features:
• m/c presentation: Intussusception
• Pathognomonic finding: Perioral melanosis

• Mnemonic:
• Dominant Jungle girl → 11 year old (age 11) → In LKG (LKB1 ) → pigmented lips (perioral melanosis, lentigines) → smooth muscles (branches smooth muscles) → walk with a stick (STK11) → lives in a tree (arborising) → has maturity of 19 years (chr 19)

3. Cowden Syndrome:

• Genetics: P10 (chromosome 10, P10 gene).

• Associated Tumors: 
• Mnemonic: PTEN → EN, T, P ⇔ B
• Endometrial cancer
• Thyroid cancer
• Trichilemmomas
• Polyps
• Breast cancer (P changed to B)*
• Mnemonic: Cow (Cowden) nte breast (Breast cancer) thirich (Trichilemmomas) Palu (Polyp) eduthu → thyru (thyroid) undakki

4. Bannayan Riley Ruvalcaba Syndrome:

• Genetics: Also P10.

• Key Feature: Associated with mental retardation.

5. Tuberous Sclerosis:

• Genetics: 
• TSC1 (chromosome 9) 
• TSC2 (chromosome 16)

• Associated with polyps.

• Also cardiac rhabdomyoma

Mnemonic:

• Rhabdomyoma → Rat (Rhabdomyoma) and Spider (spider cells) in a Pasta (PAS positive) tube (Tuberous sclerosis)

• Myxoma → Mixed in Los Angles (Left atrium) → Leopard (Lepidic) Kaarnnu (Carney) Nashipich (gNAS)

6. Cronkhite Canada Syndrome:

• Age: Above 50 years.
• Mnemonic: Takes many years to "earn" Canada citizenship

• Non-genetic / Non-hereditary.

• Associated with: Polyps, hair loss, skin pigmentation, nail atrophy.

Cancerous (Neoplastic/Precancerous):

Sessile serrated adenoma:

• Serrations throughout crypt,

• "boot-shaped crypts".

Tubular adenoma:

• Round tubules

Villous adenoma:

• Finger-like villi,

• maximum risk of intestinal cancer 

• villain (most cancerous) 

Tubulovillous adenoma:

• Combination.

Familial Adenomatous Polyposis (FAP):

• Inheritance: Autosomal dominant.

• Genetics: APC gene mutation on chromosome 5q21
• FAP → APC → 5q
• Mnemonic: Fap → 5 days a week → 21 days a month

• Risk of Cancer: 100% risk of cancer.

• Pathognomonic Finding: >100 adenomatous flat polyps

• Types/Associated Syndromes:
1. Classical FAP:
• 100+ polyps
• Congenital hypertrophy of retinal pigment epithelium (CHRPE).
2. Turcot Syndrome:
• Associated brain tumors: Medulloblastoma, Glioblastoma.
• Mnemonic: TUR for Turban (brain tumors) and COT for Colon (FAP)
3. Gardner Syndrome:
• Skin: Sebaceous cysts.
• Fibrous tissue: Fibromas.
• Bone: Osteomas.
• Dental: Supernumerary teeth
• GI: Intestinal polyposis.
• Desmoid tumor
• Mnemonic: Gardener (gardening through body layers)

• Mnemonic:
• Say who Faps by looking at eye (CHRPE), brain (MB, GB) and teeth (supranumery teech)

• m/c Site: Rectum (where polyps commonly develop first)

• Surgery: Total proctocolectomy + IPAA

Screening

• Genetic counseling.

• Testing for 1st-degree relatives.

• If mutation (+): Sigmoidoscopy from age 10 years.

Haggitt Classification (for cancer in polyp)

• Hobbits (Haggits) live in a tree (like Polyps)

MUTYH Associated Polyposis (MAP)

• Similar to FAP

• Autosomal recessive

• APC mutation not identified (different gene involved)

• Multiple colonic polyps (usually fewer than FAP, but >10 often seen)

• 3-4x risk of colorectal cancer.

• Surveillance: 
• 2-year colonoscopies;
• surveillance for duodenal adenomas.

Colorectal Cancers (CRC)

m/c Site

• Rectum > Rectosigmoid > Sigmoid

• Constricting colon cancer (Apple core deformity)
• Left side > Right side
• Increasing Constipation

• Ulcerative type
• Right side > Left side
• Anemia & anemia

m/c histological variant of rectal carcinoma

• Adenocarcinoma

Other m/cs

• Second most common malignancy worldwide

• Second most common cancer in women

• Third most common cancer in men

• Fourth most common cause of cancer-related death

Pathogenesis: 

• Adenoma-carcinoma sequence → multi-step carcinogenesis.

• Genetics:
• Mnemonic: AK-53 and even numbers
• APC gene → K-RAS gene → P53 gene.
• Other: SMAD2 and SMAD4.

• Diagnosis:
• Barium study/enema:
• "apple core deformity".
• Tumor marker: 
• CEA (Carcinoembryonic Antigen).
• CK 7 (-), CK20 (+), and CDX-1 (+) IHC markers
• Occult blood test: 
• Guaiac test (detects hidden blood in stools, positive indicates blood).

• Mnemonic: AK 53 vach apple vayattil vach fire cheyth → cancer vann

Screening

• Start Age: 50 years.

• Family History Positive: 10 years before diagnosis of youngest relative.

• Screening Modalities:
• Colonoscopy: 
• Every 10 years.
• Length of scope: 110 – 140 cm (rectum to cecum visualized).
• Sigmoidoscopy: 
• Every 5 years.
• Length of scope: 60 cm - 90cm.
• FOBT (Fecal Occult Blood Test): 
• Annually.

Virtual Colonoscopy (CECT with 3D Reconstruction)

• Use: Screening tool.

• Advantages:
• Better extracolonic details.
• Better patient compliance.

• Disadvantage: Mucosal details not well appreciated.

Diagnostics & Staging

• IOC for Diagnosis: 
• Colonoscopic biopsy.

• IOC for ca rectum:
• MRI

• IOC for Staging: 
• PET-CT.

• T & N Staging for Rectal Cancer: 
• MRI with endorectal coil.

Presentation

• Right-sided CRC:
• Ulcero-proliferative growth.
• Causes bleeding → Iron deficiency anemia.

• Left-sided CRC:
• Annular (constricting) growth.
• Altered bowel habits → Early onset symptoms.
• Bowel obstruction.
• Radiology: Apple core deformity.

Management: Surgery - Colectomy

Duke's Staging (Based on Depth of Tumor)

• A: Mucosa + Submucosa involved.

• B: Muscle involvement, no LN.
• B1: Into muscle layer.
• B2: Beyond muscle layer.

• C: Muscle involvement, LN positive.
• C1: Into muscle layer.
• C2: Beyond muscle layer.

• D: Distant metastasis.

Surgical Procedures & Resected Structures

Surgery in Rectal Lesions

Procedures & Structures Removed

• Lesions >5 cm from Anal Verge:
• Relatively good → sphincter not affected → no need for stoma
• Low Anterior Resection (LAR):
• Colo-anal anastomosis (sphincters spared).
• Removes: Rectum, part of sigmoid.

• Lesions <5 cm from Anal Verge:
• Abdominoperineal Resection (APR):
• Permanent end colostomy (sphincters cut).
• Removes: Rectum, anal canal, part of sigmoid.

• In old and frail
• Hartman procedure

Plane of Dissection for LAR/APR

 

• Between neurovascular bundle of prostate & sacrum.

Total Mesorectal Excision: 

• Key for thorough lymph node removal and reducing recurrence.

Complications of Rectal Surgery (Nerve Injury)

• Ligation of the inferior mesenteric artery (first vessel) during abdominoperineal resection (APR)

• Sympathetic → Ejaculation → Retrograde ejaculation

• Parasympathetic → Micturition and Erection → Bladder dysfunction and Impotense

TaTME (Transanal Total Mesorectal Excision)

• Type of NOTES procedure.

• Used for early rectal cancers (T1, T2).

Anal Carcinoma

• Most Common Type: Squamous Cell Carcinoma (SCC).

• Risk: Homosexual man

• Management: 
• Nigro's Regime (combined chemoradiation for ~1 month).
• Chemo → 5FU + Mitomycin C
• Radio → 35 Gy
• If Residual Disease/Recurrence: 
• Surgery → Abdominoperineal repair (APR)
• Mnemonic:
• Nigro () homosexual → got SCC () → afraid of surgery → took chemo and radio ()
• 35 guys (35 Gy)
• 5 fucked (5FU) mightly (Mito)