GI Part 1: Colorectal, Anal Canal, Esophagus

What is the epidemiology of colorectal cancer?

3rd most common and 2nd most common cause of death

What is the most common histology for colorectal cancer?

Adenocarcinoma

What are the common etiology risks of colorectal cancer?

High fat/low fiber diet, red meats, smoking, type 2 diabetes, alcohol

What are 4 conditions that can lead to colorectal cancer?

Chronic ulcerative colitis, FAP (familial adenomatous polyposis), Lynch syndrome, 1st degree family hx

At what vertebral level does the rectum begin?

S3.

Describe the lymphatic drainage of the colon vs. rectum.

- Colon → Superior mesenteric vessels → ileocolic / right colic nodes

- Rectum → Peri-rectal nodes FIRST → then internal iliac nodes - Spreads through the submucosal layer

What are the classic presenting symptoms of LEFT colon cancer vs. RIGHT colon cancer?

- Left colon: Blood in stool, bowel habit changes, obstruction, abdominal pain
- Right colon: Abdominal pain/mass, nausea & vomiting

What is hematochezia and with which colon cancer site is it associated?

Hematochezia = bright red

blood per rectum. Associated with rectal cancer.

What staging investigations are used for colorectal cancer?

CBC, CEA, MRI, CT

chest/abdomen/pelvis, endoscopic ultrasound.

Define T3 and T4 colorectal cancer.

- T3 = tumour into pericolorectal tissues
- T4a = through visceral peritoneum
- T4b = invades adjacent organ

What does N1c mean in colorectal TNM staging?

N1c = tumour deposits in pericolorectal tissue with no

regional lymph nodes involved.

What are the most common sites of distant metastasis for colorectal cancer?

Liver and lung.

At what dose does cystitis occur from pelvic RT? At what dose does diarrhea/enteritis occur?

-Cystitis: 1500–3000 cGy
- Diarrhea/enteritis: 1000 cGy

What surgery is performed for upper 2/3 of rectum vs. lower 1/3?

- Upper 2/3 → LAR (Low Anterior Resection)
- Lower 1/3 / distal 5 cm → APR (Abdominoperineal Resection)

Compare short vs long course RT for colorectal cancer (Dose, intent, chemo, tx sequence)

Short: 25/5 fx, neoadjuvant (downstaging), no chemo, RT → Sx

Long: 45-50.4/25-28 fx, neoadjuvant (downstaging and sphincter preservation), Oral capecitabine, Induction chemo → CRT + RT → Sx

What is the adjuvant chemo regimen for Stage 3 colon cancer?

FOLFOX.

What is the adjuvant RT dose for rectal cancer?

50 Gy/25 fx OR 45 Gy/25 fx.

Is anal canal cancer more common in men or women?

More common in women. Median age 60.

What is the most important etiological agent for anal canal cancer?

HPV-16.

Describe the anatomy of the anal canal.

3–4 cm long; extends from the anal verge to the anorectal ring.

Where does anal canal cancer spread depending on location relative to the dentate line?

- Above dentate line → internal iliac + lateral sacral nodes
- Below dentate line → inguinal lymph nodes - More commonly spreads to inguinal LN overall

What is the primary histology of anal canal cancer?

SCC

How is anal canal cancer diagnosed?

Digital anorectal exam, palpation of inguinal LN, anoscopy.

What staging investigations are used for colorectal cancer?

CT abdomen/pelvis, PET scan, MRI, CXR.

What is the definitive treatment for anal canal cancer — and why not surgery?

Definitive CRT (chemoradiation). Surgery is avoided to preserve the anal sphincter (organ-preservation strategy).

What is the preferred chemo regimen for anal canal CRT — and why not cisplatin?

5-FU + MMC (Mitomycin C) — proven superior outcomes compared to 5-FU + cisplatin.

What is the Nigro Protocol and why is it historically significant?

5-FU + MMC + 45 Gy RT. Historical landmark demonstrating that definitive CRT could achieve sphincter preservation, avoiding the need for colostomy

(APR).

What is the typical demographic for esophageal cancer?

Men, age 55–85.

What are the main etiology factors?

Alcohol + smoking (synergistic on mucosal surfaces), low fresh fruit/veg, high nitrate foods (cured meats), Barrett’s Esophagus.

What is Barrett’s Esophagus and what cancer risk does it create?

Columnar epithelium replaces the normal stratified squamous epithelium in the distal esophagus. This is a precancerous change that leads to adenocarcinoma risk.

Describe the anatomy of the esophagus — length, start/end points, and lining.

- 25 cm tube - Begins at C6; ends at esophageal-gastric junction (T10–T11) - Lined with stratified squamous epithelium

What level and how long is the the cervical esophagus

C6 – T2/3 , 18 cm

What level and how long is the the middle esophagus

Carina to EGJ, 32 cm

What level and how long is the the lower esophagus

8cm

Which esophageal location is most common? Least common?

Most common = lower 1/3. Least

common = upper 1/3.

What are the lymphatic drainage nodes of the esophagus?

Celiac axis, left gastric nodes, nodes of the

lesser curvature of the stomach.

What are the classic symptoms of esophageal cancer?

Dysphagia, weight loss, food sticking,

odynophagia (painful swallowing).

What is characteristic about esophageal cancer metastases?

Skip lesions (tumour deposits that skip

segments of the esophagus). Most common distant mets: liver and lung.

What staging investigations are used for esophageal cancer?

FDG-PET and CT.

What is the treatment for upper esophageal cancer?

CRT: 70 Gy/35 fx + cisplatin. (Surgery typically

not performed for cervical/upper esophagus due to morbidity.)

What is the treatment regimen for all other (non-upper) esophageal cancers?

Primary surgery +

neoadjuvant CRT: carboplatin + paclitaxel + 41.4 Gy/23 fx.

What is the standard definitive CRT regimen for colorectal?

50 Gy/25 fx + cisplatin + 5-FU.

What are the RT-alone dose options?

- 50 Gy/20 fx - 60 Gy/30 fx - Cervical: 70 Gy/35 fx

How do you manage esophagitis side effects?

Lidocaine (topical analgesia) for pain. Chemo can cause severe esophagitis/ulceration.