Carcinoma Rectum | Medical Science Optional Notes for UPSC PDF Download

Etiology

• The second most prevalent form of cancer.
• Colorectal cancers are predominantly associated with advancing age, affecting approximately 60% of individuals aged 70 and above.
• Risk factors include dietary habits, obesity, smoking, and insufficient physical activity.
• Genetic conditions such as HNPCC or LYNCH syndrome (3%), Gardener syndrome, and FAP can contribute to colorectal cancer susceptibility.

Clinical features

• Initial symptoms include rectal bleeding, tenesmus, and diarrhea in the early morning.
• Rectal bleeding appears as painless bright red blood (Differential Diagnosis: Hemorrhoids).
• Tenesmus refers to the sensation of needing to have a bowel movement without being able to do so.
• Changes in bowel habits manifest as:
  (a) Increased frequency of defecation with looser stools.
  (b) Early morning urgency to defecate, often with blood and mucus (early morning bloody diarrhea).
  (c) Progressing constipation, possibly indicating a stenosing carcinoma at the rectosigmoid junction.
• Pain emerges as a late symptom:
  (a) Colicky pain results from advanced tumors obstructing the rectosigmoid area.
  (b) Severe, relentless pain may indicate infiltration of nearby structures like the prostate, bladder, or sacral plexus.
• Weight loss typically indicates metastatic spread.

Spread of carcinoma rectum

Carcinoma Rectum

Possible Differential Diagnoses

• Benign adenomas
• Hemorrhoids
• Arteriovenous malformation (AVM)
• Carcinoid/neuroendocrine tumors and rare gastrointestinal tract tumors
• Ischemic bowel
• Small-intestine carcinomas
• Gastrointestinal lymphoma
• Crohn's Disease
• Ileus
• Small Intestinal Diverticulosis
• Ulcerative Colitis
• Amoebic granuloma
• Inflammatory strictures
• Endometriomas
• Solitary rectal ulcers

Diagnostic Examination

• Abdominal Examination: Observation for signs of subacute intestinal obstruction, detection of an enlarged liver (indicative of metastasis), and presence of ascites (suggestive of peritoneal dissemination).
• Rectal Examination: Assessment of neoplasm mobility or fixation, estimation of the distance between the lower margin and the top of the anal sphincter complex, and identification of irregular and firm endoluminal masses felt during digital rectal examination (typically within 7-8cm of the anal verge). Evaluation of the anal sphincter complex.

Colonoscopy with biopsy (GOLD STANDARD)

• Assists in ruling out simultaneous or synchronous cancers.
• Distinguishing between benign adenomas and malignant lesions relies on assessing the mucosal 'pit-patterns' visible with 'dye-spray' colonoscopy.
• If a proximal adenoma is identified, it can be easily grasped and excised using the colonoscope.
• Prior to treatment, magnetic resonance imaging (MRI) serves as the preferred assessment method for rectal cancer, aiding in guiding both surgical and oncological approaches.

Diagnosis

• Diagnosis involves performing a biopsy followed by histological analysis.
• Most common histology found is Adenocarcinoma, which can be well-differentiated, moderately differentiated, or undifferentiated.

Poor prognosis

• Vascular and perineural invasion
• Presence of infiltrating margins
• Detection of tumor budding
• Presence of signet ring carcinomas (primary mucoid carcinomas)
• Evaluation involves:
• Assessing the patient's suitability for surgery.
• Determining the tumor's spread:
  • Local spread is assessed using endoluminal ultrasound and MRI.
  • Metastasis evaluation entails CT scans of the chest, abdomen, and pelvis, as well as whole-body PET-CT scans.

Staging

Duke's staging

• A: Limited growth within the rectal wall (excellent prognosis)
• B: Growth extends into extrarectal tissues (reasonable prognosis)
• C: Secondary deposits identified in regional lymph nodes (poor prognosis)
• D: Distant metastasis (not initially part of Dukes staging)

T staging indicates local spread

• TX: Unable to assess the primary tumor
• T0: No evidence of the primary tumor
• Tis: Carcinoma in situ or invasion limited to the lamina propria
• T1: Invasion into the submucosa
• T2: Invasion into the muscularis propria
• T3: Penetration through the muscularis propria into pericolorectal tissues
• T4a: Penetration to the visceral peritoneum surface
• T4b: Direct invasion or adherence to other organs or structures

N describes nodal involvement

• NX: Inability to assess regional lymph nodes
• N0: No regional lymph node metastasis
• N1: Metastasis in 1-3 regional lymph nodes (further divided into N1a and N1b)
• N1c: Tumor deposit(s) in specific areas without regional nodal metastasis
• N2: Metastasis in 4 or more regional lymph nodes (further divided into N2a and N2b)

M indicates distant metastases

• M0: No distant metastasis
• M1: Presence of distant metastasis:
• M1a: Limited to a single organ or site
• M1b: Metastases present in more than one organ/site or the peritoneum

Principles of surgical treatment

• Objective: Complete removal of the rectum along with the mesorectum and related lymph nodes.
  • Sphincter-saving surgery (anterior resection) is possible if the tumor's lower margin is ≥2 cm above the anorectal junction.
  • For tumors closer than 2 cm from the anal verge, removal of the anus and rectum with a permanent colostomy (Abdominoperineal excision with permanent colostomy) is performed.
• Latest Approach:
  • "Wait and watch" strategy post long-term chemoradiotherapy, as about 20% of patients exhibit complete clinical response and undergo rigorous surveillance.
  • Organ-preserving methods:
    (a) Early-stage T1 and T2 tumors with favorable prognostic features undergo full-thickness excision using Transanal Endoscopic Microsurgery (TEMS).
    (b) For patients unsuitable for radical resection or for palliative purposes, options include Brachytherapy or contact radiotherapy.
• High Risk of Local Recurrence:
  • Peri-rectal lymph node involvement leads to a short course of 5-day radiotherapy.
• Locally Advanced Cases:
  • To reduce cancer stage and improve chances of complete resection:
    • Neoadjuvant radiotherapy.
    • Chemoradiotherapy, involving 5 fractions of radiotherapy combined with chemotherapy over a 6-week period.
• Widespread Metastasis:
  • Palliative treatment options such as endoluminal stenting, External Beam Radiotherapy, or palliative resection are considered.

Carcinoma Rectum

Principles of surgical treatment

Chemotherapy Agents

• First-line therapy predominantly involves 5-Fluorouracil (5-FU) based regimens, which exhibit a 10% improvement in disease-free survival for patients with node-positive rectal cancer.
• Second-line therapies encompass oxaliplatin, irinotecan, and biological agents like cetuximab.

Surveillance for Recurrence

• Approximately 80% of local recurrences occur within 2 years post-surgery and are notably challenging to manage.
• Monitoring techniques include regular CEA measurements (Carcinoembryonic Antigen), CT and MRI scans, as well as PET-CT scans.

Previous Question

Q: A 40-year-old male is diagnosed with rectal cancer located 7-8 cm from anal verge. Briefly enumerate how you will assess this patient. What are the treatment options available for this patient who is unwilling for permanent colostomy? (2012)