Definition
A.Cancer that forms in the tissues of the colon.
B.Most colon cancers are adenocarcinomas and develop from polyps.
Incidence
A.Colorectal cancer is the third most common cancer in both men and women, and is also the third leading cause of cancer deaths.
B.In 2016, there were an estimated 134,490 cases diagnosed in the United States: 39,220 cases of rectal cancer and 95,270 cases of colon cancer.
C.The incidence of colon cancer has continued to decline over the past three decades, likely associated with improved screening and treatment of colorectal polyps. Despite this decline, there were still an estimated 49,140 deaths from colon and rectal cancer in 2016.
D.Greater than 90% of new cases of colorectal cancer occur in patients over the age of 50, with the median onset age at 73.
E.While the risk of colorectal cancer increases with age, in recent years there has been a significant increase in the incidence of colorectal cancer in younger patients.
Pathogenesis
A.Colorectal cancer is a complex process that derives from the epithelial cells lining the colon.
B.Genetic mutations, either inherited or acquired, are thought to occur that irritate the lining, causing inflammation and necrosis of the colon.
C.Over time, lesions can develop which can disrupt cellular DNA and cause dysplasia, which can lead to the development of cancer.
Predisposing Factors
A.Approximately 2% to 5% of colorectal cancers are hereditary, while the majority of cases are sporadic.
B.Risk factors associated with the development of colorectal cancer include:
1.Dietary factors including the consumption of red meat, processed meat, and animal fat.
2.Cigarette smoking.
3.Inflammatory bowel disease (e.g., ulcerative colitis).
4.History of a prior colorectal cancer or adenomatous polyps.
5.Obesity.
6.Familial syndromes: Familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC).
Subjective Data
A.Common complaints/symptoms.
1.Colorectal cancer is often asymptomatic, with symptoms appearing once the disease has become more advanced. Screening colonoscopies often detect early, asymptomatic colorectal cancers.
2.The most common presenting signs and symptoms include:
a.Abdominal pain.
b.Anorectal pain.
c.Iron deficiency anemia.
d.Weight loss.
e.Fatigue.
f.Hematochezia.
g.Melena.
h.Bowel changes.
i.Constipation.
ii.Diarrhea.
iii.Urgency.
iv.Frequency.
v.Tenesmus.
vi.Mucous discharge.
i.Nausea/vomiting.
j.Urinary dysfunction.
k.Erectile dysfunction.
Physical Examination
A.Gastrointestinal.
1.Percussion.
a.Dull areas may be present over the tumor site.
b.A protuberant, tympanic abdomen may be indicative of an obstruction.
2.Auscultate for bowel sounds in all four quadrants.
a.Absent or decreased bowel sounds are often indicative of obstruction.
3.Palpate for tenderness and/or masses in all four quadrants.
a.Larger tumors of the colon are often palpable on physical examination in nonobese patients.
b.Liver is one of the two most common sites for colorectal metastasis, and patients with advanced liver metastasis may have tender hepatomegaly.
4.Digital rectal examination to assess for tumor location, circumferential nature, and sphincter tone.
B.Gynecologic examination in females with rectal cancer is important secondary to the proximity of the rectum to the vagina. Vaginal examination should be performed to evaluate for posterior vaginal wall involvement and to rule out rectovaginal fistula.
C.Evaluate for metastatic disease: Primarily liver, lung, and/or lymph nodes.
Diagnostic Tests
A.The workup for colorectal cancers includes diagnostic studies to help determine the extent of disease, as well as the presence of metastatic disease.
B.Colon cancer workup.
1.Colonoscopy, complete to the cecum with adequately prepped colon.
2.Pathology review of biopsies.
3.Laboratory studies: Complete blood count (CBC), comprehensive metabolic panel (CMP),
carcinoembryonic antigen (CEA) level.
4.CT scan of the chest, abdomen, and pelvis with intravenous (IV) and oral contrast.
C.Rectal cancer workup.
1.Colonoscopy, complete to the cecum with adequately prepped colon.
2.Pathology review of biopsies.
3.Laboratory studies: CBC, CMP, CEA.
4.CT scan of the chest, abdomen, and pelvis with IV and oral contrast.
5.Pelvic MRI is the preferred staging study; however, if not available, perform endorectal ultrasound.
6.Flexible sigmoidoscopy or rigid proctoscopy is often performed by a surgeon to verify the tumor location for radiation treatment planning and surgery planning.
7.Enterostomal therapist referral is made for patient education and ostomy site marking.
D.Diagnosis and staging.
1.Colorectal cancer diagnosis is established via tissue biopsy. Colonoscopy is the most common mode to obtain a tissue diagnosis, although an image-guided biopsy of a tumor may confirm the diagnosis.
2.Adenocarcinomas are the most common histologic subtype, accounting for greater than 90% of all cases. Less common histologic subtypes include: Mucinous carcinoma, signet-ring cell carcinoma, squamous cell carcinoma, and undifferentiated carcinoma.
3.Confirmed tissue diagnosis and a complete workup provide the necessary data to clinically stage colorectal cancer. Proper clinical staging is important, as it influences treatment planning and serves as an indicator for prognosis.
4.Staging for colorectal cancer is similar to the staging of many cancers, and utilizes the tumor, node, metastasis (TNM) system.
Differential Diagnosis
A.Inflammatory bowel disease.
B.Ileus.
C.Ischemic bowel.
D.Diverticulosis.
Evaluation and Management Plan
A.General plan.
1.The primary treatment for colorectal cancer is surgery; however, disease stage and presence of metastatic disease can alter the treatment modalities offered as well as their sequencing.
2.Chemotherapy agents are commonly administered in the adjuvant setting; however, they may be administered in patients with locally advanced disease or with metastatic disease at presentation.
3.Radiation therapy.
4.Surgical management for colorectal cancers.
a.Should include resection of the primary tumor, as well as the lymphatic, venous, and arterial supply.
b.Treatment side effects are a potential threat from all three treatment modalities with the most common including:
i.Bowel dysfunction.
ii.Sexual dysfunction.
iii.Genitourinary dysfunction.
iv.Neuropathies.
B.Acute care issues in colorectal cancer.
1.Colorectal cancer patients will be admitted to the hospital following surgical resection or for urgent situations including bowel obstructions or perforations.
2.Postoperative hospitalization varies by surgical approach. The average hospital stay is 2 to 7 days, with a shorter average stay for patients who have undergone a minimally invasive surgical approach.
a.Postoperative management is focused on return of bowel function, ostomy care (if applicable), and pain control.
3.Patients admitted for complications such as bowel obstruction or perforation are managed based on the severity of the complication.
a.Bowel obstruction.
i.Nothing by mouth (NPO) and bowel rest.
ii.Nasogastric tube.
iii.Surgery: Exploratory laparotomy with possible bowel resection.
b.Perforation.
i.NPO and bowel rest.
ii.Surgery is indicated in the majority of cases to remove the area of perforation and to wash out the abdomen.
iii.Antibiotics.
Follow-Up
A.Colon cancer recurrence typically occurs within 3 years of resection; therefore, patients should have routine follow-up for at least 5 years after resection.
B.Colonoscopy is necessary after resection for surveillance.
Consultation/Referral
A.Gastroenterology referral for screening is critical in patients who are high risk for colorectal cancer.
B.Any patient with suspected colon cancer should be referred to surgery immediately. Surgery is the only curative option for localized cancer and should not be delayed.
C.Medical oncology referral for treatment and surveillance.
D.Refer patients to support groups.
Special/Geriatric Considerations
A.Most patients with colorectal cancer are older than 70 years old.
B.Elderly patients may be undertreated and are underrepresented in clinical trials, making treatment guidelines difficult.
C.Life expectancy, quality of life, and patient’s functional status should be taken into consideration when determining a plan of action.
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