Colorectal cancer management
Colorectal cancer symptoms and signs are, in general, nonspecific. Unfortunately, the majority of patients with colorectal cancer are diagnosed because they have symptoms or signs. The most common presenting symptom of colon cancer is vague abdominal pain. In the rectum, patients most frequently complain of blood in the stools. Any patient who presents with either blood in the stools or rectal bleeding should be worked up. Rectal bleeding should not be attributed to hemorrhoids unless a complete evaluation has been performed.
Most of the time, right-sided tumors present less symptomatology than left-sided or rectal tumors. Commonly patients with right-sided tumors present with anemia. Left-sided or rectal cancer patients most commonly present with change in bowel habits or blood in the stools. Other symptoms of colorectal cancer include nausea, vomiting, bloating, diarrhea, tenesmus, constipation, and weight loss.
Partial or complete bowel obstructions as well as perforation, whether localized or free into the abdomen, are not uncommon presentations of colorectal cancer.
Both of these situations carry a worse prognosis. In two prospective randomized trials of Dukes’ B and C colorectal cancer, the National Surgical Adjuvant Breast and Bowel Project (NSABP) reported that patients with bowel obstruction were at greater risk of treatment failure than those without obstruction. These investigators also reported that the effect of bowel obstruction was influenced by the location of the tumor. The occurrence of bowel obstruction in the right colon was associated with a significantly diminished disease-free survival, whereas obstruction in the left colon demonstrated no such effect.
Perforation occurs most commonly at the site of the tumor itself or in the bowel proximal to the obstruction. These patients can present with localized peritonitis or diffuse peritonitis. In addition, they can be dehydrated, septic, and with electrolyte imbalances. All these factors add to the morbidity of emergent surgery. Perforation can result in adherence to adjacent organs or fistula formation. Concomitant perforation is not uncommon in patients with obstruction. The principles of surgical management are the same as with patients with obstructing carcinomas. Ideally, an attempt at resection should be performed. However, there are times that the inflammatory reaction or patient’s condition precludes resection, and thus, it is safer to divert the patient and drain the perforation rather than embark on an unsafe surgical procedure. A downside of this approach is seeding of the drainage tract. The tract must be removed en bloc with the tumor at the time of definitive resection. This potential downside must be weighed with the complications of an unsafe resection through unclear planes in a potentially unstable patient.
Adherence to adjacent organs or fistula formation may be another presentation of colorectal cancer. Any intra-abdominal organ can be adhered to the tumor. These adhesions are malignant in nature in over 40% of the cases. Because clinically it cannot be determined whether the adhesions are inflammatory of malignant in nature, an en bloc resection must be performed. Performing less than an en bloc resection will increase recurrence rate and decrease survival.
Some patients will present with carcinomatosis at the time of diagnosis. Peritoneal carcinomatosis carries a dire prognosis. Cytoreductive surgery combined with intraperitoneal hyperthermic chemotherapy has been shown to improve survival when compared with patients who underwent palliative resection and systemic chemotherapy. Further randomized studies are being planned to confirm the utility of cytoreductive surgery in carcinomatosis.
Approximately 25% of patients with colorectal carcinoma present with metastatic disease. In these patients, symptomatology depends not only on the primary site, but also on the metastases. Usually hepatic and pulmonary metastases do not cause symptoms. However, bulky hepatic metastases may cause right upper quadrant pain. Ascites could be present secondary to carcinomatosis or hepatic metastases. In females, an ovarian or an adnexal mass may be the presenting sign. Fever of unknown origin is an uncommon presentation of metastatic colorectal cancer. Another uncommon presentation of colorectal cancer is Streptococcus bovis sepsis.
Once colorectal cancer has been diagnosed, preoperative evaluation must be performed to assess the best approach for treatment. Surgical resection is the procedure of choice for treatment. However, not all patients will be candidates for surgical resection. Some patients will have comorbidities that will preclude safe surgical resection. Others will have asymptomatic primary tumors with unresectable metastatic disease. The latter patients can be managed selectively with nonoperative therapy.106 In patients with excessive comorbidities, palliation of the symptoms should be the goal. Endoscopic stents or laser therapy for obstructing tumors may be possible. In patients with bleeding tumors, fulguration, laser therapy, and, at times, radiation therapy may help.
A complete history including a detailed family history and physical examination should be performed on any patient who presents with colorectal adenocarcinoma. The work-up of colorectal cancer includes complete blood count (CBC), electrolytes and liver enzymes, carcinoembryonic antigen (CEA), urinalysis, coagulation profile, electrocardiogram, chest x-ray, and computed tomography (CT) scan of the abdomen and pelvis. If there is a rectal cancer, a transrectal ultrasound should be performed as well as a rigid proctoscopy. The former is useful in determining the pretreatment clinical stage of the tumor. The latter is useful in assessing the distance from the anal verge. Both of these factors are extremely important in the management of rectal adenocarcinoma. The colon should be evaluated for synchronous tumors, not only cancer, but also adenomas, preferably by colonoscopy. If colonoscopy cannot be performed prior to surgery because of obstruction, colonography may be an alternative. Otherwise, careful palpation of the colon should be performed at the time of surgery followed by a colonoscopy 3 to 6 months after recovery. FDG- PET scanning is still investigational in the evaluation of primary colorectal cancer.
Miguel A. Rodriguez-Bigas, MD, Paulo Hoff, MD, Christopher H. Crane, MD