Surgical Treatment of Rectal Cancer

Introduction

There were more than 28,000 new cases of colorectal cancer in the United Kingdom, which account for 63 percent of colon cancer and 37 percent of cancer in the rectum of the large intestine. The colon and rectum are the parts of the large intestine in our body. More than 5000 patients died because of rectal cancer in 2004. The main goal for treating rectal cancer is to obtain an overall disease-free state. Surgical resection of the rectum is the keystone of managing rectal cancer.

What Is Rectal Cancer?

Cancer in the rectum is called rectal cancer. It involves the rectum and colon of the large intestine. Sometimes, rectal cancer also involves the surrounding organs. The large intestine functions as an excretory organ in our body. The rectum is the end segment of the large intestine, and it connects to the anus (end part of the large intestine). Cancer in the colon is called colon cancer. These both assemble and are referred to as colorectal cancer.

What Are the Symptoms of Rectal Cancer?

Rectal cancer causes problems in bowel movement in the patient. The following are the symptoms of rectal cancer:

• Dark stools.

• Blood in stools.

• Weight loss.

• Fatigue.

• Weakness.

• The patient faces problems in passing stool.

• Abdominal pain.

• Constipation.

• Urge to defecate.

How to Diagnose Rectal Cancer?

Rectal cancer has two stages, early rectal cancer and advanced rectal cancer. The imaging is important to identify the stage of rectal cancer. Identification of rectal cancer stages helps in planning the surgical resection.

• Palpitation - Digital rectal examination is vital in assessing a rectal tumor. The tumor mass can be palpated in 40 to 80 percent of cases. In addition, the index finger can palpate rectal mass.

• Biopsy - The Stages of rectal cancer can be diagnosed by biopsy.

• Ultrasound - Ultrasound is an established modality for evaluating the later stages of rectal cancer, with accuracies varying from 62 percent to 92 percent.

• Computed Tomography Scan (CT) - CT scan diagnoses the local staging of rectal cancer.

• Magnetic Resonance Imaging (MRI) - CT has been replaced by MRI imaging for regional rectal cancer staging. However, MRI has limited availability, is costly, has a limited field of view, and can be uncomfortable for patients.

How Is Rectal Cancer Treated?

Chemoradiotherapy is the standard treatment for later stages of rectal cancer. The standard treatment for early rectal cancer is tumor resection. The local excision of tumors can be done in patients unfit for radical surgery in cases of metastatic disease. The selection of appropriate patients for local excision depends on the number of tumors, stages of rectal cancer, and patient-related severity. Pre-operating staging is important for diagnosing stages of rectal cancer. Pre-operating staging of rectal cancer stratifies the patient into different categories.

• Patients with superficial tumors can be treated by surgery alone.

• Patients with an increased risk of operable large tumors need radiotherapy before surgical resection.

• Patient with advanced rectal cancer needs long-term chemotherapy followed by surgery.

What Is Surgical Treatment of Rectal Cancer?

Pre-operative staging of rectal cancer is used to plan the treatment of early rectal cancer. Total mesorectal excision is the standard treatment for advanced rectal cancer. The main challenge faced by the clinician in the surgical excision of the rectum is sparing the anus for its bowel and sexual function. The modern treatment modalities include a multifaceted approach to the preliminary staging of rectal cancer before surgical resection. Early rectal cancer does not require neoadjuvant therapy. Neoadjuvant therapy refers to chemotherapy administered before surgery to enhance the outcome. The combination therapy of surgical resection with chemoradiotherapy improves overall survival and decreases recurrence rates.

The modern treatment modality suggests local excision of tumors in early rectal cancer. Only tumors less than 3cm in diameter were considered for local excision. The bigger the tumor, the more challenging it is to excise locally. Therefore, local excision can only be accepted as the definitive treatment in selected lesions. There are four main types of local excision: transanal, transanal endoscopic microsurgery (TEM), trans sacral, and trans sphincteric.

• Transanal Excision - Transanal excision is the most commonly performed operation, where a full-thickness excision is performed. The rectal wall defect is then usually closed.

• Transanal Endoscopic Microsurgery (TEM) has several advantages over transanal excision, with improved visualization and exposure. TEM gives access to more lesions in the rectum. This technique uses a closed instrument for operating with CO2 insufflation, binocular scope, and laparoscopic type instrument to access the lesion properly.

The morbidity rate for surgery is two to four percent. Therefore, the following are the criteria for the selection of the patients appropriate for surgery:

• Tumor Size - Tumour size is not a contraindication to local excision. The bigger the tumor, the more technically challenging it is to excise locally. Therefore, only tumors less than 3cm in diameter were considered for local excision.

• Tumor Morphology - Surgery of the lesion depends on the tumor's nature. Ulcerated tumors are more locally advanced than non-ulcerated tumors. The five-year survival was higher in non-ulcerated tumors.

• Tumor Histology - The incidence of local recurrence rates has been associated with the degree of tumor differentiation. The poorly differentiated tumors have a higher risk of metastasis and worse prognosis than well or moderately-differentiated tumors.

• Stages Of The Tumor - The tumor stage is vitally important because the incidence of tumor metastases correlates directly with the depth of invasion in the rectum.

• Patient-Related Characteristics - Patients with metastatic disease are not appropriate for surgery. These patients may also be managed with local palliative procedures. Patients with early rectal cancers with unfavorable histology or more advanced lesions are appropriate for local excision. Adjuvant therapy (chemotherapy or radiotherapy) can be given to them if they have significant co-morbidities prohibiting major abdominal surgery.

Conclusion

Surgical removal of tumors provides a disease progression-free survival. Surgery in the form of TEM has become the standard of care for mid and distal rectal cancers. Pre-operative staging is important for the treatment of rectal cancer. Some studies have suggested that immediate radical surgery after local excision of rectal cancer does not affect overall survival or compromise the outcome. Pre-operative radiotherapy improves local control and lower toxicity. Combining chemotherapy and radiation therapy reduces the recurrence of the disease from 55 percent to 33 percent. The prognosis of surgery for rectal cancer is excellent.