March is colorectal cancer awareness month which allows us to reflect on the advances in prevention and treatment of colorectal cancer. Colon cancer is the third most common cancer in the United States and the second most common cause of cancer related deaths. Approximately 6% of the population will eventually develop colorectal cancer. The overall mortality continues to decrease because of our advanced treatments, yet the overall incidence has remained stable since the 1990s.  

 

Malignancies of the colon & rectum begin as an abnormal proliferation of cells that form a polyp. Most polyps are insignificant in the progression of sporadic colorectal cancer and include inflammatory, hyperplastic and hamartomatous polyps. The most noteworthy, however, is the adenoma, from which most cancers arise. Removing adenomas has shown to effectively decrease the incidence of cancer. These premalignant tumors are clinically silent and are usually found on screening colonoscopy. We know that 30-40% of people over the age of 50 have adenomas and that the lifetime risk of developing a colorectal cancer is 1 in 17 (6%). This signifies that only a few adenomas eventually progress to a full blown cancer. Furthermore, those that do can take up to 10 years before attaining malignant status. Since we are unable to determine which adenomas will progress to cancer, we therefore have to assume they are all pre-malignant and so our effort to prevent cancer focuses on removing them. 

 

Most colon cancers are diagnosed in asymptomatic patients who are undergoing a screening colonoscopy. Some symptoms may include abdominal pain, changes in bowel habits, rectal bleeding, or Guaiac positive stool. Typically, symptomatic patients have more advanced tumors than asymptomatic patients. Of the symptoms listed, rectal bleeding is the most significant and is associated with up to 25% of colorectal cancers. Studies have shown an incidence of colorectal cancer in 18% of patients younger than 50 who present with rectal bleeding. Therefore, almost all patients with rectal bleeding, regardless of age, should undergo colonoscopic evaluation. 

 

Because most colorectal cancers are asymptomatic, screening is critical in both prevention and more importantly, early and successful treatment. Colonoscopy is the only screening method that allows for detection and removal of premalignant lesions. Although colonoscopy is the gold standard screening test, the incidence of colorectal cancer has remained stable since the 1990s. This tells us that there are many people who are not adequately being screened. CT colography, also known as virtual colonoscopy, was developed in an attempt to improve compliance in colorectal cancer screening. It is a 3-D reconstructed digital image of the colon that is non-invasive and does not require sedation. However, this test does require a bowel prep which is a major reason for poor compliance with colonoscopy. The other drawback is that if a polyp is found on CT colography, a colonoscopy is required to remove it.

 

Once a colon cancer is diagnosed, patients are evaluated for surgical resection. The basic surgical principles regarding resection of colon cancer have remained the same throughout the past several decades. Some of the changes we have seen are in the pre-operative preparation and the surgical approach. Bowel preparation has historically been a critical component of bowel surgery. More recent studies have not only questioned the benefit of bowel prep, but they have shown it to have an increased risk of anastomotic leak and wound infections. Another important study in the surgical treatment of colon cancer has compared the open versus laparoscopic, or minimally invasive, approach. It concluded that laparoscopic colectomy for curable cancer results in equivalent cancer related survival when compared to its older, open counterpart. It also showed that the benefits of laparoscopic surgery include a shorter length of stay, less post-operative pain and a quicker return of bowel function and diet. 

 

The management of rectal cancer is more challenging. Currently, there are three curative options which include local excision, sphincter-sparing abdominal surgery and abdominoperineal resection (APR). There is a group of patients with small T1 or T2 lesions that can be treated with transanal excision or transanal endoscopic microsurgery (TEM). TEM is a newer technique that allows full thickness excision of lesions in the rectum that are as proximal as 12 centimeters from the anal verge. This requires special equipment and training but it spares patients from major abdominal surgery. These patients will usually require chemoradiation to obtain similar outcomes as patients undergoing more extensive resection. 

 

Another challenge in rectal cancer is the extent of distal resection margins. Historically, patients with tumors that were 5 centimeters from the anal verge underwent an abdominoperineal resection and permanent colostomy. Sphincter-sparing surgery has gained significant popularity in order to avoid permanent colostomies. Several studies have shown that a distal margin of 2 cm or even less has equal oncologic outcomes as the traditional 5 cm margin. This has significantly decreased the incidence of APR. Sphincter sparing is not an option in tumors that invade the sphincter complex but can be successfully performed with tumors as low as the dentate line with good outcomes. 

 

In conclusion, adequate screening can decrease the incidence of colorectal cancer by 76-90%. The earlier a cancer is detected, the more likely it can be cured. Many minimally invasive surgical techniques are available for the treatment of colon and rectal cancers. In my practice at Osceola Surgical Associates, in conjunction with Osceola Regional Medical Center, I evaluate each patient, ranging from those who have undiagnosed rectal bleeding to those who have a documented malignancy found on colonoscopy, as an individual. I offer them the most minimally invasive approach that will achieve the most effective oncologic outcome, and perhaps just as important, the best quality of life.